HESI A2
Biology HESI A2 Practice Test
1. Which of the following describes the situation where one allele takes a different form from another in a gene?
- A. phenotype
- B. heterozygous
- C. homolog
- D. homozygous
Correct answer: B
Rationale: Heterozygous is the term used to describe the genotype of an individual with two different alleles for a specific gene. In this case, one allele takes a different form from another, resulting in genetic diversity and variation in trait expression. The other choices are incorrect: 'phenotype' refers to the observable traits of an organism, 'homolog' typically refers to chromosomes that are similar in structure, and 'homozygous' describes the genotype where both alleles for a gene are the same.
2. ___________ is a symbiotic relationship in which one organism benefits and the other is not affected.
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: C
Rationale: The correct answer is 'Commensalism.' In commensalism, one organism benefits from the relationship while the other is neither helped nor harmed. This type of symbiotic relationship is characterized by one organism deriving a benefit, such as food or shelter, without impacting the other organism in any significant way. Choice A, 'Mutualism,' is a symbiotic relationship in which both organisms benefit. Choice B, 'Parasitism,' is a symbiotic relationship in which one organism benefits at the expense of the other. Choice D, 'Competition,' refers to a relationship in which organisms compete for limited resources, with both being affected in terms of access to resources.
3. Which organelle would you expect to be present in a cell responsible for detoxifying multiple molecules?
- A. rough ER
- B. smooth ER
- C. lysosome
- D. Golgi apparatus
Correct answer: B
Rationale: The smooth endoplasmic reticulum (ER) is the organelle responsible for detoxifying multiple molecules in a cell. It contains enzymes that help break down toxins and drugs, making it an essential organelle for detoxification processes. The rough ER, lysosome, and Golgi apparatus do not play direct roles in detoxification. The rough ER is mainly involved in protein synthesis and transport. Lysosomes are responsible for digestion and recycling within the cell. The Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or for use within the cell.
4. 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.
5. In contrast with triglycerides, phospholipids are lacking one of which of the following components?
- A. Monosaccharide
- B. Glycerol
- C. Phosphates
- D. Fatty acid
Correct answer: B
Rationale: Phospholipids are structurally similar to triglycerides but lack one of the fatty acid chains that triglycerides possess. Triglycerides consist of three fatty acid chains attached to a glycerol molecule, while phospholipids have two fatty acid chains and a phosphate group attached to a glycerol backbone. Therefore, phospholipids are lacking the third fatty acid chain found in triglycerides. Choice A (Monosaccharide) is incorrect because neither triglycerides nor phospholipids contain monosaccharides in their structure. Choice C (Phosphates) is incorrect because phospholipids actually contain phosphates, unlike triglycerides. Choice D (Fatty acid) is incorrect as both triglycerides and phospholipids contain fatty acids, but the number of fatty acid chains differs between the two.
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