Question

28.What is the definition of a gene pool? a. All alleles that exists in a population b. relative amount of each allele c. A few alleles that exists in a population d. Alternative versions of the same gene e. allele that is specific for a protein 29. Explain what is the Biological Species concept and its limitations. 30. T/F: An organism's fitness depends on their environment 31. Explain how the Sonoran Pocket Mice are a good example of Natural Selection. 32. T/F Differential survival and reproduction according to natural selection is not random. 33. Which of the following is NOT an example of a pre-zygotic barrier? a. 2 insects cannot breed due to incompatible sex organs b. Amino acid sequences vary in sea urchins, causing matings to fail c. 2 birds mate, but their offspring are infertile d. 2 beaver species are geographically isolated, preventing mating e. 2 trees release pollen at different times of the year 34.Polyploidy is the most common in __ a. mammals b. plants c. protists d. amphibians e. fish 35. T/F Polymorphic species look the same but are different.

Answer 1

28. Gene pool is a collection of all alleles that are present in a population.

29. Biological species concept defines species as the group of organisms that can interbreed and produce fertile offsprings. This definition of biological species was given by Ernst Mayr.

Limitations of biological species concept:

a. It is not relevant to allopatric speciation.

b. It is not applicable to fossil species.
c. It is not applicable to organisms reproducing through asexual mode or organisms with extensive self fertilisation.

d. Sexually reproducing organisms that freely hybridise.
30. True

An organism’s fitness depends on their environment. Fitness is relative term an organism which is fit in the desert environment might not be fit in a polar environment.

31. Sonoran pocket mice have two coat colour varieties- a light coloured variety and a dark coloured variety. The desert surface is also found in two colour variations- light coloured sand and rocks and patches of dark coloured volcanic rocks. Most of the mice have light coloured fur which blends better with the light coloured surface but the mice inhabiting dark coloured volcanic rocks have dark coat. This is an example of natural selection to avoid predation from hungry owls.

32. True

Differential survival and reproduction according to natural selection is not random. Variations that occur in a population are random but selection acts on those variations in a non-random way. Variations that are likely to give fitness advantage are more likely to become common.

33. Correct option is C

Two birds mate but their offspring is infertile. It is an example of post- zygotic barrier since the zygote formation took place.

34. Polyploidy is most common in fish. Some fish species have as many as 400 chromosomes.

35. False
Polymorphic species are generated due to the occurrence of discontinuous genetic variation. This results in the formation of several different forms of a single species.