Study Guide

Biology
Sample Questions

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Competency 0001
Understand the practices of scientific inquiry and engineering design.

1. A scientist would like to determine the effect of night length on the flowering of the mustard plant Arabidopsis thaliana. Thirty of these plants will be randomly assigned to each of three experimental groups. The best rationale for including 30 plants in each experimental group is that doing so will:

  1. minimize the effects of individual variations among the plants on the experimental results.
  2. allow more conditions to be varied at once for each group.
  3. reduce the chance that the scientist's expectations will bias the outcome of the experiment.
  4. provide a sufficient number of plants for a control group.
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Correct Response: A. In sexually reproducing organisms, all individuals are genetically unique and thus vary in their characteristics. The inclusion of 30 plants in each experimental group, instead of just a few, provides a statistical measure of how much of the observed variation within a treatment group reflects individual variation among the plants rather than variation that is the result of the experimental treatment.

Competency 0002
Understand crosscutting concepts in the sciences and engineering.

2. For which of the following reasons is the periodic table of the elements a useful model in science?

  1. It lists the elements in order of their percent abundance in Earth's crust and atmosphere.
  2. It organizes the elements into groups with shared chemical and physical properties.
  3. It provides a historical record of the order in which the elements were discovered.
  4. It separates the elements into three groups based on the state they are in at room temperature.
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Correct Response: B. Each column in the periodic table of the elements represents a group of elements with the same number of valence, or outer shell, electrons. This means that all the elements in a column are capable of forming the same number of chemical bonds and exhibit similar chemical behaviors. Elements are placed into rows, or periods, according to the number of shells occupied by their electrons, and are arranged across the table by increasing total numbers of electrons and atomic weights.

Competency 0003
Understand the relationships between science, technology, and human activity in a global context.

3. In which of the following ways has recombinant DNA technology been used to advance the development of vaccines?

  1. It has provided the tools needed to manufacture vaccines containing live pathogenic agents.
  2. It has enabled the production of vaccines that allow transmission of lifelong immunity from one generation to the next.
  3. It has generated the data needed to synthesize vaccines that provide lifelong immunity.
  4. It has expanded the production of vaccines composed only of viral coat proteins.
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Correct Response: D. The development of recombinant DNA techniques have expanded the production of vaccines composed only of viral coat protein antigens. These techniques have facilitated the development of vaccines for viruses that are difficult to grow in the laboratory. In addition, this genome-free approach to vaccine development has the potential to reduce the risk of infection posed by exposure to vaccines containing attenuated live viruses.

Competency 0004
Understand the chemistry of living systems.

4. Which of the following best explains carbon's central role in the composition of biomolecules?

  1. Carbon exists as a solid at room temperature.
  2. Carbon's four valence electrons allow it to bond with other atoms in a wide variety of ways.
  3. Carbon is the element with the greatest electronegativity.
  4. Carbon's six protons make it easy for it to achieve an octet by reacting with the alkaline earth metals.
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Correct Response: B. Carbon has four electrons in its valence shell and by sharing electrons forms stable single and double covalent bonds with a number of other elements, including oxygen, nitrogen, and hydrogen. It is thus capable of forming large, complex molecules with skeletons that differ in their length, degree of branching, or arrangement in closed rings. This diversity in molecular structures makes possible the diversity of living organisms.

Competency 0005
Understand cell structure, function, and bioenergetics.

5. Which of the following is most likely to occur when yeast cells have exhausted the supply of oxygen present in their growth medium?

  1. Lactic acid will accumulate in the lysosomes of the yeast cells.
  2. Fermentation will regenerate NAD+, and glycolysis will continue.
  3. Carbon dioxide production will increase and acidify the medium.
  4. ATP production will cease, and the yeast cells will die.
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Correct Response: B. In the absence of oxygen that can serve as the final electron receptor, the end product of glycolysis, pyruvate, is converted to ethanol. This is accomplished by the reduction of acetaldehyde by NADH, thus regenerating a supply of NAD+ that can accept electrons during the oxidation step of glycolysis, and allowing that process to continue.

Competency 0006
Understand molecular genetics.

6. Which of the following is the most likely cause of a base pair mutation?

  1. Sister chromatids fail to separate during meiosis.
  2. A small portion of one chromosome is added to another chromosome.
  3. A segment of a chromosome breaks, flips, and reinserts itself.
  4. The DNA is not accurately duplicated during replication.
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Correct Response: D. Mutations that involve nucleotide base pairs typically result from the substitution, insertion, or deletion of one or more incorrect bases. These most commonly occur during the replication of DNA when the new complementary strands are being produced.

Competency 0007
Understand patterns and processes of inheritance.

