Human Reproduction — BIOLOGY STD 12 Science — Question

1. Draw a pyramid of numbers of a situation, where a large population of insects feeds upon a very big tree. The insects in turn are eaten by small birds, which in turn are fed upon by big birds.
2. Differentiate, giving reason, between the pyramid of biomass of the above situation and the pyramid of numbers that you have drawn.

OR

In a botanical garden of a city there is a huge banyan tree growing on which hundreds of birds and thousands of insects live. Draw the pyramids of numbers and also biomass represented by this community. Comment giving reasons on the two different pyramids drawn.

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.

How bacterial cells are made competent to take up DNA?

Raj was a known sportsman in his school. While returning home he found some unknown miscreants beating a young fellow. He tried to drive them off, but by that time the fellow died of injury. The police arrested Raj and he was put on trial. The judge being convinced by Raj's plea, ordered for DNA fingerprinting reports.

1. What is the basis of DNA fingerprinting?
2. Explain the steps in DNA fingerprinting.
3. Write the applications of DNA fingerprinting.
4. Raj's fingerprints on the dead body were sufficient to convict him but the judge asked for authentic proof. What values can be observed by the judge?

Answer the following questions:
Why is banana called a parthenocarpic fruit? Would you call banana a true fruit? Give reason in support of your answer.

Mention three applications and future challenges of human genome project.

Study the schematic representation of the genes involved in the lac operon given below and answer the questions that follow.

1. Identify and name the regulatory gene in this operon. Explain its role in 'switching off the operon.
2. Why is lac operon's regulation referred to as negative regulation?
3. Name the inducer molecule and the products of the genes 'z' and 'y of the operon. Write the function of these gene products.

Categorise the following plants into hydrophytes, halophytes, mesophytes and xerophytes. Give reasons for your answers.

1. Salvinia.
2. Opuntia.
3. Rhizophora.
4. Mangifera.

Answer the following questions:
Four children with four different blood groups are born to parents where the mother has blood group ‘A’ and the father has blood group ‘B’. Work out the cross to show the genotypes of the parents and all four children.

What essential features must be present in a cloning vector?