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

Grasshopper is an example of XO type of sex determination in which the males have ______.

In XO type of sex determination ______.

Which of the following combination of chromosome numbers represents the correct sex determination pattern in honey bees?

In humans, males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?

Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.

Which of the following are the reason(s) for Rheumatoid arthritis? Choose the correct option.

1. The ability to differentiate pathogens or foreign molecules from self-cells increases.
2. Body attacks self cells
3. More antibodies are produced in the body
4. The ability to differentiate pathogens or foreign molecules from self-cells is lost

Explain the process of binding of ribosomal units to mRNA during protein synthesis.

Given below is a stretch of DNA showing the coding strand of a structural gene of a transcription unit?

5’-ATG ACC GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TAA-3’

1. Write the corresponding template strand and the mRNA strand that will be transcribed, along with its polarity.
2. If GUA of the transcribed mRNA is an intron, depict the sequence involved in the formation of mRNA/the mature processed hnRNA strand.
   i. In a bacterium
   ii. In humans
3. Upon translation, how many amino acids will the resulting polypeptide have? Justify.

Name the primary lymphoid organs.

The following is well-known abbreviation, which have been used in this chapter. Expand to its full form:

MALT

Which of the following glands is large-sized at birth but reduces in size with ageing?  

In our society a woman is often blamed for not bearing male child. Do you think it is right? Justify.

Which of the following is not a lymphoid tissue?

Where are B-cells and T-cells formed? How do they differ from each other?

What would happen to the immune system if the thymus gland is removed from the body of a person?

Lymph nodes are secondary lymphoid organs. Explain the role of lymph nodes in our immune response.

What does the term `memory' of the Immune system mean?

Epithelial lining of our intestine is considered as secondary lymphoid organ. Justify the statement.

Explain the role of Primary and Secondary Lymphoid organs with the help of suitable examples.

Name the secondary lymphoid organs.