DAT - Dental Admission Reading Comprehension: Scientific Passages Questions and Answers 1 — Questions and Answers
Question 1: What is the primary purpose of the passage?
- To argue for increased funding for research into extremophiles.
- To describe the molecular adaptations of psychrophiles and their biotechnological applications. (Correct answer)
- To compare the enzymatic activity of psychrophiles and mesophiles.
- To detail the process of ice recrystallization inhibition in polar organisms.
Correct answer: To describe the molecular adaptations of psychrophiles and their biotechnological applications.
The passage provides a comprehensive overview of psychrophiles, dedicating the first three paragraphs to their specific molecular adaptations (membrane composition, enzyme structure, and protective proteins) and the final paragraph to the practical and biotechnological uses of these adaptations. While it does compare enzymes (Choice C) and discuss ice recrystallization (Choice D), these are supporting details, not the main purpose. There is no argument for funding (Choice A).
Question 2: According to the passage, how do psychrophiles maintain cell membrane fluidity at low temperatures?
- By increasing the production of antifreeze proteins to prevent membrane freezing.
- By synthesizing a thicker, more insulating cell wall.
- By incorporating a higher percentage of unsaturated and short-chain fatty acids. (Correct answer)
- By reducing the number of transport proteins embedded in the membrane.
Correct answer: By incorporating a higher percentage of unsaturated and short-chain fatty acids.
The first paragraph explicitly states that a primary challenge is reduced membrane fluidity and that 'Psychrophilic bacteria counteract this by incorporating a higher proportion of unsaturated and short-chain fatty acids into their membrane phospholipids.' This directly answers the question.
Question 3: The passage suggests that a cold-adapted enzyme from a psychrophile would most likely:
- function optimally in the human body (approximately 37 °C).
- have more rigid and stable protein structures than its mesophilic counterpart.
- be highly effective in a high-pressure, deep-sea environment.
- lose its catalytic function if heated to 50 °C. (Correct answer)
Correct answer: lose its catalytic function if heated to 50 °C.
Paragraph 2 describes the 'thermolability trade-off,' stating that the flexibility that allows psychrophilic enzymes to work in the cold 'makes them more susceptible to denaturation at even moderate temperatures.' Since 50 °C is a moderate temperature where a mesophilic enzyme might be stable, the less stable psychrophilic enzyme would likely denature and lose its function.
Question 4: A biotechnology company wants to develop a laundry detergent that effectively removes protein-based stains in cold water washes. Based on the passage, which of the following would be the most promising component to include?
- A protease isolated from a psychrophilic organism. (Correct answer)
- A lipase isolated from a mesophilic bacterium.
- Antifreeze proteins (AFPs) from an alpine insect.
- Cold-shock proteins (CSPs) from a deep-sea microbe.
Correct answer: A protease isolated from a psychrophilic organism.
The final paragraph states that 'enzymes like proteases...from these organisms are used in...cold-water laundry detergents.' A protease is an enzyme that breaks down proteins, making it ideal for protein-based stains. The enzyme must come from a psychrophilic (cold-adapted) organism to be effective in cold water.
Question 5: In the context of the third paragraph, what is the best definition for the word 'adsorbing'?
- Absorbing and integrating into the crystal's interior.
- Chemically reacting with and dissolving the ice.
- Repelling and pushing the ice crystals away.
- Accumulating on the surface of the ice crystals. (Correct answer)
Correct answer: Accumulating on the surface of the ice crystals.
The sentence reads, 'By adsorbing to the surface of ice, they inhibit the growth of these crystals...' The phrase 'to the surface' provides direct context, indicating that adsorption is a surface phenomenon where molecules adhere to the exterior of a substance, as opposed to absorption, which involves permeating the interior.
Question 6: Which of the following is NOT mentioned in the passage as an adaptation for survival in cold environments?
- An altered metabolism to generate more internal heat. (Correct answer)
- The production of RNA chaperones.
- Increased flexibility in enzyme active sites.
- Modification of fatty acids in the cell membrane.
Correct answer: An altered metabolism to generate more internal heat.
The passage details several adaptations: modification of fatty acids in membranes (paragraph 1), increased enzyme flexibility (paragraph 2), and the production of cold-shock proteins which act as RNA chaperones (paragraph 3). There is no mention of thermogenesis or any mechanism for generating internal heat to counteract the cold.
DAT - Dental Admission Reading Comprehension: Scientific Passages Questions and Answers 1
What is the primary purpose of the passage?