Part 2 — Answer key

Compare your answers after you have finished Part 1.

1. Which structure is found in all cells, both prokaryotic and eukaryotic?
   Cell membrane
2. Osmosis is the diffusion of water across a selectively permeable membrane from an area of higher water concentration to lower water concentration.
   True
3. A student examining a cell under a microscope sees a nucleus, a large central vacuole, a cell wall, and chloroplasts. Which type of organism is this cell most likely from?
   Plant
4. Which situation is the best example of osmosis rather than simple diffusion?
   Water moving into root hair cells from the soil
5. In 9th grade biology practice tests, students often mix up genes and alleles. Which description best defines an allele?
   A different form of a gene, such as A or a
6. A cell division process produces four genetically different cells, each with half the chromosome number of the original cell. Which process is described?
   Meiosis
7. In ecology, a community is defined as all the individuals of one species living in a particular area.
   False
8. Chloroplasts are found in plant cells but are not present in animal cells.
   True
9. In pea plants, tall (T) is dominant to short (t). Two heterozygous plants (Tt) are crossed. What is the probability that an offspring will be short?
   25%
10. A biology honors 9th grade student describes a process that "uses oxygen to break down glucose and release ATP inside mitochondria." Which process is being described?
    Cellular respiration
11. A field contains several hundred maple trees, many squirrels, dozens of bird species, and insects in the soil. The group of all squirrels living there is best described as a:
    Population
12. A graph of a rabbit population in a fenced grassland shows rapid growth at first, then levels off and fluctuates around 200 individuals over several years. In ecology, what does the value of 200 most likely represent?
    Carrying capacity
13. Meiosis produces daughter cells that are genetically identical to the parent cell and are used for growth and tissue repair.
    False
14. In a typical plant cell, which of the following structures contain DNA? Select all that apply.
    Mitochondrion; Chloroplast; Nucleus
15. Which statements correctly describe the Law of Independent Assortment? Select all that apply.
    The inheritance of one gene usually does not affect the inheritance of a second unlinked gene.; Allele pairs for different genes separate into gametes independently of one another.; This law applies when genes are located on different chromosomes.
16. Which statements about photosynthesis and cellular respiration are accurate? Select all that apply.
    Photosynthesis occurs in chloroplasts and stores energy in glucose.; Both plants and animals perform cellular respiration.; Photosynthesis requires carbon dioxide and water as reactants.
17. Two pea plants that are heterozygous for seed shape (Rr) and seed color (Yy) are crossed. According to the Law of Independent Assortment, which statement about their gametes is accurate?
    Gametes can contain any combination of one allele for shape and one for color, such as RY, Ry, rY, or ry.
18. A population of beetles shows variation in shell thickness. Birds can more easily crush beetles with thin shells, so beetles with thicker shells survive and reproduce more often. Over many generations, the average shell thickness in the population increases. What process best explains this change?
    Natural selection
19. Which of the following are density-dependent limiting factors for a deer population in a forest? Select all that apply.
    Disease spreading through close contact; Food availability; Competition for mates
20. Arrange the phases of mitosis and the final division of the cytoplasm in the correct order, starting with the first phase after interphase.
    Correct order: Prophase → Metaphase → Anaphase → Telophase → Cytokinesis
21. An enzyme from human cells shows low activity at 10°C, higher activity at 25°C, a clear peak at 37°C, and a sharp drop by 50°C on a graph. Which conclusion is best supported by this data?
    The enzyme has an optimum around 37°C and loses activity as temperature increases past that point.
22. Students design an experiment to test how light intensity affects the rate of photosynthesis in Elodea plants. They place three plants in different light intensities but use different volumes of water and different amounts of dissolved carbon dioxide in each beaker. Which changes would improve this experiment? Select all that apply.
    Use the same volume of water in all beakers.; Keep the amount of dissolved carbon dioxide the same in all treatments.; Use at least three plants in each light intensity group and average the results.