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What is the function of the epiglottis?
- A. Produces saliva
- B. Senses taste
- C. Prevents food from entering the windpipe
- D. Filters blood
Correct Answer: C
Rationale: The epiglottis is a flap of cartilage located at the base of the tongue that covers the opening of the windpipe (trachea) during swallowing to prevent food and liquids from entering the airway. This action ensures that food and liquids are directed to the esophagus and down into the stomach, rather than entering the respiratory system, which could lead to choking or aspiration pneumonia. Options A, B, and D are incorrect as they describe functions of other structures in the body that are not related to the role of the epiglottis.
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What determines the defining characteristic of an element?
- A. Neutrons in its nucleus
- B. Electrons surrounding the nucleus
- C. Protons in its nucleus
- D. All of the above
Correct Answer: C
Rationale: The defining characteristic of an element is determined by the number of protons in its nucleus, which is referred to as the atomic number. The number of protons uniquely identifies an element. The correct answer is choice C because the number of protons in the nucleus of an atom defines its elemental identity, as different elements have a unique number of protons. Neutrons and electrons do play essential roles in the atom, but they do not determine the defining characteristic of an element. Neutrons contribute to the stability of the nucleus and isotopes of an element, while electrons are involved in chemical bonding and the reactivity of an atom.
The 'fight-or-flight' response is triggered by the hormone released from the:
- A. Thyroid gland
- B. Adrenal glands
- C. Pituitary gland
- D. Pancreas
Correct Answer: B
Rationale: The 'fight-or-flight' response is triggered by the release of adrenaline (epinephrine) and norepinephrine from the adrenal glands. These hormones prepare the body to either confront or flee from a perceived threat or stressor. The adrenal glands are crucial in initiating this rapid physiological response. Choices A, C, and D are incorrect because the thyroid gland primarily regulates metabolism and energy levels, the pituitary gland controls other endocrine glands but does not directly trigger the 'fight-or-flight' response, and the pancreas is responsible for regulating blood sugar levels through insulin and glucagon, not for triggering the 'fight-or-flight' response.
Which organ plays a significant role in immune cell production and maturation?
- A. Liver
- B. Kidneys
- C. Bone marrow
- D. Spleen
Correct Answer: C
Rationale: The bone marrow is the correct answer. It is the primary site for immune cell production and maturation. The bone marrow is responsible for generating various types of blood cells, including white blood cells crucial for the immune system's function. The liver, kidneys, and spleen have essential functions in the body, such as filtering blood, detoxification, and storage of blood, respectively. However, they are not primarily involved in immune cell production and maturation, making them incorrect choices for this question.
What is the work done by a force of 20 N acting on an object that moves 5 meters in the direction of the force?
- A. 100 Joules (J)
- B. 25 Joules (J)
- C. 4 Joules (J)
- D. Work cannot be determined without knowing the object's mass.
Correct Answer: A
Rationale: The work done is calculated using the formula: Work = Force x Distance x cos(theta), where theta is the angle between the force and the direction of motion. In this case, the force and the direction of motion are in the same direction, so cos(theta) = 1. Therefore, Work = 20 N x 5 m x 1 = 100 Joules. Since the force and distance are given and are in the same direction, the work done can be directly calculated without needing to know the object's mass. Choice A, 100 Joules, is the correct answer as calculated. Choice B and C are incorrect as they do not correspond to the correct calculation. Choice D is incorrect because knowing the object's mass is not necessary to calculate work in this scenario, as work is dependent on force, distance, and the angle between them, not mass.
The adaptive immune system develops a targeted response to specific pathogens. What type of immune cell is responsible for producing antibodies?
- A. Natural killer cells
- B. Phagocytes
- C. Helper T cells
- D. B cells
Correct Answer: D
Rationale: B cells are responsible for producing antibodies as part of the adaptive immune response. When activated by a specific antigen, B cells differentiate into plasma cells that secrete antibodies to target and neutralize pathogens. Natural killer cells are primarily involved in killing infected or cancerous cells, phagocytes engulf pathogens, and helper T cells assist in activating other immune cells. Therefore, the correct answer is B cells because they play a crucial role in antibody production, a key component of the adaptive immune response.