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

• caused only by CO₂

• caused by CO₂, CFCs, CH₄ and NO₂ gases

• caused by combination of many gases

• none of the above

Photorespiration is favoured by

• high O₂ and low CO₂

• high CO₂ and low O₂

• high temperature and low O₂

• high humidity and temperature

Cochineal insects have proved very useful for

• rodents control

• Parthenium control

• cactus prevention

• Eicchornia prevention

'Gymnosperm' have how many species?

• 1000

• 900

• 640

• 300

What are the sex organs provided in some bacteria?

• Circular DNA

• Gametes

• Sex pili

• Plasmid

2,4- D is an effective

• fungicide

• weedicide

• rodenticide

• wormicide

Which vertebrate orgen receives only oxygenated blood?

• Gill

• Lung

• Spleen

• Liver

Which typical stage is known for DNA replication?

• Metaphase

• G₁- phase

• S- phase

• G₂- phase

The formation of canal system in sponges is due to

• reproduction

• porous walls

• folding of inner walls

• gastro- vascular system

The term 'Meiosis' was given by

• Johansen

• Knoll and Ruska

• A. Flemming

• Farmer and Moore