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

"Post-industrialization, the population of melanised moth increased in England at the expense of white-winged moths." Provide explanations.

Transplantation to save certain patients often fails due to rejection by the patient. What is transplantation? Which type of immune response is responsible for such rejections?

Rahul introduced Ronit to his uncle and told him that Ronit is pursuing a course in biotechnology in America.
His uncle had never heard of this term earlier and was curious to know about this term. Ronit pointed towards a big tree at the base of which were present numerous tumour-like structures and said that this is the example of natural biotechnology:

1. What is biotechnology?
2. How these crown gall tumours are formed?
3. What are the values shown by Rahul's uncle?

Sperms have a tail, whereas eggs do not. Why?

Draw a well labelled diagram of mature graafian follicle.

Ornithologists observed decline in the bird population in an area near a lake after the setting of an industrial unit in the same area. Explain the cause responsible for the decline observed.

Describe the experiment that helped Louis Pasteur to dismiss the theory of spontaneous generation of life.

What is Bt? How does it create resistance to the insect?

In the 1950s, there were hardly any mosquitoes in Delhi. The use of pesticide DDT on standing water killed their larvae. It is believed that now there are mosquitoes because they evolved DDT resistance through the interaction of mutation and Natural selection. Pointwise, state in a sequence how that could have happened.

Name the important mammary gland secretions that help in resistance of the new born baby.