Nokea
How many different types of nucleotides are there in DNA?
- A. one
- B. two
- C. four
- D. eight
Correct Answer: C
Rationale: The correct answer is C: four. DNA is composed of four different types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides pair specifically (A with T and C with G) to form the double-stranded DNA structure.
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Why do cells require a large surface-to-volume ratio?
- A. For complexity.
- B. Compartmentalization.
- C. Size of organelles.
- D. Nutrient and gas exchange.
Correct Answer: D
Rationale: The correct answer is D: Nutrient and gas exchange. Cells require a large surface-to-volume ratio to efficiently exchange nutrients and gases with their environment. With a larger surface area, cells can absorb more nutrients and oxygen while expelling waste and carbon dioxide more effectively.
Rationale:
1. Nutrient exchange: A larger surface area allows for more nutrient absorption, essential for cell metabolism and function.
2. Gas exchange: A high surface-to-volume ratio facilitates the exchange of gases like oxygen and carbon dioxide necessary for cellular respiration.
3. Efficiency: Cells need to maintain a balance between surface area and volume to ensure optimal nutrient and gas exchange.
4. Other choices:
- A: Complexity is not directly related to the surface-to-volume ratio.
- B: Compartmentalization refers to the organization of organelles within a cell, not the surface-to-volume ratio.
- C: While size of organelles can affect cell function, it is not the primary reason for requiring a
Which of the following is a benefit of the intermolecular hydrogen bonding of water? (Select one that doesn't apply.)
- A. Water has a relatively high specific heat value.
- B. Water has strong cohesive and adhesive properties.
- C. Polarity of water allows it to act as a versatile solvent.
- D. Water moves from higher to lower concentrations.
Correct Answer: D
Rationale: Intermolecular hydrogen bonding in water leads to various unique properties. Options A, B, and C are benefits of this bonding. Water's high specific heat value allows it to resist temperature changes, which is advantageous for temperature regulation in organisms. The strong cohesive and adhesive properties of water contribute to capillary action and surface tension, essential in biological systems. Additionally, water's polarity enables it to dissolve a wide range of substances, making it a versatile solvent. Option D, 'Water moves from higher to lower concentrations,' is not a direct benefit of intermolecular hydrogen bonding of water. Instead, it describes the process of osmosis, which is driven by differences in solute concentrations rather than hydrogen bonding.
Which of the following organisms would not have eukaryotic cells?
- A. Bacteria
- B. Dog
- C. Human
- D. Onion
Correct Answer: A
Rationale: The correct answer is A, Bacteria. Bacteria are prokaryotic organisms, meaning they lack a true nucleus and membrane-bound organelles, unlike eukaryotic cells found in dogs, humans, and onions. Dogs, humans, and onions are examples of organisms with eukaryotic cells that contain a true nucleus and various membrane-bound organelles.
Which genetic descriptor refers to an organism's actual appearance?
- A. Phenotype.
- B. Homozygote.
- C. Genotype
- D. Karyotype.
Correct Answer: A
Rationale:
The aerodynamic nature of a bird's wing is an example of what central theme in biology?
- A. Heredity.
- B. Ontogeny.
- C. Organisms and their environment.
- D. Structure and function.
Correct Answer: D
Rationale: