Bio Midterm

Old Test Questions

How were conditions on the early earth of more than 3 billion years ago different from those on today’s Earth?

Only early earth was intensely bombarded by large space debris

A protobiont is a spherical collection of organic molecules that are thought to be a precursor to cells and the first living organisms.

Which of the following is the correct sequence of events in the origin of life?

1. Formation of protobionts
2. Synthesis of organic molecules
3. Synthesis of organic polymers
4. Formation of DNA based genetic systems

2,3,1,4

The first genes on earth were probably

Auto-catalytic RNA molecules

Approximately how far back does the fossil record extend?

3.5 billion years

The first terrestrial organisms probably were considered which of the following?

1. Burrowers
2. Photosynthetic
3. Multicellular
4. Prokaryotes
5. Eukaryotes

2, 4

An exaptation is a trait or feature of an organism that evolves for one purpose and is later used for a different purpose.

If one organ is an exaptation of another organ, then what must be true of these two organs?

They are both homologous organs

The existence of evolutionary trends, such as increasing sizes among horse species, is evidence that

In particular environments, similar adaptations can be beneficial in more than one species

Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short only live bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

Species selection

Systematics is concerned with

All of the above

Which of the following taxonomic categories contains all the others?

Order

Which of the following characteristics would increase the likelihood that organisms would be well represented in the fossil record?

All of the above contribute

Stromatolites are

Layered communities of prokaryotes, fossils of which represent the oldest known prokaryotes

According to the endosymbiont theory

The mitochondria and plastids of eukaryotic cells were originally prokaryotic endosymbionts that became permanent parts of the host cell

The more than 500 species of fruit fly on various Hawaiian Islands, all apparently descended from a single ancestral species, are an excellent example of

Adaptive radiation

Which of the following is thought to have been the first step in the origin of life?

Abiotic formation of small organic molecules

If arrows indicate locations in the column where fossils of a particular type (see key above) first appear, then which core in Figure 25.2 has the most accurate arrangement of fossils?

core A

Which of the following reasons may explain why the sediment core lacks fossils of dragonflies with 3-feet wingspans?

1. This particular sediment core includes the correct stratum, but the part of the stratum captured by the core lacks such fossils
2. The sea was not present at this site during the time that 3-feet dragonflies existed
3. Dragonflies have no hard parts, such as exoskeletons, to fossilize
4. The sediments containing these fossils at this site may have been eroded away during a time when the sea had receded from this site
5. Dragonflies are terrestrial; therefore, fossils of terrestrial organisms should not be expected in the sediments of seas

1,2,or 4

If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled “II,” at which other location, labeled A—E, would a search be most likely to find more fossils of this organism?

C only

Which section of sea-floor crust should have the thickest layer of overlying sediment, assuming a continuous rate of sediment deposition?

E

The element nitrogen is present in all of the following except

Monosaccharides

Which of the following molecules acts as building blocks of polypeptides?

2, 7, 8

Which of the following molecules is a saturated fatty acid?

9

Water’s surface tension and heat storage capacity is accounted for by its

Hydrogen bonds

Which of the following effects is produced by the high surface tension of water?

A water strider can walk across the surface of a small pond

Why does ice float in liquid water?

Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

Hydrophobic substances such as vegetable oil are

Nonpolar substances that repel water molecules

Which of the following is a hydrophobic material?

Wax

The figure above shows the structures of glucose and fructose. These two molecules differ in the

number of carbon, hydrogen, and oxygen atoms

Which of the following is not a polymer?

Glucose

Which of the following best summarizes the relationship between dehydration synthesis and hydrolysis?

Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers

Which of the following statements is true for the class of biological molecules known as lipids?

They are insoluble in water

All the following contain amino acids except

Cholesterol

Polysaccharide, triglycerides, and proteins are similar in that they

All contain nitrogen in their monomer building blocks

Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein?

99

Which bonds are created during the formation of the primary structure of a protein?

Peptide bonds

All of the following are part of a prokaryotic cell except

An endoplasmic reticulum

The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that

Plant cells contain a large vacuole that reduces the volume of the cytoplasm

Which of the following is a major cause of the size limits for certain types of cells?

The need for a surface area of sufficient area to support the cell’s metabolic needs

The evolution of eukaryotic cells most likely involved

Endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria

Which structure is the site of the synthesis of proteins that may be exported from the cell?

