Control and Co-ordination — BIOLOGY STD 12 Science — Question

Read the following and answer any four questions from (i) to (v) given below:
A group of teenagers was involved in drug abuse. 'They used syringes and needles to inject drugs. 'They indulged in this habit when they became adults. Administration of drug through needles became a piece of cake for them. Raj was the most active drug abuser amongst them and used to take drugs in high profile parties. In a span of time he started losing weight and suffered persistent diarrhoea. He developed constant low grade fever and used to catch opportunistic infection. When he consulted a doctor, he got himself tested for HIV in his blood and finally diagnosed with AIDS.
Based on the above information, answer the following questions.

1. Select the incorrect statement.

1. AIDS is a disorder of cell mediated immune system of the body.
2. AIDS is caused by Human Immunodeficiency virus.
3. AIDS infections were detected in India for the first time in prostitutes of Chennai, Tamil Nadu in 1986.
4. December 10 is recalled as World AIDS Day.

2. How do you think Raj got AIDS infection?

1. Through transfusion of HIV infected blood
2. Sexual intercourse with an infected partner
3. Sharing towel with infected friend
4. Use of contaminated needles and syringes to inject drugs

3. How AIDS can be diagnosed?

1. ELISA test
2. Ames test
3. Pap's test
4. Wida! test

4. How can AIDS be prevented?

1. Blood tests of blood donor before transfusion to check for the presence of AIDS virus.
2. Use of disposable needles and syringes for injecting medicines and vaccination
3. Having protected sex by use of condoms
4. All of these

5. Select the correct statement for AIDS virus.

1. It is rhomboid in shape with a diameter of 10-15 cm.
2. Its genome consists of ds DNA.
3. It consists of reverse transcriptase enzyme.
4. Its envelope consists of lipid bilayer and three protein coats.

Read the following and answer any four questions from (i) to (v) given below:
During teaching about various environmental factors, a teacher draw a figure that depicts like history strategies for three plant species (X, Y and Z) along 3 axes - strength of competition with other organisms, level of disturbance in the habitat and level of environmental stress in the habitat. Species X grows in habitats where competition among species is high but disturbance and stress are low. Species Y grows in habitats with high environmental stress but with low intraspecies competition. Species Z grows in highly disturbed habitats with low environmental stress.

1. Which of the following is correct regarding plant type X?

1. It has slow growth rate.
2. It lives in area with high probability of severe environmental changes.
3. It has good competitive ability at low population densities near the carrying capacity.
4. None of these.

2. Environmental stress occurs through.

1. Very low temperature.
2. Drought.
3. Nutrient deficiency.
4. All of these.

3. Select the correct option regarding plant type X, Y and Z.

1. X type of plants are likely to be trees.
2. Y type of plants could be desert plants.
3. Z type of plants could be herbaceous plant.
4. All of these.

4. Y type of plants grow under high stress and:

1. Produce large number of seeds in a short time after rains.
2. Have rapid growth.
3. Produce less number of seed in a long time after rain.
4. Both (a) and (b).

5. Assertion: Plant growth rate is high in area of high stress and high disturbance.

Reason: High stress and high disturbance promote breeding capacity in plants.

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 : Neutrophils and Eosionophils.

Read the following and answer any four questions from (i) to (v) given below:
Disposal of untreated sewage into the river or freshwater pond causes huge water pollution. Four water samples from different sources (A, B, C, D) are collected and tested for BOD value in a lab to assess their quality. The BOD values are presented in the given table. Water samples are collected from primary effluent, secondary effluent, untreated sewage and river water. Study the given table and answer the following.

Sample	BOD
A	20mg/ L
B	5mg/ L
C	300mg/ L
D	400mg/ L

1. The source of sample 'C' is:

1. River water.
2. Primary effluent.
3. Secondary effluent.
4. Untreated sewage water.

2. If sewage in untreated condition is disposed off in a freshwater body then.

1. BOD and dissolved oxygen both will increase.
2. BOD will increase and dissolved oxygen will decreas.
3. BOD will decrease and dissolved oxygen will increase.
4. BOD and dissolved oxygen both will decrease.

3. A large number of pathogenic microbes can be present in water sample of:

1. C
2. A
3. D
4. Both (a) and (c).

4. High value of BOD in sample O is due to:

1. High amount of organic wastes and aerobic microbes.
2. High amount of inorganic wastes and anaerobic microbes.
3. High amount of organic wastes and anaerobic microbes.
4. High amount of inorganic wastes and aerobic microbes.

5. River water is represented by the sample.

1. A
2. B
3. C
4. D

Distinguish Between: Dominant characters and Recessive characters.