MODEL PAPER 7 — BIOLOGY STD 11 Science — Question

Each plant or group of plants have some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called as the 'relic of past'. Can you establish a phylogenetic relationship to Cycas with any other group of plants that justifies the above statement?

With the help of well-labelled diagrams, describe the process of plasmolysis in plants, giving appropriate examples.

How are gibberellins useful in agriculture to improve productivity? Give three points in support of your answer.

Eukaryotic cells have organelles which may bound by a single membrane. Group the various sub-cellular organelles into these categories.

Give a brief account of exchange of gases during respiration.

Write a short note on electrocardiogram (ECG).

Explain arithmetic growth in plants.

What is the need of a classification system in biology? How did different classification systems develop over a period of time?

Mention the layers of body wall of earthworm.

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.