Rough ER

Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells?

Lysosomes

Which organelle often takes up much of the volume of a plant cell?

Vacuole

Which organelle is the primary site of ATP synthesis in eukaryotic cells?

Mitochondria

A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from

An animal, but not a plant

When a potassium ion moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures. Which of the following correctly describes the order in which these structures will be encountered by the ion?

Primary Cell Wall Plasma Membrane Cytoplasm 2n cell wall vacuole

Which structure is common to plant and animal cells?

Mitochondrion

Which of the following is present in a prokaryotic cell?

Ribosome

Which cell would be best for studying lysosomes?

Phagocytic white blood cell

Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition?

The lysosome

Which of the following summarizes the relationship between dehydration reactions and hydrolysis?

Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?

40

The chemical reactions involved in respiration are virtually identical between identical prokaryotic and eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. In light of the endosymbiotic theory for the evolutionary origin of mitochondria, where is ATP synthesis likely to occur in prokaryotic cells?

On the plasma membrane

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

All variation between individuals is due only to environmental factors

Natural selection is based on all of the following except

Individuals adapt to their environments and, thereby, evolve

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection?

2→4→1→3

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

If natural selection can change one gene’s frequency in a population over the course of generations then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

These bacteria should be outcompeted and replaced by bacteria that have lost these genes

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is

Humans and chimpanzees share a relatively recent common ancestor

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

None of the organisms depicted by the tree ate the same foods

If, on average, 46% of the loci in a species’ gene pool are heterozygous, then the average homozygosity of the species should be

54%

In modern terminology, diversity is understood to be a result of genetic variation. Which of the following is a recognized source of variation for evolution?

Recombination by crossing over in meiosis

Which of the following is a true statement concerning genetic variation?

It must be present in a population before natural selection can act upon the population

In peas, a gene controls flower color such that R = purple, and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

0.80

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?

0.81

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined, thereby producing a genetically distinctive virus, which can subsequently cause widespread disease.

The production of new types of flue virus in the manner described above is most similar to the phenomenon of

gene flow

What is true of natural selection?

Natural selection is a random process

Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different color patterns?

disruptive selection

Which of the following statements best summarizes evolution as it is viewed today?

It is the descent of humans from the present-day great apes

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes.

Which of these is closest to the allele frequency in the founding population?

0.1 a , 0.9 A

In the formula for determining a population’s genotype frequencies, the pq in the term 2pq is necessary because

the population is diploid

If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of

genetic drift

Anopheles mosquitos, which carry the malaria parasite, cannot live above elevations of 5,900 feet. In addition, oxygen availability decreases with higher altitude. Consider a hypothetical human population that is adapted to life on the slopes of Mt. Kilimanjaro in Tanzania, a country in equatorial Africa. Mt. Kilimanjaro’s base is about 2,600 feet above sea level and its peak is 19,341 feet above sea level. If the incidence of the sickle-cell allele in the population is plotted against altitude (feet above sea level), which of the following distributions is most likely, assuming little migration of people up or down the mountain?

In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

Population B

Which population is most likely to be subject to the bottleneck effect?

Population A

What is true of macroevolution?

It is evolution above the species level

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

habitat isolation

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not yet been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?

morphological

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms are applicable?

1. sympatric species
2. prezygotic isolation
3. postzygotic isolation
4. allopatric species
5. habitat isolation
6. reduced hybrid fertility

1 and 2

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms are applicable?

mechanical isolation

Dogs (Canis lupus familiaris) and gray wolves (Canis lupus) can interbreed to produce viable, fertile offspring. These species shared a common ancestor recently (in geologic time) and have a high degree of genetic similarity, although their anatomies vary widely. Judging from this evidence. which two species concepts are most likely to place dogs and wolves together into a single species?

biological and phylogenetic

Two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of following is not a possible outcome when they meet?

They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations

According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that

speciation occurred rapidly in geologic time

Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?

They have been geographically isolated from each other for a long time

The sickle-call allele is pleiotropic (i.e. it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one’s susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell “crises”. Such individuals remain less susceptible to malaria. Thus, pleiotropic genes/alleles such as this can help explain why

adaptations are often compromises

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?

bones in the flipper of a whale