Evolution — BIOLOGY STD 12 Science — Question

How biodiversity is important for functional ecosystem?

Explain any three inbreeding devices in flowering plants.

Draw a diagram of E.coli cloning vector pBR322.

Pollen banks are playing a very important role in promoting plant breeding programme the world over. How are pollens preserved in the pollen banks? Explain. How are such banks benefitting our farmer? Write any two ways.

Fill in the missing stages in the given primary hydrarch succession.
Phytoplankton → (a) → (b) → (c) → Submerged free-floating → (d) → Forest plant stage.
What is common between hydrarch and xerarch succession?

A colour blind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled 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, 8 mg/L and 400 mg/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?

What is recombinant DNA? Describe the micro injection and gene gun methods of introducing foreign DNA into host cells.