HESI A2
HESI A2 Biology 2024
1. Why do high-salt content foods not require refrigeration to prevent spoilage?
- A. Osmosis
- B. Diffusion
- C. Active transport
- D. Passive transport
Correct answer: A
Rationale: Osmosis is the natural process that prevents high-salt content foods from spoiling without the need for refrigeration. Osmosis involves the movement of water across a semi-permeable membrane from an area of lower solute concentration (water) to an area of higher solute concentration (salt). In high-salt content foods, the salt acts as a preservative by drawing moisture out of bacteria or other microorganisms, making it difficult for them to survive and spoil the food. This process helps in preserving the food and preventing spoilage even without refrigeration. Choices B, C, and D are incorrect because they do not involve the specific mechanism of water movement in response to the salt concentration in high-salt content foods.
2. What helps the cell maintain its shape and allows it to adapt?
- A. Microfilaments
- B. Cytoplasm
- C. Cytoskeleton
- D. Centrioles
Correct answer: C
Rationale: The cytoskeleton is the correct answer. It provides structural support to the cell, helps maintain its shape, and enables it to adapt to different environments. Microfilaments are part of the cytoskeleton, but they alone do not encompass the entire cytoskeleton's functions. Cytoplasm is the fluid inside the cell where organelles are suspended and is not directly responsible for maintaining cell shape. Centrioles are involved in cell division and do not primarily contribute to maintaining the cell's shape and adaptation.
3. Which bacteria are spherical in shape?
- A. Clostridia
- B. Bacilli
- C. Spirilla
- D. Cocci
Correct answer: D
Rationale: The correct answer is D, Cocci. Bacteria that are spherical in shape are known as cocci. They can be found in various arrangements such as clusters, chains, or pairs. Examples of cocci bacteria include Staphylococcus aureus and Streptococcus pneumoniae. Choice A, Clostridia, consists of rod-shaped bacteria. Choice B, Bacilli, refers to rod-shaped bacteria as well. Choice C, Spirilla, are spiral-shaped bacteria, not spherical.
4. What is the purpose of the mitochondria?
- A. Control the cell
- B. Create energy
- C. Create proteins
- D. Package waste for removal
Correct answer: B
Rationale: The correct answer is B: Create energy. The primary purpose of the mitochondria is to generate energy for the cell. Mitochondria are known as the 'powerhouses' of the cell because they produce ATP (adenosine triphosphate), which is the energy currency used by cells to carry out various functions and processes. Choice A is incorrect as the mitochondria do not control the cell but rather produce energy. Choice C is incorrect as protein synthesis primarily occurs in the ribosomes. Choice D is incorrect as packaging waste for removal is a function associated with lysosomes, not mitochondria.
5. What are the two catabolic pathways that lead to cellular energy production?
- A. Fermentation and internal respiration
- B. Fermentation and external respiration
- C. Fermentation and cellular respiration
- D. Fermentation and anaerobic respiration
Correct answer: C
Rationale: The correct answer is 'Fermentation and cellular respiration.' Fermentation is an anaerobic catabolic process that occurs in the absence of oxygen, producing limited amounts of ATP. Cellular respiration, on the other hand, is the aerobic catabolic pathway that occurs in the presence of oxygen and is the most efficient way of producing ATP. Choices A, B, and D are incorrect because internal respiration, external respiration, and anaerobic respiration are not the correct pathways leading to cellular energy production.
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