Nokea
What are the cellular functions of cilia and flagella?
- A. Cilia and flagella are responsible for cell movement.
- B. Cilia and flagella synthesize proteins.
- C. Cilia and flagella help protect the cell from its environment.
- D. Cilia and flagella have enzymes that help with digestion.
Correct Answer: A
Rationale: Cilia and flagella are microtubule-based structures found on the surface of many eukaryotic cells. Their primary function is to facilitate cell movement. Cilia are short, numerous, and move in coordinated waving motions to move substances along the cell's surface. Flagella are longer and usually limited to one or a few per cell, providing a propeller-like movement for the cell. Both cilia and flagella aid in cell motility and are essential for various cellular functions, primarily involved in cell movement rather than protein synthesis, protection, or digestion. Therefore, choice A is correct as it accurately describes the primary function of cilia and flagella. Choices B, C, and D are incorrect as cilia and flagella are not involved in protein synthesis, cell protection, or digestion in cells.
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How is homeostasis defined?
- A. The ability of human beings to keep body weight within normal limits.
- B. The maintenance of a constant external temperature inside a room.
- C. The ingestion of enough food to prevent hunger pains.
- D. The tendency of the body to maintain a stable internal environment.
Correct Answer: D
Rationale: Homeostasis is defined as the tendency of the body to maintain a stable internal environment despite external changes. This process involves regulating various physiological parameters such as body temperature, blood pressure, and glucose levels to ensure optimal functioning and health. Option A is incorrect as it specifically refers to body weight regulation, which is not the sole focus of homeostasis. Option B is incorrect as it describes maintaining a constant temperature in a room, rather than the internal environment of the body. Option C is incorrect as it only addresses the prevention of hunger pains through food ingestion, which is not the overarching concept of homeostasis.
How will mildly elevated levels of thyroxine affect the heart rate?
- A. Stop the heart rate
- B. No effect
- C. Decrease the heart rate
- D. Increase the heart rate
Correct Answer: D
Rationale: Mildly elevated levels of thyroxine will increase the heart rate. Thyroxine, a hormone produced by the thyroid gland, regulates metabolism. Elevated thyroxine levels can lead to increased metabolism, resulting in an elevated heart rate. Choice A is incorrect as mildly elevated thyroxine levels do not stop the heart rate. Choice B is incorrect because elevated thyroxine levels do have an effect on heart rate. Choice C is incorrect as elevated thyroxine levels typically lead to an increase rather than a decrease in heart rate.
Which human body system is correctly matched with its function?
- A. Respiratory system; exchanges oxygen and carbon dioxide in the lungs.
- B. Circulatory system; transports oxygen to cells and removes carbon dioxide.
- C. Lymphatic system; produces antibodies that destroy virally affected or foreign cells.
- D. Endocrine system; regulates hormones controlling bodily functions and metabolism.
Correct Answer: B
Rationale: The circulatory system is responsible for the transportation of oxygen from the lungs to all the body's cells and tissues, as well as removing carbon dioxide from the cells and transporting it back to the lungs to be exhaled. This process is crucial for cellular respiration and the exchange of gases necessary for bodily functions. Choice B accurately matches the role of the circulatory system by describing its function of transporting oxygen to cells and removing carbon dioxide, which is essential for maintaining proper cellular activities. Choices A, C, and D are incorrect because they do not accurately match the body system with its function. The respiratory system primarily involves the exchange of gases in the lungs, not transportation to cells; the lymphatic system deals with immunity through the production of antibodies, not gas exchange; and the endocrine system's main function is hormone regulation, not the transport of gases.
Which statement correctly matches the valve with its function in the heart?
- A. The aortic valve allows oxygenated blood to flow from the left ventricle to the rest of the body.
- B. The mitral valve opens to allow blood flow from the left atrium to the left ventricle.
- C. The pulmonic valve allows deoxygenated blood to flow from the right ventricle to the pulmonary artery.
- D. The tricuspid valve allows deoxygenated blood to flow from the right atrium to the right ventricle.
Correct Answer: A
Rationale: The correct answer is A. The aortic valve allows oxygenated blood to flow from the left ventricle to the rest of the body. When the left ventricle contracts, the aortic valve opens to allow blood to be pumped into the aorta, the body's main artery that carries oxygen-rich blood to various parts of the body. Choices B, C, and D are incorrect because they do not match the described functions of the mitral, pulmonic, and tricuspid valves, respectively. The mitral valve controls the flow of blood between the left atrium and left ventricle, the pulmonic valve regulates the flow of blood from the right ventricle to the pulmonary artery, and the tricuspid valve manages the blood flow between the right atrium and right ventricle.
How many chromosomes must a normal human sperm cell contain?
- A. An X chromosome.
- B. A Y chromosome.
- C. 23 chromosomes.
- D. Both an X and Y chromosome.
Correct Answer: C
Rationale: A normal human sperm cell contains a total of 23 chromosomes, half the number found in a typical human cell which has 46 chromosomes. This includes 22 autosomes and one sex chromosome, which can be either an X or a Y chromosome. Therefore, the correct answer is that a normal human sperm cell must contain 23 chromosomes. Choices A and B are incorrect because a single sex chromosome alone does not represent the total number of chromosomes in a sperm cell. Choice D is incorrect because a sperm cell carries only one sex chromosome, either X or Y, not both.