21. Evolution

Evaluate this statement: Evolution is said to occur when new traits accumulate over time, increasing complexity.

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet?

a. Maltose

b. Starch

c. Mannose

d. Lactose

The similarity in skin color among different human populations appears to be primarily the result of:

a. Natural selection

b. Convergent evolution

c. Which biological race they belong to

d. A and B are correct

e. A, B, and C are correct

When H₂ and CO₂ react, acetic acid can be formed spontaneously while the production of formaldehyde requires an input of energy. Which of these conclusions can be drawn from this observation?

a. More heat is released when formaldehyde is produced compared to the production of acetic acid.

b. Compared to the reactants that it is formed from, formaldehyde has more potential energy than does acetic acid.

c. Entropy decreases when acetic acid is produced and increases when formaldehyde is produced.

d. Only acetic acid could be produced under conditions that existed in early Earth.

Which of the following taxonomic levels contains organisms that share the most recent common ancestor?

a. Family

b. Order

c. Phylum

d. Genus

e. Class

The geneticist James Crow wrote that successful scientific theories have the following characteristics: (1) They explain otherwise puzzling observations; (2) they provide connections between otherwise disparate observations; (3) they make predictions that can be tested; and (4) they are heuristic, meaning that they open up new avenues of theory and experimentation. Crow added two other elements of scientific theories that he considered important on a personal, emotional level: (5) They should be elegant, in the sense of being simple and powerful; and (6) they should have an element of surprise. How well does the theory of evolution by natural selection fulfill these six criteria?

From what you have learned about water, why do coastal regions tend to have milder climates with cooler summers and warmer winters than do inland areas at the same latitude?

What is an evolutionary adaptation?

a. A trait that improves the fitness of its bearer, compared with individuals without the trait

b. A trait that changes in response to environmental influences within the individual's lifetime

c. The ability of an individual to adjust to its environment

d. A trait that an individual wants so that it can survive

How can the Darwinian concept of descent with modification explain the evolution of such complex structures as an eye?

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators. Apply Darwin's four postulates to a population of mice living on sand dunes in coastal Florida.

A population of snails is preyed on by birds that break the snails open on rocks, eat the soft bodies, and leave the shells. The snails occur in both striped and unstriped forms. In one area, researchers counted both live snails and broken shells. Their data are summarized below: Which snail form seems better adapted to this environment? Why? Predict how the frequencies of striped and unstriped snails might change in the future.

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

Compare how evolution by inheritance of acquired characters and the theory of evolution by natural selection would explain the observation that HCN production is often high in rural environments with many herbivores and low in urban environments with few herbivores.