7. Use the pedigree below to answer the question that follows.

The pedigree shows the sex-linked inheritance pattern of a gene. This pattern of inheritance suggests that the allele is:

  1. X-linked dominant.
  2. X-linked recessive.
  3. Y-linked dominant.
  4. Y-linked recessive.
Enter to expand or collapse answer.Answer expanded
Correct Response: A. The allele cannot be inherited as Y-linked, since females in the first generation of offspring express the trait. If the trait is X-linked recessive, the affected females of the first generation must be homozygous recessive and their offspring should show sex linkage, with the males affected and the females unaffected. This is not the case. The pattern in the pedigree is consistent with an X-linked dominant, however. The affected females of the first generation must be heterozygous for the trait so the expression of the trait in their offspring would not show sex linkage. This is the pattern in the pedigree.

Competency 0008
Understand the mechanisms of biological evolution.

8. The occurrence of similar features in organisms from different phylogenetic lineages can be attributed to:

  1. gradualism.
  2. stabilizing selection.
  3. convergent evolution.
  4. uniformitarianism.
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Correct Response: C. Organisms that are only distantly related may adapt by developing similar characteristics in response to similar selective pressures. This is known as convergent evolution.

Competency 0009
Understand the scientific explanations and evidence for the history of life on Earth.

9. Which of the following would provide the strongest evidence of a relatively close evolutionary relationship between two species?

  1. Both species occupy similar niches in their respective ecological communities.
  2. Fossils of ancestors of both species are found in the same geographic area.
  3. The embryos of both species look almost identical until late stages of development.
  4. Both species use the same 20 amino acids to synthesize peptides and proteins.
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Correct Response: C. Homologous patterns of development that appeared early are shared by all members of an evolutionary lineage. The sharing of homologies by some but not all members of a lineage suggests that the species sharing these homologies have a more recent common ancestor than other members of the lineage. Thus, species whose embryos differ from each other only in the very late stages of development are likely to be more closely related to each other than species that diverge at earlier stages of development.

Competency 0010
Understand the structures and functions of organisms and their life cycles.

10. The process of conjugation is significant in the bacterial life cycle because it allows:

  1. a bacterium to switch from being heterotrophic to autotrophic.
  2. deleterious mutations in a bacterium's genome to be corrected.
  3. a bacterium to make an exact duplicate of itself.
  4. genetic material to be transferred from one bacterium to another.
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Correct Response: D. Conjugation in prokaryotes is the direct one-way transfer of DNA from one cell to another.

Competency 0011
Understand how organisms obtain, store, and use energy and matter to maintain homeostasis.

11. Which of the following best describes how mushrooms and similar fungi obtain nutrients?

  1. The hyphae secrete enzymes that break down large organic molecules in the immediate environment and then absorb the resulting smaller molecules for use as food.
  2. Cells in the hyphae engulf large food particles, forming food vacuoles that fuse with lysosomes so that digestive enzymes can break down the particles.
  3. Tubes formed by the hyphae transport food particles to specialized storage structures where the food is digested and the nutrients are absorbed.
  4. Hyphae periodically organize into structures that grow toward sunlight and produce nutrients by photosynthesis.
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Correct Response: A. Unlike animals, fungi do not ingest their food before digesting it. Instead, they secrete enzymes that break down complex organic molecules in the surrounding environment and then absorb the nutrients.

Competency 0012
Understand populations and communities.

12. Use the graph below to answer the question that follows.

What does the survivorship curve shown indicate about a population made up of individuals with an average life expectancy of 40 years?

  1. The greatest increase in survivorship occurs at the end of the life span.
  2. Members of the population are most vulnerable during infancy.
  3. The population has a low mortality rate during middle age.
  4. Individuals begin reproduction very early in the life span.
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Correct Response: C. The graph shown is an example of a Type I survivorship curve, reflecting low death rates at early and middle ages and a steeper drop-off in old age.

Competency 0013
Understand ecosystems and biomes.

13. Which of the following would most likely increase the amount of phosphorus available to organisms in an ecosystem?

  1. the burning of fossil fuels
  2. the rising of air temperature
  3. the cultivation of leguminous plants
  4. the weathering of rocks
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Correct Response: D. Of the possible responses, only the weathering of rocks would increase the availability of phosphorus to organisms because the largest reservoir of phosphorus is in sedimentary rocks of marine origin.

Competency 0014
Understand the effects of human activities on the biosphere.

14. Scientists have observed reduced fertility in a variety of aquatic animals including fish, reptiles, and insects in waterways near urbanized or agricultural areas. This reduction in fertility rates is most likely a result of:

  1. an increase in the number of invasive species present in degraded habitats.
  2. a disruption of endocrine systems caused by the introduction of natural hormones and synthetic compounds.
  3. a decline in the quantity and quality of food resources needed to sustain reproduction.
  4. an interruption of mating behaviors and the destruction of breeding sites caused by human activity.
Enter to expand or collapse answer.Answer expanded
Correct Response: B. The introduction of endocrine disrupters into wetlands and waterways negatively affects the reproduction, growth, and development of wildlife, especially carnivorous animals. Widely publicized examples of endocrine disrupters include DDT and PCBs, but human medicines and cosmetics are now also known to interfere with the functioning of hormones and endocrine glands in seals, fish, alligators, and snails, for example.