Biology Semester 2 FINAL EXAM REVIEW

Why were Mendel's experiments important to biology? Select all that apply.

• they showed that mathematical models could be used to explain inheritance

• they showed that inheritance was a random process

• they showed that DNA contains the genes that control traits

• they showed that all traits are either dominant or recessive

What explains how the parents in a family both have the same eye color, but some of their children have a different eye color? Assume for this example that eye color is determined by a single gene.

• The parents are both heterozygous for a gene that controls eye color allowing some of the children to get two recessive alleles.

• One parent is homozygous dominant, and the other heterozygous for a gene that controls eye color allowing some of the children to express a different trait.

• One parent is homozygous dominant, and the other homozygous recessive for a gene that controls eye color allowing some of the children to express a different trait.

• The parents are both homozygous dominant for a gene that controls eye color allowing some of the children to get two recessive alleles.

Which of the following disorders describes cystic fibrosis?

• mitochondrially inherited

• autosomal dominant

• sex linked

• autosomal recessive

Scientists are studying a genetic disorder. They discover that when both parents are carriers, and do not express the disorder themselves, their children have a 25% chance of developing the disorder. If only one parent is a carrier, none of the children express the disorder. What type of disorder are they most likely studying?

• sex linked

• autosomal dominant

• autosomal recessive

• mitochondrially inherited

What molecule forms a double helix structure composed of two complementary strands of nucleotides?

• Ribonucleic Acid

• Deoxyribonucleic Acid

• Hydrogenous base

• Nitrogen

An ecosystem contains more individuals of a certain species than it can support. Which of the following describes if natural selection will occur and why?

• Natural selection will not occur because there is no competition

• Natural selection will occur because there is competition

• Natural selection will occur because there is lowered fitness

• Natural selection will not occur because there is no mutation

A piece of DNA from a gene found in a deer is compared to the same gene in four other species of mammals. Based on this analysis, which animal is the closest relative of the deer?

• kangaroo

• deer

• anteater

• Chimpanzee

Scientists were studying the DNA from Antarctic fish, including two species of icefish, that have no hemoglobin in their blood. They constructed the following cladogram.

• The C. anacticus is more closely related to C. mawsoni than it is to the other hemoglobinless icefish.

• The most closely related species to the hemoglobinless icefish is C. mawsoni.

• The two species of hemoglobinless icefish are more closely related to each other than they are to other Antarctic fish studied.

• N. coriceps is the closest relative to the hemoglobinless icefish from the fish that were studied.

The graph shows the natural variation in size of a population of fish, with some small, some medium, and some large types of fish. A new predator is introduced to an aquatic ecosystem. In a population of fish that live there, very small fish are more easily able to hide from the predators, and very large fish cannot be easily eaten by predators. What type of natural selection is acting on the population, and what will be the expected result?

• Stabilizing selection: Over time the fish population will change. Medium-sized fish will become rare, small and large fish will be common.

• Disruptive selection: Over time the fish population will change. Medium-sized fish will become rare, small and large fish will be common.

• Disruptive selection: Since both extremes are selected against, the fish population will remain about the same.

• Stabilizing selection: Since both extremes are selected against, the fish population will remain about the same.

A population of plants growing in a field is examined over a period of years. The plants have either white or yellow flowers. What best explains the observations?

• White flowers increase the plant's fitness, so the population is under disruptive selection.

• Yellow flowers increase the plant's fitness, so the population is under directional selection.

• White flowers increase the plant's fitness, so the population is under directional selection.