Zoology MCQs for NEET — Practice Questions with Answers

Answer:  3

Factual

Jean Baptiste de Lamarck proposed "theory of inheritance of acquired characters" or populary known as "use and disuse" theory.

(a) Analogous structures are a result of convergent evolution. When organisms with completely different organisation, living in the same habitat come to possess superficial resemblance, this is known as convergent evolution.

(b) Genetic drift is a random change in allele frequencies over the generations. It is brought by chance alone. Gene flow or gene migration is the physical movement of alleles into and out of a population. The existence within the population of disadvantages alleles in heterozygous genotypes is known as genetic code.

(b) Convergent evolution occurs in unrelated group of organisms. It is the development of similer functional structure but in unrelated groups.

The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography is called adaptive radiation. Natural selection is the basis of evolution. 

(d) According to Hardy-Weiberg principle, allele frequencies in a population are stable and is constant from generation to generation allele frequencies in a population will remain constant over generation only if the following condition are met
(i) There is no mutation no gene flow and all mating is random.
(ii) All genotypes reproduce equally well (i.e. no natural selection). But, all there conditons rarely met in nature.

(c) The analogous organs are not anatomically similar structures though they perform similar functions. Hence, analogous structures are a result of convergent evolution different structures evolving for the same function and hence, having similarity. Homologous organs developed along different direction due to adaptations to different needs. This is divergent evolution and the structures are homologous.

Population can be defined as a group or assemblage of organisms of the same species that live at a given time in a particular area. In human beings a dominant X-linked gene is necessary for formation of colour sensitive cells the cones, in the retina of eye. The recessive form of this gene is incapable of producing the colour sensitive cones and homozygous recessive female and homozygous recessive males are unable to distinguish between these two colours. As the isolated population do not have any hereditary diseases like colourblindness, so they do not spread accordingly. 

According to the theory of inheritance of acquired characters of Lamarck the Wrestlers, who developed strong body muscles in their life time, must pass this character onto their progeny, but this is not found true. 

Gene pool is defined as the sum total of genes present in a Mendelian population. The study of gene pool tells us the total number of genes, their kinds and variety present in the population.

For a normal distribution the mean, median and mode are actually equivalent. 

(c) Evolution is the sequence of gradual changes which take place in the primitive organisms over million of years in which new species are produced. It is through the constant process of evolution taking place in the organisms since the origin of life that such an enormous variety of plants and animals have come to exist on this earth at present.