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Which of the following DNA strands would complement the segment: ACTTGCA?
- A. TGAACGT
- B. GACCATG
- C. ACTTGCA
- D. None of the above
Correct Answer: A
Rationale: In DNA, adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G). To find the complementary strand, you need to match each base with its complementary base. The segment ACTTGCA consists of bases A, C, T, T, G, C, A, which would pair with T, G, A, A, C, G, T, respectively. Therefore, the complementary strand would be TGAACGT. Thus, option A (TGAACGT) is the correct choice as it follows the base-pairing rules in DNA.
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Which statement accurately describes the head of a phospholipid?
- A. It is hydrophilic.
- B. It is hydrophobic.
- C. It is located on the outer side of the layer.
- D. Both A and C
Correct Answer: D
Rationale: The head of a phospholipid is hydrophilic, meaning it is attracted to water. This property allows the head to interact with water molecules. Additionally, the head is positioned on the outer side of the lipid bilayer in cell membranes, facing the watery environments inside and outside the cell. As a result, the correct answer is 'Both A and C,' as the head of a phospholipid is both hydrophilic and located on the outer side of the layer.
Which process is the movement of particles from a high concentration to a low concentration?
- A. Diffusion.
- B. Filtration.
- C. Osmosis.
- D. Facilitation.
Correct Answer: A
Rationale: Correct Answer: A (Diffusion)
Rationale:
1. Diffusion is the movement of particles from areas of high concentration to low concentration.
2. This process occurs due to random movement of particles until equilibrium is reached.
3. Filtration is the movement of particles through a barrier due to pressure differences.
4. Osmosis is the movement of water molecules across a semi-permeable membrane.
5. Facilitation involves the assistance of carrier proteins in the movement of particles.
Summary:
Diffusion is the correct answer as it aligns with the movement of particles from high to low concentration. Filtration, osmosis, and facilitation involve different mechanisms and are not specifically related to concentration gradients.
Which of the following is always true about molecules?
- A. They can travel through all cell membranes
- B. They move from low concentration to high concentration without using energy
- C. They move from high concentration to low concentration without using energy
- D. They cannot move
Correct Answer: C
Rationale: The correct answer is C: 'They move from high concentration to low concentration without using energy.' This statement aligns with the concept of passive transport, where molecules naturally move from areas of higher concentration to lower concentration to reach equilibrium. This process does not require energy input. Option A is incorrect because not all molecules can freely pass through all cell membranes due to factors like size and charge. Option B describes active transport, which involves the movement of molecules against their concentration gradient, requiring energy. Option D is incorrect as molecules are in constant motion.
What type of tissue is fat composed of?
- A. Connective
- B. Muscle
- C. Nervous
- D. Epithelial
Correct Answer: A
Rationale: The correct answer is A: Connective tissue. Fat tissue, also known as adipose tissue, is a type of connective tissue that stores energy in the form of fat. It provides insulation and serves as a reserve of energy. Muscle tissue (choice B) is responsible for movement, nervous tissue (choice C) transmits electrical signals throughout the body, and epithelial tissue (choice D) covers and protects body surfaces.
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.