# Module A Quiz — Question Bank **Source:** Canvas quiz, submitted May 27 at 7:43 p.m. (attempt took 24 minutes) **Score:** 1.9 / 2.0 — Question 10 answered incorrectly; all others correct. **Note:** Correct answers are marked with ✅. For multiple-choice questions the student's selection was not captured in the paste; correct answers are identified from course content. For dropdown questions the recorded correct answers are shown. --- ## Question 1 — SA/V and body shape (dropdown) ✅ Correct > In general, as organisms increase in size (assume trying to maintain maximum efficiency), evolution favors organisms that keep their surface area to volume ratio ___ and their shape ___. - Answer 1: **high** ✅ - Answer 2: **non-spherical** ✅ *Rationale: A high SA/V makes exchange with the environment easier. A sphere has the lowest possible SA/V, so large efficient organisms are never spherical.* --- ## Question 2 — Why the continental shelf is so productive ✅ Correct > Why is the continental shelf the location of some of the highest biological productivity in the ocean? - Continental shelves are typically much bigger in temperate and polar biomes. - **Continental shelves are typically relatively shallow with high light and nutrient availability.** ✅ - Continental shelves produce the most nutrients from their deep sediments. - The continental shelf makes up the highest amount of surface area of the Earth's oceans. - Continental shelves are typically around 2000 m deep and typically support high nutrient concentrations. *Rationale: The shelf is shallower than ~200 m, so light reaches the bottom, and the nearby land supplies nutrients.* --- ## Question 3 — What is NOT an SA/V adaptation ✅ Correct > Which of the following is NOT an adaptation that an organism may utilize to deal with a change in the surface area to volume ratio as an organism gets bigger? Assume that one of the main goals is to keep energy utilization low. - Increased invaginations along its surface - Increased projections on the outside - **Evolve an overall shape that is more spherical** ✅ - Begin to use energy to directly import nutrients/food into the organism - Evolve energy dependent excretory and respiration systems *Rationale: A spherical shape makes SA/V worse. All other options either raise SA/V (projections, invaginations) or compensate with active transport systems.* --- ## Question 4 — Benthic vs. pelagic zones ✅ Correct > The continental shelf is part of the ________ zone and the bathypelagic is part of the ________ zone. - It depends on location. - benthic, benthic - **benthic, pelagic** ✅ - pelagic, benthic - pelagic, pelagic *Rationale: The continental shelf is seafloor (benthic). The bathypelagic is open water column, 1,000–4,000 m (pelagic).* --- ## Question 5 — When eukaryotes evolved ✅ Correct > Eukaryotes are thought to have originally evolved ______ years ago. - 500 to 400 million - 5000 years - 100 million - **2.2 to 1.7 billion** ✅ - 3.5 to 2.5 billion *Rationale: Eukaryotes appear in the fossil record ~1.8 billion years ago.* --- ## Question 6 — Evidence life originated in the oceans ✅ Correct > Which of the following is an important example that life on Earth originated in the oceans? - Many dinosaur fossils originated in the ocean. - All present day organisms are aerobic - Hydrothermal vents have examples of many aerobic plankton similar to the ones thought to exist over 3 billion years ago. - **Some stromatolite fossils date back at least 3 billion years ago.** ✅ - Most space debris only remains intact if it fails into the ocean *Rationale: Stromatolites (layered mounds built by cyanobacteria) are found in shallow seas and date back as far as ~3.5 billion years.* --- ## Question 7 — What does NOT affect salinity ✅ Correct > Which of the following does NOT affect seawater salinity? - Water movements from other parts of the ocean. - **Respiration** ✅ - Evaporation. - Inputs from rivers. - River input *Rationale: Salinity changes only when water or salt is added or removed (evaporation, precipitation, rivers, freezing, melting, currents). Respiration exchanges gases, not salt.* --- ## Question 8 — SA/V and increasing size (True/False) ✅ Correct > The surface area to volume ratio of an organism generally increases when the organism gets larger because surface area is proportional to the square of the length (L²) while volume is proportional to the cube of the length (L³). - True - **False** ✅ *Rationale: The geometry is correct, but the conclusion is backwards. SA/V is proportional to L²/L³ = 1/L, so SA/V **decreases** as the organism gets larger.* --- ## Question 9 — Energy storage molecules in animals (select all) ✅ Correct > Which of the following is used as an energy storage molecule in most animals? (select all that apply) - Nucleic Acids - **Lipids** ✅ - Starch - **Glycogen** ✅ *Rationale: Animals store energy as glycogen and lipids. Starch is the plant storage molecule. Nucleic acids store information, not energy.