Human Health and Disease — BIOLOGY STD 12 Science — Question

A woman with blood group “A” marries a man with blood group “O”. Discuss the possibilities of the inheritance of the blood groups in the following starting with “yes” or “no” for each:

1. They produce children with blood group “A” only.
2. They produce children some with “O” blood group and some with “A” blood group.

Polymerase chain reaction (PCR) is a laboratory technique used to amplify DNA sequences. The method involves using short DNA sequences called primers to select the portion of the genome to be amplified. The temperature of the sample is repeatedly raised and lowered to help a DNA replication enzyme copy the target DNA sequence. The technique can produce a billion copies of the target sequence in just a few hours.

i. List the three steps involved in Polymerase Chain Reaction (PCR).
ii. Name the source organism of Taq polymerase.
iii. Explain the specific role of this enzyme in PCR.

What will be the P/ R ratio of a climax community and a pioneer community. What explanation could you offer for the changes seen in P/ R ratio of a pioneer community and the climax community.

Explain the ovarian and uterine events that occur during a menstrual cycle in a human female, under the influence of Pituitary and Ovarian hormones respectively.

What does the lac operon consist of? How is the operator switch on and off in the expression of gene in this operon? Explain.

In what way anaerobic sludge diagestion is important in sewage treatments?

Describe the disease 'AIDS' under the following headings :
(i) Name of the pathogen
(ii) Name of the test to confirm the disease
(iii) Four main symptoms of the disease
(iv) Four measures of prevention
(v) Picture of viral replication.

a. Why did Hershey and Chase use radioactive ³²P and ³⁵S in their experiments? Explain.
b. Following the experiments conducted by them, write what conclusion did they arrive at and how.

The following is the illustration of the sequence of ovarian events (a-i) in a human female.

Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.

Answer the following questions:
Seeds offer several advantages to angiosperms. Describe any three such advantages.