Nokea
By what process do sex cells reproduce?
- A. Cytokinesis.
- B. Meiosis.
- C. Mitosis.
- D. Fission.
Correct Answer: B
Rationale:
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Which of the following is the best example of a hypothesis?
- A. Dogs like treats
- B. Red is the best color
- C. If I eat 100 donuts, then I will feel sick
- D. If a plant is exposed to red light, then it will show less growth than natural light.
Correct Answer: D
Rationale: A hypothesis is a testable statement that predicts the outcome of an experiment based on observations or research. Option D is the best example of a hypothesis as it presents a clear cause-and-effect relationship that can be tested through an experiment. Options A, B, and C do not provide a clear prediction or testable statement, making them weaker examples of hypotheses. In contrast, option D clearly states the expected outcome of exposing a plant to red light, allowing for a specific experiment to test this hypothesis.
Which of the following is not an RNA base?
- A. Adenine
- B. Thymine
- C. Uracil
- D. Cytosine
Correct Answer: B
Rationale: In RNA, the bases are Adenine, Uracil, and Cytosine. Thymine is uniquely found in DNA and not RNA. Adenine pairs with Uracil, while Cytosine pairs with Guanine in RNA. Thus, Thymine is not an RNA base, making it the correct answer.
What is the characteristic of the cell membrane consisting of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins that creates a hydrophobic region between two layers of lipids?
- A. Impermeable
- B. Permeable
- C. Selectively permeable
- D. Selectively impermeable
Correct Answer: C
Rationale: The correct answer is 'C: Selectively permeable.' The cell membrane is selectively permeable because it allows certain molecules to pass through while restricting the passage of others. The hydrophobic region formed by the lipid bilayer makes it selectively permeable by controlling the movement of substances in and out of the cell. This selective permeability is vital for cellular functions, as it regulates the transport of essential molecules and maintains the internal environment required for proper cell operation and overall cellular homeostasis.
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 bond in the base of the DNA nucleotides holds the strands together?
- A. Hydrogen.
- B. Sodium chloride.
- C. Copper.
- D. Potassium bromide.
Correct Answer: A
Rationale: