Nokea
How many amino acids can make up a protein?
- A. 10-20
- B. 50-100
- C. 100-500
- D. 1000+
Correct Answer: A
Rationale: Proteins are made up of long chains of amino acids, and there are 20 standard amino acids commonly found in proteins. The sequence and arrangement of these amino acids determine the structure and function of a protein. While proteins can vary in size and complexity, the number of amino acids typically ranges from around 10 to 20 in smaller proteins to hundreds or even thousands in larger proteins. Therefore, the range of 10-20 amino acids is the most accurate representation of the number of amino acids that can make up a protein. Choices B, C, and D are incorrect as they provide ranges that are beyond the typical number of amino acids found in proteins and may lead to confusion. The correct answer is A (10-20).
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What is the largest lymphatic vessel in the body responsible for draining lymph from most of the body called?
- A. Jugular vein
- B. Thoracic duct
- C. Subclavian vein
- D. Aorta
Correct Answer: B
Rationale: The correct answer is B: Thoracic duct. The thoracic duct is the largest lymphatic vessel in the body and is responsible for draining lymph from most of the body. The jugular vein, subclavian vein, and aorta are not lymphatic vessels responsible for draining lymph. The jugular vein and subclavian vein are blood vessels, while the aorta is the main artery that carries oxygenated blood from the heart. Understanding the role and anatomy of the lymphatic system is crucial for comprehending the body's immune response and fluid balance.
What is the protective sac surrounding the testes in the male reproductive system?
- A. Vas deferens
- B. Scrotum
- C. Epididymis
- D. Urethra
Correct Answer: B
Rationale: The scrotum is the correct answer, as it is the protective sac surrounding the testes in the male reproductive system. The scrotum's role is crucial in maintaining the optimal temperature for proper sperm production by regulating the distance of the testes from the body. The vas deferens is a duct responsible for transporting sperm from the testes to the urethra, not the protective sac surrounding the testes. The epididymis is a coiled tube where sperm mature and are stored before ejaculation, not the protective sac. The urethra is a tube that serves as a common passageway for both urine and semen to exit the body, not the protective sac surrounding the testes.
What is the primary function of the placenta during pregnancy?
- A. Produce insulin
- B. Facilitate gas exchange between mother and fetus
- C. Excrete waste products from the fetus
- D. All of the above
Correct Answer: B
Rationale: The primary function of the placenta during pregnancy is to facilitate the exchange of oxygen and carbon dioxide between the mother and the fetus. This ensures that the fetus receives oxygen and eliminates carbon dioxide, supporting its growth and development. While the placenta also allows for the transfer of nutrients and waste products between the mother and the fetus, its main role is to ensure proper gas exchange. Therefore, choices A, C, and D are incorrect as the primary role of the placenta is not to produce insulin or excrete waste products from the fetus. Selecting the correct answer, choice B, highlights the crucial role of the placenta in providing oxygen to the fetus and removing carbon dioxide, which are essential for fetal well-being and development.
What is the primary function of the atrioventricular (AV) node within the heart?
- A. Generate the electrical impulse for contraction (pacemaker function)
- B. Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction.
- C. Increase blood pressure within the ventricles during systole.
- D. Separate oxygenated and deoxygenated blood flow in the heart.
Correct Answer: B
Rationale: The correct answer is B: Transmit the electrical impulse from the atria to the ventricles, regulating the timing of contraction. The primary function of the atrioventricular (AV) node is to coordinate the transmission of electrical signals between the atria and the ventricles. It ensures proper timing between atrial and ventricular contractions, allowing for efficient blood pumping through the heart. Choice A is incorrect because the AV node does not generate the initial electrical impulse; that role is typically attributed to the sinoatrial (SA) node. Choice C is incorrect as the AV node does not directly influence blood pressure within the ventricles. Choice D is also incorrect as the separation of oxygenated and deoxygenated blood is primarily achieved by the anatomical structure of the heart (e.g., atria and ventricles) and not the AV node.
What information can be obtained from the mass number of an element?
- A. The number of protons in the nucleus
- B. The total number of protons and neutrons
- C. The number of electrons in the valence shell
- D. The element's chemical reactivity
Correct Answer: B
Rationale: The mass number of an element represents the total number of protons and neutrons in the nucleus. This information is crucial for determining the atomic mass of the element and understanding its stability and isotopes. The number of protons in the nucleus (option A) is represented by the atomic number, not the mass number. The number of electrons in the valence shell (option C) is related to the element's position in the periodic table and its chemical properties, but it is not directly determined by the mass number. The element's chemical reactivity (option D) is influenced by the number and arrangement of electrons in the atom's energy levels, not by the mass number.