If Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?
A) If natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic change to produce new species from old ones.
B) If an organism's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring.
C) If an organism acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will result.
D) A single mutation in a single gene in a single gamete, if inherited by future generations, will produce a new species.
Rank the following one-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide.
1. insertion mutation deep within an intron
2. substitution mutation at the third position of an exonic codon
3. substitution mutation at the second position of an exonic codon
4. deletion mutation within the first exon of the gene
A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 3, 1, 4, 2
Arrange the following in order from most general to most specific.
1. natural selection
3. intrasexual selection
5. sexual selection
A) 4, 1, 2, 3, 5
B) 4, 2, 1, 3, 5
C) 4, 2, 1, 5, 3
D) 1, 4, 2, 5, 3
The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-nineteenth century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?
A) Yes, because natural selection has affected the frequency of the two different forms.
B) Yes, because they have completely different coloration.
C) Yes, because they are reproductively isolated based on habitat.
Rank the following in order from most general to most specific:
1. gametic isolation
2. reproductive isolating mechanism
3. sperm-egg incompatibility in sea urchins
4. prezygotic isolating mechanism
A) 2, 3, 1, 4
B) 2, 4, 1, 3
C) 4, 1, 2, 3
D) 4, 2, 1, 3
You want to study divergence of populations, and you need to maximize the rate of divergence to see results within the period of your grant funding. You will form a new population by taking some individuals from a source population and isolating them so the two populations cannot interbreed. What combination of characteristics would maximize your chance of seeing divergence in this study?
1. Choose a random sample of individuals to form the new population.
2. Choose individuals from one extreme to form the new population.
3. Choose a species to study that produces many offspring.
4. Choose a species to study that produces a few, large offspring.
5. Place the new population in the same type of environment as the source population.
6. Place the new population in a novel environment compared to that of the source population.
A) 1, 3, and 6
B) 1, 4, and 6
C) 2, 3, and 5
D) 2, 3, and 6
Which of the following is the correct sequence of events in the origin of life?
I. formation of protobionts
II. synthesis of organic monomers
III. synthesis of organic polymers
IV. formation of DNA-based genetic systems
A) I, II, III, IV
B) I, III, II, IV
C) II, III, I, IV
D) II, III, IV, I
What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?
1. origin of mitochondria
2. origin of multicellular eukaryotes
3. origin of chloroplasts
4. origin of cyanobacteria
5. origin of fungal-plant symbioses
A) 4, 3, 2, 1, 5
B) 4, 1, 2, 3, 5
C) 4, 1, 3, 2, 5
D) 4, 3, 1, 5, 2
A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?
A) Among themselves, they should share relatively few ancestral traits, especially those that enabled ancestral forms to adapt to extreme conditions.
B) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.
C) They should contain genes that originated in eukaryotes that are the hosts for numerous species of bacteria.
D) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic archaeans.
The predatory bacterium Bdellovibrio bacteriophorus drills into a prey bacterium and, once inside, digests it. In an attack upon a Gram-negative bacterium that has a slimy cell covering, what is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey's cytoplasm?
1. membrane composed mostly of lipopolysaccharide
2. membrane composed mostly of phospholipids
A) 2, 4, 3, 1
B) 1, 3, 4, 2
C) 1, 4, 3, 2
D) 4, 1, 3, 2
In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here?
1. nutrient recycler
5. primary producer
A) 1, 3, 4
B) 2, 3, 4
C) 2, 4, 1
D) 1, 2, 5