HSEB Notes of Zoology 11

Origin of life

There are different theories about the origin of life on the earth.
Theory of special creation
According to this theory, the life was created by super natural power of the god. This theory is based on religious faith.
According to Hindu Mythology, the god of creation is Brahma. He created universe and human beings.
According to Christian thought the god created universe, earth, plants, animals, and man within seven days.

Theory of spontaneous generation
According to this theory, the life originates spontaneously from the non-living things. For example the frog, toad, snake originated from mud. The insects and flies originated from the fruit juices and the microorganisms originated from air and water.

Theory of Biogenesis
According to this theory, the life originated from preexisting life but not spontaneously. Francis Redi and Louis Pasteur prove this
Reddi's Experiment (1688 AD)
He was an Italian biologist. He kept dead fish, snake, and meat in wide mouthed flasks and left them opened. He again placed same things in other flasks and sealed the mouth. He observed little white worms and larvae in opened flasks but absent in sealed flasks. He concluded that the life can arise from pre-existing life only, means some preexisting life went in open-mouthed flasks then worms and larvae were developed in open mouthed flask.
Louis Pasteur's Experiment (1862 AD)
He was French microbiologist. He conducted an experiment to prove theory of biogenesis.
  • He poured nutrient solution into the flask.
  • He bent the neck of the flask in the shape of S using heat.
  • The liquid was boiled for several minutes so that the bacteria were either killed or driven out of flask.
  • The solution was then cooled. The dust particles remained trapped at the bend of the tube. The solution remained sterile for months.
  • When the neck was broken and flask was tilted, liquid came in contact with dust or microorganisms. Bacterial colonies or moulds appeared in the flask within a few days.

Biochemical Theory (Modern Theory)
The scientific theory proposed by A.I. Oparin in 1923 and J.B.S. Hal Dane in 1928 is called biochemical theory or modern theory or Oparine and Haldane's Theory. According to this theory, the life originated through a series of bio chemical reactions.

Origin of earth
About 4600 million years ago, the earth originated. The earth was a molten fireball having temperature of about 4000 to 8000 ºC. The earth began to cool down and the volume decreased. During the process, the heavier elements settled towards the centre forming the crust of the earth and the lighter elements remained on the outer surface-forming atmosphere. In the atmosphere, there were free atoms like C, H, O, N etc. The free atoms combined forming molecules like O2, N2, and H2.
O+O……..       O2        /          N+N……..       N2        /          H+H……...      H2

Origin of Inorganic Molecules
Then these molecules started to combine to form inorganic molecules.
H2+O2…………           H2O                            H2+N2…………           NH3
C+O2…………..            CO/CO2                      C+H2…………..           CH4

Origin of Simple Organic Molecules
The inorganic molecules combined to form simple organic molecules.
H2O + CH4…………….           Sugar/Fatty Acid/Glycerol
H2O+NH3+CH4……….          Amino Acid/Nitrogen Base
Origin of Complex Organic Molecules
The organic molecules again combined together to form complex molecules
Sugar + Sugar…………………………………    Starch/Glycogen/Cellulose etc.
Fatty acid + Glycerol…………………………  Fats
Amino Acid +Amino Acid……………………            Protein
Nitrogen Base + Sugar + Phosphoric Acid……   Nucleotides'
Nucleotide + Nucleotide ………………………          Nucleic Acid (DNA/RNA)
On further cooling water vapor condensed into rain and thunderstorm occurred. UV rays and electric discharge enhanced these reactions. The nucleic acid combined with protein and nucleoprotein particle formed. It was self-replicating particle and was first living particle 'the virus'.
Origin of Primitive Cell
The complex organic molecules aggregated together forming colloidal mass called coacervate. The nucleic acid controlled the activities of coacervate and the fats formed a layer around it. This structure is called Eobiont. It was first cell like structure. The eobiont absorbed food materials from the surrounding. It was heterotroph, prokaryotic cell, and present day bacteria.

Origin of Heterotrophs and Autotrophs
Later on, some of the eobiont became able to make food by using chemical energy. So they became chemoautotroph.
CO2+H2S………………..          C6H12O6 + H2O + S
                                      Chlorophylls
Some other eobionts developed chlorophyll molecules, which trapped solar energy to manufacture food from CO2 and H2O. They became photoautotroph.
CO2+H2S………………..          C6H12O6 + H2O + O2
In this way, photosynthetic organisms were originated on the earth. On other hand the heterotrophs modified and different types of animals evolved. They started to consume autotrophs and used O2 to break down food material to release energy.

Miller and Urey's Experiment
To prove Oparin and Haldance biochemical theory of origin of life Miller and Urey in 1952 conducted an experiment. They designed an apparatus containing glass tube, flask, and gas chamber. They kept NH3, CH4, H2, CO in gas chamber and water is boiled in the flask to produce water vapor. The energy was supplied by heating and by electric sparks.
The condenser was used to cool reaction. They run the experiment for a week. Finally, they analyzed the products formed within the tube. They found different organic compounds like fatty acid, amino acid, sugar, glycerol etc in the tube. Then they proved Oparin and Haldance's theory of origin of life through a series of chemical reaction among the inorganic gases under the influence of temperature, electric discharges, and cooling. 



Evolution

The orderly and gradual change in object from one form to another form is called evolution. The orderly and gradual change in living things is organic evolution like plant evolution and animal evolution. The orderly and gradual change in non-living things is called inorganic evolution like the evolution of earth and stars.


Evolution of Man

Evolution of Early Mammal
About 210 million years ago, the early mammal evolved from the reptiles. They were small rat like animals having long snout. The Dinosaurs were also evolved from it.

Evolution of Primates
About 65 million years ago, primates evolved from the early mammal. The primates have long snout long and busy tail. It was insectivorous. It was like present day tree shrew. At that, time dinosaurs were extinct.

Evolution of Anthropoid Ape
About 36 million years ago anthropoid ape evolved from primates. They were ancestors of monkey, ape, and man. From the primates new world monkey diverged about 50 million years ago. The nose of the new world monkey's nose was very flat, nostrils were directed upward, and tail is long and prehensile.

Evolution of Hominid
About 24 million years ago, the hominid evolved from anthropoid ape. The hominid was ancestors of man and ape. About 25 to 30 million years ago from the anthropoid ape old world monkey diverged. The old world monkey's nose is raised, the nostrils directed downward and the tail is short and non-prehensile.

Evolution of Ramapithecus and Sivapithecus (the earliest ancestor of man)
About 10-14 million years ago, Ramapithacus and Sivapithecus evolved from the hominid. They were earliest ancestors of man. The Ramapithecus was found in Asia and Africa. Its tooth was found in Butwal of Nepal. The Sivapithecus was found in Asia.
About 4-10 million years ago Apes diverged from the hominid. They include Chimpanzee, Gorilla, Orangutan, and Gibbon.

Evolution of Australopithecus
About 5 million years ago, the Australopithecus was evolved from the Ramapithecus and Sivapithecus. They were first human like animal. Their brain capacity was 400 – 600 cc. It could walk upright and about 3 – 5 ft tall and 40 – 50 Kg in weight. The Australopithecus has two species. They are A. Africans and A. robustus.

Evolution of Homo erectus
About 1.7 million years ago, Homo erectus evolved from A. africanus. The Homo erectus includes Java man found in Dubai and Pecking Man found in China.
The Java man's cranial capacity was 900 cc. It was 5 ft tall and used fire, tools. The locomotion was bipedal. The chin was absent.
The Peking man's cranial capacity was 1075 cc.
It was supposed that Homo erectus was evolved from Homo habilis about 2 million years ago and the Homo habilis was evolved form A. Africanus. The Homo habilis cranial capacity was 700 cc. It was about 4-5 feet tall, bipedal, the chin was absent.

Evolution of the Cro-Magnon man
About 3400 years ago, the Cro-Magnon man evolved from Homo erectus. The Cro-Magnon man was like modern man. Their cranial capacity was 1600 cc. They were 5 ft tall, have prominent chin, broad or flat forehead, raised nose, superior intelligence. They made weapons, lived in caves and he was artist.

Evolution of Neanderthal man
About 70-40 thousand years ago, The Neanderthal man Homo sapiens neanderthalensis diverged from Homo erectus. Their cranial capacity was 1450 cc. They resemble to modern man. They were 5 ft tall, chin was absent, they used tools for hunting used animal hides as clothes, capable of communicating, and they made tradition to bury dead bodies.

Evolution of Modern man
The modern man (Homo sapiens) evolved about 10000 years ago from the Cro-Magnon man. The modern man has changed from cave dwelling hunting life to the crop raising life. It started cultivated plants, domesticated animals, and brought about the Cultural Revolution with its superior intelligence.


Differences between Ape and Man
Ape
Man
The apes have semi erect body
The vertebral column is curved
The bipedal locomotion need support of forelimb
The fore limb is longer than hind limb
The thumb does not extend up to the base of fore finger.
They have flat nose
Canine incisor teeth are longer and thicker
The chin is absent
The eye brow ridges are heavy and prominent
They have short neck embedded in shoulder
The body is covered with hairs
The man has erect body
Vertebral column is straight
The bipedal locomotion do not need support of fore limb
The fore limb is shorter than the hind limb
The thumb extends up to the base of fore finger
They have raised nose
The canine and incisor teeth are shorter

The chin is prominent
The Eye brow ridges are not so prominent

They have long neck
Fewer amounts of hairs are present on the body.

