Model Paper 3 — BIOLOGY STD 12 Science — Question

The graph given below shows the variation in the levels of ovarian hormones during various phases of menstrual cycle:

Specify the source of the hormone marked in the diagram.

Rose plants produce large, attractive bisexual flowers but they seldom produce fruit. On the other hand, Lady’s finger produces plenty of fruits. Analyse the reasons for failure of fruit formation in rose.

Describe in detail about food chain and food web existing in an ecosystem.

Describe the functions of the following:
Seminiferous tubules.

Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.

The graph given below shows the variation in the levels of ovarian hormones during various phases of menstrual cycle:

Reason out why A peaks before B.

What is a biogeochemical cycle. What is the role of the reservoir in a biogeochemical cycle. Give an example of a sedimentary cycle with reservoir located in earth’s crust.

Enumerate the events in the ovary of a human female during:

Follicular phase.

(a) Draw the diagram of human sperm and label the cellular component. Also mention the functions of three components.
(b) Where does the head of sperm remain embedded in spermatogenesis.

A child suffering from thalassemia is born to a normal couple. But the mother is being blamed by the family for delivering a sick baby.

1. What is Thalassemia?
2. How would you counsel the family not to blame the mother for delivering a child suffering from this disease? Explain.
3. List the values your counselling can propagate in the families.