Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

How bacterial cells are made competent to take up DNA?

Use this key for Questions A-D Key:

1. thymus gland.
2. spleen.
3. lymph node.
4. red bone marrow.

1. Causes differentiation of T-cells.
2. Purifies lymph.
3. Contains red pulp and white pulp.
4. Formation of granular and a granular leukocytes.

"Plasmid is the boon to Biotechnology'. Justify the statement quotaing the production of human insulin as an example.###How did an American Company Eli Lilly use the knowldege of DNA technology to produced human insulin?

Explain the following with reason :

State the Mendelian principle which can be derived from such a cross and not from monohybrid cross.

1. Draw a diagram of a mature embryo sac of an angiosperm and label the following parts in it:

1. Filiform apparatus.
2. Synergids.
3. Central cell.
4. Egg cell.
5. Polar nuclei.
6. Antipodals.

2. Write the fate of egg cell and polar nuclei after fertilisation.

Discuss the types of seeds. Also describe its structure.

The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.

	Name of the Disease	Causative organism	Symptoms
i.	Ascariasis	Ascaris	________
ii.	________	Trichophyton	Appearance of dry, scaly lesions on various parts of the body.
iii.	Typhoid	________	High fever, weakness, headache, stomach pain, constipation.
iv.	Pneumonia	Streptococcus pneumoniae	________
v.	________	Rhino viruses	Nasal congestion and discharge, sorethroat, cough, headache.
vi.	Filariasis	________	Inflammation in lower limbs.

1. Mention the contributions of the following scientists:

1. Maurice Wilkins and Rosalind Franklin.
2. Erwin Chargaff.

2. Draw a double-stranded dinucleotide chain with all the four nitrogen bases. Label the polarity and the components of the dinucleotide.