In balancing selection, two or more alleles are kept in balance, and therefore are maintained in a population over the course of many generations. Which of the following example can support balancing natural selection?

A- Sickle cell allele kept in balance because heterozygotes have greater chance of survival if infected by the malarial parasite, compared with normal homozygotes

B. One morph has selective advantage over another morph

C. One homozygote has greater chance of survival than other genotype results in purity of population

D. many species of invertebrates exist as different colored forms, identical in all respects except color. Visually searching predators often develop a search image for one color form, usually the commoner

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#Unit 9. Diversity of Life Forms

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#Unit 8. Inheritance Biology

Four E. coli strains of genotype a+ b− are labeled 1, 2, 3, and 4. Four strains of genotype a− b+ are labeled 5, 6, 7, and 8. The two genotypes are mixed in all possible combinations and (after incubation) are plated to determine the frequency of a+ b+ recombinants. The following results are obtained, where M = many recombinants, L = low numbers of recombinants, and 0 = no recombinants. On the basis of these results, assign a sex type (either Hfr, F+, or F−) to each strain

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#Unit 11. Evolution and Behavior

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of

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#Unit 5. Developmental Biology

Double fertilization is a unique feature of flowering plants. In this process, one sperm unites with the egg to yield a zygote. The second sperm unites with the polar nuclei to initiate the formation of the

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#Unit 2. Cellular Organization

Prior to replication the DNA in the nucleus is in the form of a tangled mass called