Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

What is corona radiata?

During an excursion to a botanical garden, the teacher shows an old tree, which was on the verge of extinction. As soon as the teacher advanced with the students, some enthusiastic students climbed up the tree and started cutting the branches, collecting its leaves as precious collection. Rajesh instead took photographs of the tree from various angles. The boys mocked at Rajesh while the teacher appreciated him.

1. How can biodiversity be conserved?
2. What international initiatives were taken to conserve biodiversity?
3. What values did Rajesh possess?

It has been recorded that the temperature of the earth’s atmosphere has increased by 0.6°C.

1. What has caused this increase?
2. Explain its consequences.

Explain: Population density

Males in whom testes fail to descend to the scrotum are generally infertile. Why?

Name the kind of organisms which constitute the pioneer community of xerarch and hydrarch successions respectively.

Explain the process of pollination in Vallisneria. How is it different in water-lily, which is also an aquatic plant?

Parthenocarpy and apomixis have been observed in some plants. Give an example of each. State a similarity and a difference observed between the two processes.

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.

Mention the advantages of selecting pea plant for experiment by Mendel.