Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Biology

One of the parents of a cross has mutation in its mitochondria. In that cross, that parent is taken as a male. During segregation of F2 progenies that mutation is found in ______.

In split genes, the coding sequence are called ______.

Rate of mutation is affected by ______.

The correct sequence of gene expression is:

1. Formation of the primary transcript
2. Regulation of splicing
3. Transport of mRNA from the nucleus to the cytoplasm
4. Translation

The term gene was coined by ______.

The transcription unit is represented in the diagram given below.

Identify site (i), factor (ii), and Enzyme (iii) responsible for carrying out the process.

How do normal cells get transformed into cancerous neoplastic cells? Elaborate giving three examples of inducing agent.

Given below are the events that are observed in an artificial hybridization programme. Arrange them in the correct sequential order in which they are followed in the hybridisation programme.

1. Re-bagging
2. Selection of parents
3. Bagging
4. Dusting the pollen on stigma
5. Emasculation
6. Collection of pollen from male parent

How are alleles of particular gene differ from each other? Explain its significance.

How does a mutagen induce mutation? Explain with example.

Define a cistron. Giving examples differentiate between monocistronic and polycistronic transcription unit.

Do you think that the alternate splicing of exons may enable a structural gene to code for several isoproteins from one and the same gene? If yes, how? If not, why so?

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?