Cell Cycle and Cell Division — BIOLOGY STD 11 Science — Question

Why earthworm is called the friend of farmer?

Photosynthesis not only facilitates production of food but also cleans up the environment. Which of the following is similar to this multipronged effect of photosynthesis? Explain how deforestation affects our environment.

1. An automobile not only carries people but also releases carbon dioxide in the air.
2. A cow not only gives milk but also produces methane which is a greenhouse gas.
3. A cow not only gives milk but also produces cowdung which can be used as kitchen fuel.

Draw the labelled diagram of the following:
V.S. of maize seed.

What would be expected to happen, if:

1. GA₃ is applied to rice seedlings.
2. A rotten fruit gets mixed with unripe fruits.
3. You forget to add cytokinin to the culture medium.

What is periderm? How does periderm formation take place in the dicot stems?

Write the functions of epidermal tissue system.

Give reason for each of the following:

1. The vascular bundles of an isobilateral leaf are near similar in size, except that in the midrib.
2. Heart wood is dark brown in colour.
3. Cells of phellem/cork are impervious to water.
4. Quantity of secondary xylem produced is more than the quantity of secondary phloem during secondary growth.
5. Phellogen is a secondary meristem.

Distinguish between :
cranial nerves and spinal nerves.

Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in case of higher plants and animals on one hand, and bacteria on the other hand.

What is hibernation? Describe winter sleep (hibernation).