Homology of Man

Ø  Similarities in chromosome number of apes and man is called homology.
Ø  The chromosomes number of apes is 48.
Ø  The chromosome number of man is 46.
Ø  Similar amount of DNA.
Ø  Banding pattern of chromosome is similar.
Ø  Chromosome number 3, 6 have similar banding pattern
Ø  Banding pattern means arrangement of DNA in chromosome.

The Evidences of Evolution

To convince about the truth of evolution there are several evidences, which support the validity of evolution

(A) Structural and anatomical evidences
The types of organs like homologous organs, analogous organ and vestigial organs provide the evidences about structure.
Homologous organ
The organs, which are similar in structures and origin, called homologous organ. For e.g. human hand, Birds wing, bats wing, Horse's front foot are homologous organ.




Analogous Organ
The organs, which are not similar in structure and origin but function is same are called analogous organ. For e.g. Bird's wing and insect's wing, Fishes eye and mollusk's eye
The analogous organs are developed due to similar habitat in evolutionary process.
Vestigial Organ
The useless and reduced organ are called vestigial organs are called vestigial organ. In human body, there are about 200 types of vestigial organ. For eg. Nictitating membrane, Vermiform appendix, Canine teeth, Caudal Vertebrae, Some snakes have vestige of limbs, Fishes lived in dark caves have reduced eyes.

(b) Anatomical Evidences
The arrangement of different types of system like blood vessels, alimentary canal, skeletal system, excretory system etc is similar in vertebrates. Thus, the anatomy suggests in favor of organic evolution showing that the anatomical similarities become more and more complex progressively as one proceeds from lower animals to higher animals. All the varieties of animals have inherited the anatomical similarities from a common ancestor.

(c) Paleontological Evidences
The paleontology deals with the study of fossils thus pale ontological evidences are the evidences of evolution from the fossil record suggesting that the evolution occur from simple form to the complex form.
a) Archaeopteryx
The most favorable evidence, which prove pale ontological evidence, is a kind of fossil bird named Archaeopteryx. This provides connecting link between reptiles and birds suggesting that the birds might have been evolved from reptiles. It represented the characteristics of both a bird and the reptile. It possessed following characters
It had a beak like a bird but the beak contained teeth like reptiles.
Its forelimbs were modified into wings like birds but claws on its wing like reptiles.
It had feathers like birds but also had scales like reptiles. It had feathery tail like birds but had vertebrae like reptiles. Therefore, it is proved that the birds were evolved from reptiles and therefore the birds are called glorified reptiles.
b) Horse's Phylogeny
The evolutionary history of horse is termed as horse's phylogeny. The first horse (Eohippus) was small. The food had four toes. The time passed on and the modern horse is evolved named Equus having one toe and the size is large and high.
The major modifications occur in the course of evolution of modern horse are
Increase in the body size. Increase of length and mobility of neck. Reduction in the number of toes from four to one. Specialization of teeth for grinding grass. Fusion of metatarsals and metacarpals.

(D) Physioloical and biochemical evidences
(i) Similarity in chemical composition
In all the living forms four major elements like C, H, O, N form organic compounds. In all the living organisms C, H, O combine to form carbohydrates and fats and with N to form proteins. The protoplasm in all living organism have the same composition. The basic unit of life is cell. Therefore, from above it can be concluded that living organisms might have evolved from a common ancestor.
(ii) Precipitation test (Serological Test)
The precipitations tests are used to determine and confirm the natural relationship due to the similarity of blood proteins. The degree of similarity between plasma proteins of various animals can be tested by the antigen-antibody technique.
When the blood of man is mixed with the blood of monkey cat and dog, it gives high precipitation and when it is mixed with blood of orangutan, it gives less precipitation.
When the blood of dog and cat is mixed together, it gives less precipitation. It proves that the cat and dog are closely related than the man and the man is closely related with the orangutan than cat and dog.
(iii) Enzymes and hormones
In large group of animals, there are similar types of enzymes and hormones are available. For example, the hormone like insulin and Thyroxin are similar and produced by all the vertebrates. The enzymes like lipase, amylase, trypsin are similar and produced by all the vertebrates. It suggests that they have common ancestry.


(E) Genetic Evidences
Genetic deals with the heredity and variation of animals and plants. The DNA and RNA are called nucleic acids having genetic units found from virus to mammals with similar composition. The DNA has a double helical structure and is composed of similar type of nucleotides arranged in a linear fashion. Similarly, RNA is single stranded. The principles of genetic and its application are also quite similar in all organisms. The small segment of DNA represents gene in all the living life. This evidence also proves that the similarity among all the living organisms.










Kingdom Protista
General characters
·         All the organisms are unicellular and microscopic.
·         Mostly they are aquatic and some are terrestrial
·         They may be free-living, parasitic, saprophytic or symbiotic
·         They are holozoic or holophytic or saprozoic
·         Their reproduction takes place by sexual and asexual method
·         They can move with their locomotory organ like pseudopodia, cilia and flagella


Paramecium
Fig:- Paramecium
Habitat
Paramecium is found in fresh water. It is widely distributed and commonly found animal. Its body is unicellular. The shape of the cell is like a sole of slipper. Therefore, it is called slipper animalcule.
                                                          
Structure
Pellicle: It is outer most covering. It is thin and elastic. It is made up of a kind of gelatinous substance. The surface of pellicle has hexagonal structure and each hexagonal structure consists of cilia outer side and trichocyst inner side. Its function is to provide shape to the cell and to give elasticity to the cell.
Cilia: The outer layer is covered with fine hair like structure called cilia. The cilia arise from the cytoplasm and penetrate pellicle. The base of the cilia has nodule called kinetosome. The cilia help in locomotion and capture food.
Trichocyst: The trichocysts are spindle shaped structure, which arrange at right angle towards inner side of pellicle. They are considered as defense organs. They are discharged out as needle like structures when the paramecium is stimulated.
Oral groove: The oral groove is oblique aperture which runs backward and situated at 2/3rd part of the body. Base of oral groove is called vestibule and is conical shaped. The vestibule connects an opening called cytostome. The cytostome opens into gullet. It is tube like structures and called as cytopharynx. The gullet terminates in food vacuole.
Cytopyge: There is small opening called cytoproct or cytopyge is present behind oral groove. It acts as anus of the paramecium through which undigested matters from the cell is passed out.
Cytoplasm: Cytoplasm is differentiated into two parts. The outer part is thin and called ectoplasm, inner part is granular called endoplasm. The ectoplasm consists of trichocysts and base of cilia. Endoplasm consists of cell organelles and cell inclusions.
Nucleus: In the endoplasm, there are two nuclei. One is larger kidney shaped called macronucleus or mega nucleus which helps in vegetative reproduction. There is another is smaller round or spherical nucleus in the cavity of large nucleus called micronucleus, which helps in sexual reproduction.
Contractile Vacuole: There are two contractile vacuoles one at each end. The contractile vacuole consists of 5-10 radial canals, which appear as star like structure. Each radial canal has three parts i.e. ampulla, terminal and injecting canal.
Function of contractile vacuole
It helps in absorption of water from the body and pour into the vacuole. The vacuole contracts time to time to throw out the excess water from the body. It is the organ of osmoregulation.


Reproduction
The paramecium reproduces both sexually and asexually
Sexual reproduction
It takes place by conjugation method. During the process following events occur
·         Two paramecia come close and get attached together from side of oral groove by some sticky substances. The Paramecia that take part in conjugation are called conjugants.
·         At the point of attachment, pellicle degenerates to form cytoplasmic bridge. ·         After formation of cytoplasmic bridge, the macronucleus of each conjugant disappeared.
·         The micronucleus undergoes meiosis division in each conjugant to give four nuclei.
·         In each conjugant out of four nuclei, three nuclei degenerate and only one remain functional.
·         The remaining one nucleus of each conjugant undergoes mitosis division to produce two nuclei. Out of two nuclei, one is larger and other is smaller.
·         Small nucleus of each conjugant migrates crosswise between two paramecia through cytoplasmic bridge. That nucleus is called migratory nucleus or male nucleus. The larger nucleus remains stationary and called stationary nucleus or female nucleus.
·         The migrated nucleus fuses with stationary nucleus in each conjugant to form zygote nucleus.
·         Now two paramecia separate together and then they are called exconjugant.
·         In each exconjugant the zygote undergoes mitosis division 3 times to produce 8 nuclei.
·         Out of eight nuclei, four becomes larger and 4 becomes smaller in each exconjugant. The larger nuclei are termed as macronucleus and smaller is micronucleus.
·         Out of four micronucleus 3 degenerate and one remains functional.
·          The functional micronucleus in each exconjugant divides into two and the conjugant divide by   binary fission into two daughter paramecia from each exconjugant. The macronuclei are shared equally.
·         Again the micronuclei of two daughter paramecia divide into two and macronuclei are again shared and later the paramecia divide again to produce 8 paramecia.
Significance of conjugation
The vitality is stored, the hereditary materials or characters are exchanged between two paramecia.

There are some other methods of sexual reproduction

Autogamy
It takes place in single individual. The micronucleus divides into two and fuses to form synkaryuon or zygote. Then the Paramecium starts to divide to produce daughter paramecia.

Hemixis
In this method fragmentation and division of macronucleus takes place without any activity of micronucleus.

Cytogamy
It takes place in two individuals. In this process micronucleus divides 3 times to produce 8 nuclei. in which 6 degenerate and remaining 2 fuse together to give zygote.


