what type of molecules are enzymes

ATI TEAS 7

ATI TEAS 7 Science Practice Test

1. What type of molecules are enzymes?

A. Water molecules
B. Protein molecules
C. Tripolar molecules
D. Inorganic molecules

Correct answer: B

Rationale: The correct answer is B: Protein molecules. Enzymes are biological catalysts made up of proteins. They function by facilitating and speeding up chemical reactions in living organisms. Therefore, enzymes are primarily composed of protein molecules, not water, tripolar, or inorganic molecules. Choice A (Water molecules), Choice C (Tripolar molecules), and Choice D (Inorganic molecules) are incorrect because enzymes are specifically classified as proteins due to their structure and function in biological systems.

2. Which of the following statements is true regarding a supersaturated solution?

A. It is unstable and tends to crystallize
B. It contains more solute than it could dissolve
C. It has a higher concentration than a saturated solution
D. It is rarely encountered in everyday solutions

Correct answer: A

Rationale: A supersaturated solution is unstable and tends to crystallize because it contains more solute than it could dissolve at a given temperature. This excess solute is in a metastable state and can precipitate out if disturbed, leading to the formation of crystals. Option B is incorrect because a supersaturated solution does contain more solute than it could normally dissolve, but it becomes unstable due to this excess solute. Option C is incorrect because while a supersaturated solution does have a higher concentration than a saturated solution, the defining characteristic related to its instability is the excess solute. Option D is incorrect as supersaturated solutions can be encountered in various everyday scenarios, such as certain sugar solutions used in cooking or rock candy production.

3. Which process allows for the movement of large molecules, such as proteins and polysaccharides, across the cell membrane?

A. Endocytosis
B. Exocytosis
C. Active transport
D. Facilitated diffusion

Correct answer: A

Rationale: Endocytosis is the process by which cells engulf large molecules or particles by wrapping the cell membrane around them to form a vesicle that is brought into the cell. This mechanism facilitates the movement of large molecules like proteins and polysaccharides across the cell membrane. Exocytosis involves the release of large molecules or particles from the cell, opposite to the scenario described in the question. Active transport requires energy to move molecules against their concentration gradient and is not primarily used for transporting proteins and polysaccharides. Facilitated diffusion entails the movement of molecules aided by transport proteins but is not the primary mechanism for transporting large molecules such as proteins and polysaccharides.

4. Decomposers in an ecosystem play a vital role by:

A. Photosynthesizing and producing organic matter
B. Breaking down dead organisms and returning nutrients to the environment
C. Preying on herbivores and controlling their populations
D. Fixing nitrogen from the atmosphere and making it available to plants

Correct answer: B

Rationale: Decomposers are organisms that break down dead organic matter, such as dead plants and animals, into simpler substances. By doing so, they help to recycle nutrients back into the environment, making them available for other organisms to use. This process is essential for the functioning of ecosystems, as it ensures that nutrients are not lost but instead are continuously cycled through the ecosystem. Photosynthesis (option A) is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose, and it is not a role of decomposers. Preying on herbivores (option C) is a role typically carried out by predators, not decomposers. Fixing nitrogen from the atmosphere (option D) is a process carried out by nitrogen-fixing bacteria, not decomposers.

5. What is the primary function of lymph nodes, small, bean-shaped structures found along lymphatic vessels?

A. To store excess lymph fluid
B. To produce red blood cells
C. To filter lymph and fight infection
D. To transport lymph to the heart

Correct answer: C

Rationale: Lymph nodes primarily function to filter lymph and fight infection. They contain immune cells that help to remove pathogens and foreign particles from the lymph fluid as it passes through the nodes. This process helps to activate the immune response and defend the body against infections. Choice A is incorrect as lymph nodes do not store excess lymph fluid; they filter lymph. Choice B is incorrect as the production of red blood cells primarily occurs in the bone marrow, not in lymph nodes. Choice D is incorrect as lymph nodes do not transport lymph to the heart; they filter and process lymph to remove impurities and activate the immune response.