Science (English Medium) Class 12 - CBSE Important Questions

Write the location and function of the Sertoli cells in humans.

Draw a graafian follicle and label antrum and secondary oocyte.

Draw a diagram of a mature human sperm. Label any three parts and write their functions.

Draw a label diagram.
Draw a labeled diagram to show the interrelationship of four accessory ducts in a human male reproductive system. 

Draw a label diagram.
Draw a sectional view of the human ovary showing the different stages of developing follicles, corpus luteum, and ovulation.

Explain the menstruation phases in the menstrual cycle of a human female.

‘A proper understanding of the menstrual cycle can help immensely in family planning.’ Do you agree with the statement? Provide reasons for your answer.

Assertion: Functional ADA cDNA genes must be inserted in the lymphocytes at the early embryonic stage.

Reason: Cells in the embryonic stage are mortal, differentiated and easy to manipulate.

Draw a diagram showing human foetus within the uterus and label any four, parts in it.

After a brief medical examination a healthy couple came to know that both of them are unable to produce functional gametes and should look for an ‘ART’ (Assisted Reproductive Technique). Name the ‘ART’ and the procedure involved that you can suggest to them to help them bear a child.

What is amniocentesis and why there is a statutory ban on it?

Explain the principle on which the AIDS diagnostic test works.

Name the type of genetic material present in AIDS causing pathogen.

Name and explain a surgical contraceptive method that can be adopted by the male partner of a couple.

The following is well-known abbreviation, which have been used in this chapter. Expand to its full form:

NACO

Explain the mechanism of sex determination in birds.

Name the greenhouse gases that contribute to global warming.

Answer the following question.
Two children, A and B aged 4 and 5 years respectively visited a hospital with a similar genetic disorder. The girl A was provided enzyme-replacement therapy and was advised to revisit periodically for further treatment. The girl, B was, however, given a therapy that did not require revisit for further treatment.

Name the ailments the two girls were suffering from?

Assertion: When the two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations is much higher than the nonparental type.

Reason: Higher parental gene combinations can be attributed to crossing over between two genes.

By using Punnett square depict the genotypes and phenotypes of test crosses (where green pod colour (G) is dominant over yellow pod colour (g)) in Garden pea with unknown genotype.