Asexual Reproduction
It takes place by binary fission method
At first, micronucleus divides into 2 nuclei by mitosis. Macronucleus divides into 2 by mitosis. The cytpharynx also divides into 2 parts. The cytoplasm is also divided into 2 parts. Then transverse constriction is made from two sides. New contractile vacuoles are formed. The constriction meet at centre and two daughter paramecia re produced.



Plasmodium vivax

It is a kind of protozoa, which causes malaria. A French microbiologist Charles Laveran in 1880 discovers plasmodium in the blood of patient suffering form Malaria. In RBC, he found a cell which is amoeba like and this structure was not found in healthy man. Then he injected the blood of patient to the healthy man them the healthy man suffered from fever soon.
There are four species of malarial parasites.
Plasmodium vivax: It produces fever at every 48 hours. This is mostly found in India and Nepal.
Plasmodium malariae: It produces fever at every 72 hours.
Plasmodium falciperum: It produces continuous fever with high temperature
Plasmodium ovalae: It produces night fever.

Habitat
Plasmodium lives in RBC and liver of man. It also lives in some stages in mosquito stomach and salivary gland. It is widely distributed in tropical to temperate region

Structure
It is unicellular. A stage of plasmodium in RBC is called trophozoite which is amoeba like and feeding stage. The cell in this stage is covered by plasma lemma and is filled with cytoplasm. In the cytoplasm, double membrane nucleus is present. Endoplasmic reticulum is scattered in cytoplasm and mitochondria are double membrane. Small vesicles form golgibody, food vacuoles and concentric bodies are included in the cytoplasm.

Reproduction (Life Cycle)
Asexual Cycle in Man
·         When an anopheles mosquito bites a man to suck blood, she injects saliva-containing sporozoites. The sporozoites are unicellular, uninucleate, and spherical and slightly curved stage of the Plasmodium.
·         The sporozoites after inoculation into the body circulate for about ½ an hour in the blood and reach to the liver.
·         There in liver the sporozoites start to penetrate the liver cells. Within the liver cell they become large and spherical in shape. This structure is called as Schizont. The Schizont undergoes multiple divisions to produce many spindle shaped structure called merozoites or cryptozoites. The process upto the formation of cryptozoites is called PRE  ERYTHROCYTIC SCHYZOGONY.
·         Now cryptozoite infects the new liver cells and penetrate into the cells. Within the cell, it becomes large and spherical in shape and called as schizont. The schizont undergoes multiple binary fission to produce many spindle shape structures called Metacryptozoites. Some metacryptozoites again infect the new liver cells and repeat the same cycle.
The process from infection of new liver cell to the cormation of metacryptozoites is termed as
Exo- erythrocytic schizogony.

·         But some metacryptozoites divide and form two types of cryptozoites, one type of cryptozoites are larger and called macrometacryptozoites and another are smaller called as micrometacryptozoites.

·         Now micrometacryptozoites infect the RBC within the RBC it becomes large and spherical in shape. This structure is called trophoizoite. Within trophozoites large vacuole is formed and nucleus of its move at a side. This stage is called signet ring stage. Now vacuole breaks into small vacuole and the nucleus appear at centre and shape of the cell becomes like amoeba. This stage in RBC of the parasite is called amoeboid trophozoites.

In amoeboid trophozoite stage, haemoglobin of RBC is broken into haematin and protein. The protein is used by cell and hematin gets converted into haemozoin which is toxic. At this stage in the cytoplasm of RBC, small granules are present and called as Schuffner's Granules.

Now the amoeba like trophozoite becomes spherical. This is called schizont or mature trophozoite.
Now the schozont again divides to produces many spindle shaped micromerozoites. 
This cycle is called erythrocytic schizogony.

·         Some micromerozoites again infect the RBC and new liver cells and repeat the same cycle. This cycle is called post erythrocytic schizogony.

Sexual Cycle in Man
·         But some of the micromerozoites infect the RBC but do not repeat the same cycle. The micromerozoites having nucleus at the centre is called microgametocyte and those having nucleus at a side is called macrogametocyte. Now when mosquito bites man both the gametocytes are sucked through the blood and they reach to the stomach of the mosquito.
Sexual Cycle in Mosquito
In Stomach of the mosquito, macrogametocyte produces ovum and microgametocyte produces four to eight flagellate sperms. Now one of the sperm fertilizes ovum and when sperm penetrates the ovum zygote is formed.
The cycle from the formation of gametocytes to the formation of zygote is called sexual cycle and it is termed as gamogony.
Asexual Cycle in Mosquito

The zygote in the stomach of mosquito show movement and becomes elongated and called ookinete. The ookinete moves and get attached to the wall of stomach. At this stage, ookinete becomes thick walled and called as oocyst. The oocyst becomes large thick walled and nucleus undergoes multiple divisions to produce number of nuclei. Within oocyst groups of cytoplasm having many nuclei are formed called sporoblast. The sporoblast gets ruptured and number of spindle shaped structures comes out which are called sporozoites. Now sporozoites move towards salivary glands so that it can again enter to the man's body.
The process from the formation of zygote to the formation of sporozoites is called sporogony.
Hence, half sexual cycle takes place in man and half takes place in mosquito. If mosquito does not eat gametocytes they degenerate in human body.

Symptoms of malaria
Fever, chilling, sweating, weakness, nausea, vomiting, loss of apetite, loss of weight.

Prevention
use mosquito net, antimosquito cream or oil, antimosquito coil or mat, screening in door and windows, Removing bushes and water from the surrounding, spreading of kerosene oil in polluted water, DDT or insecticide should be sprayed, Mosquito larva eating fishes should be introduced in the water.

Systematic position
Kingdom                   Protista.
Phylum                      Protozoa
Subphylum               Sporozoa
Genus                        Plasmodium
Species                       vivax






Earthworm (Pheritima posthuma)


It is found in soil, which is rich n humus. It is found abundantly in rainy season. Other days it is found in soil. The earthworm is usually active at night and so called nocturnal. They feed on soil; digest organic matters and undigested matter are excreted out called castings. The earthworm plough soil, makes soil fertile, and so called farmers friend.

Morphology
Body is long elongated and cylindrical. Anterior and posterior ends are blunted. Body is bilaterally symmetrical. A mature worm is 150 mm long and 4-5 mm width. Body is segmented. There are about 100-120 segments. All the segments are similar and so called metamerically segmented.
The first segment is called peristomium and the last is called anal segment. In front of peristomium there is a lobe like sensitive structure called prostomium. The 14th 15th and 16th segments are thick and united to form clitellum. The region before clitellum is called pre-cliteller and the region after clitellum is called post-clitellar region. At ventral surface on 14th segment there is a mid pore called female genital pore. On ventral surface, at 18th segment there is pair of pore called male genital pores. There are two pairs of outgrowths on 17th and 19th segments called genital papillae. It helps in reproduction.
At each 5-6, 6-7, 7-8, 8-9th segment there is a pair of opening called spermathecal pore. Below each spermathecal pore, small sac like structure is resent called spermathecae. Except one and two segments, minute pores are scattered throughout the body called nephridiopores, which are excretory organs. On the dorsal surface after 12th segment, small pore is present at each segment called dorsal pore, which communicates body cavity to the environment. The locomotion is carried out by setae. The setae are S shaped structure, which penetrate the body wall and embedded into saetal sac. The setae are made up of chitin, which is complex polysaccharide. At the mid portion of setae there is round structure called nodule.

Digestive System
The process of ingestion, digestion, absorption, and excretion is called digestion. The digestive system is divided into following heads.
Alimentary Canal
The alimentary canal is long tube, which starts from mouth and ends to anus.
Mouth: Mouth is small cresentric aperture. It is situated below prostomium at first segment.
Buccal Cavity: It is thin walled, short tube behind mouth, which extends upto 3rd segment. It helps to ingest food.
Pharynx:  It is pear shaped muscular chamber, which extends up to 4th segment. On inner dorsal side of the pharynx, there is salivary gland. Two lateral enfolding are also present called shelves. Pharynx helps to pump the food inside the mouth.
Oesophagus: It is narrow, elongated; thin walled tube extends up to 7th segment. It acts as food pipe.
Gizzard:  It is oval, hard, thick walled, highly muscular organ, which extends up to 9th segment. It helps to grind the food particles.
Stomach: It is a narrow tube, which extends from 9th to 14th segment. It is longitudinally internal folded.
Intestine: It is very long, wide tube, which extends from 15th segment to anus. In 26th segment two lateral finger like projections move forward up to 22nd segment, which is called intestinal Intestinal caeca. Internally intestine is highly folded. The foldings are called villi. On mid dorsal side there is a large vilus called typhlosole. Based on presence of typhlosole intestine is divided into 3 parts.
Pretyphlosolar region
It is the region between 14th segments to 26th segment where typhlosole is absent.
Typhlosolar region
It is the region from 26th segment to 23-25th segment in front of anus where typhlosole is present.
Post tyhlosolar region
It is the region form last 23rd segment to 26th segment where typhlosole is absent. This region is also called rectum.
Anus:  It is circular aperture situated at last segment through which undigested food materials is thrown out.

