Nokea
Which of the following glands helps regulate calcium levels?
- A. Osteotoid gland
- B. Pineal gland
- C. Parathyroid glands
- D. Thymus gland
Correct Answer: C
Rationale: The correct answer is C: Parathyroid glands. The parathyroid glands are responsible for regulating calcium levels in the body. They produce parathyroid hormone (PTH), which helps control calcium levels in the blood by acting on the bones, kidneys, and intestines. The other options, such as the osteotoid gland, pineal gland, and thymus gland, do not play a significant role in calcium regulation. The osteotoid gland is a fictitious term, the pineal gland is involved in regulating sleep-wake cycles and producing melatonin, and the thymus gland is part of the immune system and plays a role in T-cell maturation.
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What is the normal (complete) flow of blood through the heart?
- A. Right atrium → lungs → left atrium → body
- B. Left atrium → left ventricle → body → right atrium
- C. Right atrium → right ventricle → lungs → left atrium → left ventricle → aorta → body
- D. Right ventricle → left ventricle → body
Correct Answer: C
Rationale: The correct flow of blood through the heart starts with the right atrium receiving deoxygenated blood from the body, followed by the right ventricle pumping blood to the lungs for oxygenation. Oxygenated blood then returns to the heart through the left atrium, then passes to the left ventricle which pumps it out to the body through the aorta. This flow ensures that blood is properly oxygenated before circulating through the body. Choice A is incorrect as the blood does not go directly from the left atrium to the body, skipping the left ventricle. Choice B is incorrect as it does not follow the correct flow sequence in the heart. Choice D is incorrect as it does not include the full pathway of blood through the heart.
What is the anatomical term for the back of the body? Example: Shoulder blade.
- A. Anterior
- B. Superior
- C. Posterior
- D. Inferior
Correct Answer: C
Rationale: The correct answer is C: Posterior. 'Posterior' is the anatomical term that refers to the back of the body. It is the opposite of 'anterior,' which refers to the front of the body. 'Superior' typically describes a structure that is positioned above another structure, while 'inferior' refers to a structure that is below another. In this case, the term 'posterior' specifically indicates the back of the body, making it the most appropriate choice among the options provided.
Which molecules are soluble in nonpolar solvents but are hydrophobic?
- A. Carbohydrates
- B. Lipids
- C. Proteins
- D. Nucleic acids
Correct Answer: B
Rationale: Lipids are hydrophobic molecules that are soluble in nonpolar solvents like oils but insoluble in water. They consist of fats, oils, waxes, and steroids and play essential roles in energy storage, insulation, and cell membrane structure. Carbohydrates, proteins, and nucleic acids are not typically soluble in nonpolar solvents and do not exhibit the same hydrophobic characteristics as lipids. Carbohydrates are usually hydrophilic and soluble in water, proteins have both hydrophilic and hydrophobic regions but are not generally soluble in nonpolar solvents, and nucleic acids are polar molecules that are not known for their solubility in nonpolar solvents.
What is the structure of DNA?
- A. Single-stranded, linear
- B. Double-stranded, linear
- C. Double-stranded, helix
- D. Single-stranded, helix
Correct Answer: C
Rationale: The correct answer is C: Double-stranded, helix. DNA is structured as a double helix formed by two strands of nucleotides. The nucleotides are paired with complementary bases (A-T and C-G) in the center, held together by hydrogen bonds. This double-stranded helical structure is a fundamental characteristic of DNA and essential for its function in storing genetic information. Choices A, B, and D are incorrect because DNA is not single-stranded; it consists of two strands that run antiparallel to each other and are connected via hydrogen bonds. Additionally, DNA does not have a linear structure but rather a helical one, providing stability and protection to the genetic information it carries.
Which cells myelinate neurons in the CNS?
- A. Schwann cells
- B. Astrocytes
- C. Microglia
- D. Oligodendrocytes
Correct Answer: D
Rationale: The correct answer is D, Oligodendrocytes. Oligodendrocytes are responsible for myelinating neurons in the central nervous system (CNS). Schwann cells, found in the peripheral nervous system, are responsible for myelinating neurons there. Astrocytes support and maintain the neuronal environment, while microglia function as immune cells in the CNS, participating in immune responses and cellular debris clearance. Therefore, choices A, B, and C are incorrect for myelination of CNS neurons.