Human Reproduction — BIOLOGY STD 12 Science — Question

Why does the 'insertional inactivation' method to detect recombinant DNA is preferred to 'antibiotic resistance' procedure?

List any four symptoms of Down's syndrome. What is the basis of this disorder?

1. Identify the polarity from a to a', in the above diagram and mention how many more amino acids are expected to be added to this polypeptide chain.
2. Mention the DNA sequence coding for serine and the anticodon of tRNA for the same amino acid.
3. Why are some untranslated sequence of bases seen in mRNA coding for a polypeptide? Where exactly are they present on mRNA?

A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help hand over the dead to their relatives.

Answer the following questions:
Mention any four strategies adopted by flowering plants to prevent self-pollination.

Flow of energy through various trophic levels in an ecosystem is unidirectional and non-cyclic. Explain.

Arrange the following parts of mammary gland in correct order in which milk secreted from the cells of alveoli of lobes reaches the nipple. Lactiferous duct, mammary duct, mammary tubules, mammary ampulla.

Transgenic animals are the animals in which a foreign gene is expressed. Such animals can be used to study the fundamental biological process, phenomenon as well as for producing products useful for mankind. Give one example for each type.

Answer the following questions:
Would Western Ghats ecosystems be less functional if one of its tree frog species is lost forever? Substantiate your answer in the light of hypothesis proposed by Paul Ehrlich.

Name the fluid which protects an embryo.