Nokea
Which white blood cell type is responsible for the initial attack on pathogens?
- A. Red blood cells
- B. Platelets
- C. Phagocytes
- D. Lymphocytes
Correct Answer: C
Rationale: Phagocytes are a type of white blood cell that is crucial in the initial attack on pathogens. These cells have the ability to engulf and digest foreign particles such as bacteria and viruses, thereby preventing infections. Red blood cells primarily function in oxygen transport, platelets are vital for blood clotting, and lymphocytes are involved in the immune response. However, phagocytes are specifically designed to provide the initial defense against pathogens by directly attacking and eliminating them.
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Which of the following constituents of blood is a biconcave disc that is round and flat without a nucleus?
- A. Plasma
- B. Platelet
- C. RBC
- D. WBC
Correct Answer: C
Rationale: The correct answer is C, RBC (Red Blood Cell). Red blood cells are biconcave discs that lack a nucleus, allowing them to carry oxygen efficiently. Plasma (A) is the liquid component of blood that carries various substances. Platelets (B) are cell fragments important for blood clotting. White blood cells (WBCs) (D) are part of the immune system and have a nucleus.
What is the primary function of red blood cells?
- A. To transport nutrients
- B. To transport oxygen
- C. To fight infection
- D. To produce antibodies
Correct Answer: B
Rationale: The correct answer is B: To transport oxygen. Red blood cells play a crucial role in carrying oxygen from the lungs to all the tissues and organs in the body. This oxygen transport is essential for cellular respiration, where oxygen is used in the production of energy. Red blood cells do not primarily transport nutrients, fight infection, or produce antibodies. Choice A is incorrect because while red blood cells do carry some nutrients, their primary function is to transport oxygen. Choice C is incorrect because immune cells, not red blood cells, are responsible for fighting infections. Choice D is incorrect as antibody production is mainly carried out by specialized white blood cells, not red blood cells.
In the process of osmosis, the solvent moves from an area of...
- A. Low solute concentration to high solute concentration
- B. Hotter solution to colder solution
- C. Colder solution to hotter solution
- D. High solute concentration to low solute concentration
Correct Answer: D
Rationale: In the process of osmosis, solvent molecules move from an area of high solute concentration to low solute concentration. This movement occurs to equalize the solute concentrations on both sides of the semi-permeable membrane. As water tends to move towards higher solute concentrations, the solvent moves in this direction to balance the concentrations and establish equilibrium. Choices A, B, and C are incorrect because osmosis involves the movement of solvent, not solute, and it moves towards the area of higher solute concentration, not lower. Therefore, the correct answer is option D.
Which of the following substances is a common base found in household products?
- A. Sodium chloride (NaCl)
- B. Ammonia (NH₃)
- C. Vinegar
- D. Lemon juice
Correct Answer: B
Rationale: The correct answer is B, Ammonia (NH₃). Ammonia is commonly found in household products and is used in cleaning agents due to its alkaline properties. Sodium chloride (NaCl) is a common salt and not a base. Vinegar is acetic acid, which is acidic in nature. Lemon juice contains citric acid, making it acidic as well. Therefore, ammonia is the only base among the choices provided.
Which of the following structures in the respiratory system is responsible for gas exchange?
- A. Trachea
- B. Alveoli
- C. Bronchi
- D. Diaphragm
Correct Answer: B
Rationale: The correct answer is B: Alveoli. The alveoli in the lungs are responsible for gas exchange. They have a thin membrane that allows for the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the capillaries surrounding them. This process is essential for respiration, providing oxygen to the body's tissues and removing carbon dioxide, a waste product of cellular metabolism. Choices A, C, and D are incorrect. The trachea is a passageway that carries air to and from the lungs but is not directly involved in gas exchange. Bronchi are airway passages that further divide into smaller bronchioles leading to the alveoli but do not perform gas exchange themselves. The diaphragm is a muscle involved in the breathing process by aiding in inhalation and exhalation, but it is not the structure responsible for gas exchange in the respiratory system.