Question

Multiple choice: Consider the following scenario: Changing conditions on an island lead to the death of all plants producing medium sized seeds. The resident bird population must now adapt to a diet of seeds from the remaining plants, some of which produce large seeds, and others that produce very small seeds. Which of the following types of selection would most likely be observed among the resident seed-eating bird populations on the island:

A) Diversifying selection

B) Stabilizing selection

C) Directional selection

D) Terminal selection

Multiple choice: All of the following statements about Darwin’s Theory are true except:

A) He observed that all members of a population have an equal chance of survival.

B) Natural selection acts on each individual member of a population.

C) Evolution cannot be observed among individual members of a population, rather it is a process that is observed as changes in the overall population.

D) While mutations yield random changes, the changes driven by natural selection are always positive, adaptive, and non-random.

Multiple choice: All of the following events are considered to have been necessary steps leading up to the appearance of the first living cells except:

A) Abiotic synthesis of building block monomers.

B) Joining together of monomers into polymers.

C) The accumulation of an oxygen (O₂) rich atmosphere.

D) The organization of molecules that could serve as hereditary material for the first cells.

Answer 1

1. Diversifying selection

In this type of selection, the nature favors the extreme phenotypes of a population excepting the intermediate phenotypes. Here also the nature has selects birds eating either large seeds or small seeds excepting the birds which can eat the middle seeds.

2. He observed that all members of a population have an equal chance of survival.

As per the natural selection theory of Darwin, in a population there are different types of individuals among which some have advanced trait while the other lack the advanced trait and it is called as variation among individuals of a population. The individuals having advanced trait can survive in the nature called as natural selection and hence all members of a population don't have equal opportunity of survival, only the members having advanced trait have the opportunity of survival. Also the survived members pass their traits to their Offsprings and shows evolution and hence a population shows evolution not a single individual. Also natural selection always favor the survival of individuals and hence is positive, while mutations may prove lethal for some organisms.

3. The accumulation of an oxygen rich atmosphere.

The accumulation of oxygen in the atmosphere has changed the life form of the organisms only but don't have any role on the evolution of first living cell. Before the accumulation of oxygen in the atmosphere, the first living cell has been evolved and when it takes place many species existing in the reducing atmosphere die as the atmosphere has changed to an oxidizing atmosphere.