* --- ## Question 10 — When aerobic organisms became dominant ❌ Incorrect (0 / 0.1) > Aerobic organisms started to become the dominant organism on Earth how many years ago (choose the best answer)? - Roughly 4 billion years ago - Roughly 1.0 billion years ago - **Roughly 0.4 billion years ago** ✅ (correct answer) - Roughly 1.8 billion years ago - Roughly 3.5 billion years ago *Rationale: Rising oxygen about 650 million years ago drove the transition from anaerobic to aerobic organisms, and the atmosphere was fully oxygenated by ~600 million years ago. Of the choices, 0.4 billion years is closest to this transition.* --- ## Question 11 — What is NOT true of organic molecules (select all) ✅ Correct > Which of the following statements about organic molecules are NOT correct? (Select all that apply) - **Organic molecules always contain oxygen atoms.** ✅ - **Organic molecules can only be produced by living things.** ✅ - Organic molecules may contain oxygen, nitrogen, phosphorus, or sulfur, but these are not always present. - Organic molecules are primarily composed of carbon and hydrogen. - Carbon dioxide (CO₂) is NOT considered an organic molecule. *Rationale: The two flagged statements are false. Lipids are mostly carbon and hydrogen (no oxygen needed), and the Miller-Urey experiment produced organic molecules abiotically. The other three statements are true.* --- ## Question 12 — Salmon osmoregulation (dropdown) ✅ Correct > To maintain their internal ion content, salmon swimming in the open ocean must ___ seawater and ___, while salmon swimming up the river to spawn must not drink the river water and ___. - Answer 1: **drink** ✅ - Answer 2: **not urinate** ✅ - Answer 3: **not drink** ✅ - Answer 4: **urinate** ✅ *Rationale: In the ocean (hyperosmotic environment) salmon lose water by osmosis, so they drink seawater and produce very little urine while excreting salt at the gills. In fresh water (hypoosmotic) they gain water, so they stop drinking and produce large amounts of dilute urine.* --- ## Question 13 — Salinity vs. temperature variation (True/False) ✅ Correct > In general, there is more variation in salinity than temperature in the surface ocean. - True - **False** ✅ *Rationale: Open-ocean salinity is very stable (~33–37‰), while surface temperature varies from −2°C to +30°C.* --- ## Question 14 — Freezing point of seawater ✅ Correct > Average salinity seawater freezes at roughly what temperature (choose best answer)? - -4°C - 1°C - -1°C - 0°C - **-2°C** ✅ *Rationale: At average ocean salinity (~35‰), seawater freezes at about −1.8°C.* --- ## Question 15 — Respiration in all organisms (True/False) ✅ Correct > All organisms utilize respiration, including organisms that photosynthesize. - **True** ✅ - False *Rationale: Respiration releases the energy stored in organic molecules and occurs in all cells. Photosynthesis is only an add-on ability in autotrophs.* --- ## Question 16 — Is CO₂ organic? (True/False) ✅ Correct > Carbon dioxide is an organic molecule because it contains carbon. - True - **False** ✅ *Rationale: CO₂ is inorganic. It is too small and contains no hydrogen. Organic molecules are built mainly from carbon and hydrogen.* --- ## Question 17 — CO₂ concentrations today (True/False) ✅ Correct > Carbon dioxide concentrations, a greenhouse gas, in our atmosphere are currently the highest ever recorded in the instrumental and ice-core record. - **True** ✅ - False *Rationale: Current CO₂ (>420 ppm) is the highest in the 800,000-year ice-core record; the pre-industrial maximum was ~300 ppm. (The pasted quiz shows an "Incorrect" label near this question, but the awarded 0.1/0.1 pts and the 1.9/2 total — with only Q10 at 0 pts — confirm the answer was scored correct.)* --- ## Question 18 — Properties of the mixed layer ✅ Correct > Which of the following statements is TRUE for most mixed layers in the ocean? - Mixed layers are typically colder than water below it. - Mixed layers only occur in Tropical and Equatorial biomes. - **Mixed layers typically have uniform density.** ✅ - Mixed layers typically have uniform light. *Rationale: Wind mixes the surface layer until temperature, salinity, and therefore density are uniform. Light still decreases with depth within the mixed layer.* --- ## Question 19 — The twilight zone ✅ Correct > Which oceanic zone is known for its dim light and is often referred to as the "twilight zone"? - chemolagic zone - **mesopelagic zone** ✅ - bathypelagic zone - euphotic zone - abyssalpelagic zone *Rationale: The mesopelagic (200–1,000 m) is the dysphotic "twilight zone": light is present but below the 1% level needed for photosynthesis.* --- ## Question 20 — Why the origin of photosynthesis is hard to date ✅ Correct > Which of the following best explains why it is difficult to pinpoint the exact date where photosynthesis first evolved on Earth? - **Bacteria cells do not preserve well in the fossil record.** ✅ - Photosynthesis evolved independently in many different organisms so it is hard to tell which one was first. - Oxygen comes from many different sources so it is difficult to trace the beginning of photosynthesis. - Eukaryotic cells were too complex to evolve quickly. - Photosynthesis had to evolve before respiration. *Rationale: The first photosynthesizers were single-celled prokaryotes (cyanobacteria), and single-celled organisms generally do not preserve well over billions of years.*