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

Explain the increase in the numbers of melanic (dark winged) moths in the urban areas of post-industrialisation period in England.

A considerable amount of lactose is added to the growth medium of E.coli. How is the lac operon switched on in the bacteria? Mention the state of the operon when lactose is digested.

Give reason:

1. Population of different species are not capable of breeding with each other.
2. Intraspecific competition is more intense than interspecific competition.
3. Parasites tend to loose certain organs.

Given below are the sequences of nucleotides in a particular mRNA and amino acids coded by it.
UUU AUG UUC GAG UUA GUG UAA
Phe - Met - Phe - Glu - Leu – Val
Write the properties of genetic code that can be and that cannot be correlated from the above given data.

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 modem scientific method and write the procedure that would help in the identification of kinship.

How are the following used in biotechnology?

1. Plasmid DNA
2. Recognition sequence
3. Gel electrophoresis

Explain the following.

1. What is the most common example of pleiotropy in humans?
2. How are the pleiotropic genes useful?

Palaeontological evidence support the theory of organic evolution. Explain with an example.

Explain adaptive radiation with the help of a suitable example.

What is meant by gestation period?