Evolution — BIOLOGY STD 12 Science — Question

"Crystals of Bt. toxic protein synthesized by some bacteria, kill the insect but not kill them-selves." Explain the statement with reason.

Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.

State the Lamarck's observation on biological evolution.

How many sperms and ova will be produced by 25 primary spermatocyte and 25 primary oocyte. Give reason also.

How is ‘Rosie’ considered different from a normal cow? Explain.

Three water samples namely river water, untreated sewage water and Secondary effluent discharged from Sewage treatment plant were subjected to BOD test. The samples were labelled in A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20 mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Give the binomials of two types of yeast and the commercial bioactive products they help to produce.

How is the child affected if it has grown from the zygote formed by an XX–egg fertilised by a Y–carrying sperm? What do you call this abnormality?

How would the gene flow or genetic drift affect the population in which either of them happen to take place?

Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?