Nokea
Which of the following options best represents complementary base pairing in DNA?
- A. A and G
- B. A and C
- C. A and A
- D. A and T
Correct Answer: D
Rationale: In DNA, adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). This is known as complementary base pairing. The correct answer is 'A and T' because they form a complementary base pair in DNA. Adenine always pairs with thymine via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds. This base pairing specificity is crucial for DNA replication and genetic information transfer.
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How does a bacterium reproduce?
- A. Mitosis
- B. Meiosis
- C. Binary fission
- D. Cytokinesis
Correct Answer: C
Rationale: Bacteria reproduce through binary fission, a process in which a single bacterium divides into two identical daughter cells. Mitosis and meiosis are processes specific to eukaryotic cells, not bacteria. Cytokinesis is the final step of the cell cycle where the cytoplasm divides, but it is not the primary reproductive method for bacteria.
What is the term for a statement predicting the outcome of an experiment?
- A. Experiment.
- B. Hypothesis.
- C. Conclusion.
- D. Observation.
Correct Answer: B
Rationale: The correct answer is B: Hypothesis. A hypothesis is a statement that predicts the outcome of an experiment based on prior knowledge or observations. It serves as the foundation for the experiment and guides the research process.
A: Experiment - This choice refers to the actual process of conducting a test or investigation, not the prediction of the outcome.
C: Conclusion - This choice pertains to the final result or summary drawn from the experiment after analyzing the data collected, not the initial prediction.
D: Observation - This choice involves gathering and recording data through direct sensory experience, not making a prediction about the experiment's outcome.
Which base has two carbon rings?
- A. N
- B. C
- C. T
- D. G
Correct Answer: D
Rationale: The correct answer is G. In organic chemistry, the base Guanine (G) contains two carbon rings in its structure. Guanine is one of the four main nucleobases found in DNA and RNA. The other options, N, C, and T, do not have two carbon rings in their structures. Therefore, Guanine is the only option that fits the description of a base with two carbon rings.
Which aspect of a biological system explains why a protein's unique shape determines what it does?
- A. Patterns of Inheritance.
- B. Taxonomy.
- C. Structure and function.
- D. Scientific method.
Correct Answer: C
Rationale: Rationale:
C is correct because structure and function are closely related in biology. A protein's unique shape determines its function due to the specific arrangement of amino acids, influencing its interactions with other molecules. A and B are irrelevant to the relationship between a protein's shape and its function. The scientific method is a process for conducting experiments, not directly related to the physical properties of proteins.
Which cell component is responsible for protection, communication, and regulating the passage of substances into and out of the cell?
- A. Nucleus
- B. Cell membrane
- C. Endoplasmic reticulum
- D. Cytoplasm
Correct Answer: B
Rationale: The cell membrane is responsible for protecting the cell, facilitating communication with other cells, and regulating the passage of substances into and out of the cell. It acts as a barrier that controls the movement of molecules, ions, and other substances, maintaining the cell's internal environment and enabling cellular interactions with the external environment. The nucleus contains genetic material and is not primarily involved in protection, communication, or regulating the passage of substances. The endoplasmic reticulum is involved in protein synthesis and lipid metabolism. The cytoplasm is a gel-like substance that fills the cell and is not directly responsible for protection, communication, or regulating substance passage.