STEM Science Content Knowledge 3 — Questions and Answers
Question 1: Which of the following best describes the process of natural selection?
- Random mutation increases genetic diversity equally in all organisms
- Organisms with traits better suited to their environment reproduce more successfully (Correct answer)
- All members of a species evolve at the same rate
- Traits acquired during an organism's lifetime are passed to offspring
Correct answer: Organisms with traits better suited to their environment reproduce more successfully
Natural selection favors individuals with heritable traits that improve survival and reproduction in their environment.
Question 2: What is the SI unit of electric charge?
- Ampere
- Volt
- Coulomb (Correct answer)
- Ohm
Correct answer: Coulomb
The coulomb (C) is the SI unit of electric charge, equal to the charge transported by one ampere in one second.
Question 3: In which organelle does the Calvin cycle (light-independent reactions) of photosynthesis occur?
- Mitochondrial matrix
- Chloroplast stroma (Correct answer)
- Thylakoid membrane
- Cytoplasm
Correct answer: Chloroplast stroma
The Calvin cycle occurs in the stroma of the chloroplast, where CO₂ is fixed into glucose using ATP and NADPH.
Question 4: What type of rock forms from the cooling and solidification of magma or lava?
- Sedimentary
- Metamorphic
- Igneous (Correct answer)
- Clastic
Correct answer: Igneous
Igneous rock forms when molten rock (magma underground or lava at the surface) cools and solidifies.
Question 5: Which gas law states that the pressure and volume of a gas are inversely proportional at constant temperature?
- Charles's Law
- Avogadro's Law
- Boyle's Law (Correct answer)
- Gay-Lussac's Law
Correct answer: Boyle's Law
Boyle's Law states that P₁V₁ = P₂V₂ at constant temperature, showing an inverse relationship between pressure and volume.
Question 6: What is the term for the energy required to remove an electron from an atom in its gaseous state?
- Electron affinity
- Electronegativity
- Ionization energy (Correct answer)
- Bond dissociation energy
Correct answer: Ionization energy
Ionization energy is the minimum energy needed to remove the outermost electron from a neutral gaseous atom.
Question 7: Which type of ecological relationship benefits one organism while the other is neither helped nor harmed?
- Mutualism
- Parasitism
- Commensalism (Correct answer)
- Competition
Correct answer: Commensalism
Commensalism describes a relationship where one organism benefits and the other is unaffected, such as barnacles on a whale.
STEM Science Content Knowledge 3
Which of the following best describes the process of natural selection?