List of top Biology Questions asked in CBSE CLASS XII

How is triple fusion achieved in these plants ?

State any two criteria for determining biodiversity hotspots.

Describe the Species-Area relationship as observed by Alexander von Humboldt, for a wide variety of taxa in nature.

Describe what is meant by downstream processing.

Explain the working of a simple stirred-tank bioreactor.

Describe how human insulin is produced using the techniques of genetic engineering.

Explain how human pro-insulin is processed in the cell to become a fully mature functional insulin.

Name and explain the role of inner and middle walls of the human female uterus.

Write the location and function of fimbriae in human female.

Explain the beneficial role of the following, produced as a result of the processes of biotechnology, to mankind:
(α) −1−antitrypsin

Explain the beneficial role of the following, produced as a result of the processes of biotechnology, to mankind:
Cow named Rosie

What do you mean by activated sludge in an STP?

Explain the biological treatment of the major part of the sludge transferred from the large aeration tank into the anaerobic sludge digesters before its final release into the natural water bodies.

If the birds have 18 pairs of autosomal chromosomes and a pair of sex chromosomes, fill in the blanks (i), (ii), (iii) and (iv) in the table given below. (Use symbols Z and W for sex chromosomes).

Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with the help of any two examples.

State any two criteria for determining biodiversity hotspots

Name the main type of antibody produced by the immune system in response to this disease.

Which two main inflammation-causing chemicals are produced by the mast cells in such an immune response?

Many children in the metro cities are suffering from a very common exaggerated response of the immune system to certain weak antigens in the air. (i) What is the term used for the above mentioned disease?

Arrange the given important steps of decomposition in their correct order of occurrence in the breakdown of complex organic matter and explain the fourth step in the process.
\( \fbox{Catabolism}\) \(\fbox{Leaching} \fbox{Fragmentation} \fbox{Mineralisation} \fbox{Humification}\)

Assertion (A): In some species of asteraceae and grasses, seeds are formed without fertilization.
Reason (R): Formation of fruit without fertilization is called parthenocarpy.

Expand PID. Name any two common viral infections transmitted through sexual contact in human females.

The animals that evolved into the first amphibians during evolutionary history were:

Assertion (A): In humans, filariasis is characterized by inflammation of the lower limbs.
Reason (R): Filarial worm usually lives in the lymphatic vessels of the lower limbs.

Bacteria growing anaerobically on cellulosic material produce large amounts of which gases? Select the correct option.