Free Scientific Reasoning MCQs with Answers
334 Scientific Reasoning MCQs from Analytical and Logical Reasoning, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Scientific reasoning evaluates hypotheses through observations, variables, controls, measurements and experimental results. Questions involve identifying independent and dependent variables, recognising a fair test, interpreting tables or graphs, distinguishing evidence from opinion, and deciding whether data supports, rejects or leaves a hypothesis unresolved.
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Read the Scientific Reasoning notesFree MDCAT chapter notes with key terms334 questions · page 11 of 17
- A. Waxy leaves improve photosynthesis.
- B. CO₂ enters only through stem bark.
- C. Plants don't need CO₂ for photosynthesis.
- D. Stomata are essential for gaseous exchange in leaves.
Explanation: The correct answer is that stomata are essential for gaseous exchange in leaves.
Correct answer: Stomata are essential for gaseous exchange in leaves.- A. The brain is inactive during sleep.
- B. Sound cannot penetrate sleep states.
- C. Only light affects brain waves.
- D. Auditory stimuli can affect brain activity even during unconsciousness.
Explanation: The correct answer is option D. The experiment clearly demonstrated that sudden loud sounds caused a sharp spike in brain wave activity…
Correct answer: Auditory stimuli can affect brain activity even during unconsciousness.- A. Excess nitrogen promotes leaf growth at the expense of fruiting.
- B. Nitrates improve all aspects of plant growth.
- C. Fruit size is unrelated to soil nutrients.
- D. Nitrate-deficient plants always die.
Explanation: The correct answer is Option A: Excess nitrogen promotes leaf growth at the expense of fruiting.
Correct answer: Excess nitrogen promotes leaf growth at the expense of fruiting.- A. All bacteria are killed regardless of resistance.
- B. Antibiotics enhance bacterial reproduction.
- C. Genetic resistance provides survival advantage under antibiotic pressure.
- D. Resistance has no evolutionary importance.
Explanation: The correct answer is Option C: Genetic resistance provides survival advantage under antibiotic pressure.
Correct answer: Genetic resistance provides survival advantage under antibiotic pressure.- A. Metallic surfaces can block radiation from reaching plant tissues.
- B. All plant tissues reflect radiation.
- C. Radiation penetrates aluminum easily.
- D. Plants generate radiation internally.
Explanation: The correct answer is that metallic surfaces, like aluminum foil, can block radiation from reaching plant tissues.
Correct answer: Metallic surfaces can block radiation from reaching plant tissues.- A. External light is necessary for circadian rhythms to function.
- B. Circadian rhythms are internally regulated by biological clocks.
- C. Darkness stops circadian rhythms from occurring.
- D. Motion sensors affect circadian rhythm patterns in rats.
Explanation: The correct answer is that circadian rhythms are internally regulated by biological clocks.
Correct answer: Circadian rhythms are internally regulated by biological clocks.- A. Candles increase oxygen by heating the air.
- B. Plants release CO₂ in light only.
- C. Combustion uses oxygen and produces carbon dioxide.
- D. Burning wax generates oxygen.
Explanation: In the experiment, the jar with the lit candle had lower oxygen levels and higher CO₂ levels compared to the plant-only jar.
Correct answer: Combustion uses oxygen and produces carbon dioxide.- A. Embryos develop faster when static.
- B. Rotation damages embryos.
- C. Rotation distributes nutrients evenly in developing embryos.
- D. Egg turning slows gas exchange.
Explanation: The correct answer is that rotation distributes nutrients evenly in developing embryos, as evidenced by the higher hatch rates and…
Correct answer: Rotation distributes nutrients evenly in developing embryos.- A. Adrenaline permanently lowers blood pressure.
- B. Adrenaline causes a temporary increase in blood pressure.
- C. Adrenaline has no cardiovascular effect.
- D. Adrenaline slows down the heart rate.
Explanation: The correct answer is Option B: Adrenaline causes a temporary increase in blood pressure.
Correct answer: Adrenaline causes a temporary increase in blood pressure.- A. Dye bypasses kidney filtration.
