Nokea
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.
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Which of the following chemicals is released by one type of immune cell to directly activate another immune cell?
- A. lysozymes
- B. cytokines
- C. perforin
- D. granzymes
Correct Answer: B
Rationale: The correct answer is B: cytokines. Cytokines are signaling molecules released by immune cells to regulate the immune response. They play a crucial role in coordinating and communicating between different immune cells. By releasing cytokines, immune cells can directly activate other immune cells, enhancing the immune response. Lysozymes are enzymes that break down bacterial cell walls, perforin is a protein involved in cell-mediated immune responses, and granzymes are enzymes that induce apoptosis in target cells, mainly used by cytotoxic T cells and natural killer cells, not for directly activating other immune cells.
Where do both digestion and absorption occur in the digestive system?
- A. Stomach
- B. Esophagus
- C. Gallbladder
- D. Small intestine
Correct Answer: D
Rationale: Both digestion and absorption take place in the small intestine. The small intestine is a crucial organ where the breakdown of food into smaller molecules, digestion, occurs with the help of enzymes. This process is essential for the absorption of nutrients, where the smaller molecules are taken up by the bloodstream for distribution throughout the body. While the stomach aids in digestion through the action of gastric juices, the esophagus serves as a tube for food passage, and the gallbladder stores bile produced by the liver to aid in fat digestion. However, neither digestion nor absorption occurs in the stomach, esophagus, or gallbladder, making the small intestine the correct answer for both processes.
What type of tissue largely makes up the pharynx?
- A. Bone
- B. Muscle
- C. Nervous
- D. Cartilage
Correct Answer: B
Rationale: The pharynx is mostly composed of muscle tissue, which enables it to carry out functions like swallowing and breathing. Muscles in the pharynx contract to propel food into the esophagus during swallowing and aid in vocalization and respiration.
Through which structure does blood exit the glomerulus?
- A. Distal tubule
- B. Proximal tubule
- C. Afferent arteriole
- D. Efferent arteriole
Correct Answer: D
Rationale: The correct answer is D, the efferent arteriole. The efferent arteriole carries blood away from the glomerulus after filtration. Blood enters the glomerulus through the afferent arteriole for filtration. The proximal and distal tubules are involved in tubular reabsorption and secretion of substances after filtration occurs in the glomerulus. The efferent arteriole plays a crucial role in maintaining the proper flow of blood through the nephron and ensures that the filtered substances are carried away for further processing in the renal tubules.
Which of the following atoms is most likely to become a cation?
- A. Potassium, atomic number 19
- B. Oxygen, atomic number 8
- C. Fluorine, atomic number 9
- D. Helium, atomic number 2
Correct Answer: A
Rationale: Among the options provided, Potassium is the most likely atom to become a cation. Atoms tend to form cations by losing electrons to achieve a stable electron configuration. Potassium has 19 electrons and only needs to lose one electron to attain an electron configuration similar to the nearest noble gas, argon. This loss of an electron leads to the formation of a potassium cation with a +1 charge.