Human Health and Diseases — BIOLOGY STD 12 Science — Question

List the various abiotic environmental factors.

Hormones are called chemical messengers and regulators. Explain.

Enlist the five main types of growth regulators and state the role of abscissic acid in plants.

State and explain with the help of a cross, the law of segregation as proposed by Mendel.

1. Name the respective forms in which the malarial parasite gains entry into

1. Human body and
2. Body of female Anopheles.

2. Name the respective hosts and the sites in their body, where the sexual and asexual reproduction of malarial parasite occur.
3. What is meant by:

1. Addiction
2. Dependence with reference to drugs/ alcohol?

Your school has been selected by the Department of Education to organise and host an interschool seminar on "Reproductive Health - Problems and Practices". However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is "too embarrassing."
Put forth four arguments with appropriate reasons and explanation to justify the topic to be very essential and timely.

For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.

Differentiate between: Oestrus and Menstrual cycles.

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.

Give the central dogma of protein synthesis. Explain the process of translation.