Home Page Textbooks Prentice Hall Biology (California) Section 16.1: Genes and Variation

Prentice Hall Biology (California)

1st Edition

Kenneth R. Miller, Levine

ISBN: 9780132013529

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Section 16.1: Genes and Variation

Exercise 1

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Change in the relative frequency of alleles (the number of times certain allele occurs in a population compare to other allele occurrence) indicate evolution in population.

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In the context of genetics, a population is said to be evolving if the relative frequencies of alleles in the population change over time. This results in altered frequencies of certain traits.

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For instance, if a population of frogs had a change in the frequency of alleles that define their skin color, then the population is said to be evolving as the frequency of a skin color changes.

Exercise 2

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Two processes that can lead to inherited variation in populations are mutations and genetic shuffling that results from sexual reproduction.

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There are two processes that can lead to inherited variations. One of them is mutation, which alters the genetic material in organisms. This alteration can result in inheritable variations.

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Another process that can lead to inherited variation is the shuffling of genes during DNA recombination. This occurs during meiosis in sexual reproduction, which also causes variations.

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As the genes of an organism are altered through mutation and DNA recombination, these traits can be passed to offspring if they occur in the germ cells, which are the sperm and egg.

Exercise 3

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Single-gene traits (traits control by one gene with two alleles) can only result in two distinct phenotypes while polygenic traits (traits control by multiple genes with two or more alleles) can result in many different phenotypes.

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Single-gene traits are generally discrete and would only exhibit two phenotypes. One example would be the presence or absence of a widow’s peak, which is controlled by a single gene.

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On the other hand, polygenic traits are generally continuous and can exhibit a range of phenotypes. One example would be height in humans, which is controlled by multiple genes.

Exercise 4

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Gene pool consists of all genes that are in a population. Allele frequency is dependent on gene pool because the allele frequency is the number of times one allele occurs in a gene pool compare to the number of times other alleles for the same gene occur.

Exercise 5

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Mutation is like shooting arrows in the dark. You don’t know how the genes are going to be altered – sometimes it may be advantageous or disadvantageous. However, it provides genetic variation that evolution acts upon.

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Mutations alter the genetic material in organisms, which can result in altered traits and variations. These alterations can be passed on to offspring if the mutations occur in the germ line.

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Therefore, mutations are considered as one of the driving forces of evolution. Mutations bring about genetic variation, which is acted upon by the process of natural selection.

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Section 16.1: Genes and Variation

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