Senior Inter Model Questions – Page 2

Q: Describe the structure of heart of rabbit.
Draw a neat labelled diagram of L. S. of heart of rabbit.
A: Heart of rabbit lies in the region in thorax between the two lungs. It is a muscular and pulsating organ that keeps the blood in constant circulation. Heart is enclosed by a double layered pericardium. The two layers of pericardium are separated by pericardial cavity, which contains pericardial fluid. This fluid reduces friction and allows free movement of heart. Heart of rabbit is four chambered with two artria and two venticles.

External structure: Heart is a pear shaped structure, that is, broad anteriorly and the pointed apex is directed posteriorly. Atria lie anteriorly and ventricles lie posteriorly. Atria and ventricles are separated by a groove called coronary sulcus. The posterior parts of atria extend over the ventricles as auricular appendix. The two ventricles are separated externally by an oblique inter ventricular groove.

Internal structure:
1. Atria: 1. There are two artia (left and right) that form the anterior part of heart. They are separated from each other by an inter atrial septum. Walls of atria are thin.
2. Inter atrial septum has a small pore in embryonic state, known as foramen ovalis. After birth, when lungs become functional, it is closed leaving an oval mark called fossa ovalis.
3. Right atrium is larger than left one. It receives deoxygenated
blood from all parts (except lungs) through three major veins, namely, two precaval veins and a post caval vein. Near the opening of post caval vein is a vestigial valve of Eustachian.
4. Blood from muscles of heart is collected by coronary sinus. It opens into left precaval vein just before it opens into right atrium. The opening of coronary sinus into precaval vein is guarded by valve of Thebesius.
5. Left atrium receives oxygenated blood from lungs by a pair of pulmonary veins, which opens into the left atrium through a common pore.
6. Atria and ventricles are separated by an atrio ventricular septum.
7. Near the Eustachian valve, in the wall of right atrium, the pacemaker, namely, sinoatrial node is present.

2. Ventricles: 1. There are two ventricles (left and right) that form the posterior part of heart. They are separated from each other by an inter venticular septum. The walls of ventricles are thick and highly muscular.
2. Left ventricle is larger than right ventricle.
3. Right atrium opens into the right ventricle through a right atrio ventricular aperture. It is guarded by a tricuspid valve. It allows the blood to flow from right atrium to right ventricle only.
4. Left atrium, opens into left ventricle through a left atrio ventricular aperture. It is guarded by a bicuspid valve or mitral
valve. It allows the blood to flow from left atrium to left ventricle only.
5. The inner surface of ventricles is raised into muscular ridges called columnae cornae. Some of them are conical and are called papillary muscles.
6. Extending between atrio ventricular valves (that is tricuspid valve, bicuspid valve) and papillary muscles, there are tendon like cords, known as chordae tendinae. They prevent the too much bulging of atrio ventricular valves into atria.
7. In the posterior right boarder of inter atrial septum, an atrio ventricular node is present. It gives off bundle of His into inter ventricular septum.

3. Aortic arches
a. Pulmonary arch: 1. It arises from right ventricle. It supplies deoxygenated blood to lungs.
2. The opening of pulmonary arch into right ventricle is guarded by a Pulmonary valve, formed by three semi lunar cusps. (semi lunar valve) Pulmonary valve allows the blood to flow into pulmonary arch only from right ventricle.
3. Pulmonary arch and systemic arch are connected by a strand called ligamentum arteriosum (remnant of ductes Botalli).
b. Systemic arch (left only)
1. It arises from left ventricle. It supplies oxygenated blood to all parts of body
2. The opening of systemic arch into left ventricle is guarded by an aortic valve, formed by three semi lunar cusps. Aortic valve allows
the blood to flow into systemic arch only from left ventricle.

Very Short Answer Questions
Q: What is meant by diastema?
A: Due to absence of canines in rabbit, in each half of the jaws a large gap is formed between incisors and premolars. This gap is
called diastema.

Q: Which vitamin is called sun shine vitamin? What is the disease caused by the deficiency it among children?
A: i. Vitamin D is called sun shine vitamin.
ii. Due to deficiency of Vitamin D in children, Rickets is caused.

Q: Name the muscles that help in breathing movements in rabbit.
A: Muscles of diaphragm and Intercostal muscles.

