Human Reproduction — BIOLOGY STD 12 Science — Question

B.
(i) Name the two types of desirable approaches to conserve biodiversity? Explain with examples bringing out the difference between the two types.
(ii) State the features of a stable biological community?

Read the following and answer any four questions from (i) to (v) given below:
Gene therapy is the technique of genetic engineering to replace a faulty gene by a normal healthy functional gene. It is a way of treating genetic disease by introducing a piece of DNA into the cells of an affected individual. Liposomes can be used for gene therapy as they target the cells affected by a genetic disease.

1. A patient suffers from adenosine deaminase (ADA) deficiency, an autosomal recessive immune deficiency in which bone marrow lymphoblasts cannot replicate to generate immuno-competent lymphocytes. The treatment option that would cure the patient is:

1. Germ-line gene therapy to replace one ADA gene copy.
2. Germ-line gene therapy to replace both ADA gene copies.
3. Somatic cell gene therapy to replace both ADA gene copies in circulating lymphocytes.
4. Somatic cell gene therapy to replace one ADA gene copy in bone marrow lymphoblasts.

2. Which type of gene therapy is least effective in transferring DNA to the nucleus?

1. Adenoviruses.
2. DNA attached to a ligand.
3. Liposomes.
4. Retroviruses.

3. Liposomes can be used for gene therapy as they target the cells affected by a genetic disease. The diagram shows the structure of a liposome.

What feature of a cell surface membrane allows the liposome to target cells affected by a genetic disease?

1. Carrier molecules.
2. Phosphate groups.
3. Protein channels.
4. Receptor molecules.

4. Which of the following disorders would gene therapy be least effective?

1. Cystic fibrosis.
2. Huntington's disease.
3. Sickle cell anaemia.
4. Type II diabetes.

5. Following are some reasons explaining why gene therapy is not yet fully an effective treatment for genetic diseases.

1. Lack of knowledge of DNA sequences.
2. Lack of efficient and safe gene delivery system.
3. Cost of the technology.
4. Some diseases involve multiple genes.
5. Problems with appropriate gene regulation.

Select the correct option.

1. I, III and V only
2. II, IV and V only
3. Ill, IV and V only
4. I, III and IV only

Read the following and answer any four questions from (i) to (v) given below:
Apomixis is a mode of reproduction which does not involve formation of zygote through gametic fusion. In plants, apomixis commonly mimics sexual reproduction but produces seeds without fertilization. There are several methods of atomistic development in seeds. Thee two common ones are recurrent agamospermy and advective embryony.

1. Apomixis is a type of reproduction in plants, in which?

1. Fertilization does not take place.
2. Male nucleus takes part in fertilization.
3. Pollen fusion takes place.
4. Generative nucleus takes part in fertilization.

2. Which of the following statements is incorrect regarding recurrent agamospermy?

1. It is the formation of seed that has an embryo formed without meiosis and syngamy.
2. All the cells of embryo sac are diploid.
3. An embryo develops directly from a diploid cell other than egg like that of nucleus and integument.
4. None of these.

3. Adventive embryony is found in:

1. Citrus.
2. Opuntia.
3. Apple.
4. Both (a) and (b).

4. Formation of embryo directly from diploid egg without fertilization is called:

1. Apospory.
2. Diplospory.
3. Polyembryony.
4. Diploid parthenogenesis.

5. If any somatic cell of sporophyte produces gametophyte without reduction division, it is called:

1. Parthenogenesis.
2. Apogamy.
3. Apospory.
4. Amphimixis.

1. What is an ecological pyramid? Compare the pyramids of energy, biomass and numbers.
2. Write any two limitations of ecological pyramids.

A cross was carried out between a pea plant heterozygous for round and yellow seeds with a pea plant having wrinkled and green seeds.

1. Show the cross in a Punnett square.
2. Write the phenotype of the progeny of this cross.
3. What is this cross known as? State the purpose of conducting such a cross.

The following is the illustration of the sequence of ovarian events (a-i) in a human female.
Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.

1. Write an equation for Verhaulst-Pearl Logistic Growth, where.

N - Population density at a timet E.

r - Intrinsic rate of natural increase.

K - Carrying Capacity.

2. Draw a graph for a population whose population density has reached the carrying capacity.
3. Why is this logistic growth model considered a more realistic one for most animal populations?
4. Draw a growth curve where resources are not limiting to growth of a population.

Define species-area relationship pattern of biodiversity in detail.

Explain any three preventive measures to control microbial infections.

Had Darwin been aware of Mendel’s work, would he been able to explain the origin of variations. Discuss.