AP Inter Practical Session

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.

1. Where and how did we preserve skeletons of animals, dry specimens, etc.?
A: The skeletons, dry specimens are preserved in museums. Animal specimens are preserved in jars filled with preservative solutions like formaldehyde. Insects are preserved in insect boxes after pinning on sheets. Large animal which are not suitable specimen jar storage are preserved in ‘stuffed’ forms.

2. Differentiate between Protostomia and Deuterostomia.
A: The animals in which mouth appears as first opening (blastopore develops into mouth) are protostomes. They are kept under division
Protostomia. In deuterstomes mouth forms as secondary opening in the development. i.e., from blastopore or closer to blastopore anus
forms. These animals are included in the division Deuterostomia.

3. Nematode is a protostomian but not a eucoelomate. Justify the statement.
A: In nematodes, like other protostomes, mouth forms as first opening from blastopore. But their body cavity is not lined by
peritoneal layers i.e, not true coelom (eucoelom).

4. What is ecological diversity? Mention the different types of ecological diversities.
A: Variation of life at various levels of biological organization is called biodiversity. Diversity at the ecosystem level is called ecological diversity. e.g.: ecological diversity in India – deserts, rain forests, mangroves, coral reefs, wetlands.

5. Define species richness.
A: Number of species per unit area is called species richness. The more the number of species in an area the more is the species
richness. German naturalist and geographer Alexander von Humboldt observed that within a region, species richness increased with increasing explored area, but only up to a limit.

6. Mention any two products of medicinal importance obtained from
Nature.
A: Medicinally important products obtained from nature are anti
cancer drugs – Vinblastin from Vinca rosea, Digitalin from fox
glove plant is used to treat cardiac problems.

7. Invasion of an Alien species leads to extinction of native species. Justify this with two examples.
A: When alien species are introduced into a habitat, they turn invasive and establish themselves at the cost of indigenous species. e.g. Nile perch introduced into Lake Victoria, in East Africa led to the extinction of 200 species of cichlid fish in the lake.
e.g.: Illegal introduction of exotic African catfish, Clarius gariepinus, for aquaculture purposes is posing a threat to the indigenous cat fishes.

8. List out any four sacred groves in India.
A: A grove of trees of special religious importance to a particular culture is called sacred grove. Some sacred groves in India are
1) Khasi and Jaintla Hills (Meghalaya),
2) Aravalli Hills (Rajasthan and Gujarat),
3) Western Ghat region (Karnataka, Maharashtra),
4) Sarguja, Bastar (Chattisgarh),

9. Explain the hierarchy of classification.
A: Systematics is the branch of science that deals with the vast diversity life. It also reveals the trends and evolutionary relationships of different groups of the organisms. A key part of systematics is taxonomy. Taxonomic hierarchy includes seven obligate categories namely kingdom, phylum, class, order, family, genus and species, and other intermediate categories such as subkingdom, grade, division, subdivision, subphylum, superclass, superorder, suborder, superfamily, subfamily, subspecies, etc.

10. What are the reasons for greater biodiversity in the tropics?
A: Tropics accommodate more species than temperate or polar regions. Species diversity is more in tropics because of 1) they are not disturbed and had a long evolutionary time, 2) constant climate 3) abundance of natural resources.

Tropical latitudes have remained relatively undisturbed for millions of years and thus had a long evolutionary time. A long duration was
available in this region for speciation, it led to the species diversification.

Tropical climates are relatively more constant and predictable than that of the temperate regions. Constant environment promotes niche
specialization and this leads to greater species diversity.

Solar energy, resources like water etc., are available in abundance in tropical region. It contributed to higher productivity in terms of
food production, leading to greater diversity.

11. What is the ‘evil quartet?
A: Evil Quartet (four horsemen of ecological apocalypse) speaks about four factors that impact on the environment that lead to loss
of biodiversity. Those four factors are 1) Habitat destruction, 2) Pollution, 3) Invasion of exotic species, and 4) Over exploitation.

12. What is the importance of slope of regression in species – area relationship?
A: One of the most important properties of a straight line is in how it angles away from the horizontal. This concept is reflected in
something called the “slope” of the line. Slope of regression is indicated by ‘Z’. It stands for increase or decrease of species per unit area. Ecologists have discovered that the value of ‘Z’ lies in the range of 0.1 to 0.2, regardless of taxonomic group or the area. But if we analyze the species-area relationships among very large areas like the entire continents ‘ Z ‘ values are in 0.6 to 1.2 and the slope of the line to be much steeper. In tropical forests of different continents the slope of line for fruit eating birds is 1.15.