Photochemical smog formed in congested metropolitan cities mainly consists of:

• Hydrocarbons, ozone and SO_x

• Hydrocarbons, SO₂ and CO₂

• Smoke, peroxyacetyl nitrate and SO₂

• Ozone, peroxyacetyl nitrate and NO_x

Acid rain is due to increase in atmospheric concentration of :

• Ozone

• CO₂ and CO

• SO₃ and CO

• SO₂ and nitrogen oxide

83.

The true statement about 'green-house effect' is that it is caused by :

• CO₂ only

• SO₂ only

• CO₂ and SO₂

• CO₂, CFC, CH₄ and NO₂ gases

The first transgenic crop was :

• pea

• flax

• tobacco

• cotton

One of the major difficulties in the biological control of insect pests is the :

• practical difficulty of introducing the predator to specific areas

• method is less effective as compared with the use of insecticides

• predator does not always survive when transferred to a new environment

• predator develops a preference to other diets and may itself become a pest

Secretion of androgens by testes is regulated by:

• LTH

• FSH

• ICSH

• Oxytocin

The formation of gametophyte, from sporophyte, without spore formation or without meiosis is known as :

• apospory

• apogamy

• parthenogenesis

• none of these

Anemophillous flowers have :

• sessile stigma

• small and smooth stigma

• coloured flower

• large and feathery stigma

During a woman's life time, she produces about:

• 40-50 eggs

• 300-350 eggs

• 400-500 eggs

• 750-850 eggs

The production and maturation of sperm in testes is known as :

• oogenesis

• sporogenesis

• gametogenesis

• spermatogenesis