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

How is DNA isolated in purified form from a bacterial cell?

OR

List the four steps to isolate DNA from a bacterium.

How is Darwin's concept of evolution different from that of de Vries?

OR

How is mutation explained by Hugo de Vries different from the Darwinian variations?

OR

How do Darwin and de Vries differ in their views on the mechanism of evolution of life on earth?

Define the terms and give one example for each: Camouflage

What do you understand by population density on which factor it dependent?

Pick out the untranslated regions from the following mRNA and mention their location.
5'-ACGUCGAUGGCGUUUUAGGAGGAA-3'

Identify a, b, c and d in the following table with reference to birth control?

Method	Example
a	Diaphragm
Female sterilisation	b
c	Saheli
d	Cut

In an experiment, the slope of regression (Z) is 0.2 and in another experiment the value obtained is 1.2. Explain the two situations in respect of species area relationships.

Draw a diagram of LS of a pistil showing growth of pollen tube.

“Pollen grains in wheat are shed at 3-celled stage while in peas they are shed at 2-celled stage.” Explain. Where are germ pores present in a pollen grain?

A vector is engineered with three features which facilitate its cloning within the host cell. List the three features and explain each one of them.