Nokea
Which type of muscle is responsible for voluntary movements?
- A. Smooth
- B. Skeletal
- C. Cardiac
- D. Involuntary
Correct Answer: B
Rationale: The corrected question is asking about the type of muscle responsible for voluntary movements, which is skeletal muscle (Choice B). Skeletal muscle is under conscious control and is responsible for voluntary movements like walking or lifting objects. Smooth muscle (Choice A) is found in organs like the intestines and blood vessels, responsible for involuntary movements. Cardiac muscle (Choice C) is specific to the heart and is also involuntary. 'Involuntary' (Choice D) is a general term and does not specify a type of muscle responsible for voluntary movements.
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How does the body maintain a relatively constant blood pH level, even with changes in blood carbon dioxide concentration?
- A. Cellular respiration
- B. Gas exchange
- C. Buffering system
- D. Deoxygenation
Correct Answer: C
Rationale: The correct answer is C: Buffering system. The buffering system is responsible for maintaining a relatively constant blood pH level by minimizing changes in pH when acids or bases are added to the blood. This system consists of chemical compounds that can donate or accept protons to help stabilize the pH. Choice A, Cellular respiration, and Choice B, Gas exchange, are processes involved in gas exchange within the body, not specifically related to maintaining blood pH. Choice D, Deoxygenation, refers to the removal of oxygen from a substance and is not directly related to the regulation of blood pH.
Which vitamin is essential for blood clotting?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin K
- D. Vitamin D
Correct Answer: C
Rationale: Vitamin K is essential for blood clotting as it plays a crucial role in the synthesis of clotting factors in the liver. Deficiency in vitamin K can result in impaired blood clotting and excessive bleeding. Vitamin K is necessary for the activation of proteins that are involved in the blood clotting process, making it a vital nutrient for maintaining proper hemostasis. Vitamin A (Choice A) is important for vision and immune function, Vitamin C (Choice B) is crucial for collagen synthesis and antioxidant protection, and Vitamin D (Choice D) is essential for calcium absorption and bone health. However, when it comes to blood clotting specifically, Vitamin K is the key vitamin involved.
When sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl), the resulting product is:
- A. Hydrogen gas and sodium chloride (NaCl)
- B. Chlorine gas and sodium oxide (Na2O)
- C. Sodium metal (Na) and water (H2O)
- D. No reaction occurs.
Correct Answer: A
Rationale: When sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl), a neutralization reaction occurs. The products of this reaction are water (H2O) and a salt, which is sodium chloride (NaCl). The chemical equation for this reaction is: NaOH + HCl -> NaCl + H2O. Choice B is incorrect because chlorine gas and sodium oxide are not the products of this reaction. Choice C is incorrect as sodium metal and water are not the products formed in this neutralization reaction. Choice D is incorrect because a reaction does occur between NaOH and HCl, resulting in the formation of NaCl and H2O. Therefore, the correct answer is A: Hydrogen gas and sodium chloride (NaCl).
Through which structure do the kidneys reabsorb water, salts, and nutrients and return them to the body?
- A. Renal artery
- B. Renal vein
- C. Nephron
- D. Glomerulus
Correct Answer: C
Rationale: The question has been corrected to specify the structure responsible for reabsorbing water, salts, and nutrients in the kidneys. The correct answer is the nephron, which is the functional unit of the kidney that performs filtration and reabsorption processes. The renal artery brings blood into the kidney for filtration, the renal vein carries filtered blood away from the kidney, and the glomerulus is a part of the nephron where filtration occurs. Therefore, the nephron is the structure that reabsorbs substances and returns them to the body.
What is the name of the structure that packages DNA in eukaryotic cells?
- A. Nucleosome
- B. Chromatin
- C. Histone
- D. Centromere
Correct Answer: A
Rationale: - A nucleosome is the basic structural unit of DNA packaging in eukaryotic cells. It consists of DNA wrapped around a core of histone proteins.
- Chromatin refers to the complex of DNA and proteins found in the nucleus of a eukaryotic cell, including nucleosomes.
- Histones are the proteins around which DNA is wrapped to form nucleosomes.
- Centromere is a region of a chromosome where the two sister chromatids are joined and to which spindle fibers attach during cell division.