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. Select the word that makes the following sentence grammatically correct. The flock huddles against the wind that ruffles ___________ feathers.
- A. its
- B. their
- C. it's
- D. they're
Correct answer: A
Rationale: In this sentence, the word 'flock' is singular, so the pronoun that follows should also be singular. Therefore, the correct choice is 'its,' which refers back to the singular noun 'flock.' Choice B ('their') is incorrect because it is a plural pronoun and does not agree in number with the singular noun 'flock.' Choices C ('it's') and D ('they're') are both incorrect contractions that do not fit grammatically in this context.
3. Choose the meaning of the word 'intramuscularly' in the following sentence: 'This vaccine must only be used intramuscularly and as a single-dose vial.'
- A. Between muscles
- B. Into muscles
- C. Without muscles
- D. On top of muscles
Correct answer: B
Rationale: The word 'intramuscularly' in the sentence indicates that the vaccine should be used by injection directly into the muscles. This means the correct meaning is 'into muscles,' making option B the most suitable choice. Choices A, C, and D are incorrect because 'intramuscularly' specifically refers to administering something inside the muscle, not between muscles, without muscles, or on top of muscles.
4. Through which organ do muscles push food into the stomach via peristalsis?
- A. Mouth
- B. Small intestine
- C. Epiglottis
- D. Esophagus
Correct answer: D
Rationale: The correct answer is D, Esophagus. Muscles push food into the stomach via peristalsis in the esophagus. Peristalsis is a coordinated muscular contraction that helps move food from the mouth to the stomach through the esophagus. The rhythmic contractions of the esophageal muscles create a wave-like motion that propels food downward toward the stomach for digestion. Choices A, B, and C are incorrect because the mouth is where digestion begins but does not push food into the stomach, the small intestine is mainly responsible for absorbing nutrients, and the epiglottis is a flap that prevents food from entering the trachea during swallowing, not involved in pushing food into the stomach.
5. Which gland is responsible for regulating metabolism?
- A. Pituitary gland
- B. Adrenal gland
- C. Thyroid gland
- D. Pineal gland
Correct answer: C
Rationale: The thyroid gland is responsible for regulating metabolism. It produces hormones such as thyroxine, which plays a key role in influencing the body's metabolic rate. The pituitary gland is known as the 'master gland' but is not directly responsible for regulating metabolism. The adrenal gland is involved in the stress response and producing hormones like cortisol, not primarily regulating metabolism. The pineal gland produces melatonin, which regulates sleep-wake cycles, not metabolism. Therefore, the correct answer is the thyroid gland.
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