Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Mention the chemical nature of an antibody and name the type of cells they are produced by. Write the difference between active and passive immune responses on the basis of antibodies.

Study the diagram given below and answer the following questions:

1. Why have DNA fragments in band 'D' moved farther away in comparison to those in band 'C'?
2. Which is the anode end, A or B?
3. What is the role of the matrix in this experiment?
4. How are the separated DNA fragments visualised?

Explain the steps involved in the production of genetically engineered insulin. Name the source from which insulin was extracted earlier. Why is this insulin no more in use by diabetic people?

In cattle, hornless (H) is dominant over horned (h) and black (B) is dominant over red (b). Consider that these two pairs of genes assort independently.

1. What proportion of the offspring from the cross, BbHh x bbhh, would be black and hornless?
2. From the cross Bbhh x Bbhh, how many will be:

1. Black and horned.
2. Red and horned.

List any four symptoms of Down's syndrome. What is the basis of this disorder?

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20 mg/L, 8 mg/L and 400 mg/L respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Match Column I with Column II.

S. No.	Column I	S. No.	Column II
A.	Acrosome	1.	Motility of sperm towards the egg.
B.	Head	2.	Powerhouse of the sperm; contains a number of mitochondria.
C.	Tail	3.	Contains the genetic material.
D.	Middle piece	4.	Contains enzymes to dissolve egg envelopes.

What are the consequences of population explosion?

Where is an operator' located in a prokaryotic DNA? How does an operator regulate gene expression at transcription level in a prokaryote? Explain.

A schematic diagram of matured human insulin is given below:

How is the process of its formation naturally in the human body different from that of its formation by rDNA technology? Explain.