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

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?

Write the types of sex-determination mechanisms the following crosses show. Give an example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ

Differentiate between male and female heterogamety.

Explain the mechanism of sex determination in birds.

Differentiate between ‘ZZ’ and ‘XY’ type of sex-determination mechanisms.

Explain the mechanism of 'sex determination' in birds. How does it differ from that of human beings?

Why did T. H. Morgan select Drosophila melanogaster to study sex linked genes for his lab experiments ?

What is heterogamety ? Explain the mechanism of sex determinatin in Drosophila.

XO type of sex determination and XY type of sex determination are examples of ____________.

How is sex determined in human beings?

Sex is determined in human beings ______.

The ‘X’ body of Henking was observed in ______.

ZZ/ZW type of sex determination is seen in ______.

Which of the following is incorrect regarding ZW - ZZ type of sex determination?

Number of autosomes present in liver cells of a human female is ______.

Haplodiploidy is found in ______.