Unit 1 of 5
Study guide for CLEP CLEP Natural Sciences — Unit 1: Biological Science. Practice questions, key concepts, and exam tips.
42
Practice Questions
11
Flashcards
4
Key Topics
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A forest ecosystem has a high level of biodiversity, with many different species of plants and animals. The primary producers in this ecosystem are the plants, which use sunlight to produce energy through photosynthesis. If the plants in this ecosystem were to suddenly die off, what would be the most likely immediate effect on the ecosystem?
Answer: A — The correct answer is A because the primary producers (plants) are the base of the energy flow in the ecosystem. If they were to die off, the energy flow would be severely disrupted, leading to a decline in the populations of herbivores and carnivores. The other options are incorrect because while the decomposition rate and nutrient cycle may be affected, they are not the most immediate effect of the plants dying off. The climate of the ecosystem is not directly related to the death of the plants.
A researcher is studying the effects of a new drug on cellular respiration. The drug is found to increase the production of ATP during oxidative phosphorylation. Which of the following best explains the increase in ATP production?
Answer: C — The correct answer, C, is the best explanation because an increase in NADH and FADH2 production would lead to a greater proton gradient, resulting in more ATP being produced during oxidative phosphorylation. Option A is incorrect because decreasing NADH and FADH2 production would decrease the proton gradient and subsequent ATP production. Option B is incorrect because decreasing ATP synthase activity would decrease ATP production. Option D is incorrect because a decrease in the proton gradient would decrease ATP production, not increase it.
A researcher is studying the transport of molecules across cell membranes. The researcher observes that a particular molecule is able to cross the membrane without the use of energy or proteins. Which of the following types of transport is most likely occurring?
Answer: A — Simple diffusion is the correct answer because it is the type of transport that occurs without the use of energy or proteins, and allows molecules to cross the membrane from an area of higher concentration to an area of lower concentration. Active transport (B) requires energy to move molecules against their concentration gradient. Facilitated diffusion (C) requires the use of proteins to assist in the transport of molecules. Osmosis (D) is the movement of water molecules across a membrane, which is not relevant to the transport of the molecule in question.
A researcher is studying the process by which cells become specialized to perform specific functions. She observes that as cells differentiate, they undergo significant changes in their structure and organization. Which of the following best describes the primary mechanism by which cells become specialized?
Answer: D — The correct answer is D) gene expression, because it is the primary mechanism by which cells become specialized. Gene expression allows cells to regulate the production of specific proteins, which in turn enables them to develop unique structures and functions. The other options are incorrect because photosynthesis (A) is the process by which plants produce energy, mitosis (B) is the process of cell division, and meiosis (C) is the process of gamete production. While these processes are important, they are not directly related to cell specialization.
A researcher is studying the transport of molecules across a cell membrane. The researcher observes that a particular molecule is able to cross the membrane without the use of energy or proteins. Which of the following types of transport is most likely occurring?
Answer: A — Simple diffusion is the correct answer because it is the type of transport that occurs without the use of energy or proteins, and allows molecules to cross the membrane from an area of higher concentration to an area of lower concentration. Active transport (B) requires energy to move molecules against their concentration gradient. Facilitated diffusion (C) requires the use of proteins to assist in the transport of molecules. Osmosis (D) is the movement of water molecules across a membrane, which is not relevant to the transport of the molecule in question.
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