Human Reproduction — BIOLOGY STD 12 Science — Question

Draw a labelled diagram and describe the clover leaf pattern model of t-RNA.

Define decomposition and describe the processes and products of decomposition.

i. What is the chemical name of smack? Why is the consumption of smack considered as an abuse?
ii. Name the source plant and one effect of the following drugs on the human body:
1. Marijuana
2. Cocaine
3. Morphine

Recombinant DNA vectors are typically attenuated viruses or bacteria that are unrelated to the pathogen of interest.
These vectors can penetrate human cells and often replicate within them, but do not cause disease in the host.


i. A recombinant vector with a gene of interest inserted within the gene of a-galactosidase enzyme, is introduced into a bacterium. Explain the method that would help in selection of recombinant colonies from non-recombinant ones.
ii. Why is this method of selection referred to as insertional inactivation?

Write a short note on electronic waste. List the various sources of e-wastes and the problems associated with its disposa

Given below is the diagram of a human ovum surrounded by a few sperms. Observe the diagram and answer the following questions:
Compare the fate of sperms shown in the diagram.

What are the advantages of tissue culture?

Describe in detail the various levels of biodiversity.

Work out a typical Mendelian dihybrid cross and state the law that he derived from it.

1. Describe the characteristics a cloning vector must possess.
2. Why DNA cannot pass through the cell membrane? Explain. How is a bacterial cell made ‘competent’ to take up recombinant DNA from the medium?