Human Health and Disease — BIOLOGY STD 12 Science — Question

i. Compare the mechanism of sex determination in humans with that of honey bees, with respect to chromosome number.
ii. How is the gamete formation comparable in the above two cases?

When Morgan conducted a dihybrid cross on Drosophila like Mendel did with pea plants, the F, ratios deviated significantly from that of Mendels F, ratio. Write the explanation Morgan and his group gave for the observations they obtained from their experiments.

Or

Morgan carried out several dihybrid crosses in Drosophila and found F, ratios deviated very significantly from the expected Mendelian ratio. Explain his findings with the help of an example.

Solar energy trapped by green plants finally returns to the environment. Comment.

What is artificial selection? Do you think it affects the process of natural selection? How?

Write a short note on advantages of seeds.

The study of:

1. Fossils of dinosaurs.
2. Forelimbs of cheetah, bat and human.
3. Thorns of Bougainvillea and tendril of Cucurbita.

Show that evolution of life forms has indeed taken place on earth. Explain.

Explain the development of embryo after fusion in dicot plants. Development of endosperm is advanced in comparison of development of embryo. Explain.

ATGGAGTACTTCGTGTGA is the coding strand of DNA in a transcription unit.

1. Write the mRNA transcribed from this DNA segment.
2. How many amino acids does it code for? Why?

Where does triple fusion take place in a flowering plant? Why is it so called? Mention its significance.

Describe the naming of the restriction enzymes with an example.