Reproduction in Lower and Higher Plants — BIOLOGY STD 12 Science — Question

1. Explain the role of regulatory gene, operator, promoter and structural genes in lac operon, when E.coli is growing in a culture medium with the source of energy as lactose.
2. Mention what would happen, if lactose is withdrawn from the culture medium.

OR
Describe how the lac operon operates both in the presence and absence of an inducer in E.coli.

1. How is artificial hybridisation considered a crop improvement programme?
2. Explain the process of artificial hybridisation, if

1. Female parent bears bisexual flowers.
2. Female parent bears unisexual flowers.

Types of mutations.

Enumerate the events in the ovary of a human female during:
Luteal phase of menstrual cycle.

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?

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

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

Give the equations of amino acid synthesis.

Distinguish between Parasitism and Mutualism

Distinguish between Hibernation and Aestivation.

Enumerate the points that have to be considered for successful bee-keeping.