12. An enzyme is added to a solution where its substrate and product are in equilibrium. What will occur?
(A) Additional substrate will be formed.
(B) The reaction will change from endergonic to exergonic.
(C) The free energy of the system will change.
(D) Nothing; the reaction will stay at equilibrium.

8. Which of the following classes of large biological molecules does NOT consist of polymers?(A) Carbohydrates (B) Proteins (C) Lipids (D) Nucleic acids

9. Which of the following processes involves the net movement of water across a selectively permeable membrane?(A) Active transport (B) Facilitated diffusion (C) Osmosis (D) Cotransport

10. To study the process of protein translation from mRNA, which cellular component would be most enriched in the finalpellet after cell fractionation?(A) Nuclei (B) Mitochondria(C) Pieces of plasma membranes (D) Ribosomes

11. Consider a metabolic pathway where compound X is converted to Y, and Y is converted to Z. If the enzyme converting X to Y is inhibited by the accumulation of Z, this is an example of:(A) Allosteric activation. (B) Competitive inhibition.(C) Noncompetitive inhibition. (D) Feedback inhibition.

13. What percentage of the human genome codes for proteins or gives rise to rRNAs or tRNAs?(A) 1.5% (B) 5% (C) 20% (D) 75%

14. The immediate energy source that directly drives ATP synthesis by ATP synthase during oxidative phosphorylation is the:(A) oxidation of glucose and other organic compounds.(B) flow of electrons down the electron transport chain.(C) H+ concentration gradient across the membrane holding ATP synthase.(D) transfer of phosphate to ADP.

15. How do transposons and retrotransposons differ in their movement mechanisms within the genome?(A) Transposons move via an RNA intermediate, while retrotransposons move via a DNA intermediate.(B) Transposons are less prevalent and move via an RNA intermediate, while retrotransposons are more prevalent and move via a DNA intermediate.(C) Transposons move via a DNA intermediate, while retrotransposons are more prevalent and move via an RNA intermediate.(D) Both transposons and retrotransposons move via a DNA intermediate, but only retrotransposons create new copies.

16. Which mechanism of evolution consistently causes adaptive evolution?(A) Genetic drift (B) Gene flow (C) Natural selection (D) Mutation

17. Which of the following is the primary role of the Calvin cycle in photosynthesis?(A) To produce ATP and NADPH.(B) To capture light energy.(C) To split water and release oxygen.(D) To use chemical energy (ATP and NADPH) to reduce CO2 to sugar.

18. A water-soluble hormone typically acts on a target cell by:(A) binding to a receptor inside the cell to alter gene expression.(B) binding to a cell-surface receptor to trigger an intracellular signal transduction pathway.(C) diffusing across the plasma membrane to directly activate enzymes.(D) being converted into a lipid-soluble form before entering the cell.