- B. Kidneys filter substances from blood into urine.
- C. Urine formation is independent of kidneys.
- D. Damaged kidneys excrete more dye.
Explanation: The correct answer is that kidneys filter substances from blood into urine.
Correct answer: Kidneys filter substances from blood into urine.- A. Wind exposure strengthens stems while inhibiting height growth.
- B. Stem thickness increases due to wind-induced mechanical stress.
- C. Mechanical stress promotes stem strengthening at the expense of height growth.
- D. Wind exposure results in stunted growth and thicker stems.
Explanation: The correct answer is Option C: Mechanical stress promotes stem strengthening at the expense of height growth.
Correct answer: Mechanical stress promotes stem strengthening at the expense of height growth.- A. Offspring developed their own immunity in utero.
- B. Pathogen was inactive.
- C. Maternal vaccination has no protective role.
- D. Antibodies were transferred from mother to offspring.
Explanation: The correct answer is that antibodies were transferred from the mother to the offspring.
Correct answer: Antibodies were transferred from mother to offspring.- A. Taste perception can be influenced by genetic variation.
- B. Taste is unrelated to receptors.
- C. Bitterness is universally perceived the same.
- D. Only environment affects bitterness sensitivity.
Explanation: The correct answer is that taste perception can be influenced by genetic variation.
Correct answer: Taste perception can be influenced by genetic variation.- A. Fish adjust their internal salt concentration over time.
- B. Fish cannot survive salt changes.
- C. Osmosis is not involved in weight loss.
- D. Weight loss is unrelated to water conditions.
Explanation: The correct answer is that fish adjust their internal salt concentration over time.
Correct answer: Fish adjust their internal salt concentration over time.- A. All plants are unaffected by toxic metals.
- B. Lead and mercury improve water absorption in roots.
- C. Arsenic promotes healthy plant metabolism.
- D. Heavy metals inhibit plant growth and disrupt chlorophyll production.
Explanation: The correct answer is that heavy metals inhibit plant growth and disrupt chlorophyll production.
Correct answer: Heavy metals inhibit plant growth and disrupt chlorophyll production.- A. Smoke improves cellular motion by stimulating cilia.
- B. Cilia regenerate rapidly in smoky conditions.
- C. Smoking impairs cilia function and may reduce airway cleaning ability.
- D. Smoke increases lung oxygen exchange rate.
Explanation: The correct answer is option C: Smoking impairs cilia function and may reduce airway cleaning ability.
Correct answer: Smoking impairs cilia function and may reduce airway cleaning ability.- A. Hydrogen peroxide inhibits catalase at all levels.
- B. Catalase activity increases with substrate concentration up to a point.
- C. Liver tissue does not affect bubble formation.
- D. All concentrations give the same enzymatic activity.
Explanation: The correct answer is that catalase activity increases with substrate concentration up to a point.
Correct answer: Catalase activity increases with substrate concentration up to a point.- A. Boiled seeds produce more CO₂ than germinating ones.
- B. All plant material releases CO₂ equally.
- C. Respiration does not occur in seeds.
- D. Germinating seeds carry out respiration and produce CO₂.
Explanation: The correct answer is that germinating seeds carry out respiration and produce CO₂, as evidenced by the increase in CO₂ levels only in the…
Correct answer: Germinating seeds carry out respiration and produce CO₂.- A. Plasmolysis occurs due to water loss in hypertonic solutions.
- B. Water floods into onion cells in salt solution.
- C. Salt thickens the cell wall.
- D. Salt enters the vacuole and bursts the cell.
Explanation: In this experiment, the higher salt concentrations led to vacuole shrinkage and membranes pulling away from the cell wall, indicating…
Correct answer: Plasmolysis occurs due to water loss in hypertonic solutions.- A. Frog hearts function independently of temperature.
- B. Temperature affects metabolic rate in ectothermic animals.
- C. Heat lowers frog heart rate.
- D. Heart rate in frogs is constant.
Explanation: The correct answer is that temperature affects metabolic rate in ectothermic animals.
Correct answer: Temperature affects metabolic rate in ectothermic animals.