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

Haplodiploidy is found in ______.

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.

In the metropolitan cities of India, many children are suffering from allergy/asthma. What are the main causes of this problem. Give some symptoms of allergic reactions.

A person shows strong unusual hypersensitive reactions when exposed to certain substances present in the air. Identify the condition. Name the cells responsible for such reactions. What precaution should be taken to avoid such reactions.

Compare the life style of people living in the urban areas with those of rural areas and briefly describe how the life style affects their health.

During a field trip, one of your friend in the group suddenly became unwell, she started sneezing and had trouble in breathing. Name and explain the term associated with such sudden responses. What would the doctor recommend for relief?

Many people experience allergic symptoms of sneezing or wheezing on exposure to certain substances in the environment. Give two examples of such substances. Which type of antibodies are produced by the body in response to these substances? Mention the role of mast cells in this kind of allergic response.

A boy developed some allergic reactions when he straight entered into his air conditioned room after a game of football outside his house. Write any two symptoms that could be noticed in such condition. How does our body combat such conditions?

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.

Match the following and choose the correct option.

The correct matches is;

Match the following and choose the correct option.

Match the following and choose the correct option.

The correct match is:

Match the following and choose the correct option.

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

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