Our Environment — Science STD 10 — Question

Bleaching powder is produced by the action of chlorine on

Which of the following is the correct sequence of parts as they occur in the human alimentary canal?

The total biomass in a terrestrial ecosystem will be greatest for which trophic level ?

Food web is constituted by

A ray of light travelling in air goes into water. The angle of refraction will be:

A pure tall and a pure dwarf plant were crossed to produce offsprings.If offsprings were self crossed, then the ratio between true breeding tall to true breeding dwarf would be :

When the power of eye lens increases, the defect of vision is produced.This defect of vision is known as

Which of the following are cerebral reflexes?

1. A person pulls away his hand on touching a hot object.
2. A person spits out immediately when a fly enters his mouth while talking.
3. A person walking bare foot lifts his foot at once on stepping on to a nail.
4. A person's pupil contracts at once in the presence of bright light.

For evolution to occur in a population, which of the following must happen?
i. The frequencies of some alleles in an organism's genotypes must change during its lifetime.
ii. The frequencies of each allele in an organism's genotype must remain constant within its lifetime.
iii. The frequencies of some alleles in a population’s gene pool must change over successive generations.
iv. The frequencies of each allele in a population's gene pool must remain constant over successive generations.