Organisms and Populations — BIOLOGY STD 12 Science — Question

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

Answer the following questions:
Describe the endosperm development in coconut.

Identify the type of growth curves observed in plants.

Both Down’s syndrome and Turner’s syndrome are examples of chromosomal disorders. Cite the differences between the two.

What are the preventive measures against Global warming?

1. A DNA segment has a total of 2,000 nucleotides, out of which 520 are adenine containing nucleotides. How many purine bases this DNA segment possesses?
2. Draw a diagrammatic sketch of a portion of DNA segment to support your answer.

Distinguish between: Passive absorption of Minerals and Active absorption of minerals

Levels of biodiversity

Ram saw a farmer spraying some chemicals on flowers. On asking farmer, he came to know that this act will lead to the formation of fruits without fertilisation. Ram thought that fruits developed in this way are not good to eat as chemicals are sprayed on it.
Next day, he asked his biology teacher about it, who explained him everything.

1. What chemicals were sprayed by the farmer?
2. Give difference between such a spray and usual pesticide spray?
3. What is parthenocarpy? Give its types.
4. What values are shown by Ram?

Draw the following diagrams related to human reproduction and label them.

1. The zygote after the first cleavage division.
2. Morula stage.
3. Blastocyst stage. (sectional view)