Feeding mechanism/physiology of digestion
The earthworm feeds upon dead organic matter in the soil. Sometimes it feeds up on grasses, microorganisms etc. the food is ingested by pumping and sucking activities of pharynx.
In the pharynx
In pharynx, food is mixed with saliva. The saliva is secreted by salivary gland. The saliva is composed of mucin and proteolytic enzymes. The mucin present here lubricates food and proteolytic enzymes digest proteins.
In gizzards
In gizzard, food is grinded up in fine state. Physical digestion or mastication takes place in gizzard due to the contraction of circular muscles of gizzard.
In stomach
The stomach secretes proteolytic enzymes from glandular cells present on stomach wall, which digest proteins present in the food, and calcium, which is also present, neutralizes acidic food.
In Intestine
The intestine secretes juice called intestinal juice where following enzymes are present
Amylase:       Digests carbohydrate into glucose
Lipase:           Digests fat into fatty acid and glycerols.
Pepsin:           Digests protein into peptones
Trypsin:         Digests peptones into amino acids.
Cellulase;      Digests cellulose.
Chitinase: Digests chitin present in food.
The digested food is absorbed through villi of intestine and undigested food is thrown out through anus.
Reproductive system
The earthworm is hermaphrodite or monocious i.e. male and female reproductive organs are found in same individual.
Male Reproductive System
Testes:       there are two pairs of testes. One pair is situated at 10th segment and another pair at 11th segment. Each testis consists of 4 to 8 digits.
Testes Sacs: Testes are enclosed by fluid filled sacs called testes sacs. One testes sac is found at 10th segment and other is at 11th segment. Two testes sacs communicate each other.
Seminal Vesicle: there are two pairs of seminal vesicles. One pair is situated at 11th and other at 12th segment. Each seminal vesicle communicates with testes sac. The spermatogonia are passed from testes into testes sacs and then they are passed into seminal vesicles where they develop into sperms. The mature sperms again go back into testes sac and pass into seminal funnel.
Seminal Funnel: There are two pairs of seminal funnel. One pair is found in 10th segment and another pair in 11th segment. They are ciliated and found below testes.
Vasa differentia: There are four tubes, which start running from 12th segment to 17th segment. In 17th segment, they unite with the duct of prostate gland to form common prostatic and spermatic duct.
Prostate gland: There are two prostate glands. They are larger, irregular, flat, and wide. They extend from 16th or 17th segment to 20th to 21st segment. Each prostate gland has small curved duct, which joins with spermatic ducts and opens through male genital aperture at 18th segment.
Accessory gland: There are two pairs of accessory gland. One pair in 17th segment and another pair are in 19th segment. They are small and round in structure. They bear small ductules, which open through genital papillae.

Female Reproductive Organ
Ovaries:    There is a pair of ovary situated at the 13th segment hanging on septum between 12th and 13th segment. Each ovary has finger like projections, which contained ova in series. The mature ova are found toward end and immature ova are found on the base of the lobules of the ovary.
Oviducal Funnel: One pair funnel like structures at 13th segment found below ovary with ciliated mouth called oviducal funnel. Each funnel opens into short conical tube called oviduct. Two oviducts fuse together at 14th segment and open outside through female genital aperture.
Spermathaceae: There are four pairs of spermathecae. Each pair is found between 5-6, 6-7, 7-8, and 8-9th segment. Each spermatheca is flask shaped. The main body of spermathaca is called ampulla and short small lobe found attached at its side is called diverticulum. They store sperms.

Copulation
In rainy season, two earthworms copulate at night. During copulation, two earthworms get attached through their ventral surface with their anterior end pointing in opposite direction.
The male genital aperture become erected and inserted into the spermathecal pore of each other. During the process sperms are exchanged together. Then they separate after about an hour.
Coocon Formation
After copulation, a membrane is secreted around clitellum by membrane secreting glands. The membrane starts to move towards anterior end of earthworm whereas the worm starts withdrawing itself backward. During the process, the membrane receives ova coming from female genital aperture and sperms coming from spermathecal pores. Lastly, the membrane is laid out on the ground. The elastic opening of membrane becomes closed. The structure is called cocoon (ootheca). Within cocoon, one of the sperm fertilized with ovum to form zygote and young worm is developed that comes out of cocoon about 2-3 weeks. A dozen of cocoons is formed after each copulation by each conjugant.


Nervous system

The nervous system of earthworm consists of three parts
a) Central Nervous system
It includes following structures:
Cerebral ganglia
There are two pear shaped cerebral ganglia fused together at 3rd segment called brain.
Circumpharyngeal connective
Two circumpharyngeal connectives arise from each cerebral ganglion laterally. They encircle pharynx and fuse at 4th segment. The fused portion is called sub pharyngeal ganglia.
Ventral nerve cord
It is white rod like structure, which starts running from sub- pharyngeal ganglia towards posterior end. In each segment, ventral nerve cord swells which is called segmental ganglia. Actually, there are two cords fuse together to form single ventral nerve cord. Ventral nerve cord is composed of nerve cells and nerve fibers. There are 4 giant fibers o mid dorsal side of nerve cord which conducts impulses rapidly. The outer covering of ventral nerve cord is called peritoneum.

b) Peripheral nervous system
It includes nerve fibers or nerve, which arises from central nervous system.
·   From cerebral ganglia, 8-10 nerves arise and supply to prostomium, buccal chamber, and pharynx.
·   From circumpharyngeal connectives, two pairs of nerves arise and supply to 1st and 2nd segment.
·   From subpharyangeal ganglia, three pairs of nerve arise and supply to 2nd, 3rd and 4th segment.
·   From each segmental ganglion, three pairs of nerves arise and supply to respective segment.

c) Sympathetic nervous system
It consists of nerve plexuses extensively branched and distributed beneath epidermis, alimentary canal that is connected to circumpharyngeal connectives.

Working of nervous system
The sensory cells from different parts of the body receive impulse. Sensory fibers (afferent fibers) carry impulse to central nervous system. Motor fibers (efferent fibers) carry impulse back to effective organs or different parts of body from central nervous system. In earthworm, impulse is also travel from one ganglion to another ganglion through ventral nerve cord.

Economic importance
Beneficial aspects
·         It makes the burrow in soil. The soil become porous and helps the plants to grow well. So they are considered as natural plough.
o   They are used as food.
o   They are used as medicines to cure stone in bladder, diarrhoea, jaundice, piles etc.
o    are used as baits for fishing.
o   There are used in laboratory for dissection.
Harmful aspects
o   They distract the fields and gardens as a result soil erosion takes place.
o   They damage different kinds of plants in field and gardens.

Systematic position
Kingdom-      Animalia
Phylum-        Annelida
Class –           Oligocheata
Genus –         Pheretima
Species-          posthuma







Frog (Rana tigrina)

Frog lives in fresh water, moist and damp place. They are poikilothermic (cold blooded). Frog becomes active in rainy season and they breed in rainy season. In winter and summer season, they live under soil and are inactive. The winter period is called hibernation and summer period is called aestivation. During hibernation and aestivation, they utilize food stored in their body.

External features of frog
The body is bilaterally symmetrical and dorsoventrally flattened. Skin is moist, smooth, and slippery. On the dorsal side, there is mid dorsal line running from head to tail. Ventral side is pale –yellow in colour and dorsal side is dark green with dark patch. Body is divided into head and trunk. In each eye, there are two eyelids .upper eyelid ids immovable and eyelid is movable. There is third eyelid arising from lower eyelid, which is thin and transparent called nictitating membrane. It is freely movable and protects eye from dirty water. male frog have vocal sac on either side of throat which produces croaking sound to attract female in breeding season.
Skin:- skin is moist, smooth. The outer most layer is epidermis. Below epidermis, two glands are present. Poison gland and mucous gland. Mucous gland secretes a kind of watery fluid called mucin, which keeps skin moist.
Function – skin is protecting covering of the body. Mucous gland are present on the which secrete mucin and keeps the skin moist. Poison glands are also present in the skin, which protects from enemy. Frog does not drink water but water but water is absorbed through skin.
Digestive system
The digestive system of frog consists of organs, which are concerned, with capturing of food (ingestion), absorption with the help of certain enzymes, absorption of the digested food, and finally removal of the waste food. Hence, digestive system is divided into 3 headings.

(i) Alimentary canal      (ii) Digestive gland         (iii) Physiology of digestion

Alimentary canal:- it is long, coiled tube which starts from mouth to anus (cloacal aperture). It consists of following organs
Buccopharyngeal cavity
The buccal cavity and pharynx together is called bucco-pharyngeal cavity. Buccopharyngeal cavity lies between upper jaw and lower jaws. Upper jaw is immovable but lower jaw is movable.
Teeth – there are two types of teeth. Maxillary teeth- they are found in upper jaw. They are polyphyodant (replaceable teeth) and homodont (all teeth are similar in size). Vomerine teeth- they are present on either side of roof buccopharyngeal cavity. They help to capture prey and prevent the captured pre from slipping out.
Tongue: It is thick, fleshy, and muscular and bifurcated (bifid). The tongue is protrusible i.e. tongue can be thrown out and retracted. It arises from in front of lower jaw. The tongue secrets a kind of sticky substance so that insects or prey coming neat sticks in tongue.
Vocal sac: In male frog on either side of the tongue on the lower jaw there are two pores called vocal sacs, which produce croaking sound.
Pharynx: Posterior part of buccopharyngeal cavity is called pharynx, which opens into oesophagus.
Oesophagus: It is broad, short muscular tube which opens into stomach.
Stomach: The stomach is large, thick walled muscular bag. Anterior part of stomach is called cardiac part and posterior part is called pyloric part. It is internally folded. It stores ingested food. Posterior part consists of pyloric constriction through which food is slowly passed.
Intestine: It is long, coiled part which starts from pyloric constriction. Intestine is divided into two parts.
Duodenum: it is c shaped structure, 3-5 cm long where hepatopancreatic duct opens.
Ileum:       it is coiled part. It is about 20-25 cm long. Ileum is internally highly folded. Folding s is called villi, which increase absorptive surface.
Rectum:    (large intestine): rectum is short, broad tube 4-5 cm long. It opens outside through cloaca and the opening id called cloacal aperture. The rectum stores undigested food for short time. Internally rectum is also folded.

