Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

In an ecosystem dominated by trees, the pyramid (of numbers) is ______ type.

Distinguish between upright and inverted pyramids.

Distinguish between a food chain and a food web.

Describe with examples of pyramids of number and biomass.

Discuss briefly Defunct ships and e-wastes.

Discuss briefly the following:

Municipal solid wastes

In an agricultural field there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly:

1. White rust
2. Leaf and stripe rust
3. Black rot
4. Jussids

Recommend the varieties of crops the farmers should grow to get rid of the existing problem and thus improve the crop yield.

How does the application of the fungal genus, Glomus, to the agricultural farm increase the farm output? 

1. What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
2. If the advise is not followed by the patient, there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.

How does the application of cyanobacteria help improve agricultural output?

Why is follicular phase in the menstrual cycle also referred as proliferative phase? Explain.

Explain the events that occur in a graafian follicle at the time of ovulation and thereafter.

Draw a graafian follicle and label antrum and secondary oocyte.

State one characteristic of millets that has been improved as a result of hybrid breeding so as to produce high yielding millet crops.

List the two steps the classical plant breeding involves.

Write the complete name of the diagnostic test for AIDS.

Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.

1. Recommend two microbes that can enrich the soil with nitrogen.
2. Why do leguminous crops not require such enrichment of the soil? 

Explain menstrual cycle in human females.

How can the scientific understanding of the menstrual cycle of human females help as a contraceptive measure?

Explain the ovarian and uterine events that occur during a menstrual cycle in a human female under the influence of pituitary and ovarian hormones respectively.