Organisms and Populations — BIOLOGY STD 12 Science — Question

What is primary productivity? Give brief description of factors that affect primary productivity.

What does amniocentesis test? On what basis does it work? Is it justified to put a statutory ban on this process? Give reason.

In a cross between two tall pea plants, some of the offspring produced were dwarf. Show with the help of a Punnett square, how this is possible.

Or

When a tall pea plant was selfed, it produced onefourth of its progeny as dwarf. Explain with the help of a cross.

In a sea shore, the benthic animals live in sandy, muddy and rocky substrata and accordingly developed the following adaptations. Find the suitable substratum against each adaptation.

1. Burrowing ______________________.
2. Building cubes ________________________.
3. Holdfasts/ peduncle _________________________.

Name and mention the events that occur in the cells when HIV gets into blood after entering into human body.

Write the physiological reason, why a woman generally cannot conceive a child after 50 years of age.

How would you find genotype of a tall pea plant bearing white flowers? Explain with the help of a cross. Name the type of cross you would use.

What is colostrum ?

Suggest the aspects of reproductive health which need to be given special attention in the present scenario.