Part 2 — Answer key

Compare your answers after you have finished Part 1.

1. In many biology trivia questions, this organelle is called the "powerhouse" of the cell. What is it?
   Mitochondrion
2. All living cells, including bacterial cells, use DNA as their genetic material.
   True
3. A plant breeder crosses a true-breeding purple-flowered pea plant with a true-breeding white-flowered plant. All offspring have purple flowers. In this classic biology trivia scenario, how is the purple flower trait best described?
   Dominant trait
4. During a biology trivia game about the heart, you are asked which chamber pumps oxygenated blood out to the rest of the body. Which chamber is it?
   Left ventricle
5. In humans, the pulmonary artery carries oxygen-rich blood from the lungs to the heart.
   False
6. In a set of biology trivia questions about food webs, you see an animal that eats both berries and small rodents. What type of feeder is it?
   Omnivore
7. A farmer has sprayed the same insecticide on her crops for many years. Over time, more insects survive the treatment and damage the plants. Which explanation best fits how resistance evolved in this population?
   Pre-existing genetic variation lets resistant insects survive and leave more offspring.
8. In a food web, about 90% of the energy at one trophic level is typically passed on to the next higher trophic level.
   False
9. A patient with seasonal influenza asks a doctor for antibiotics "to feel better faster." Which response best explains why the doctor might not prescribe them?
   Antibiotics do not work on viruses, so they would not treat the infection.
10. Under a microscope, you observe a plant cell with many green structures filled with pigment. In which process are these structures primarily involved?
    Photosynthesis
11. In humans, the sex of a baby is determined by whether the fertilizing sperm carries an X chromosome or a Y chromosome.
    True
12. Most bacteria living in the human gut are either beneficial or harmless to their host rather than causing disease.
    True
13. An endurance athlete moves to a high-altitude training camp and stays for several weeks. Which blood change most directly improves the oxygen-carrying capacity of their blood?
    Red blood cell count
14. In a coastal marsh, a dense grass species stabilizes the soil, slows waves, and provides habitat for many other organisms. When this grass is removed, much of the community collapses. How is this grass best described?
    Foundation species
15. Arrange these stages of natural selection in the order they typically occur in a population over time.
    Correct order: Heritable variation exists in a population. → Environmental conditions create a selection pressure. → Individuals with advantageous traits have higher survival and reproduction. → Favorable traits become more common in the population.
16. A rare disorder in a family is always passed from an affected mother to all of her children, but affected fathers never pass it on to any of their children. Which inheritance pattern best explains this pedigree?
    Mitochondrial inheritance
17. A researcher studying an enzyme finds that adding a small molecule decreases the reaction rate, but greatly increasing the substrate concentration restores the rate almost to normal. What type of inhibition is most consistent with these results?
    Competitive inhibition