Reproduction in organisms — BIOLOGY STD 12 Science — Question

What is the principle of Gel electrophoresis? Name the compound used for staining DNA to be used in recombinant technology. What is the colour of such stained DNA?

Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship.

Bring out the relation between BOD, microorganisms and the quantity of biodegradable organic matter.

1. Name the organic material exine of the pollen grain is made up of. How is this material advantageous to pollen grain?
2. Still it is observed that it does not form a continuous layer around the pollen grain. Give reason.
3. How are 'pollen banks' useful?

During extraction of a tooth, the dentist gives an injection of Anaesthesia to the patient before extraction. Is the action potential generated? How does the local anaesthesia work? What is the effect of pain killer on the nervous system?

What is reproductive isolation? DEscribe any two types each of pre - mating and post  -mating isolating mechanisms.

Draw a labelled diagrammatic view of human male reproductive system.

Name the three RNA polymerases found in eukaryotic cells and mention their functions.

What are stem cells in a human embryo?

Apart from plants and animals, microbes form a permanent biotic component in an ecosystem. While plants have been referred to as autotrophs and animals as heterotrophs, what are microbes referred to as? How do the microbes fulfil their energy requirements?