Respiration and Circulation — BIOLOGY STD 12 Science — Question

We can see and enjoy the beautiful colours of the nature after the sunrise.

For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chormogenic substrate.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

Explain how Ti plasmid of Agrobacterium tumefaciens acts as a vector for transferring genes to plants?

Carbon monoxide poisoning.

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.

1. Draw a labelled diagram of L.S. of an embryo of grass (any six labels).
2. Give reason for each of the following:

1. Anthers of angiosperm flowers are described as dithecous.
2. Hybrid seeds have to be produced year after year.

Write an account of hormones secreted by the thyroid gland.

Types of endocrine systems.

Trace the path of spermatozoa from the testes upto the ejaculatory duct only.
OR
Schematically represent and explain the events of spermatogenesis in humans.

(i) Provide tissues for human transplants
(ii) Cancer research
(iii) E. coli hygromycin resistant gene
(iv) Supply of factor IX.

Column A: (Transgenic animal)	Column B : (Application)
(a) Transgenic mice	——————
(b) Transgenic cattle	——————
(c) Pig clones	——————
(d) Transgenic fish	——————