Which biogas is not produced by the decomposition of dung and dead plants? (a) CH₄ (b) NH₃ (c) H₂S (d) H₂

With which step of Nitrogen Cycle microbes like Nitrosomonas and Nitrobacter are associated? (a) Nitrification (b) Denitrification (c) Nitrogen fixation (d) Ammonification

Which is the correct sequence of the Nitrogen Cycle? (a) Fixation of Nitrogen → Denitrification → Ammonification → Nitrification (b) Ammonification → Nitrification → Nitrogen Fixation → Denitrification (c) Nitrogen Fixation → Ammonification → Nitrification → Denitrification (d) Nitrification → Nitrogen Fixation → Denitrification → Ammonification

Which environmental problems arise if nitrogen cycle is hampered?

Explain the following three problems related to ever-increasing human population- Over-exploitation and depletion of natural resourcese Changes in atmospheric condition and global warming Deforestation and loss of ecosystems Two major causes behind the loss of biodiversity are over-exploitation and destruction of habitat due to change in land use pattern - establish the validity of the statement with proper example. [3+2=5] Or What might be the reasons behind the disturbances in Nitrogen Cycle ? It is very much essential to publish a PBR document for each village of India — which information can be gathered from a PBR regarding biodiversity ? [3+2=5]

Three environmental problems of the Sunderbans are- imbalance in the numbers of prey and predators destruction of mangrove plants due to urbanisation rising sea level Analyse the probable effects of the three problems. Mention the location and the name of one endangered species of a biodiversity hotspot distributed in and outside the geographical area of India. [3+2=5] OR Describe the nitrogen cycle with the help of a word diagram. Analyse any two problems which may arise if the nitrogen cycle is disturbed. [3+2=5]

In DNA, which of the following base pairs is correct? (a) A—T (b) A—T (c) G = C (d) G—C

Compare the steps of mitosis in plant cells and animal cells and select which are correct: Mitosis in plant cell Mitosis in animal cell I. Spindle is formed from the cytoplasm. I. Spindle is formed from centrioles or asters. II. Cytokinesis occurs by cell plate formation. II. Cytokinesis occurs by cleavage furrow formation. III. Centrosomes are not involved. III. Centrosomes form from centrioles and are involved in mitosis. IV. Division of cytoplasm occurs through the formation of a cell plate. IV. Division of cytoplasm occurs through furrow formation. Which are correct? (a) I, IV (b) II, IV (c) II, III (d) III, IV

Which of the following statements is NOT correct? (a) Fibrin helps in blood clotting. (b) Platelets stop bleeding; many platelets reach the site of injury and begin the process of blood clotting. (c) Insulin increases the level of glucose in blood. (d) Adrenaline helps to increase heartbeat.

Which one of the following is an incorrect food chain? (a) Grass → Rabbit → Snake → Hawk (b) Grass → Grasshopper → Frog → Snake (c) Grass → Cow → Man → Tiger (d) Grass → Insect → Rat → Snake

Which of the following is not an example of mutualism? (a) Man and intestinal bacteria (b) Water hyacinth and fish (c) Fish and sea anemone (d) Lichen and blue green algae

Which of the following statements about self-pollination is correct? Self-pollination occurs within the same flower. New characters do not arise by self-pollination. The chance of pollination failure is less if self-pollination is not dependent on an external agent. Seed production is higher if self-pollination is not dependent on an external agent. (a) 3 (b) 1 (c) 4 (d) 2