Nokea
Which of the following does not describe a general trait of macromolecules?
- A. They can exist as single chains.
- B. They can be branched.
- C. They all contain carbon, hydrogen, and phosphorus.
- D. They are all used by the body.
Correct Answer: C
Rationale: The correct answer is C. While many macromolecules contain carbon, hydrogen, and phosphorus, not all of them do. For example, lipids, a type of macromolecule, may not contain phosphorus. Choice A and B describe structural features that macromolecules can exhibit, whether as single chains or branched forms. Choice D is incorrect as not all macromolecules are used by the body, such as synthetic polymers or certain non-digestible fibers.
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Which hormone is responsible for regulating the body's metabolism?
- A. Insulin
- B. Thyroxine
- C. Melatonin
- D. Adrenaline
Correct Answer: B
Rationale: Thyroxine, also known as T4, is produced by the thyroid gland and plays a vital role in regulating the body's metabolism. Insulin is not responsible for regulating metabolism; instead, it helps regulate blood sugar levels. Melatonin is involved in regulating sleep-wake cycles, not metabolism. Adrenaline, also known as epinephrine, is a stress hormone that prepares the body for fight or flight responses, not primarily involved in metabolic regulation.
What is the primary function of the cardiovascular system?
- A. To transport oxygen and nutrients
- B. To regulate blood pressure
- C. To digest food
- D. To filter waste products
Correct Answer: A
Rationale: The primary function of the cardiovascular system is indeed to transport oxygen and nutrients to various tissues in the body. Choice B, 'To regulate blood pressure,' is incorrect as blood pressure regulation is one of the functions of the cardiovascular system but not its primary function. Choice C, 'To digest food,' is incorrect as digestion is primarily a function of the digestive system, not the cardiovascular system. Choice D, 'To filter waste products,' is incorrect as waste product filtration is primarily carried out by the kidneys and liver, not the cardiovascular system.
Which of the following structures prevents food from entering the windpipe?
- A. Pharynx
- B. Esophagus
- C. Larynx
- D. Epiglottis
Correct Answer: D
Rationale: The epiglottis is the structure that prevents food from entering the windpipe by covering the trachea during swallowing. When food is swallowed, the epiglottis folds over the opening of the trachea to ensure that food goes down the esophagus and not into the airway. The pharynx is a shared pathway for both food and air, leading to the esophagus and larynx respectively. The esophagus is the muscular tube that carries food from the throat to the stomach. The larynx is responsible for producing sound and protecting the airway during swallowing, but the epiglottis is specifically designed to prevent food from entering the windpipe.
Which of the following statements is true about an allergic reaction?
- A. An allergic reaction, such as hives or wheezing, results from overactive body systems such as the integumentary and respiratory systems.
- B. An allergic reaction is a result of overactive B-cells in the body that release various immunoglobulins.
- C. An allergic reaction is caused by overactive mast cells in the body, which are stimulated by Immunoglobulin E.
- D. An allergic reaction involves substances like histamine, keratin, and collagen.
Correct Answer: C
Rationale: The correct answer is C. Mast cells are responsible for releasing histamine and other chemicals during an allergic response. Choice A is incorrect because hives and wheezing are symptoms of an allergic reaction, not the causes. Choice B is incorrect as B-cells are not directly involved in allergic reactions. Choice D is incorrect as keratin and collagen are not typically involved in allergic reactions, and histamine is released by mast cells.
What is the function of white blood cells?
- A. To transport oxygen
- B. To fight infection
- C. To carry oxygen
- D. To produce antibodies
Correct Answer: B
Rationale: White blood cells play a crucial role in the immune system by fighting infection and protecting the body from foreign invaders. Choice A, 'To transport oxygen,' is incorrect because red blood cells are responsible for transporting oxygen. Choice C, 'To carry oxygen,' is also inaccurate for the same reason. Choice D, 'To produce antibodies,' while related to the immune system, is not the primary function of white blood cells, as their main role is to directly combat infections.