Digestive glands
1. Gastric glands: They are present on the stomach wall. They secret HCL and enzyme pepsinogen.
2. Liver
It is large gland. It has two lobe-right lobe and left lobe. Liver is reddish brown in color. Left lobe is again divided into two lobes. There is a small sac like thin walled bladder present on right lobe called gall bladder. The duct of gall bladder is called cystic duct. The duct of liver is called hepatic duct. Liver secretes bile and excess bile is stored by gall bladder. Then both cystic and hepatic duct merge forming common bile duct. Common bile duct run through pancreas and receives pancreatic duct to form hepatopancreatic duct, which opens into duodenum.
Functions:
·         The liver secrets bile, which is used in small intestine for digestion of food.
·         It regulates the amount of sugar in the blood.
·         It maintains the protein concentration in blood.
·         It stores copper and iron and forms vitamin A.
·         It kills many bacteria.
3. Pancreas
The pancreas is second largest gland. It is flat and irregular lobed gland. It has two functions
·         It secrets hormones insulin which directly mix with blood.
·         It secret pancreatic juice which contain several enzymes which is poured into duodenum through duct. The enzymes help digestion of ingested food.
·         Therefore, pancreas acts as both endocrine and exocrine glands as it does secrets insulin and pancreatic juice respectively.
Functions:
·         Enzymes secreted by pancreas helps in digestion of ingested food.
·         Hormones secreted by pancreas helps in metabolism of carbohydrates and regulate the storage glycogen in liver and muscles.
4. Intestinal glands
Intestinal glands are found on wall if intestine. They secrete a kind of juice called intestinal juice, which contains several enzymes.

Physiology of digestion
·         Frog is insectivorous (insects eating).
·         The prey is captured by the action if tongue and swallowed without mastication.
·         The food becomes lubricated by mucous secreted by mucin gland. (Salivary gland is absent). When the food reach to stomach the chemical digestion starts.
In stomach
·         The gastric glands present on stomach wall secrete HCl and the Pepsinogen enzyme.
·         The food is mixed with HCl. the HCl kills the bacteria, and softens the hard food.
·         The pepsinogen is inactive enzyme. But in presence of HCl, it becomes active and then it is called Pepsin which digests protein into proteases and peptones.
·         Pepsinogen----------------Pepsin
·         Protein---------------------Proteoses and peptones
The food becomes creamy fluid called Chyme. From the pyloric constriction, the chyme slowly moves towards duodenum.
In Duodenum
The food is mixed with bile and pancreatic juice.
Bile:   It is a kind of alkaline juice secreted by liver. It has mainly two functions like It neutralizes the acidic food and It emulsifies fat i. e. the fat droplets are broken into fine droplets and mixes with the food.
Pancreatic Juice: It is also a kind of juice secreted from the pancrease. It contains following enzymes
Trypsinogen - In presence of enterokinase it is converted into trypsin and the trypsin digests the protein into peptones and polypeptides.
Trypsinogen---------------------Trypsin
Protein----------------------------Peptones and polypeptides.
Amylase - It digests the carbohydrate into maltose.
In Ileum
The food is mixed with intestinal juice in ileum, which contains following enzymes.
Eryption:    It digests peptones and proteoses into amino acids.
Peptidase: It digests peptides into amino acids
Sucrase:      It digests sucrose into glucose.
Maltase:      It digests maltose into glucose.
Lactase:       It digests lactose into glucose.
Nucleotidase:        It digests nucleic acid into nucleotides.

Absorption
The completely digested food material contains glucose, amino acids, fatty acids, glycerols etc. The simple molecules like water and minerals are not required to digest. All these simple compounds are now absorbed through the villi of intestine. There are two methods to absorb food materials. The food materials are absorbed by diffusion or osmosis through the villi and are mixed into the blood around the intestine. It is slow process and food molecules pass into blood from the high concentration in lumen of intestine. This method is called passive method. There is another method of absorption i.e. active method. It is fast and the food molecules are absorbed by using energy against concentration gradient from the lumen of intestine into the blood. The energy used in this method is ATP. Hence, all the food materials are absorbed completely into the blood. The remaining undigested and unabsorbed materials are stored in rectum for short time and ultimately passed out through the anus.


Respiratory System
The process of gaseous exchange (O2 and CO2) and utilization of oxygen to breakdown food to release energy is called respiration. The process of respiration involves three stages.
External respiration
It also refers to breathing. In this process, the O2 is taken into the body and the CO2 is thrown out from the body into the environment.
Internal respiration
It refers to utilization of O2 to break down food to release energy and release of CO2 during the process.
Transport of gases
It refers to transportation of O2 from the respiratory surface to the cell and tissues and the CO2 from cell and tissues to the respiratory surface.
There are three types of respiration in frog
1. Cutaneous respiration
 






·   The respiration through skin is called coetaneous respiration.
·   The coetaneous respiration occurs in hibernation and aestivation and in water.
·   The skin of frog is thin and vascularised (skin is supplied with fine blood vessels).
·   The skin is always becomes moist by mucous secreted from the mucous glands.
·   Due to moist skin, the oxygen from the environment diffuses into the blood through skin and the carbondioxide diffuses out from the blood into the environment.

2. Buccopharyngeal respiration
·   The respiration through the buccopharyngeal cavity is called buccopharyngeal respiration.
·   The buccal cavity consists of moist mucous membrane and richly supplied with blood vessels.
·   The air enters into the cavity through nares and gaseous exchange takes place through the lining of buccal cavity between blood and air present in the cavity.

3. Pulmonary respiration
·   The respiration through the lungs is called pulmonary respiration.
·   This respiration occurs only when the need of oxygen is more during swimming and jumping.
·   There is a pair of lungs. The lungs are thin walled elastic sacs. They are present within thoracic cavity on either side of heart.
·   Numerous small air sacs are present in the lungs called alveoli.
·   The alveoli are very thin walled and supplied by blood vessels. The air enters into the alveoli of the lungs through the external nares, internal nares, buccopharyngel cavity, glottis, laryngotrachial camber, and bronchi.

Mechanism of pulmonary respiration
Inspiraton          
·   Process of inhaling of air is called inspiration.
·   The mouth remains closed. The sternohyalas contract and the floor of buccal cavity is lowered. The space in cavity is increased and air pressure is decreased. Therefore, air is taken in into cavity through nare.
·   The nares remain closed and petrohyals contract and floor is raised up. Space in cavity is decreased and pressure is increased. The air passed into lungs.
·   In lungs, alveoli are filled with air and gaseous exchange takes place between blood and alveoli. Then oxygen is carried to cells and tissues in the same manner as in cutaneous respiration.

Expiration
·   The process of exhaling of CO2 is called expiration.
·   The lungs get contracted. The external nare remains closed.
·   The floor of the cavity is lowered and the air is drawn into the cavity from the lungs.
·   The nares then open and the cavity raises and then the air is passed out through the nares.

Transportation of gases
The oxygen diffused into the blood through coetaneous, buccopharyngeal and pulmonary respiration is carried to the cells and tissues by hemoglobin of the blood RBC. When the oxygen reacts with hemoglobin, the oxyhemoglobin is formed, this is unstable and soon dissociates into hemoglobin and oxygen in cell surface. The released oxygen in cell surface from oxyhemoglobin diffuses into the cytoplasm of the cell. In the cytoplasm, the oxygen is utilized to break down the food to release energy. The process is called internal Respiration or cell Respiration. During the process, the CO2 is produced.
C6H12O6 + O2---------------------------------CO2 + H2O + energy
The released CO2 from the cell cytoplasm diffuses out through cell membrane into the blood. In the blood CO2 may reacts with water in plasma to form carbonic acid (H2CO3) or carbonic acid dissociates into HCO3 and H ions, which may react with sodium and potassium ions to form sodium and potassium bicarbonates. The carbondioxide is transported to respiratory surface in the form of these compounds. 

Circulatory system
Circulatory system is the system of blood, heart, and blood vessels.
1. Heart
·   Heart is triangular muscular pumping organs.
·   Heart of frog is situated ventrally to the liver in the pericardial cavity.
·   Heart is three –chambered.
·   Upper two chambers are called auricle sand lower one chamber is called ventricle.
·   Its anterior end is broader then posterior end.
·   The broader part anterior is known as auricle.
·   The posterior part is known as ventricle.
·   The ventricle is thick walled than auricles .right auricle is larger than left auricle.

