STD 12 - 2. human reproduction — NEET STD 11 Science — Question

The fertilized egg divides by the process of

Pesticides disturb the ecosystem by eliminating the

Fibrous joints in humans

Which of the following statements are incorrect regarding universe including earth ?
(i) The Big Bang theory attempts to explain to us the origin of universe.
(ii) The universe expanded and hence, the temperature came down. Hydrogen and Helium formed sometime later.
(iii) The gases condensed under gravitation and formed the galaxies of the present day universe.
(iv) There was no atmosphere on early earth.
(v) Water vapour, methane, carbon dioxide and ammonia released from molten mass covered the earth surface.
(vi) The UV rays from the sun brokeup water into Hydrogen and Oxygen and the lighter O₂, escaped.

Which of the following is not a secondary messenger ?

Coelom is absent in

Which character is present in frog but absent in cockroach?

Identify the correct statement :
(i) Henking could trace a specific nuclear structure all through spermatogenesis in a few insect and named it a X - body
(ii) In XX + XY type of sex determination both males and females have usually unequal number of chromosomes.
(iii) Grasshopper is an example of XO - XX type of sex determination.
(iv) In XO and XY type of mechanism male heterogamety is observed.
(v) Sex chromosome of a female bird is designated to be Z and W chromosomes.