HESI A2
Biology HESI A2 2024
1. Which part of a plant’s reproductive system is of a different “gender” than the others?
- A. Stamen
- B. Pistil
- C. Stigma
- D. Style
Correct answer: A
Rationale: The stamen is the male reproductive organ of a plant, producing pollen grains. The pistil, consisting of the stigma, style, and ovary, is the female reproductive organ. Therefore, the stamen is of a different 'gender' than the other parts of the plant's reproductive system. The pistil, stigma, and style are all part of the female reproductive system, involved in receiving pollen and supporting fertilization. Stamen is the correct answer as it is the male part of a plant's reproductive system, making it different 'gender-wise' from the female parts.
2. The mixture of gases surrounding a planet is referred to as its ______.
- A. Atmosphere
- B. Stratosphere
- C. Biosphere
- D. Troposphere
Correct answer: A
Rationale: The mixture of gases surrounding a planet is referred to as its atmosphere. The atmosphere plays a crucial role in supporting life on Earth by providing oxygen, regulating carbon dioxide levels, and shielding the planet from harmful radiation. While the stratosphere, troposphere, and other layers are part of the atmosphere, the term 'atmosphere' encompasses the entire gaseous envelope surrounding a planet. The stratosphere, troposphere, mesosphere, thermosphere, and exosphere are specific layers within the atmosphere, each with distinct characteristics and functions.
3. 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.
4. How do green plants use nitrates in the nitrogen cycle?
- A. To synthesize proteins
- B. To store food
- C. To decompose ammonia
- D. To break down nitrites
Correct answer: A
Rationale: Green plants use nitrates in the nitrogen cycle to synthesize proteins. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. Plants take up nitrates from the soil through their roots and incorporate nitrogen into their proteins through the process of protein biosynthesis. This helps in their growth, development, and overall health. Choice B, 'To store food,' is incorrect because nitrates are primarily used for protein synthesis, not food storage. Choice C, 'To decompose ammonia,' is incorrect as plants do not decompose ammonia but rather utilize it through nitrification. Choice D, 'To break down nitrites,' is incorrect as plants typically convert nitrites into nitrates through a process called nitrate assimilation for protein synthesis.
5. 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.
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