Nokea
Enzymes are ________ molecules that serve as _______ for certain biological reactions.
- A. Enzymes are irrelevant molecules that serve as suppressors for certain biological reactions.
- B. Enzymes are acidic molecules that serve as catalysts for certain biological reactions.
- C. Enzymes are lipid molecules that serve as catalysts for certain biological reactions.
- D. Enzymes are protein molecules that serve as catalysts for certain biological reactions.
Correct Answer: D
Rationale: Enzymes are protein molecules that serve as catalysts for certain biological reactions. Enzymes are biological molecules that speed up chemical reactions in living organisms by lowering the activation energy required for the reactions to occur. They are typically proteins that have specific shapes and active sites that allow them to interact with specific substrates and facilitate reactions without being consumed themselves. The other choices are incorrect because enzymes are not irrelevant, acidic, or lipid molecules; they are primarily proteins known for their catalytic properties.
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In an oxidation reaction,
- A. an oxidizing agent gains electrons.
- B. an oxidizing agent loses electrons.
- C. a reducing agent gains electrons.
- D. a reducing agent loses electrons.
Correct Answer: B
Rationale: In an oxidation reaction, the substance being oxidized loses electrons, not gains them. An oxidizing agent is responsible for causing oxidation in another substance by accepting electrons, hence it undergoes reduction and loses electrons. Therefore, the correct statement is 'an oxidizing agent loses electrons,' making choice B the correct answer. Choices A, C, and D are incorrect because in an oxidation reaction, the oxidizing agent does not gain electrons, a reducing agent does not gain electrons, and a reducing agent does not lose electrons.
Which of the following functions would be most affected by laryngeal damage?
- A. Blinking
- B. Walking
- C. Singing
- D. Hearing
Correct Answer: C
Rationale: Laryngeal damage would most affect the function of singing. The larynx, or voice box, houses the vocal cords responsible for producing sound during singing. Damage to the larynx can impair the ability to phonate and control pitch, tone, and quality of the voice, which are crucial for singing. Choices A, B, and D are unrelated to the larynx. Blinking is controlled by the facial nerve, walking involves motor functions and coordination, and hearing is related to the ear structures and auditory nerves.
Which of the following areas has the least amount of sweat glands?
- A. Back
- B. Palms
- C. Axilla
- D. Forehead
Correct Answer: B
Rationale: The correct answer is B - Palms. The palms have the least amount of sweat glands compared to the other options listed. The back, axilla (armpits), and forehead are all areas with a higher concentration of sweat glands in the body. The palms have fewer sweat glands to minimize water loss and maintain a better grip for activities requiring precise and controlled movement. The back, axilla, and forehead have more sweat glands to assist in thermoregulation and cooling of the body, while the palms have fewer sweat glands for functional reasons related to grip and dexterity.
Which organ system is most responsible for maintaining control of body temperature?
- A. The skeletal system.
- B. The circulatory system.
- C. The immune system.
- D. The muscular system.
Correct Answer: B
Rationale: The circulatory system is the correct answer as it plays a crucial role in maintaining control of body temperature through a process called thermoregulation. Blood vessels near the skin surface dilate to dissipate heat when the body is too warm and constrict to reduce heat loss when it's too cold. Additionally, the circulatory system helps distribute heat produced from metabolic processes throughout the body to keep a stable internal temperature. The skeletal system provides structural support, the immune system defends against pathogens, and the muscular system is responsible for movement, but they are not primarily involved in regulating body temperature.
What effect does a catalyst have on a chemical reaction?
- A. It speeds up the reaction.
- B. It slows down the reaction.
- C. It makes a reaction go in reverse.
- D. It prevents a reaction from taking place.
Correct Answer: A
Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by providing an alternate pathway for the reaction to occur, lowering the activation energy needed for the reaction to proceed. As a result, more reactant molecules can overcome this energy barrier and participate in the reaction, leading to a faster overall reaction rate. This explanation contradicts choices B, C, and D as a catalyst does not slow down, reverse, or prevent a reaction; instead, it accelerates the reaction by facilitating a more efficient route for the reaction to take place. Therefore, the correct answer is that a catalyst speeds up the reaction.