The concept of chemical evolution is based on

• interaction of water, air and clay under intense heat

• effect of solar radiation on chemicals

• possible origin of life by combination of chemicals under suitable environmental conditions

• crystallization of chemicals

Delicate hair-like feathers which remain sparsely distributed over the body are

• coverts

• filoplumes

• plumules

• remiges

Homo erectus evolved during

• pleistocene

• miocene

• pliocene

• holocene

Which of the following postulates is related with Neo-Darwinism?

• Mutations are believed to help form new species

• It incorporates isolation as an essential component of evolution.

• It can explain the occurrence of unchanged forms over millions of years.

• All of the above

By all of the following ways bacteria become resistant to antibiotic except

• making enzymes that inactivate the drug

• becoming impermeable to the drug

• modifying the target of the drug

• moving away from the drug

Which of the following evidences does not favour the Lamarckian concept of inheritance of acquired characters

• Absence of limbs in snakes

• Melanization in peppered moth

• Presence of webbed toes in aquatic birds

• Lack of pigment in cave-dwelling animals

Which of the following features can be said to be a true defining feature of living beings without any exception

• They can digest their food.

• All of them can reproduce.

• They can regenerate.

• They can respond to external stimuli.

Two opposite forces operate in the growth and development of every population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called

• fecundity

• environmental resistances

• biotic control

• mortality.

279.

What is a keystone species

• A species which makes up only a small proportion of the total biomass of a community, yet has a huge impact on the community's organization and survival.

• A common species that has plenty of biomass, yet has a fairly low impact on the community's organization.

• A rare species that has minimal impact on the biomass and on other species in the community.

• A dominant a large proportion of the biomass and which affects many other species.

Assertion : Bursa fabricii lies on the ventral side of the cloaca in birds.

Reason : Bursa fabricii is related with flight adaptation.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false