Ecosystems — BIOLOGY STD 12 Science — Question

How many pairs of chromosomes does a male Drosophila fly have?

Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because –

1. Bacteria are resistant to the toxin.
2. Toxin is immature.
3. Toxin is inactive.
4. Bacteria encloses toxin in a special sac.

What is meant by 'competitive release'?

Fill in the blanks:
Zygote is _____________. (diploid/ haploid)

Name the transcriptionally active region of chromatin in a nucleus.

Name the two intermediate hosts which the human liver fluke depends on to complete its life cycle so as to facilitate parasitization of its primary host.

Define adolescence.

Define fossil.

What is Archaeopteryx? What is its significance in evolution?

Who gave theory of biogenesis?