Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Biodiversity in living beings started about 3 billion years ago. Since then, new species are emerging on the earth and at the same time, their mass extinction is also taking place.
(a) How many phenomena of mass extinction have occurred on Earth and which extinction is in progress at present?
(b) How is the current phenomenon of extinction different from earlier occurrences and explain why.

What is the difference between endemic and exotic species?

What are single cell proteins? What is its significance? Explain with examples

A farmer is advised to sow leguminous seeds inoculated with a bacterial culture that helps in increasing crop yield. Name the bacterium in the culture. How is this bacterium useful to the crop?

A woman of 47 years, delivered an abnormal child with flattened nasal bridge and mouth usually open with a large protruding tongue. Name this genetic abnormality. What causes this condition?

(a) Name the disease in which uncontrolled division of cells occurs, resulting in the formations of tumours. How is this disease detected?
(b) How do the interferons help in controlling the disease?

What is the role of filiform apparatus?

Write a note on the barrier method of family planning.

Name the group of bacteria involved in setting milk into curd. Explain the process they carry in doing so. Write another beneficial role of such bacteria.

Why do people suffer from altitude sickness after reaching the high altitude regions? How does their body acclimatised after a couple of days?