Nokea
What is the name of a condition where the immune system mistakenly attacks healthy body tissues?
- A. Allergy
- B. Autoimmune disease
- C. Immunodeficiency
- D. Sepsis
Correct Answer: B
Rationale: Autoimmune diseases occur when the immune system mistakenly targets and attacks healthy body tissues, leading to inflammation and damage. This results in conditions such as rheumatoid arthritis, lupus, and type 1 diabetes. Allergies, on the other hand, involve an exaggerated immune response to harmless substances like pollen or certain foods. Immunodeficiency refers to a weakened immune system, making individuals more susceptible to infections. Sepsis is a severe systemic response to an infection, leading to organ dysfunction and potentially life-threatening complications.
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During vigorous exercise, why does the respiratory rate increase?
- A. Meet the increased demand for oxygen in working muscles
- B. Eliminate excess carbon dioxide more slowly
- C. Conserve energy for physical activity
- D. Decrease the amount of oxygen delivered to the body
Correct Answer: A
Rationale: During vigorous exercise, the muscles require more oxygen to produce energy for physical activity. The increased respiratory rate helps to deliver more oxygen to the working muscles to meet this demand. This process is essential for sustaining physical activity and preventing fatigue. Choice A is the correct answer as it accurately describes the purpose of the increased respiratory rate during vigorous exercise. Choices B, C, and D are incorrect. Choice B, 'Eliminate excess carbon dioxide more slowly,' is inaccurate as the primary reason for the increased respiratory rate during exercise is to meet the increased demand for oxygen, not to eliminate carbon dioxide. Choice C, 'Conserve energy for physical activity,' is incorrect because increasing the respiratory rate actually expends energy to meet the oxygen demand of the working muscles. Choice D, 'Decrease the amount of oxygen delivered to the body,' is incorrect as the increased respiratory rate is specifically to deliver more oxygen to the body during exercise.
What is the name for the process where a solid changes directly into a gas?
- A. Evaporation
- B. Sublimation
- C. Condensation
- D. Melting
Correct Answer: B
Rationale: Sublimation is the process by which a solid directly transforms into a gas without passing through the liquid phase. This occurs when the atmospheric pressure is lower than the vapor pressure of the solid, causing it to transition to a gas state. Choice A, evaporation, is the process where a liquid changes into a gas, not a solid. Choice C, condensation, is the opposite process where gas changes into a liquid. Choice D, melting, is the process where a solid changes into a liquid, not a gas.
Muscles that work in opposition to each other, producing opposing movements, are called:
- A. Synergists
- B. Antagonists
- C. Agonists
- D. Fixators
Correct Answer: B
Rationale: Antagonist muscles are pairs of muscles that work in opposition to each other, producing opposing movements. When one muscle contracts, the other relaxes to allow the movement to occur smoothly. Synergists are muscles that work together to create a movement, not in opposition. Agonists are muscles primarily responsible for producing a specific movement, not opposing each other. Fixators are muscles that stabilize joints to allow other movements to take place, providing a stable base for muscle actions but do not produce opposing movements.
Which of the following properties is NOT characteristic of a covalent bond?
- A. Sharing of electrons between atoms
- B. High melting and boiling points
- C. Low electrical conductivity in solid state
- D. Directional bonding
Correct Answer: B
Rationale: Covalent bonds are formed by the sharing of electrons between atoms, leading to the formation of molecules with directional bonding. This means that the atoms are held together in a specific orientation. Covalent compounds generally exhibit low melting and boiling points compared to ionic compounds due to the weaker intermolecular forces present in covalent compounds. Furthermore, covalent compounds do not conduct electricity in the solid state because the electrons are localized between the atoms and are not free to move and carry charge. Hence, high melting and boiling points are not characteristic of covalent bonds. The correct answer is 'B' because high melting and boiling points are typically associated with ionic compounds due to their strong electrostatic interactions, while covalent compounds have lower melting and boiling points. Choices A, C, and D are all characteristics of covalent bonds, making them incorrect answers for this question.
When a person throws a ball horizontally, what force changes the direction of the ball's motion?
- A. The force of throwing
- B. Gravitational force
- C. Air resistance
- D. Normal force from the ground
Correct Answer: B
Rationale: When a person throws a ball horizontally, the initial force that propels the ball forward is the force of throwing (A). However, the force that changes the direction of the ball's motion is the gravitational force (B). Gravitational force acts vertically downward, causing the ball to follow a curved path. Air resistance (C) and normal force from the ground (D) do not directly change the direction of the ball's motion in this scenario.