Human Health and Disease — BIOLOGY STD 12 Science — Question

'Analysis of age pyramids for human population can provide important inputs for long-term planning strategies'. Explain.

Describe the advantages for keeping the ecosystems healthy.

Mention the biological factors of ecology.

A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.

Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.

What is the role of Biotechnology in crop improvement?

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

Plants having foreign genes in their genome through genetic engineering are called transgenic plants. Genes can be incorporated either through a vector or through direct introduction of DNA. Bt cotton is a genetically modified organism which is pest resistant. It contain gene cry I Ac and cry II Ab of Bacillus thuringiensis. It is used to control lepidopterans, coleopterans and dipterans. Bt cotton can resist cotton bollworm and produce higher yields. Cry gene produces cry protein or Bt toxin. It is an endotoxin which remains as protoxin in plants and converted to active toxin after getting ingested by the insects. Alkaline pH of the insect gut solubilises the protein crystals, the activated toxin creates pores to the mid guts wall of the insects which cause them to death.

1. Bt cotton crops are:

1. Fungal resistant.
2. Insect resistant.
3. Drought resistant.
4. All of these.

2. Cotton bollwonns are killed by the protein encoded by the gene:

1. cry I Ac
2. cry I Ab
3. cry I Ab
4. Both (a) and (c).

3. Which of the following is not an advantage of GM crops?

1. GM plants enhance nutritional value of food.
2. GM plants are more tolerant to abiotic stresses.
3. GM plants have helped to reduce post harvest losses.
4. GM plants can cause gene transfer to non-target plant species.

4. Bacillus thuringiensis is a:

1. Air borne bacteria.
2. Soil borne bacteria.
3. Soil borne fungus.
4. Food borne bacteria.

5. Assertion: Cotton bollworms are killed by ingesting the leaves of the transgenic plant.

Reason: Bt toxin binds with the midgut wall of the insect and make pores in them.

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.

Represent diagrammatically the steps in amplification of a DNA segment. Who designed the process?

Discuss the principle and work of PCR.###Describe diagrammaticaly the different steps of PCR.###Write a note on PCR.###How is gene of interest amplified by using PCR?###Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.

Describe in detail the human reproductive system.