Science (English Medium) Class 12 - CBSE Important Questions

The wall layer of microsporangium, which nourishes the pollen grain, is ______.

Explain the menstrual phase in a human female. State the levels of ovarian and pituitary hormones during this phase.

Describe the roles of pituitary and ovarian hormones during the menstrual cycle in a human female.

How is 'oogenesis' markedly different from 'spermatogenesis' with respect to the growth till puberty in the humans?

Draw a sectional view of human ovary and label the different follicular stages, ovum and Corpus luteum.

When and where do chorionic villi appear in humans?

Draw a diagrammatic sectional view of the female reproductive system of human and label the parts

(i) where the secondary oocytes develop

(ii) which helps in collection of ovum after ovulation

(iii) where fertilization occurs

(iv) where implantation of embryo occurs.

Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females

The following is the illustration of the sequence of ovarian events (a − i) in a human female

(i) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.

(ii) Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.

(iii) Explain the changes that occur in the uterus simultaneously in anticipation.

(iv) Write the difference between ‘c’ and ‘h’.

(v) Draw a labeled sketch of the structure of a human ovum prior to fertilization.

During the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?

Describe the changes that occur in ovaries and uterus in human female during the reproductive cycle.

Explain the development of a secondary oocyte (ovum)  in a human female from the embryonic stage upto its ovulation. Name the hormones involved in this process.

Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present.

Write the location and functions of the following in human testes :

Leydig cells

Draw a labelled diagram of the female reproductive system.

Name the function of the following:

Corpus luteum

Name the functions - Acrosome of sperm.

Where in the fallopian tube does fertilization occur in humans?

Describe the development of a fertilized ovum upto implantation.

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