Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$\ \mathrm{M}$$

Question 1

Which of the following best illustrates the concept of emergent properties in biological systems?

Accepted Answer

A population of bacteria can evolve antibiotic resistance, even though individual bacteria cannot.

Question 2

A scientist is testing the effect of a new fertilizer on plant growth. She keeps the amount of sunlight, water, and soil type the same for all plants, but varies the amount of fertilizer. Which variable is the dependent variable in this experiment?

Accepted Answer

Plant growth (measured as height or mass)

Question 3

Which of the following statements about water is FALSE?

Accepted Answer

Ice is denser than liquid water, causing it to sink.

Question 4

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$\ \mathrm{M}$$

Question 5

Which of the following best describes the difference between facilitated diffusion and active transport across a cell membrane?

Accepted Answer

Facilitated diffusion uses membrane proteins to move substances down their concentration gradient without energy input, while active transport requires energy to move substances against their gradient.

Question 6

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 7

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 8

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the expected phenotypic ratio according to Mendel's law of independent assortment?

Accepted Answer

9:3:3:1

Question 9

A woman who is a carrier for an X-linked recessive disorder has children with a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

50%

Question 10

Which of the following events increases genetic variation during meiosis?

Accepted Answer

Crossing over between homologous chromosomes

Question 11

Which equation correctly represents the relationship between free energy, enthalpy, entropy, and temperature?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 12

Which process produces the most ATP during cellular respiration?

Accepted Answer

Oxidative phosphorylation

Question 13

A plant cell is placed in a hypertonic solution. What will most likely happen to the cell?

Accepted Answer

It will lose water and undergo plasmolysis.

Question 14

Which of the following is a real-life example of positive feedback?

Accepted Answer

Blood clotting after an injury

Question 15

Which of the following best explains why C4 and CAM plants have evolved different mechanisms of carbon fixation?

Accepted Answer

To reduce photorespiration and conserve water in hot, dry environments

Question 16

Which organelle is primarily responsible for detoxifying drugs and synthesizing lipids in liver cells?

Accepted Answer

Smooth endoplasmic reticulum

Question 17

A patient is diagnosed with a mitochondrial disorder that impairs ATP production. Which cellular process is most directly affected?

Accepted Answer

Cellular respiration

Question 18

Which of the following best describes the role of tRNA during translation?

Accepted Answer

It brings specific amino acids to the ribosome based on codon-anticodon pairing.

Question 19

A researcher observes that a certain enzyme's activity decreases when a molecule binds to a site other than the active site, changing the enzyme's shape. This is an example of:

Accepted Answer

Allosteric regulation

Question 20

Which of the following best explains why Trisomy 21 (Down syndrome) occurs?

Accepted Answer

Nondisjunction during meiosis leading to an extra chromosome 21

Foundations of Biology: Key Concepts and Processes

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