23. Speciation

Explain how molecular chaperones facilitate protein folding in many different polypeptides, each with their own specific shape.

Cells that line your intestines are known to possess a large number of membrane proteins that transport small molecules and ions across the plasma membrane. Which of the following cell structures would you expect to be required for this characteristic of the cells?

a. The endoplasmic reticulum

b. Peroxisomes

c. Lysosomes

d. The cell wall

The biological definition of 'race' corresponds to all of the following except:

a. The genealogical species concept

b. The idea that subgroups within the same species can be distinguished from each other by ancestry

c. There is a natural hierarchy of groups within a species from 'lowest' to 'highest' forms

d. It should be possible to identify races on the basis of shared allele frequencies among populations

e. Races within a species are not reproductively isolated from each other.

Biologists have found more than 500 species of fruit flies on the various Hawaiian Islands, all apparently descended from a single ancestor species. This example illustrates

a. Polyploidy.

b. Temporal isolation.

c. Adaptive radiation.

d. Sympatric speciation.

Why are proteins not considered to be a good candidate for the first living molecule?

a. Their catalytic capability is not sufficient for most biological reactions.

b. Their amino acid monomers were not likely present in the prebiotic soup.

c. They cannot serve as a template for replication.

d. They could not have polymerized from amino acid monomers under early Earth conditions.

All of the following statements support the hypothesis that humans cannot be classified into biological races except:

a. There is more genetic diversity within a racial group than average differences between racial groups.

b. Alleles that are common in one population in a racial group may be uncommon in other populations of the same race.

c. Geneticists can use particular SNP alleles to identify the ancestral group(s) of any individual human.

d. There are no alleles found in all members of a given racial group.

e. There is genetic evidence of mixing among human populations occurring thousands of years ago until the present.

Predict the effect on protein function if each polypeptide adopted only a single, inflexible shape based on its primary structure.

True or false? Speciation is a slow process. Justify your answer.

Based on what you know of the peptide bonds that link together amino acid residues, why would proline's side chain reduce the flexibility of the backbone?

When analyzing a sample of cells from a patient, you find the lysosomes are filled with undigested material. This observation makes you think that the lysosomes are not functioning properly. What are three different defects that could be responsible for malfunctioning lysosomes?

Three-spine sticklebacks are small fish that originated in the ocean and continue to exist there, but then some took up residence in hundreds of streams and freshwater lakes in the Northern Hemisphere. Predict whether you would expect to find different species in lakes today.

Make a concept map that relates the four levels of protein structure and shows how they can contribute to the formation of hemoglobin. Your map should include the following boxed terms: Primary structure, Secondary structure, Tertiary structure, Quaternary structure, Amino acid sequence, R-groups, αα-helices, and ββ-pleated sheets.

What prevents horses and donkeys from hybridizing to form a new species?

a. Limited hybrid fertility

b. Limited hybrid viability

c. Hybrid breakdown

d. Gametic isolation

All over the world, natural habitats are being fragmented into tiny islands by suburbs, ranches, farms, and roads. If asked to join a science panel to speak to Congress, could you explain how this fragmentation process could lead to extinction? How it could lead to speciation?