Nokea
What is the atomic number of an atom that has 12 protons and 12 neutrons?
- A. 1
- B. 144
- C. 12
- D. 24
Correct Answer: C
Rationale: The atomic number of an element is determined by the number of protons in its nucleus. In this case, the atom has 12 protons, which directly corresponds to its atomic number. Neutrons have no impact on the atomic number; they contribute to the atomic mass. The atomic number uniquely identifies an element based on the number of protons in its nucleus. Therefore, the correct answer is 12, as it represents the number of protons in the nucleus and defines the element, regardless of the presence of neutrons.
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Which of the following is used to determine a person's DNA sequence?
- A. hormones
- B. enzymes
- C. blood types
- D. genes
Correct Answer: D
Rationale: Genes are the correct choice for determining a person's DNA sequence. Genes carry genetic information that dictates various traits and characteristics in individuals. A person's unique DNA sequence is determined by the specific arrangement of nucleotides within their genes. Scientists can analyze genes to decode the DNA sequence that represents an individual's genetic composition.
Which type of joint is the hip an example of?
- A. Hinge
- B. Gliding
- C. Ball-and-socket
- D. Pivot
Correct Answer: C
Rationale: The correct answer is C: Ball-and-socket. The hip joint is a ball-and-socket joint, allowing for a wide range of motion in multiple directions. This joint type permits flexion, extension, abduction, adduction, and rotation. Hinge joints, like the knee, allow movement in one plane, similar to a door hinge. Gliding joints permit limited sliding movements. Pivot joints allow rotation around a single axis.
Which of the following microorganisms lacks its own metabolic pathways and can only reproduce inside a host cell?
- A. Bacteria
- B. Viruses
- C. Protozoa
- D. Muscle
Correct Answer: B
Rationale: The correct answer is B: Viruses. Viruses are obligate intracellular parasites, lacking metabolic pathways and being dependent on a host cell for replication. Unlike bacteria, protozoa, or muscle cells, viruses utilize the host cell's resources and machinery to replicate their genetic material and produce new viral particles.
Which of the following ions binds to the troponin complex, initiating muscle contraction?
- A. Sodium
- B. Potassium
- C. Phosphorus
- D. Calcium
Correct Answer: D
Rationale: The correct answer is calcium (D). Calcium ions bind to the troponin complex, initiating muscle contraction. When calcium binds to troponin, it causes a conformational change in the troponin-tropomyosin complex, exposing the binding sites on actin for myosin. This interaction allows muscle contraction by facilitating the sliding of actin and myosin filaments past each other, leading to muscle contraction.
Blockage and inflammation of which of the following structures most often leads to facial acne?
- A. Lacrimal glands
- B. Sebaceous glands
- C. Ceruminous glands
- D. Sudoriferous glands
Correct Answer: B
Rationale: Sebaceous glands are responsible for producing sebum, an oily substance that can clog pores when overproduced or combined with dead skin cells. This blockage promotes the growth of acne-causing bacteria and leads to inflammation. The other glands listed in the choices do not play a significant role in the development of facial acne. Ceruminous glands produce earwax (cerumen) to protect the ear canal, sudoriferous glands produce sweat to regulate body temperature, and lacrimal glands produce tears to lubricate and protect the eyes.