Respiration and Circulation — BIOLOGY STD 12 Science — Question

An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?

Write important features of a sedimentary cycle in an ecosystem.

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?

Differentiate between the following:mRNA and tRNA.

Name the hormone secreted by the heart. What is its function?

In ecosystem the movement of nutrients is called cycling while the term 'flow' used for energy. Why?

Describe diagrammatic representation of age structure showing declining population.

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.

State what is apomixis. Comment on its significance. How can it be commercially used?

How does industrial melanism in Biston betularia illustrate the action of natural selection? Explain briefly.