which of the following is not true about enzymes

HESI A2

Biology HESI A2 Practice Test

1. Which of the following is not true about enzymes?

A. They catalyze reactions
B. They lower the activation energy needed
C. They have an active site
D. They are typically proteins

Correct answer: B

Rationale: Enzymes lower the activation energy needed for a reaction to occur, not raise it. By lowering the activation energy, enzymes facilitate reactions, making them occur more easily and rapidly. Choice A is correct as enzymes indeed catalyze reactions. Choice C is correct as enzymes have specific active sites where substrates bind. Choice D is correct as enzymes are commonly proteins, although some RNA molecules also exhibit catalytic properties.

2. Muscles are connected to bones by , and bones are connected to each other by .

A. Muscles
B. Tendons, ligaments
C. Muscles
D. Ligaments

Correct answer: B

Rationale: Muscles are connected to bones by tendons, which allow the muscle to exert force on the bone for movement. Bones are connected to each other by ligaments, which provide stability and support to the joints between bones. This relationship between muscles, tendons, bones, and ligaments is essential for proper movement and function of the musculoskeletal system. Choice A is incorrect because muscles are not directly connected to bones; tendons serve as the connection between muscles and bones. Choice D is incorrect because ligaments connect bones to each other, not muscles to bones.

3. What is represented by this formula: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂?

A. Glycolysis
B. Cellular respiration
C. Photosynthesis
D. Electronic transport

Correct answer: C

Rationale: The formula represents the process of photosynthesis, where carbon dioxide (CO₂) and water (H₂O) are converted into glucose (C₆H₁₂O₆) and oxygen (O₂) using light energy. This process is essential for plants and some microorganisms to produce food and oxygen. Glycolysis and cellular respiration involve breaking down glucose to produce energy, and the electron transport chain is part of cellular respiration, not photosynthesis.

4. Tonicity refers to the movement of:

A. Water
B. Solute
C. Cells
D. None of the above

Correct answer: A

Rationale: Tonicity refers to the movement of water across a membrane in response to differences in solute concentration. In a hypertonic solution, where there is a higher concentration of solutes outside the cell, water will move out of the cell to try to reach equilibrium. In a hypotonic solution, where there is a lower concentration of solutes outside the cell, water will move into the cell to balance the concentrations. Cells and solutes themselves do not actively move in response to tonicity; it is the movement of water that helps achieve equilibrium. Therefore, the correct answer is water (Choice A). Choices B, C, and D are incorrect as tonicity specifically refers to water movement and not the movement of solutes, cells, or none of the above.

5. Which type of sugar is a disaccharide?

A. Sucrose
B. Fructose
C. Glucose
D. Galactose

Correct answer: A

Rationale: The correct answer is A, Sucrose. Sucrose is a disaccharide composed of one molecule of glucose and one molecule of fructose. When glucose and fructose combine, they form sucrose. Choice B, Fructose, is a monosaccharide, not a disaccharide. Choice C, Glucose, is also a monosaccharide, not a disaccharide. Choice D, Galactose, is another monosaccharide and not a disaccharide.