Genome size (the length of DNA associated with one haploid complement of chromosomes) varies substantially between different organisms. Because more genes are required to direct the formation of more complex organisms, it is not surprising that genome size is roughly correlated with an organism’s apparent complexity. Which of the following statements is/are correct in reference to this rough correlation?

I. Many organisms of apparently similar complexities have very different genome sizes.

II. The number of genes, rather than genome size, is more closely related to organism complexity.

III. There is a roughly inverse correlation between organism complexity and gene density—the less complex the organism, the higher the gene density.

IV. Gene density in eukaryotic organisms is consistently higher and more variable than in their prokaryotic counterparts.

#Question id: 3275

#Unit 9. Evolution & Diversity of Life Forms

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of ________.

#Question id: 3276

#Unit 9. Evolution & Diversity of Life Forms

Which of these conditions are always true of populations evolving due to natural selection?

Condition 1: The population must vary in traits that are heritable.

Condition 2: Some heritable traits must increase reproductive success.

Condition 3: Individuals pass on most traits that they acquire during their lifetime.

#Question id: 3277

#Unit 9. Evolution & Diversity of Life Forms

Which of the following describes the most likely order of events in allopatric speciation?

#Question id: 3278

#Unit 9. Evolution & Diversity of Life Forms

What does the biological species concept use as the primary criterion for determining species boundaries?

#Question id: 3279

#Unit 9. Evolution & Diversity of Life Forms

Which two of the following have operated to increase divergence between mosquito fish populations on island?

a. improved gene flow

b. bottleneck effect

c. sexual selection

d. founder effect

e. natural selection

#Question id: 3280

#Unit 9. Evolution & Diversity of Life Forms

Small populations are threatened by the loss of genetic diversity from

a. Inbreeding

b. Genetic drift

c. Limited mating