Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Explain the different ways of diagnosing cancer.

Describe the functions of the following:
Seminiferous tubules.

Explain the process of transcription in a prokaryote.
OR
Describe the process of transcription in a bacterium.

What are recombinant DNA vaccines? Give two examples of such vaccines. Discuss their advantages.

Shown above is the electron micrograph (EM) picture of 'beads-on-string'.

1. Identify and explain the detailed structure of a bead with the help of a labelled diagram.
2. Describe the packaging of 'beads-on-string'in a eukaryotic cell.

Differentiate between an inbred line and a hybrid variety of crop. Explain the steps involved in the production of the hybrid variety.

Answer the following questions:
How is ‘oogenesis’ markedly different from ‘spermatogenesis’ with respect to the growth till puberty in the humans?

The biology teacher was explaining about restriction enzymes and came to a point explaining that these enzymes are extracted from bacteria and are called as molecular scissors. Varun got curious and asked some questions for more clarity on the concept to his teacher.

1. From which part of microorganisms are restriction enzymes derived?
2. Why are restriction enzymes called molecular scissors?
3. What if some strands are needed to be cut from within. Would that lead to wastage of DNA?
4. What values are shown by Varun?

Define aneuploidy. How is it different from polyploidy? Describe the individuals having following chromosomal abnormalities.

1. Trisomy of 21st Chromosome.
2. XXY.
3. XO.

For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.