Strategies for Enhancement in Food Reproduction — BIOLOGY STD 12 Science — Question

Drugs and alcohol give short-term 'relief and long term 'damages'. Discuss.

Define species-area relationship pattern of biodiversity in detail.

Describe the functions of the following:
Seminiferous tubules.

Compare the processes of DNA replication and transcription in prokaryotes.

Draw a labelled diagram of L.S. of a flower to show the growth of pollen tube reaching egg apparatus.

Describe female reproductive system.

Sometimes due to biotic/ abiotic factor the climax remain in a particular seral stage (pre climax) without reaching climax. Do you agree with this statement. If yes give a suitable example.

Comment on the following diagrams: A, B, C, D, G, P, Q, R, S are species.

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

1. Work out a dihybrid cross upto F, generation between pea plants bearing violet-coloured axial flowers and white-coloured terminal flowers. Give their phenotypic ratio.
2. State the Mendel's law of inheritance that was derived from such a cross.