Nokea
Which of the following blood vessels contains the least oxygenated blood?
- A. Aorta
- B. Vena cava
- C. Pulmonary artery
- D. Femoral vein
Correct Answer: C
Rationale: The correct answer is C: Pulmonary artery. The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. This blood is considered the least oxygenated in the body as it has just returned from circulating through the body's tissues and is in need of oxygen replenishment. Choice A, the aorta, is incorrect as it carries oxygenated blood from the heart to the rest of the body. Choice B, the vena cava, carries deoxygenated blood from the body back to the heart. Choice D, the femoral vein, also carries deoxygenated blood back to the heart from the lower extremities.
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Which of the following is most different from the others?
- A. Thyroid gland
- B. Stomach
- C. Intestines
- D. Pancreas
Correct Answer: B
Rationale: The correct answer is B, 'Stomach.' The stomach is an organ of the digestive system responsible for breaking down food through mechanical and chemical digestion. In contrast, the thyroid, intestines, and pancreas are glands. The thyroid gland regulates metabolism through hormone secretion, the intestines aid in digestion and nutrient absorption, and the pancreas secretes digestive enzymes and hormones. Therefore, the stomach is functionally different from the other options as it is an organ involved in digestion, while the others are glands with specific secretory functions.
Which of the following is a constant?
- A. The number of protons in an oxygen atom
- B. The temperature at which iron ore will melt
- C. The human population size
- D. The time the sun rises each day
Correct Answer: A
Rationale: The number of protons in an oxygen atom is a constant. This value is determined by the atomic number of the element and does not change regardless of the isotope of oxygen. The number of protons defines the element and remains consistent under normal conditions. Choices B, C, and D are not constants. The temperature at which iron ore will melt can vary depending on factors like pressure, the human population size is constantly changing, and the time the sun rises each day varies with the seasons and location.
Which part of the cell serves as the control center for all cell activity?
- A. Nucleus
- B. Cell membrane
- C. Cytoplasm
- D. Mitochondria
Correct Answer: A
Rationale: The corrected question and answer are accurate. The correct answer is A: Nucleus. The nucleus is known as the control center of the cell as it contains the cell's genetic material (DNA) and directs all cell activities including growth, metabolism, and reproduction. The other organelles listed in the choices, while important for various cellular functions, do not serve as the central control center for overall cell activity.
What is the cellular function of cilia and flagella?
- A. Cilia and flagella are responsible for cell movement.
- B. Cilia and flagella synthesize proteins.
- C. Cilia and flagella help protect the cell from its environment.
- D. Cilia and flagella have enzymes that help with digestion.
Correct Answer: A
Rationale: The correct answer is A: Cilia and flagella are responsible for cell movement. Cilia and flagella are specialized structures found on the surface of many types of cells. They are involved in the movement of the cell itself or in moving substances around the cell. This movement helps in various functions such as propulsion, moving fluids, and sensing the environment. Choices B, C, and D are incorrect. Cilia and flagella are not involved in synthesizing proteins, protecting the cell from its environment, or aiding in digestion. Their primary function is related to cell movement and cellular transport.
How do DNA and RNA function together as part of the human genome?
- A. DNA carries genetic information from RNA to the cell cytoplasm.
- B. RNA carries genetic information from DNA to the cell cytoplasm.
- C. DNA and RNA carry genetic information from the cell nucleus to the cytoplasm.
- D. DNA and RNA do not interact within the cell.
Correct Answer: B
Rationale: The correct answer is B. RNA acts as a messenger carrying genetic instructions from the DNA in the nucleus to the cytoplasm, where proteins are synthesized. This process is known as transcription and translation, where DNA provides the blueprint for protein synthesis, and RNA delivers this information to the cellular machinery in the cytoplasm. Choice A is incorrect as it inaccurately states that DNA carries genetic information from RNA, which is the opposite of the actual flow of information. Choice C is incorrect as it suggests that both DNA and RNA together carry genetic information from the nucleus to the cytoplasm, which is not accurate. Choice D is incorrect as DNA and RNA do interact within the cell, playing crucial roles in genetic information processing and protein synthesis.