Human Reproduction — BIOLOGY STD 12 Science — Question

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?

What are the two types of nucleases? What is their function?

Name three incurable sexually transmitted diseases and their causative organisms.

What could be the possible explanation for greater vulnerability of amphibians to extinction as compared to other animal groups?

What is hybrid vehicle technology? Explain its advantages.

Prior to a sports event blood & urine samples of sportspersons are collected for drug tests.

1. Why is there a need to conduct such tests?
2. Name the drugs the authorities usually look for.
3. Write the generic names of two plants from which these drugs are obtained.

What are biogeochemical cycles? Mention their two kinds, giving instances of each.

Why didn’t natural selection lead to the evolution of such totally harmless parasites?

Draw a diagram of the structure of a human ovum surrounded by corona radiata. Label the following parts:

1. Ovum.
2. Plasma membrane
3. .Zona pellucida.

Although sexual reproduction is a long drawn, energy-intensive complex form of reproduction, many groups of organism in Kingdom Animalia and Plantae prefer this mode of reproduction.
Give at least three reasons for this.