Critical Thinking Flashcards

A student observes a plant bending toward a light source. What is the best explanation for this behavior?

Answer: Phototropism

Phototropism is the growth response of a plant in response to a light stimulus. When a plant bends toward a light source, it is exhibiting positive phototropism, a mechanism that helps it maximize light absorption for photosynthesis.

If a cell is placed in a hypertonic solution, what will most likely happen to the cell?

Answer: The cell will shrink

A hypertonic solution has a higher solute concentration outside the cell than inside. Due to osmosis, water will move from an area of higher water concentration (inside the cell) to an area of lower water concentration (outside the cell) to equalize the solute concentration, causing the cell to lose water and shrink.

Which conclusion is best supported by the discovery of fossils with similar bone structures in different species?

Answer: They share a common ancestor

The discovery of fossils with similar bone structures (homologous structures) in different species provides strong evidence for common ancestry. These shared anatomical features suggest that these species evolved from a common ancestor, with modifications occurring over time due to adaptation to different environments.

Why is it important to have a control group in a biological experiment?

Answer: To serve as a baseline for comparison

A control group in a biological experiment is essential because it provides a baseline for comparison. This group does not receive the experimental treatment or manipulation, allowing researchers to isolate the effect of the independent variable and determine if observed changes in the experimental group are truly due to the treatment.

A scientist finds that changing the pH of a solution stops an enzyme from working. What is the most logical explanation?

Answer: The enzyme denatured due to pH change

Enzymes are highly sensitive to changes in environmental conditions like pH and temperature because these factors can alter their specific three-dimensional structure, particularly the active site. When the pH changes drastically, the enzyme can denature, meaning its shape is altered, rendering it unable to bind to its substrate and function effectively.

If a genetic mutation occurs in a somatic (body) cell, what is the likely result?

Answer: It may cause disease in the individual

A genetic mutation occurring in a somatic (body) cell affects only the individual in which it arises and is not passed on to offspring. While not inheritable, such mutations can lead to various consequences within that individual, including cellular dysfunction, uncontrolled cell growth (cancer), or other diseases.

Which is the most reasonable hypothesis if two closely related species show different traits?

Answer: They adapted to different environments

Even closely related species can develop different traits if they adapt to distinct environmental conditions or ecological niches. Natural selection favors characteristics that enhance survival and reproduction in a particular environment, leading to the divergence of traits over time as species specialize.

A researcher notices bacteria grow faster in warm temperatures. What is the best next step?

Answer: Test bacteria at different temperatures

To scientifically validate the observation that bacteria grow faster in warm temperatures, the best next step is to systematically test bacterial growth across a range of different temperatures. This controlled experiment would help establish an optimal temperature for growth and quantify the relationship, while keeping other variables constant.

Why do biologists repeat experiments multiple times?

Answer: To ensure consistent results

Biologists repeat experiments multiple times, a practice known as replication, to ensure the consistency and reliability of their results. Repeating experiments helps to confirm that the observed outcomes are not due to random chance or experimental error, thereby increasing confidence in the validity of the findings.