Nokea
Which of the following physiological responses is caused by the release of anti-diuretic hormone?
- A. Decrease in water reabsorption in the collecting duct
- B. Decrease in the concentration of calcium in the glomerulus
- C. Increase in the concentration of calcium in the glomerulus
- D. Increase in water reabsorption in the collecting duct
Correct Answer: D
Rationale: The correct answer is D: Increase in water reabsorption in the collecting duct. Anti-diuretic hormone (ADH), also known as vasopressin, acts on the kidneys to increase water reabsorption in the collecting ducts, leading to the concentration of urine and conservation of water in the body. This hormone helps regulate water balance by decreasing urine output and increasing blood volume and pressure when needed.
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Which class of biological molecules includes enzymes?
- A. Carbohydrates
- B. Vitamins
- C. Lipids
- D. Proteins
Correct Answer: D
Rationale: Enzymes are proteins that serve as biological catalysts, accelerating chemical reactions in living organisms. Proteins, a class of biological molecules crucial for the structure and function of cells, tissues, and organs, include enzymes. While carbohydrates, vitamins, and lipids are essential biomolecules, they do not encompass enzymes. Therefore, the correct answer is Proteins (Choice D).
Which of the following structures is present in both prokaryotic and eukaryotic cells?
- A. Cell membrane
- B. Chromoplast
- C. Golgi apparatus
- D. Endoplasmic reticulum
Correct Answer: A
Rationale: The correct answer is the cell membrane (choice A). The cell membrane is a vital structure present in both prokaryotic and eukaryotic cells. It plays a crucial role as a selectively permeable barrier, controlling the movement of substances into and out of the cell. On the other hand, chromoplasts, Golgi apparatus, and endoplasmic reticulum are specific organelles found only in eukaryotic cells. Chromoplasts are responsible for pigment synthesis, Golgi apparatus is involved in protein processing and packaging, and endoplasmic reticulum is crucial for lipid synthesis and protein folding. Therefore, the cell membrane is the correct choice as it is the common feature shared by both prokaryotic and eukaryotic cells.
Which of the following adult structures is made by the fusion of bones that were separate during childhood?
- A. Hip
- B. Ankle
- C. Arm
- D. Skull
Correct Answer: D
Rationale: The correct answer is D: Skull. The skull is formed by the fusion of several bones that were separate during childhood. In adults, the skull is a solid structure composed of bones that have fused together at the sutures. These bones, such as the frontal, parietal, temporal, and occipital bones, gradually fuse as a person grows and develops. This fusion results in a protective and supportive structure for the brain and sensory organs. The fusion of separate bones into a single structure is a common feature in the development of the human skull.
Which of the following properties of water explains its solvent abilities for certain substances?
- A. High specific heat
- B. Polarity
- C. Volume
- D. High surface tension
Correct Answer: B
Rationale: The correct answer is B: Polarity. Water's polarity, resulting from its unequal sharing of electrons and the formation of hydrogen bonds, makes it an excellent solvent. The polar nature of water allows it to interact with and dissolve substances that have charges or partial charges, aiding in their breakdown at a molecular level. Choices A, C, and D are not directly associated with water's solvent capabilities. High specific heat (Choice A) refers to water's ability to resist temperature changes, volume (Choice C) is the amount of space occupied by water, and high surface tension (Choice D) pertains to water's cohesive properties.
Which of the following describes the covalent bonds linking two carbon atoms in an acetylene molecule (C2H2)?
- A. Single bond
- B. Triple bond
- C. Double bond
- D. Quadruple bond
Correct Answer: B
Rationale: The correct answer is B, 'Triple bond.' In an acetylene molecule (C2H2), the covalent bonds linking the two carbon atoms form a triple bond. A triple bond involves the sharing of three pairs of electrons between the carbon atoms, resulting in a very strong bond. Acetylene is a reactive compound used in various chemical processes due to its high reactivity, facilitated by the strength of the triple bond. This bond imparts stability to the molecular structure of acetylene, contributing to its unique properties and applications in organic chemistry.