Plant Kingdom — BIOLOGY STD 11 Science — Question

What is the basis for designating C₃ and C₄ pathways of photosynthesis?

Amrita while playing with her friend, near the pond noticed in the pond that a green colour covering is floating on the surface of the water. She discussed this with her friend and both got surprised. Next day in the school Amrita asked her teacher about the same. Teacher told her, that was nothing, but green algae which occur both in fresh and marine water habitats.

1. Mention the economic importance of algae.
2. Why green algae are considered to be the ancestors of all land plants. Justify the statement by giving reasons.
3. What values as a good biology student are reflected from Amrita's character.

On world AiDs day Ankit and his friends arranged an awareness compaign programme in their locality. Some elderly people rebuked the children and asked them not to talk of such things in public. The children convinced the elders about the need ror the programme and on understanding their point of view, they also joined the campaign.

1. What is AIDS?
2. Name the causal agent of AIDS.
3. What type of genetic material is found in AIDS virus?
4. What values did Ankit and his friends show on the occasion.

Explain the reasons of following.

1. Photosynthesis can occur in the absence of light.
2. Even non-green leaves can make the food.
3. Photosynthesis can occur under water.

Mango and coconut are ‘drupe’ type of fruits. In mango fleshy mesocarp is edible. What is the edible part of coconut? What does milk of tender coconut represent?

Which structures form gynoecium? How is placenta related to gynoecium? What are its types?

Explain the autoregulatory mechanism of GFR.

Describe in proper sequence, the steps involved in pulmonary respiration in human beings.