Q.1 Which of the movable joint makes the hip joint ?
Ans1. Ball and socket joint.

Q.2 Write the full form of tRNA.
Ans2. Transfer Ribosenucleic Acid.

Q.3 Mention any two factors by which the environment or the nature checks the pollution size.
Ans3. (i) Competition and struggle.
(ii) Drought and flood.

Q.4 Give two examples of analogous organs from animals.
Ans4. Wings of :
(i) an insect,
(ii) a bird, and
(iii)a bat are analogous organs.

Q.5 Mention one difference in the structure of chlorophyll-a and chlorophyll-b.
Ans5. Chlorophyll-a has a methyl (-CH₃) group whereas chlorophyll-b has an aldehyde (-CHO) group.

Q.6Name the source glands of glucagon and parathormone.
Ans6. Glucagon : Islets of Langerhans in Pancreas
Parathormone: Parathyroid gland

Q.7 Mention one difference between benign tumour and malignant tumour.
Ans7. A malignant tumour is different from a benign tumour in the formers capacity to undergo metastasis.

Q.8 Name any two structures in our body, which bear ciliated epithilium.
Ans8. (i) Kidney tubules, and
(ii) Fallopian tubes

Q.9 A women travels in a crowded compartment along with people suffering from diabetes, influenza and amoebiasis. With which one of these diseases she is most likely to be infected during this journey and why ?
Ans9. Influenza; because among diabetes, influenza and amoebiasis only influenza is a disease communicable through air.

Q.10 Amongst pea tendrils, opuntia spines, lemon thorns and cucurbit tendril, which ones are homologous structures ? Give reason.
Ans10. Pea tendrils are homologous to Opuntia spines because both are modifications of leaves; lemon thorns are homologous to Cucurbit tendril because both are modified stems.

Q.11 Describe one example of artificial selection.
Ans11. Cabbage, cauliflower and kohlrabi are derrived from a comman ancestor, colewort by artificial selection.

Q.12 Mention two differences in the vascular bundles of Sunflower and Maize stems
Ans12. Sunflower and maize stems are different in that :
(1) Sunflower has radially arranged, fewer vascular bundles, whereas maize has randomly distributed numerous vascular bundles.
(2) Sunflower has open (with cambium) vascular bundles, whereas maize has closed (without cambium) vascular bundles.

Q.13 Give any four examples of human reflexes.
Ans13. (1) Salivation on the sight or smell of a tasty food.
(2) Constriction of pupils on the illumination with bright light.
(3) Blinking of eye lids on the approach of an object close to the eyes.
(4) Jerk in the legs when a pin pricks sole.

Q.14 How were exact replicas of master plate obtained in Lederberg replica plating experiment ?
Ans14. A sterile velvet disc, mounted on a wooden bloc, was gently pressed on the master plate. Some bacteria from each colony adhered to the velvet. By pressing this velvet on to new agar plates, Ledeberg and Lederberg obtained exact replicas of the master plate because the few bacteria
transferred by the velvet formed colonies on the new plates.

Q.15 In humans, genetically the sex of the child is determined by the father and not by the mother. Explain
Ans15. Human male is heteromorphic with respect to chromosome: XY. A son gets one of its chromosomes from the father and the other from the mother. The mother being homomorphic contributes only X. If the father contributed X, the embryo develops into a daughter, whereas if he contributed Y, the embryo develops into a son.

Q.17 Explain any two palaeontological evidences in favour of organic evolution.
Ans17. (i) Archaeopteryx provides evidences for the evolution of birds from reptiles.
(ii) Fossils provide evidences of the evolution of modern day horse (Equus) from Eohippus- Mesohippus.

Q.18 Distinguish between bacterial transduction and bacterial transformation.
Ans18.

Q.19 Mention four aspects in which uricotelism differs from ureotelism.
Ans19.

Q.20 Specify how a pentose phosphate is a CO₂ acceptor in the dark reaction of photosynthesis.
Ans20. 3 molecules of a pentose phosphate (ribulose bisphosphate) accept 3 molecules of CO₂ and this carboxylation is mediated by the enzyme RUBISCO. The 3 molecules of six-carbon intermediate, which form are short-lived and break down into two molecules of three-carbon phosphoglyceric
acid each.The 6 molecules of phosphoglyceric acid carry the rest of the dark reaction cycle.

Q.21 How would non-secretion of hydrochloric acid in our stomach affect food digestion ? Explain ?
Ans21. Hydrochloric acid is responsible for the following :
(i) Activates pepsinogen, prorenin and other protease proenzymes.
(ii) Denatures food proteins and facilitates action of pepsin on them.
(iii) Stops the action of salivary amylase.
(iv) Disinfect the ingested food.
In the absence of HCl in the gastric juice no protein digestion would occur and only carbohydrate digestion would continue.

Q.22 A farmer adds Azotobactor culture in the soil before sowing maize. How does it increase the yield of maize.
Ans22. Azotobacter is a free living non-symbiotic soil-bacteria, which can fix atmospheric nitrogen. The fixed nitrogen becomes available to cereal crops. The inoculation of maize seeds with Azotobacter will ensure simultaneous growth of Azotobacter in the field and will provide better nitrogen availability, better yields and saving of mineral nitrogen fertiliser's.

Q.23 Give one example of co-dominance in human genetics.
Ans23. The ABO system of blood in humans is an example of both multiple allelism and codominance. The gene exists as three alleles: I^A, I^B, and i. Both I^A and I^B are dominant over i. Both the dominant alleles confer AB phenotype when present together.

Q.26 If abiotic origin of life is in process on a planet other than the earth, what would be the conditions then ? Explain them.
Ans26. If the abiotic origin of life has to take place on any planet :
(i) Hydrogen, nitrogen, water vapour, carbon dioxide, methane, and ammonia must be present in its environment.
(ii) Sources of energy such as thermal energy, radiation, and lightening should be available.
(iii) Atmosphere must be non-reducing.

Q.29 Describe the mode of infection, symptoms and preventive measure of Diphtheria, Tetanus and Measles.
Ans29.

Q.30 Describe two important functions each of the elements P, B and S in green plants and also write the deficiency symptoms of any two of them.
Ans30.

Q.31 Describe how our brain gets a continuous supply of oxygen from the atmosphere.

Ans31. Respiratory gas exchange and the blood circulation provide a continuous supply of oxygen from the atmosphere to the brain. Inhalation draws in fresh air from the atmosphere into lungs through nostrils and via nasopharynx, and trachea. In the alveoli of the lungs gaseous exchange occurs between blood and the inhaled air. The high PO₂ and low PCO₂ in the lungs cause diffusion of O₂ into the RBCs where it combines loosely with the Fe²⁺ ions of haemoglobin to form oxyhaemoglobin. When the oxygenated blood reaches in the brain tissue, the lower PO₂ and higher PCO₂ there causes dissociation of oxyhemoglobin to deoxyhemoglobin (reduced haemoglobin) and molecular oxygen.
The brain tissue picks up O₂ and releases CO₂ to blood.