Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

List the four important changes, taking place during biotic succession.

The base sequence in one of the strands of DNA is TAGCATGAT

1. Give the base sequence of its complementary strand.
2. How are these base pairs held together in a DNA molecule?
3. Explain the base complementarity rules. Name the scientist who framed this rule.

Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg / L 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Recently a girl baby has been reported to suffer from haemophilia. How is it possible? Explain with the help of a cross.

Briefly classify the extinction processes.

Selecting the recombinants becomes cumbersome when antibiotic is inactive- explain.###How can we distinguish between recombinant and non recombinant plasmid? Illustrate.

What is parturition? Which hormones are involved in induction of parturition?

Name the glandular layer of human uterus.

Why is earthworm considered a farmer's friend? Explain humification and mineralisation occurring in a decomposition cycle.