Q: What is meant by chloride shift?
A: When bicarbonate ions increase in the red blood cells, they diffuse into the plasma. To maintain ionic balance in blood, for every bicarbonate ion that comes into plasma, one chloride ion diffuses into the red blood cell. This phenomenon is known as chloride shift or Hamberger’s phenomenon.

2 Marks Questions
1. Differentiate between cryptogams and phanerogams.
A: Cryptogams are non-flowering, seedless spore bearing plants. They include thallophyta, bryophyta and pteridophyta. Phanerogams are flowering, seed producing plants. They include gymnosperms and
angiosperms.

2. How does holdfast cell differ from other vegetative cells of Spirogyra filaments ?
A: Holdfast cell is colorless due to absence of chloroplasts and does not show cell division.

3. Distinguish between Zygophore and zygospore of Rhizopus.
A: Zygophore is the sexual hypha formed during sexual reproduction of Rhizopus. Zygospore is the fertilized product of gametangial copulation which contains many diploid nuclei.

4. Write about ‘peristome’ in Funaria. Give its function.
A: The whorls of peristomal teeth present in the operculum are called peristome. It shows peristomal teeth in two whorls of 16 each.
They are hygroscopic and help in liberation of spores.

5. Distinguish between annulus and stomium of Pteris.
A: A ring like portion of the sporangial jacket with vertically elongated cells is called annulus. A group of long, flat and thin walled cells in the sporangial jacket that help in dehiscence
of sporangium is called stomium.

6. In which plant do you find mixed type of sorus? Define it.
A: Pteris. A mixed sorus is one in which both old and young sporangia
are arranged irregularly.

7. How is coralloid root useful for Cycas plant?
A: The coralloid root of Cycas lodges bluegreen algae like Anabaena cycadacearum and Nostoc punctiforme which help in nitrogen
fixation.

8. Name the species of Cycas that grow wild in Tirumala hills. What is its common name?
A: Cycas beddomi, Madras Cycas.

9. Name the organism from which streptomycin is obtained. Who isolated it?
A: Streptomyces griseus, Waksman.

10. Define botulism. Name the bacterium responsible for botulism.
A: Botulism is a type of food poisoning caused by toxins from Bacteria.
e.g.: Clostridium botulinum.

11. Define peplos and peplomers. Give an example.
A: The outer envelope of a virus made up of lipids, proteins and carbohydrates is called peplos. The subunits of peplos are peplomers.
e.g.: Influenza virus.

12. Name any fungus and the nematode that transmit viruses in plants.
A: Fungus – Olpidium brassicae. Nematode – Xiphenema and
Longidorus

4 Marks Questions
1. Elucidate the dioecious conjugation in Spirogyra.
A: Scalariform conjugation in Spirogyra is also called Dioecious
conjugation.
1. It occurs between two different filaments, one male and the other female called dioecious filaments.
2. During this process the two filaments come and lie parallel to each other.
3. Bud like outgrowths form from two cells lying opposite to each other called papillae.
4. The two papillae grow towards each other and form a conjugation tube due to break down of cell walls between them by the action of the enzyme cytase.
5. Many such conjugation tubes formed between two filaments appear like a ladder, hence called scalariform conjugation.
6. The protoplasts of both cells on either sides of the conjugation tube form aplano gametes.
7. The gamete from each male filament moves slowly into the female filament and fuses with the female gamete to form a diploid zygote in
the female filament.
8. Thus the male filament shows empty cells after fertilization and the female filament is filled with zygotes.
9. This kind of conjugation where both the gametes are structurally alike but functionally dissimilar is called physiological anisogamy.

2. Explain the conjugation in bacteria.
A: Conjugation is a type of genetic recombination in bacteria.
1. It was first reported by Lederberg and Tatum in Escherichia coli.
2. The circular DNA present in the cytoplasm of bacteria is called plasmid or F factor.
3. The bacterial cells with F factor are called donors or F+ cells.
4. The cells without F factor are called acceptors or F− cells.
5. The F+ cells have sex pili, but F− cells do not have sex pili.
6. During conjugation F+ cells and F− cells come together and bind up with the help of sex pili.
7. Thus a conjugation tube is established between F+ and F− cells.
8. The F plasmid in the F+ cell replicates and one of the copies moves into the F− cell through the conjugation tube.
9. Thus the F− cell that receives F plasmid becomes F+ cell. Then the conjugants separate.

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