most enzymes are made up of

HESI A2

Biology HESI A2 Practice Exam

1. Most enzymes are made up of what?

A. proteins
B. lipids
C. starches
D. simple sugars

Correct answer: A

Rationale: Most enzymes are made up of proteins. Proteins are large biomolecules composed of amino acids that are vital for the structure and function of enzymes. Enzymes act as catalysts in biochemical reactions, speeding up the rate of chemical reactions in living organisms. They exhibit high specificity and efficiency due to their unique protein structures. Lipids, starches, and simple sugars are not typically the primary components of enzymes, making them incorrect choices.

2. Which part of cellular respiration produces the greatest amount of ATP?

A. electron transport chain
B. glycolysis
C. citric acid cycle
D. fermentation

Correct answer: A

Rationale: The electron transport chain (ETC) produces the greatest amount of ATP during cellular respiration. This process occurs in the inner mitochondrial membrane and involves the transfer of electrons through a series of protein complexes, creating a proton gradient that drives the synthesis of ATP. By utilizing the energy from the electron carriers NADH and FADH2 produced in earlier stages of cellular respiration, the ETC can generate a large amount of ATP efficiently through oxidative phosphorylation. Glycolysis only produces a small amount of ATP in comparison to the ETC. The citric acid cycle generates some ATP but not as much as the ETC. Fermentation does not produce ATP through oxidative phosphorylation and yields a much smaller amount of ATP compared to the ETC.

3. What is the process by which cells divide to form two identical daughter cells?

A. Mitosis
B. Meiosis
C. Binary Fission
D. Cellular Division

Correct answer: A

Rationale: The correct answer is A, Mitosis. Mitosis is the process in which a cell divides to form two identical daughter cells. Choice B, Meiosis, is a type of cell division that results in four non-identical daughter cells with half the number of chromosomes. Choice C, Binary Fission, is a form of asexual reproduction used by prokaryotic organisms. Choice D, Cellular Division, is a general term that encompasses various processes of cell division, but specifically, mitosis refers to the division resulting in two identical daughter cells.

4. Which of the following is true of optical microscopy?

A. Utilizes scanning electrons
B. Utilizes visible light
C. Utilizes dye for samples
D. More than one of the above is true

Correct answer: D

Rationale: The correct answer is D, 'More than one of the above is true.' Optical microscopy utilizes visible light (Choice B) and often involves the use of dyes for samples (Choice C). Using dyes helps enhance contrast, making it easier to visualize the structures being observed. Choice A is incorrect as optical microscopy does not utilize scanning electrons, but rather visible light.

5. Which structure might be described as a core of nucleic acid surrounded by a protein coat?

A. RNA
B. Virus
C. Blue-green alga
D. Saprophyte

Correct answer: B

Rationale: A virus can be described as a core of nucleic acid (either RNA or DNA) surrounded by a protein coat, known as a capsid. This structure distinguishes viruses from other microorganisms such as blue-green algae (Cyanobacteria), fungi known as saprophytes, or individual RNA molecules. Viruses depend on a host cell to replicate and are considered non-living entities due to their inability to carry out metabolic functions independently.