Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

The pedigree chart given below shows a particular trait which is absent in parents but present in the next generatoin irrespective of sexes. Draw your conclusion on the basis of the pedigree.

A normal visioned woman, whose father is colour blind, marries a normal visioned man. What would be probability of her sons and daughters to be colour blind? Explain with the help of a pedigree chart.

What are the functions of methylated guanasine cap?

What are the functions of poly-A “tail” in a mature on RNA?

Give an account of post transcriptional modifications of a eukaryotic mRNA.

Cancer causing genes are called ______.

In malignant tumors, the cells proliferate, grow rapidly and move to other parts of the body to form new tumors. This stage of disease is called ______.

AIDS is caused by HIV. Among the following, which one is not a mode of transmission of HIV?

The immune system of a person is suppressed. In the ELISA test, he was found positive to a pathogen.

1. Name the disease the patient is suffering from.
2. What is the causative organism?
3. Which cells of body are affected by the pathogen?

If a patient is advised Anti Retroviral Therapy, which infection is he suffering from? Name the causative organism.

In the given flow diagram, the replication of retrovirus in a host is shown. Observe and answer the following questions.

Fill in (1) and (2)

Why is the virus called retrovirus?

Can the infected cell survive while viruses are being replicated and released?

Give the full form of CT and MRI. How are they different from each other? Where are they used?

What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?

What are the methods of cancer detection? Describe the common approaches for treatment of cancer.

Study the Pedigree chart given below and answer the questions that follow:

Symbols used in the given Pedigree Chart are as follows:

	Carrier male
	Affected male
	Normal male
	Carrier female
	Affected female
	Normal female

(a) On the basis of the inheritance pattern exhibited in this pedigree chart, what conclusion can you draw about the pattern of inheritance?

(b) If the female is homozygous for the affected trait in this pedigree chart, then what percentage of her sons will be affected?

(c) Give the genotype of offspring 1, 2, 3 and 4 in III generations.

OR

(c) In this type of inheritance pattern, out of male and female children which one has less probability of receiving the trait from the parents? Give a reason.

Observe the segment of mRNA given below.

(a) Explain and illustrate the steps involved to make fully processed hnRNA?

(b) Gene encoding RNA Polymerase I and III have been affected by mutation in a cell. Explain its impact on the synthesis of a polypeptide, stating the reasons.

Why is a malignant tumour considered to be more damaging than a benign tumour? Explain.

Name any two techniques used to detect the cancer of internal organs and write about any one of them.

Immunotherapy these days is one of the most efficient ways of treatment of cancer. The therapy involved activates the immune system and destroys the tumour.

1. Write an example of one such biological response modifier used in immunotherapy.
2. Why do patients need such substances if immune system is already working in body?
3. State what is 'Contact inhibition'.

What should be the genotype of the indicated member?