Origin and Evolution of Life — BIOLOGY STD 12 Science — Question

Distinguish between: Phase of cell division and Phase of cell enlargement

Read the following and answer any four questions from (i) to (v) given below:
Kangaroo rat seldom drinks water. It has thick coat to minimise evaporative desiccation. TI1e animal seldom comes out of its comparatively humid and cool burrow during the day time. 90% of its water requirement is met from metabolic water (water produced by respiratory breakdown of fats) while 10% is obtained from its food. Loss of water is minimised by producing nearly solid urine and faeces. As the animal faces acute water scarcity, it develops two types of adaptations : reducing water loss and ability to tolerate desert conditions.

1. Kangaroo rat is a:

1. Partial regulators
2. Partial conformer
3. Regulator
4. Conformer

2. Metabolic water refers to:

1. Water required for metabolic activities.
2. Water present in intercellular fluid.
3. Water produced during oxidation of fat or carbohydrate.
4. Water taken in, to promote metabolism.

3. Desert animals minimise water loss by:

1. Producing highly concentrated urine.
2. Promoting maximum reabsorption of water in kidney tubules.
3. Possessing one of the longest loop of Henle in kidney tubules.
4. All of these.

4. Assertion: Kangaroo rat can tolerate and thrive in wide temperature range and is known as stenothermal.

Reason: Kangaroo rats go into hibernation during winter to escape cold weather.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

5. The adaptations in an organism are meant for:

1. Optimum primary production.
2. Optimum life span.
3. Optimum mobility.
4. Optimum survival and reproduction.

A regulatory body working under MoEF for the release of transgenic crop is ____________:

1. NBPGR
2. NSC
3. NIPGR
4. GEAC

Read the following and answer any four questions from (i) to (v) given below:
Intrauterine devices are most widely accepted methods of contraception. These are used by females and are inserted by doctor or nurses in the uterus through vagina. However, these devices are not recommended for those who eventually intend to conceive.

1. How does CuT prevent conception?

1. Cu ions make uterus unsuitable for implantation.
2. Cu ions make cervix hostile to the sperms.
3. Cu ions suppress sperms motility.
4. Cu ions inhibit ovulation.

2. Which of the following IUDs makes uterus unsuitable for implantation?

1. LNG-20.
2. Multiload 375.
3. Cu7.
4. Lippes loop.

3. Identify the correct statement for IUDs.

1. They slowly release synthetic progesterone in the body.
2. They increase phagocytosis of sperms within the uterus.
3. They block entry of sperms through the cervix.
4. Both (b) and (c).

4. Select the correct matched pair.

1. Hormone releasing IUD - LNG-20.
2. Non-medicated IUD - Progestasert.
3. Copper releasing IUD - Lippes loop.
4. None of these.

5. Assertion: IUDs can cause excess menstrual bleeding and pain.

Reason: IUDs can perforate uterus.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Distinguish between : Atria and Ventricles.