External structure of heart
From the ventral view
·   The tubular structure is present on right side of anterior part of ventricle, which is called truncus arterious gives two branches called aortic trunks.
From the dorsal view
·   There is somewhat triangular structure called sinus venosus. It opens into right auricle. The right precaval, left precaval and post caval veins open into sinus venosus.
Internal structure of heart:
·   Two auricles are separated by a septum called internal auricular septum.
·   The right auricle bears opening of sinus venosus called sinu-auricular aperture which is guarded by valves called sinu- auricular valves.
·   It allows flow of blood from sinus venous to right auricle and prevents back flow of blood.
·   Left auricle bears opening of pulmonary vein without valve.
·   Auricles open into ventricles by auriculo-ventricular aperature, which is guarded by four auriculo –ventricular valves.
·   The flaps of these valves are connected to the wall of ventricles by chordae tendinae.
·   A ventricle is thick walled and internally give in folding called trabecule.
·   Ventricle opens into truncus arterious.
·   The opening is guarded by four semilunar valves, which prevent backward flow of blood from truncus arterious to ventricle.
·   A truncus arterious is divided into two parts at the base.
o   conus arteriosus ( plangium)-                     which consists spiral valves.
o   Bulbous arteriosus ( synangium)- which is again divided into two parts.
    • Cavum aorticum and cavum pulmocutanum.
Each aortic trunk again divides into three vessels: Carotid arch, Systemic arch, Pulmo -cutanous arch

Arterial system of frog
Blood vessels, which carry oxygenated blood away from heart to different part of the body, are called arteries. They constitute a system called arterial system.
Truncus arterious gives two branches right aortic trunk and left aortic trunk. Each aortic trunk again divides into three branches-
a) Carotid arch:   it divides into –
Lingual artery –         it supplies blood to tongue and hyoid.
Common carotid – it supplies blood to buccal cavity and brain. it consists swelling at the base called carotid labyrinth.

b) Systemic arch – two systemic arches move upward and then curve backward to join each other behind the heart to form dorsal aorta before meeting each other each systemic arch gives-
Oesophageal artery – it supplies blood to osephagus.
Occipito vertebral artery – it supplies blood to head and vertebral column.
Subclavian – it supplied blood to shoulder and forelimb. From the junction of two systemic arches coeliaco – mesenteric artery arise which gives following branches.
Coeliac artery arises and gives two branches –
Hepatic artery artery – it supplies blood to liver.
Duodenal artery –it supplies blood to duodenum.
Intestinal artery – it supplies blood to small intestine (ileum).
Spleenic artery – it supplies blood to spleen (meeting place of ileum and rectum).
Posterior mesenteric artery-  It is Long Branch and supplies blood to the rectum.
The dorsal aorta runs backward and gives following branches-
Gonadial artery –      it supplies blood to testes and ovary.
Renal artery-   it supplies blood to kidney.
At the end, the dorsal aorta runs posterior and bifurcates into
right and left common iliac arteries. Each of iliac arteries gives
Femoral artery –              it supplies blood to hip and thigh.
Sciatic artery –                 it supplies blood to lower region of hind legs.
Epigastric artery-                        it supplies blood to urinary bladder.

c) Pulmo-cutanous arch-         it divides into
Pulmonary artery – it receives deoxygenated blood from different parts of the body and open into lungs.
Cutanous artery- it supplies oxygenated blood to skin.

Venous System of frog
Blood vessels, which carry the deoxygenated blood from different parts of the body to the heart, are called veins. They constitute a system called venous system.
Venous system of frog can be studied under too heading
A) Systemic Venous System
This system includes the three large veins, which receives the deoxygenated blood from all the parts of the body and collect to the sinus venous. The three veins are-
Right Precaval, Left precaval and Post cavals

1. Right and Left Precaval Vein: Each precaval is formed by the union of 3 veins
External jugular vein - it is formed by the two veins.
a. lingual vein –   it receives deoxygenated blood from mouth and tounge.
b. mandibular vein –     it receives deoxygenated blood from lower jaw.
innominate vein – it is formed by two veins.
a. internal jugular vein-           it receives deoxygenated blood from eye brain and skull.
b. subscapular vein- it receives deoxygenated blood from shoulder and arm.
subclavian vein- it is formed by two veins-
            a. brachial veins-             it receives deoxygenated blood from fore limb.
b. muscub cutanous vein – it receives deoxygenated blood from muscles and skin.

2. Post Caval Vein: It receives deoxygenated blood from following 3 veins.
Hepatic vein-                    it receives deoxygenated blood from liver.
Gonodial vein-                  it receives deoxygenated blood from gonads.
Renal vein –                                  it receives deoxygenated blood from kidney.
B) Pulmonary Venous System
The pulmonary vein receives pure blood from lungs into left auricle of heart.

Urinogenital System
The excretory and reproductive systems are functionally unrelated but products of these two systems have common passage. In frog the sexes are separate hence it can be studied under two headings Male and female reproductive system.
Male reproductive system
It consists of a pair of testes, vasa efferentia, bidder’s canal, transverse collecting tubules, urinogenital ducts, and cloaca.
Testes are elongated or oval, light yellow, is found attached to the anterior ventral side of each kidney to which they are suspended by a double fold of peritoneum called Mesorchium. Each testes consists coiled structures called seminiferous tubules. The epithelial lining of seminiferous tubules consists of germinal cells, which produce spermatozoa. Many seminiferous tubules unite to form vasa efferentia, which is narrow tube like structure.
The vasa efferentia runs through kidney and open into the Bidder’s canal, which is then connected to the ureter. The sperms pass through vasa efferentia, bidder’s canal, ureter and cloaca.
The urine and sperms pass through ureter so that it is also called as urinogenital duct. Each urinogenital duct expands to form seminal vesicle where the sperms are stored until they are ejected out during copulation




Female urinogenital system
It consists of ovaries, oviducts, ovisacs and coaca.
Ovary
Each ovary lies like testes on ventral to the kidneys and hang in loops of peritoneum called mesovarium. It is lobulated sac like structures composed of ovarian follicles consists of countless ova.
Ova are produced by oogenesis from epithelial cells of ovary. The mature ova are shed into the abdominal cavity and reach to the oestium by pressure of fore arms of clasping of male.
Oviduct
Long coiled glandular tubes one on either side of abdominal cavity. Anterior of oviducts oviducal funnel or ostium is present. The posterior of oviducts swollen ovisacs where the ova are stored temporarily are present. Oviducts open into the cloaca. The inner wall of oviducts is ciliated.








Environmental pollution

 
Any undesirable change in the environment, which affects biotic community, is known as pollution. The matter which cause pollution is undesirable change in the environment is called pollutant. There are two types of pollutants.
Degradable pollutants
Pollutants, which can degrade or decompose naturally, are degradable pollutant. They do not remain in the nature for long time. They increase fertility of the soil and suitable for plant growth, e.g. Domestic sewage and domestic fertilizers.
Non degradable pollutants
The pollutants which do not degrade naturally and cause pollution are non degradable pollutants. They remain in the nature for long time. They decrease fertility of soil and unsuitable for plant growth e.g. aluminium cans mercuric salts, DDT, plastics and glasses.


1. The air pollution
Any undesirable change in physical, chemical, and biological character of air, which affects the living organisms, is called air pollution
Sources and pollutants
Automobiles
Automobiles are the major sources of air pollution. In Nepal, there are more than two lakes automobiles and 50% of them are confined in Kathmandu valley. In the world, there are more than 300 million automobiles.
The main pollutants emitted form are: CO2, CO, SO2, NOx, Hydro carbon compounds, aldehydes, acids, dusts, particulate matters, smoke, lead etc. In major cities 800 to 1000 tons pollutants per day produced from automobiles.

Industries
Sugar, Paper, Leather, Iron, Steel, Brick, Cement, Carpet, Plastic, Dyes manufacturing industries are also major sources of air pollution.
The pollutants emitted from industries are: CO, CO2, So2, NOx, Hydrocarbons acids, metals like Hg, Mn, Zn, Pb, Cd, smoke, dust etc. The Himal cement factory of Kathmandu produces about 5-6 tons dust per day.

Domestic resources
Burning firewood, crop residues, burning gas, stove, oils etc are also source of air pollution. These are indoor pollution.
The pollutants from domestic resources are: CO, CO2, So2, NOx, smoke, ashes etc.
Nepalese woman daily 6-8 hours expose to fire, but it is estimated that 3 hrs exposures provide smoke equivalent to 20 packets of cigarettes. Tobacco smoking is another indoor pollution from where CO, CO2, So2, NOx, hydrocarbons, and smokes are produced.

Effects of air pollution
CO: It is most dangerous air pollutant. It reacts with hemoglobin 210 times faster than oxygen forming carbamino hemoglobin. It reduces oxygen carrying capacity of blood causing disease called hypoxia. It reduces cellular respiration, mental activities, reduces leaf size, and destroys chlorophylls.
300 ppm of CO causes vomiting, 500 ppm causes coma and 1000 ppm causes death.
SO2:    It causes eye irritation, air tract construction, vomiting, and headache, leaf reduction in plants and affects in stomata opening and causes acid rain.
NOx: It causes lungs damage, injuries to plants, oxide of nitrogen react with hydrocarbon in presence of UV rays forming peroxyacetyl nitrate (PAN) which is a toxic substance.
H2S:  It causes headache, nausea, conjunctivitis, diarrhea, pneumonia, respiratory failure. High concentration of H2S in body causes coma and death.
CO2:  It causes global warming i.e. increase earth's temperature or green house effect.
Pb:     it causes neurological problems; hematological problems i.e. destroy R.B.C. anemia, liver kidney diseases, dangerous in pregnancy, and high concentration of Pb in children affects neurology and hematological problems.
Zn:     it is heavy metal which is injected in the atmosphere mainly from automobile exhaust when it react with air it gives zinc oxide fume which is toxic
Cd:     it affects liver and kidney and increase blood pressure i.e. cause hyper tension, and cancer.
Hg:     it damage brain eye and liver, cause headache, fatigue, loss of appetite.
HCs (benzene, benzopyrine, Methane etc): They cause respiratory diseases, lung cancer, and noise throat and eye problem
Ozone: it damage plant, reduces crop yield and it affect negatively in human health.
Smoke: smoke when react with water gives smog. It causes eye irritation, asthma, lung cancer etc.
Particulate matter: particulate matter like dust reduce visibility, damage plants and live stock, cause cancer and allergy.
Aerosol: aerosols are chemicals produced from jet or planes. The chemicals contain chlorofluorocarbon which destroys ozone layer.

