Evolution — BIOLOGY STD 12 Science — Question

Write the name of any one water-borne disease. Explain the measures to prevent water-borne diseases.

What is ecosystem? Mention its biotic components. Draw a diagram of four trophic levels food chain for a grassland ecosystem.

What is Pulse Polio Programme of Government of India? What is OPV? Why is it that India is yet to eradicate Polio?

Answer the following questions:
Draw a diagrammatic sectional view of the female reproductive system of human and label the parts:

1. Where the secondary oocytes develop.
2. Which helps in collection of ovum after ovulation.
3. Where fertilisation occurs.
4. Here implantation of embryo occurs.

Study the flow chart given below. Name the hormones involved at each stage and explain their role.

a. Why did Hershey and Chase use radioactive ³²P and ³⁵S in their experiments? Explain.
b. Following the experiments conducted by them, write what conclusion did they arrive at and how.

During her tour to a renowned forest, Sakshi saw a highway being constructed, which passes through the middle of the forest. She was unhappy seeing that and on return, she contacted the local eco-club and approached the concerned department to stop the work.

1. What would be the effect on biodiversity, if the highway is constructed?
2. How forests are useful to mankind?
3. What values of Sakshi reflect here?

Explain the post pollination events up to double fertilisation, that occur in an angiosperm.

No evidence was found on a crime scene, other than only a few hair strands. The inspector wants to proceed for DNA fingerprinting, but the amount of DNA is very less.

1. In your opinion what could be the solution to this problem?
2. Write the basic steps of this technique.
3. Name the scientist who developed this technique.
4. What values shown by the inspector?