Biotechnology and its Applications — BIOLOGY STD 12 Science — Question

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

Read the following and answer any four questions from (i) to (v) given below:

Over population causes number of family problems. Strategies like birth control methods help to control population explosion. Natural methods of birth control do not involve medications or devices to prevent pregnancy, but rather rely on behavioural practices and/ or making observations about menstrual cycle.

1. Which method helps in contraception by temporary absence of sex?

1. Coitus interruptus.
2. Withdrawal method.
3. Rhythm method.
4. Lactational amenorrhea method.

2. Assertion: The effectiveness of coitus interruptus method is limited.

Reason: Some sperms may pass into vagina before ejaculation.

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.

3. Why is lactational amenorrhea effective for about 4-5 months after parturition?

1. Ovulation occurs on about the 14^th day of menstruation.
2. Ovulation does not occur during intense lactation.
3. This method inhibits mobility of sperms.
4. Both (b) and (c).

4. Which fact is not the basis of periodic absence method of birth control?

1. Ovum remains alive for about 1-2 days.
2. Ovulation occurs on about 14^th day of menstruation.
3. Sperms survive for about 3 days.
4. Alteration in uterine endometrium.

5. On which days of menstrual cycle should coitus be avoided to prevent fertilisation?

1. 10-17
2. 6-13
3. 1-5
4. 15-28

Explain: separation and isolation of DNA fragments.###How will you make separation and isolation of DNA fragments by using gel electrophoresis?

Explain incomplete dominance in dog flower (snapdragon or Antirrhinum sp.) with the help of a chart.###During monohybrid experiment, in F 2 generation, the ratio of phenotype & genotype remains same - explain by giving suitable example (chart is necessary).

Read the following and answer any four questions from (i) to (v) given below:

Pollen-pistil interaction is the group of events that occur from the time of pollen deposition over the stigma to the time of pollen tube entry into ovule. It is a dynamic process which has checks at several places for promotion or inhibition of pollen growth. Pollen-pistil interaction is a safety measure to ensure that illegitimate crossings do not occur. Compatibility and incompatibility of the pollen-pistil is determined by special proteins. The compatible pollens are able to absorb water and nutrients from the surface of the stigma. They germinate and produce pollen tubes. Pollen tubes grow into the style. Their growth and path through the style are also determined by specific chemicals.

1. Which of the following parts of gynoecium determines the compatible nature of pollen?

1. Stigma.
2. Style.
3. Ovary.
4. Thalamus.

2. In Triforium, which type of self-incompatibility is found?

1. Gametophytic self-incompatibility (GSI).
2. Sporophytic self-incompatibility (SSI).
3.  Both GSI and SSI.
4. None of these.

3. Select the incorrect statement.

1. In Asteraceae, incompatibility is due to the genotype of the sporophytic stigmatic tissues.
2. In members of Brassicaceae, incompatibility is due to the genotype of the pollen.
3. Nature has imposed self-incompatibility to avoid highly homozygous individuals, which have a very low survival value.
4. None of these.

4. Which of the following are examples of self incompatibility?

1. Tobacco.
2. Potato.
3. Crucifers.
4. All of these.

5. Given figures show the pollen-stigma interaction, where pollen wall proteins are released onto the pellicle of stigmatic papillae, where a recognition reaction occurs.

Which of the following statements drawn from given figures is incorrect?

1. P indicates compatible reaction in which the pollen tube penetrates the cuticle and grows down the papilla.
2. Development of callose plug between the plasma membrane and pectocellulosic layer of stigmatic papillae results in the incompatibility reaction in Q.
3. A callose plug, which appears at the tip of pollen in Q, is dissolved by callase enzyme secreted by stigma resulting in compatibility reaction.
4. Deposition of callose can be employed as a reliable bioassay to detect compatibility or incompatibility reactions of pollen and stigma.

Read the following and answer any four questions from (i) to (v) given below:

Organism P has thick lips and tongue so that it can easily feed on the commonly available spiny plants. Organism Q has thick layer of insulating fat under the skin. It was strong hooves to walk steadily on steep surfaces and lives in burrows during winters. Organism R has bright colours and sticky pads on its fingers and toes. It lives on trees.

1. Which of the following is correct habitat for organisms P regarding its adaptation?

1. Grassland biome.
2. Desert biome.
3. Tropical rainforest.
4. Tropical deciduous forest.

2. Which of the following is correct match regarding organism Q and its habitat?

1. Tundra - Polar bear.
2. Tropical rain forest - Deer.
3. Grassland - Bighorn sheep.
4. Desert - Camel.

3. Which of the following is incorrect regarding organisms R's habitat?

1. The vegetation shows stratification.
2. Epiphytic growth is rich.
3. Standing crop is highest.
4. Deep rooted shrubs are common due to abundant sunlight.

4. The dominant plants in habitat where P lives could be:

1. Opuntia
2. Nymphaea
3. Deodar
4. both (a) and (c).

5. Organisms P, Q and R respectively most likely occur in:

1. F, B and A.
2. C, A, E.
3. A, F and C.
4. B, D and A.

Read the following text carefully and answer the questions that follow:
The diagram shows the replication of the retrovirus in the host.


i. Fill in the missing data in boxes labelled 1 & 2. (1)
ii. Why is it named as retrovirus? (1)
iii. While the virus is being replicated and released, does the infected cell survive and why the virus infected cells prevent spreading of virus to healthy cells? (2)
OR
What is the effect of HIV infection on immune system? (2)

Read the following and answer any four questions from (i) to (v) given below:
Villagers in a place near Chambur started planning to make power supply for agricultural purposes from cow dung. 'Tiley have started a biogas plant for the purpose. Study the flow chart for biogas production given below and answer the following questions.

1. Biagas is composed of majorly:

1. Methane, CO₂ and O₂
2. CO₂, H₂S and H
3. Methane, CO₂
4.  H₂S, H and O₂

2. In the given flow chart, 'A' denotes:

1. Aerobic bacteria.
2. Methanogenic bacteria.
3. Cellulose degrading bacteria.
4. Yeast and protozoa.

3. What is represented by 'B' in the flow chart?

1. Carbohydrates.
2. Protein polymers.
3. Organic acids.
4. Fat globules.

4. 'C' in the given flow chart causes:

1. Aerobic breakdown of complex organic compounds.
2. Anaerobic digestion of complex organic compounds.
3. Fermentation of organic compounds.
4. Fermentation of monomers.

5.  If 'A' is not added in the procedure.

1. Methane will not be formed.
2. CO₂ will not be formed.
3. Organic compounds will not be converted to H₂S
4. O₂ will not be formed.