Control and prevention
·         Industrial effluents must be treated before mixing it with air.
·         Smoke must be filtered.
·         Alternate source of energy are used like solar energy and electrical energy water energy etc.
·         Plantation should be done
·         Use catalyst process to change CO, HC into CO2, similarly catalyst converter should be used to convert NOx to N2 and O2
·         CO, HC into CO2
·         Check population growth health education awareness and legislation
·         Establishment of laboratory for monitoring and study of pollution.

2. THE Soil pollution
Any undesirable change in physical chemical and biological characteristics of soil, which reduces soil fertility and affects plants and animals life, is called soil pollution
Sources and pollutants
Industries
Several organic and inorganic pollutants come out from several industries like paper, pulp; iron, steel leather etc pollute soil.
The pollutants from industries are: pollutants oils, acids, salts, dyes, cyanides, phenols, metals, plastics and detergents etc are the major sources of pollution of soil
Sewage and domestic wastes
Water borne domestic waste and animal waste is called sewage. The dumping of sewage on soil pollutes soil. The sewage also includes industrial waste.
The pollutants are: Human excreta, animal dung, paper, cloths, souls and detergents etc.
Agricultural discharge
Fertilizers, pesticides, fungicides, herbicides are used in agriculture. Different chemicals are dumped into land which pollutes land.
The pollutants are: DDT, BHC, aldrin dialdrin endrin malathion and urea etc.
Radio active substance
Substances which are produced by nuclear explosion are radio active substances.
The pollutants are:  iodine, caesium, strontium, tritium etc.
Acid rain
Due to the mixing of gases like SO2, NOx coming from automobiles into rain cause acid rain. The acid rain gets accumulate into soil causing soil pollution.
The pollutants are: HNO3 and H2SO4

Effects of soil pollution
Chemical fertilizers: chemical fertilizers contain nitrate, which is toxic, when we eat food containing nitrate it is converted into nitrites in intestine of man. The nitrites react with hemoglobin forming methamoglobin in blood, which reduces the O2 carrying capacity of blood. 20% methamoglobin causes headache and giddiness
60% causes eye problem and stiffness and unconsciousness, and 80% causes death.
Pesticides: When pesticides are used in agricultural land, they accumulate in plant. Through food chain, they reach to animal body. Pesticides in animal body decline rate of reproduction, calcium deficiency like thinning of eggshells of birds, hormonal imbalances, and inhibition of gonad development.
Metals:Metals like Pb Zn Hg Cd Ni are toxic. All these metals cause adverse effect in human health. Besides this, they reduce the soil fertility. High concentration affects micro flora and fauna. It also reduces the water holding capacity of the soil.
Acids:           acids like HNO3 and H2SO4 coming from acid rain makes the soil acidic which cause death of number of micro flora and plants. They also degrade the quality and fertility of soil.
Waste Products: the domestic waste consists of sewage detergents animal refuge and solid wastes like plastics aluminium etc are also dumped in the soil. They decrease quality of soil productivity of the soil and make the soil acidic as well as reduce water holding capacity of the soil.
Radioactive substance: strontium accumulates in bone and replaces the calcium of bone. This makes the bone weak. The iodine accumulates on the thyroid gland and the excess iodine damage the thyroid gland. The caesium replaces potassium from every part of the body.

Control and Prevention
·         The waste product should be recycled
·         The industrial effluents should be treated before discharging on the soil and water
·         Sewage or dumping sites should be properly managed.
·         The biofertilizers should be used instead of chemical fertilizers
·         The use of pesticides should be reduced and the biological method should be used to control pests and diseases
·         Education awareness campaign legislation improving habit and plantation should be increased.

3. THE Water Pollution
Addition of any substance to the water or any undesirable change in physical chemical or biological characteristics of water, which interferes with its use for legitimate purpose, is called water pollution. The water is never pure in chemical sense. There are many natural impurities, which normally do not pollute water. Polluted water is turbid unpleasant bad smelling and unfit for drinking and other use.

Sources of water pollution
Industries
Several organic and inorganic pollutants come out from several industries like paper and pulp mills, iron, still, leather etc.
The pollutants are: oils, acids, salts, dyes, cyanides, phenols, metals, plastics and detergents.

Agricultural discharges
The fertilizers, pesticides, Fungicides, herbicides are used in agriculture. Different chemicals of these reach to water sources and pollute water. The pollutants are: DDT, BHC, aldrin, endrin, dialdrin, malathion, urea etc.
Sewage and other wastes
The water borne domestic wastes and animal waste is called sewage. The sewage also includes industrial waste. Due to uncontrolled dumping water becomes polluted.
The pollutants are: Human excreta, animal dung, paper, clothes, soap, detergents and microorganisms.
Thermal pollution
Water is used to cooling process. The hot water after cooling is discharged into water source, which cause thermal pollution.

Effects of water pollution
Nitrate: the nitrate fertilizers are used in agricultural land it can inter our ponds and well. When we drink nitrate containing water, the nitrate is converted into nitrites in the intestine. the nitrites then reacts with haemoglobin to form methamoglobin in blood which reduces oxygen carrying capacity of blood.. 20% methamoglobin causes headache3 and giddiness, 60% causes eye problem and stiffness and unconsciousness, 80% causes death.
Biocides:Different types of biocides are used to prevent agriculture from the pests and diseases. These are composed of different toxic chemical substances. From agricultural land, such toxic chemical substance can reach to water resources when we drink such water they cause various problems like kidney disorders, brain tissue damage and blood abnormalities. About 1000 people die per year by pesticide poisoning in developing countries.
Industrial effluents: the industrial effluents contain several toxic substances.
The paper and pulp industries cause mercury pollution. The symptoms of mercury poisoning include visual disturbance, mental disorders, convulsions and genetic diseases and death. The lead causes liver and kidney damage and mental disorder as well as weakness. The oils, hydrocarbon compounds acids, alkalis, cyanides and metals cause several effects in human health.
Sewage and other waste: several pollutants though sewage reaches to water bodies where they are decomposed by microbes and water becomes unfit for drinking and use. Sewage become rich in nutrients, especially phosphate and nitrate ions accumulate in water bodies. The process is called eutrophication. Due to the eutrophication several microorganisms and aquatic plants grow excessively in water. They absorb oxygen of water but carbondioxide level increases and the water gives foul small.
When the microbes and algae absorb oxygen from water, the BOD is increased. The BOD (Biological Oxygen Demand) is the amount of O2 required for biological oxidation by microbes per unit volume of water. The BOD value is proportional to amount of organic waste present in water.
Several microbes cause different types of diseases like hepatitis, cholera, typhoid, dysentery diarrheas, amoebiasis, and other fatal diseases.
The chlorinated water of Kathmandu is heavily contaminated with faecal materials.
The 80% drinking water in Kathmandu valley contain about 8400 bacterial cell per 100 ml.
Hot Water: when hot water is mixed with water bodies from industries affects aquatic animals.

Prevention and control of water pollution
·         Different types of waste should be recycled or treated before discharging into the water bodies
·         Dissolved substances from the water should be removed by physical or chemical method.
·         Sedimentation floatation and screening can be done to remove several wastes
·         Proper drainage for sewage and efficient sewage collection should be managed properly
·         Industrial effluents should be treated before discharging into the water bodies
·         Bad habits of people like open defecation disposal of wastes, and washing clothes near the water sources must be changed
·         By education, awareness, campaign and legislation.





Animal Behavior


 
The movement or res0ponse of animal with their environment is called animal behavior. There are three types of animal behavior.
1. Reflex action
The quick or immediate response toward stimulus is called reflex action. This is automatic or unconscious. The reflex action is also known as automatic response. There are two types of reflex action
Simple reflexes
Simple reflexes are inborn or unlearned, for example closing of eyes when an object approaches and secretion of saliva in mouth seeing sweet or sour food.
Conditional reflexes
The responses brought about by learning or experiences, for example ringing a bell and secretion of saliva in dog.
Mechanism of Reflex Action
The centre of reflex action is spinal cord
The afferent fiber or sensory fiber enters the spinal cord through the dorsal root and carry the impulse from the effectors organ to spinal cord. The efferent fiber or motor fiber passes through the ventral root and carries impulses away from the spinal cord to the effectors organ. The adjustor neuron in spinal cord communicates between afferent and efferent neuron.
2. Taxis
The movement of animals towards or away from the stimulus is called the taxis. The taxis may be negative or positive. The movement away from stimulus is called negative taxis and the movement towards the stimulus is called positive taxis.
Thermotaxis:         it is response to the stimulus of temperature. For example during winter we attract toward heat and in summer we go away from the heat.
Phototaxis: it is the response to stimulus of light. For example, the cockroach and earthworm go away from the light. The euglena move towards light.
Geotaxis: the response to stimulus of gravity is called geotaxis. Earth worm move deep into the soil.
Rheotaxis: the response to the stimulus of water current. Flow towards direction of water current.
Chemotaxis            it is response to chemicals. The mosquitos fly away from the burning coil.
Sociotaxis: it is response to the groups or family. The man attract toward the family.
Klinotaxis: In some organism the receptor cells are distributed on body surface, mostly on dorsal surface of anterior part. They try to orient their body by bending first on one direction and then other which continues until the receptor of two sides are equally stimulated. For example Euglena.
Tropotaxis: The orientation of body in response to a stimulus is straight, not sideways like klinotaxis due to presence of receptor organs in pair. for eg. Lice and ticks.
Telotaxis: The animals orient to any one of stimulus when they are stimulated by two sources of stimuli. The honey bee moves to flowers in presence of light and in evening she left flowers and moves to hives.
Menotaxis: The animals orient their body in response to stimulus at a constant angle. The ant move in a path guided by the direction of sun.
Mnemotaxis: Some animals orient their body towards different types of stimuli. The wasps use light direction, land marks, and trial of chemicals left.

