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Cartilage, a type of connective tissue, provides flexible support in various structures. Which of these structures does NOT contain cartilage?
- A. Ears
- B. Joints
- C. Muscles
- D. Nose
Correct Answer: C
Rationale: Cartilage is a type of connective tissue that provides flexible support in various structures. Ears, joints, and the nose all contain cartilage. Muscles, however, are made up of muscle tissue, not cartilage. Therefore, muscles do not contain cartilage. Choice A, ears, choice B, joints, and choice D, nose, are incorrect as they all contain cartilage. Choice C, muscles, is the correct answer as muscles are not composed of cartilage.
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What is the process of breaking down fatty acids into acetyl-CoA, a key molecule in cellular respiration, called?
- A. Beta-oxidation
- B. Lipolysis
- C. Carbohydrate catabolism
- D. Nucleic acid catabolism
Correct Answer: A
Rationale: Beta-oxidation is the correct term for the process of breaking down fatty acids into acetyl-CoA molecules. This essential process takes place in the mitochondria and is a pivotal step in fatty acid metabolism for energy production. Lipolysis, however, refers to the breakdown of fats into fatty acids and glycerol but does not specifically involve the conversion of fatty acids into acetyl-CoA. Carbohydrate catabolism focuses on breaking down carbohydrates into glucose for energy production and is not directly linked to the conversion of fatty acids into acetyl-CoA. Nucleic acid catabolism involves the breakdown of nucleic acids into nucleotides and is not associated with the conversion of fatty acids into acetyl-CoA.
What is the oxidation state of carbon in CH4?
- A. +1
- B. -1
- C. +2
- D. -4
Correct Answer: D
Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.
Which of these is NOT a function of the large intestine?
- A. Absorbing water and electrolytes
- B. Producing vitamins
- C. Breaking down fiber
- D. Eliminating waste products
Correct Answer: B
Rationale: A) Absorbing water and electrolytes: The large intestine plays a crucial role in absorbing water and electrolytes from the indigestible food matter that passes through it. This helps in maintaining the body's fluid balance and preventing dehydration. B) Producing vitamins: While the large intestine contains bacteria that can produce some vitamins like vitamin K and certain B vitamins, the primary site for vitamin production is the small intestine and other organs like the liver. Therefore, producing vitamins is not a primary function of the large intestine. C) Breaking down fiber: The large intestine is responsible for breaking down fiber that was not digested in the small intestine. The bacteria in the large intestine ferment fiber, producing short-chain fatty acids that can be used as an energy source by the body. D) Eliminating waste products: One of the main functions of the large intestine is to eliminate waste products, including indigestible food matter, dead cells, and bacteria, from the body in the form of feces. Therefore, the correct answer is B, as producing vitamins is not a primary function of the large intestine.
Which of the following hormones is produced by the adrenal medulla and prepares the body for a stressful situation?
- A. Testosterone
- B. Cortisol
- C. Epinephrine (adrenaline)
- D. Growth hormone
Correct Answer: C
Rationale: The correct answer is C: Epinephrine (adrenaline). Epinephrine is produced by the adrenal medulla and is responsible for preparing the body for a stressful situation. It increases heart rate, dilates airways, and mobilizes energy stores to help the body respond to a fight-or-flight scenario. Testosterone (Choice A) is a sex hormone produced by the testes in males and in smaller amounts by the ovaries in females, not by the adrenal medulla. Cortisol (Choice B) is a stress hormone produced by the adrenal cortex, not the adrenal medulla. Growth hormone (Choice D) is produced by the pituitary gland and is involved in growth, metabolism, and various bodily functions, not by the adrenal medulla.
During swallowing, what is the role of the epiglottis, a small flap of cartilage located near the base of the tongue?
- A. Initiates the swallowing reflex
- B. Grinds food into smaller pieces
- C. Covers the trachea to prevent food aspiration
- D. Stores saliva for lubrication
Correct Answer: C
Rationale: The epiglottis plays a crucial role during swallowing by covering the trachea to prevent food or liquid from entering the airway, which could lead to aspiration. By acting as a lid over the trachea, it ensures that food passes down the esophagus to the stomach, preventing it from entering the lungs. Choice A is incorrect as the swallowing reflex is a coordinated muscular action involving the tongue and throat muscles. Choice B is incorrect as grinding food into smaller pieces is primarily the function of the teeth and the initial stages of digestion. Choice D is incorrect as the storage of saliva for lubrication is not a function of the epiglottis, but rather involves salivary glands.