MCAT Chemical and Physical Foundations of Biological Systems Flashcards: Analyze Evaluate Scientific Explanations Predictions

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This deck focuses on Analyze Evaluate Scientific Explanations Predictions, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Chemical and Physical Foundations of Biological Systems.

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Flashcard 1: What is a confounding variable in an experimental design?

Answer: A factor correlated with the independent variable that affects the outcome. Confounders obscure true causal relationships by introducing extraneous influences on the dependent variable.

Flashcard 2: Identify the correct interpretation if correlation coefficient $r=0$ for two variables.

Answer: No linear association is present. A correlation of $r=0$ signifies no linear relationship between variables, though nonlinear associations may still exist.

Flashcard 3: Which term describes how close repeated measurements are to one another?

Answer: Precision. Precision reflects the reproducibility of measurements, indicating low variability regardless of proximity to the true value.

Flashcard 4: Identify the correct conclusion if a proposed explanation conflicts with a well-established conservation law.

Answer: The explanation is invalid unless assumptions or measurements are corrected. Conservation laws are fundamental principles; violations indicate flaws in the explanation or underlying assumptions.

Flashcard 5: What is the formula for density used to evaluate plausibility of a physical explanation?

Answer: $\rho=\frac{m}{V}$. Density relates mass to volume, enabling evaluation of material properties and consistency in physical models.

Flashcard 6: Which prediction best follows if a model claims $y$ is proportional to $x$?

Answer: Doubling $x$ should double $y$. Proportionality implies a linear relationship through the origin, so scaling the input directly scales the output.

Flashcard 7: What is the definition of random error in measurements?

Answer: Unpredictable variation that reduces precision but not accuracy on average. Random error arises from unpredictable fluctuations, averaging to zero over many trials but increasing variability.

Flashcard 8: Which concept is violated if an observed association is due to an unmeasured third variable?

Answer: Causal inference (association does not imply causation). An unmeasured third variable can create spurious associations, preventing valid causal conclusions from correlational data.

Flashcard 9: What is the purpose of a control group in evaluating a scientific explanation?

Answer: Provide a baseline for comparison to isolate the tested effect. Control groups eliminate alternative explanations by providing a reference point without the experimental treatment.

Flashcard 10: Which term describes the outcome variable that is measured in response to manipulation?

Answer: Dependent variable. The dependent variable reflects changes resulting from alterations in the independent variable, serving as the key outcome metric.

Flashcard 11: Which term describes the variable that is deliberately manipulated by the experimenter?

Answer: Independent variable. The independent variable is controlled by the researcher to examine its causal impact on other factors.

Flashcard 12: What is the operational definition of a variable in an experiment?

Answer: The specific, measurable way a variable is defined and assessed. Operational definitions ensure variables are concretely specified for reliable measurement and replication in experiments.

Flashcard 13: What is the definition of a scientific hypothesis in the context of experimental testing?

Answer: A falsifiable, testable proposed explanation for an observation. A hypothesis must be empirically testable and potentially disprovable to qualify as scientific, allowing for experimental validation or refutation.

Flashcard 14: What is the definition of systematic error in measurements?

Answer: Consistent bias that shifts results away from the true value. Systematic error introduces consistent deviation due to flaws in methodology or instrumentation, affecting all measurements uniformly.

Flashcard 15: Which choice best describes a mechanism-based explanation in chemical or biological systems?

Answer: A causal account specifying intermediate steps linking cause to effect. Mechanism-based explanations enhance understanding by detailing the underlying processes and causal pathways in systems.

Flashcard 16: Which conclusion is supported if two independent experiments produce the same result within error?

Answer: The finding is reproducible (greater reliability). Replication across independent studies strengthens confidence in the result's validity and reduces the likelihood of artifacts.

Flashcard 17: What is the formula for percent error when comparing experimental and accepted values?

Answer: $\left|\frac{\text{exp}-\text{acc}}{\text{acc}}\right|\times 100\%$. Percent error quantifies the relative discrepancy between measured and true values, assessing experimental accuracy.

Flashcard 18: Which statement is correct if the slope of a best-fit line is negative in a scatterplot?

Answer: As $x$ increases, $y$ tends to decrease. A negative slope in regression indicates an inverse linear relationship, where increases in $x$ correspond to decreases in $y$.

Flashcard 19: Which conclusion is most justified if a $95\%$ confidence interval excludes $0$ for a mean difference?

Answer: The mean difference is statistically significant at $\alpha=0.05$. Exclusion of zero in a 95% CI implies the difference is unlikely due to chance, supporting rejection of the null at $\alpha=0.05$.

Flashcard 20: What is the definition of a confidence interval for a parameter estimate?

Answer: A range expected to contain the true parameter at a stated confidence. Confidence intervals provide a plausible range for the population parameter, with the level indicating long-run coverage probability.

Flashcard 21: Which error occurs when a false null hypothesis is incorrectly not rejected?

Answer: Type II error (false negative). Type II error occurs when an actual effect is missed, often due to insufficient power or sample size.

Flashcard 22: Which error occurs when a true null hypothesis is incorrectly rejected?

Answer: Type I error (false positive). Type I error represents the risk of falsely detecting an effect when none exists, controlled by the significance level.

Flashcard 23: What does statistical significance at p$<0.05$ indicate in null hypothesis testing?

Answer: Data are unlikely under $H_0$ at the $5\%$ level. A $p<0.05$ threshold indicates sufficient evidence to reject the null hypothesis at the 5% significance level.

Flashcard 24: What does a $p$-value represent when evaluating evidence against a null hypothesis?

Answer: Probability of results at least as extreme, assuming $H_0$ is true. The $p$-value quantifies the evidence against the null hypothesis by calculating the likelihood of observed data under its assumption.

Flashcard 25: Which term describes how close a measurement is to the true or accepted value?

Answer: Accuracy. Accuracy measures the closeness of results to the actual value, distinguishing it from mere consistency.