3. Leadership
The property of giving guidance, control, and security to other members is called leadership. The leadership requires a Leader. A real leader will be the one who initiates, stabilizes, or integrates the group. It is found in socially organized animals. The ants, bees, birds, mammals, monkeys, dear etc show this property. The leadership increases cooperation among the members.
4. Migration
The migration is defined as the active or passive movement of animals from one habitat to another.
Migratory behavior of fishes
The movement or migration of fishes from one place to another place for food, shelter, breeding, or protection is called migratory behavior of fishes.
Types of Migration in fishes
Catadromous migration
The migration of fishes from fresh water to seawater is called catadromous migration. This migration is especially for breeding purpose. They spawn in deep water and die there. The new larvae come back to the fresh water the original place and grow. This behavior is shown by Anguila bengalensis
Anadromous migration
The migration of fishes from seawater to fresh water especially for breeding purpose is called anadromous migration. They spawn in deep water and die.………eg. Salmon.
Oceanodromous migration: The migration, which is confined in ocean for shelter food, is called oceanodromous migration. eg. Clupea.
Potamodromous migration
The migration which is confined in fresh water for food, shelter is called potamodromous migration. eg. Carpfish

Migratory behavior of birds
Longitudinal migration
The migration from the east to west or vice versa is called longitudinal migration.
eg. Starling bird.
Latitudinal migration
The migration from the north to south and vice versa is called latitudinal migration,
eg. Ducks.
Altitudinal migration
The migration from the mountain region to low land and vice versa is altitudinal migration. This migration occurs due to change in season. In summer, birds fly to mountain and in winter return back to low land. eg. Woodcock.
Irregular migration
The migration is dispersing in all direction. eg.  Sparrow
Nocturnal migration
The migration that occurs only in night is called nocturnal migration. eg ducks and gulls
Diurnal migration
The migration that occurs only in day is diurnal migration. eg. Hawks and swallows.


Animal Adaptation
The adjustment to the environment or character of animals to fit to their environment is called animal adaptation.

1. Aquatic adaptation
The adaptation to water medium is aquatic adaptation. The characters of animals of aquatic adaptation are
·         Elongated and streamlined body, Fins are present in the body, Tail is present for change in direction.
·         Gills are present for respiration, Lateral line present in the body as a sensitive organ, The air bladders are present for swimming.
·         The neck is short
·         The external ear is absent
·         The scales are present instead of hairs
·         Some animals have weebed feet.
·         The body is spongy and light
·         The air holding capacity is large in the lungs.

Amphibious Adaptation
The adaptation to both water and lad medium is called amphibious adaptation
For water
·         Nictitating membrane is present
·         Webbed feet is present
·         Coetaneous respiration
·         Body is elongated and boat shaped
·         Fins are present
·         Gills and lateral lines are present

For Land
·         Muscles are powerful for jumping
·         Hind limbs are long and strong
·         The lungs are present for lung respiration
·         The fingers are present
·         The vertebral column is short

2. Terrestrial Adaptation
The adaptation to the land is called terrestrial adaptation. It is of following types
Arboreal adaptation
·         The adaptation to live on trees or walls is called arboreal adaptation
·         The characters are
·         Tows are provided with adhesive pads
·         The claws are present
·         The forelimbs are well developed
·         The body size is reduced
·         The tail is long and prehensile
·         The girdle bones are strong
·         For eg the monkeys, squirrel, bat, wall lizard
3. Volant Adaptation
The adaptation to fly is Volant adaptation is called Volant adaptation. There are two types of flight

True flight or active flight
·         The body is streamlined.
·         The forelimbs are modified into wings
·         The body is covered with feathers
·         The tail is also feathery
·         The bones are spongy, light and hollow (pneumatic)
·         The flight muscles are developed
·         The beak present and the teeth absent
·         The air sacs are present in lungs which help to fly
·         The eyes and ear are developed
·         For eg birds and insects

Temporary flight or passive flight
·         Some fishes can fly with the help of fins for eg. Exocetus
·         Some frogs can fly with the help of webbed feet for eg. Rhacophorus
·         Some reptiles are provided with patagium, which helps to fly eg. Draco
·         The folded skin of flying fox helps to fly

4. Fussorial adaptation
·         The adaptation to live in burrows under ground is called fussorial adaptation. The characters are
·         The snout is pointed
·         The incisor teeth are developed
·         The muscles are developed
·         The claws are developed
·         The scales are developed and the tail size is reduced
·         The body is elongated and the limbs are absent
·         The eye and the ear are reduced







CONSERVATION OF NATURE

 
The nature has been so kind to man ever since it appearance on the earth, man has been dependant on it. They needed plant and animal for different purposes. The expanded human population is resulting into expanded needs of man. The utilizing modern technology man started to utilize them. We have taken loans from the nature that cannot be paid back. The biological community that too million of years to develop are been divest by human activities. The umber of animals and plants are already eliminated from the world and the numbers of organisms are in the process. Therefore, there is urgent need to conserve them.

Conservation
The care, management, protection, and preservation of natural resources is called conservation.
Wild life
The living organisms in its natural habitat is called wild life or the non domesticated animals (fauna) and uncultivated plants (flora) in the wild form is called wild life.

Conservation of wild life
The care, management, protection and preservation of wild life is called conservation of wild life.
Importance of wild life
Economic value
From plants timber, furniture, resin, gum, latex, flower etc can be obtained and by selling them money can be earned. From animals fur, wool, horn, bone, silk, meat, leather etc can be produced and by selling them money can be earned
Scientific value
Plants and animals both are useful to study ecosystem, environment, pathology, taxonomy, paleontology, genetic engineering and evolution etc.
Food value
The most of the plants and the animals are edible, used as our daily food and diet
Recreation value
The wild lives provide ornamental plants, varieties of animals which give natural beauty which attracts tourists.

Types of wild life

1. Endangered species (E)
Those species if their use is continue then they are in danger of extinction.
Endangered animals are
Elephas maximus, Panthera uncial, Panthera tigirs, Bos grunnieus, Catreus wallichii, Gravialis gangetius
Some endangered plants
Cordyceps sinensis, Rauvolfia serpentine, Dactylorhiza hatageria, Taxus baccata, Vythea spinulosa
2. Vulnerable species (V)
Those species, which are likely to be endangered, are called vulnerable species
Vulnarable Animals
Pyths morulus (AGINGER), Cuon alpinus (wild dog), Antilope cervicarpa (Black buck), Platanista gangetica (Dolphin), Sclenarctor thibetanus (Black deer)
Vulnarable Plants
Nardostachys grandiflora, Picrorhiza scrophulariflora, Swertia chiruita, Asparagus racemosus, Acorus calamus


3. Rare species
Those species which are at risk but not vulnerable and endangered are called rare species
Rare Animals
Elachistodon westermani, Aquila heliaca, Aceros nipalensis, Falco naumanni

4. Threatened species
It is common term used for endangered, vulnerable, and rare species
5. Endemic species
This is not category or wild life. It includes those species, which is native confined within particular area. There are 20 species algae, 16 species fungi, 30 species lichen and 246 species of angiosperms are endemic to Nepal

The causes of wild life extinction
Habitat destruction: the destroying habitat of wild life by over population for cropland, resident, industries, road, canal developmental activities cause wildlife extinction
Poaching or Hunting: the hunting of animals for meat, money, enjoyment and hobby and the international trade cause extinction of wild life
The tiger hunting for leather, the rhino hunting for horn, the elephant hunting for tusk and musk deer for musk
Pollution: creating pollution by over population, forest destruction, industrialization by development activities, use of pesticides or insecticides in agriculture, use of poison to kill fished, dog, birds to cause extinction of wild life.
Natural disasters: the natural disasters like diseases, land slide, flood, fire, and earthquake also cause extinction of the wild life. in 17th century 7 species extinct, in 18th century 11 species, in 19th century 27 species, and in 20th century 67 species extinct from the world.

Conservation strategy
·         Habitat study: The habitat study of habitat protection habitat improvement and habitat management.
·         Maintain statistical data
·         By implementation of laws against trade or hunter of wild life
·         Education, awareness and camping about importance of wild life
·         Bilateral agreement between government and people for conservation of wild life
·         Multilateral agreement of nations for conservation of wild life
·         Establishment of national parks and wild life reserves
·         Scientific researches like genetic engineering by gene library and biotechnologically like tissue culture and clone etc.



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