HESI A2
Chemistry HESI A2 Quizlet
1. What does the mass number minus the atomic number equal?
- A. Number of electrons
- B. Number of neutrons
- C. Number of protons
- D. Number of isotopes
Correct answer: B
Rationale: The mass number of an atom represents the total number of protons and neutrons in its nucleus. The atomic number indicates the number of protons in the nucleus. The difference between the mass number and the atomic number provides the number of neutrons present in the nucleus of an atom. Therefore, mass number minus atomic number equals the number of neutrons. Choice A is incorrect because the number of electrons is not determined by the mass number and atomic number. Choice C is incorrect as it represents the number of protons, not the difference between the mass number and atomic number. Choice D is incorrect as isotopes refer to atoms of the same element with different numbers of neutrons, not the difference between mass number and atomic number.
2. The cell membrane consists of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins. What does this bilayer create?
- A. Impermeable
- B. Permeable
- C. Selectively permeable
- D. Selectively impermeable
Correct answer: C
Rationale: The correct answer is 'Selectively permeable.' The cell membrane's bilayer structure allows it to be selectively permeable, meaning it can control the passage of substances. This property enables the membrane to regulate the entry and exit of specific molecules, ions, and other substances. Choice A, 'Impermeable,' is incorrect as the cell membrane is not completely impermeable and does allow certain substances to pass through. Choice B, 'Permeable,' is also incorrect as it does not address the selective nature of the membrane. Choice D, 'Selectively impermeable,' is a contradictory term and does not accurately describe the cell membrane's function.
3. What is the primary function of the small intestine in the digestive system?
- A. To secrete digestive enzymes
- B. To absorb nutrients
- C. To break down food
- D. To absorb water
Correct answer: B
Rationale: The correct answer is B: To absorb nutrients. The small intestine's main role in the digestive system is to absorb nutrients from digested food. It has specialized structures, such as villi and microvilli, that increase its surface area for efficient absorption of nutrients into the bloodstream. Choice A is incorrect because the small intestine does not primarily secrete digestive enzymes; that role is mainly carried out by the pancreas and other digestive organs. Choice C is incorrect because the small intestine primarily absorbs nutrients rather than breaking down food. Choice D is incorrect because the absorption of water primarily occurs in the large intestine, not the small intestine.
4. How does yeast reproduce?
- A. Binary fission
- B. Spore formation
- C. Budding
- D. Cloning
Correct answer: C
Rationale: Yeast typically reproduces through a process called budding. During budding, a small outgrowth forms on the parent yeast cell, gradually enlarging in size until it separates to become a new, genetically identical daughter cell. This method of reproduction allows yeast to rapidly multiply and grow in favorable conditions. It is different from binary fission, spore formation, and cloning. Binary fission involves the division of a single organism into two genetically identical organisms. Spore formation is a method seen in certain fungi where specialized cells develop into spores for reproduction. Cloning involves producing genetically identical copies of an organism. Therefore, budding is the correct answer for how yeast reproduces.
5. A truck driver traveled 925 miles from 8 am Tuesday to 5 pm Wednesday. During that time, he stopped for 30 minutes for lunch and gas at 1 pm Tuesday. He stopped for the night at 7 pm and was back on the road at 5 am. What was his average speed?
- A. 42 mph
- B. 35 mph
- C. 30 mph
- D. 50 mph
Correct answer: A
Rationale: To find the average speed, divide the total distance traveled (925 miles) by the total time taken (22 hours). Subtracting the time for the lunch and gas stop (30 minutes) and overnight stop (7 pm to 5 am, 10 hours), we have a total elapsed time of 22 hours. Dividing 925 miles by 22 hours gives an average speed of approximately 42 mph. Choice B, 35 mph, is incorrect because it doesn't account for the total time spent including the stops. Choice C, 30 mph, is incorrect as it underestimates the speed. Choice D, 50 mph, is incorrect as it overestimates the speed.
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