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What are the phases of bacterial growth and infection?
- A. Lag, exponential, stationary, death
- B. Exponential, stationary, lag, death
- C. Stationary, exponential, lag, death
- D. Lag, stationary, exponential, death
Correct Answer: A
Rationale: The correct answer is A: Lag, exponential, stationary, death. The phases of bacterial growth start with the lag phase where bacteria acclimate to their environment, followed by the exponential phase characterized by rapid growth. This is then followed by the stationary phase where growth slows as resources deplete, and finally, the death phase where the population declines. Choice B is incorrect as it has the order of phases mixed up. Choice C is incorrect as it also has the order of phases mixed up. Choice D is incorrect as it has the stationary phase occurring before the exponential phase, which is inaccurate.
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A rock has a mass of 3 grams (g) and a volume of 4 cm³. What is its density?
- A. 8.90 g/cm³
- B. 0.38 g/cm³
- C. 77.22 g/cm³
- D. 2.65 g/cm³
Correct Answer: D
Rationale: Density is determined by the formula Density = Mass / Volume. For this rock, the mass is 3g, and the volume is 4 cm³. Applying the formula: Density = 3g / 4cm³ = 0.75 g/cm³. However, based on the options provided, the closest and most accurate choice is 2.65 g/cm³, corresponding to option D. Choice A, 8.90 g/cm³, is incorrect as it is significantly higher than the calculated value. Choice B, 0.38 g/cm³, and Choice C, 77.22 g/cm³, are also incorrect and do not match the correct calculation.
What is the atomic number of an atom?
- A. The number of protons in an atom
- B. The number of neutrons in an atom
- C. The number of electrons in an atom
- D. The sum of protons and neutrons
Correct Answer: A
Rationale: The correct answer is A: The atomic number of an atom is the number of protons in its nucleus. This number uniquely identifies the element, as each element has a distinct number of protons. Neutrons and electrons play roles in the atom's structure and stability, but the atomic number specifically refers to the number of protons. Choice B (The number of neutrons in an atom) is incorrect because the atomic number does not include neutrons; it only represents the number of protons. Choice C (The number of electrons in an atom) is incorrect because the atomic number is not related to the number of electrons, which can vary in different atomic configurations. Choice D (The sum of protons and neutrons) is incorrect because it refers to the mass number of an atom, which is the total number of protons and neutrons in the nucleus, not just the protons.
What are the two layers of the spinal cord?
- A. White matter and grey matter
- B. Epithelial and connective tissue
- C. Adipose and muscular tissue
- D. Dermis and hypodermis
Correct Answer: A
Rationale: The correct answer is A: White matter and grey matter. The spinal cord is composed of an exterior layer of white matter, which surrounds an interior core of grey matter. White matter consists mainly of myelinated axons, while grey matter contains cell bodies, dendrites, and unmyelinated axons. White matter is responsible for transmitting nerve signals up and down the spinal cord, while grey matter processes sensory information and initiates motor commands. The other choices (B, C, D) are incorrect as they do not represent the anatomical layers of the spinal cord. Epithelial and connective tissue, adipose and muscular tissue, dermis, and hypodermis are not the layers of the spinal cord but are found in other parts of the body such as skin and organs.
Which cells myelinate neurons in the CNS?
- A. Schwann cells
- B. Astrocytes
- C. Microglia
- D. Oligodendrocytes
Correct Answer: D
Rationale: The correct answer is D, Oligodendrocytes. Oligodendrocytes are responsible for myelinating neurons in the central nervous system (CNS). Schwann cells, found in the peripheral nervous system, are responsible for myelinating neurons there. Astrocytes support and maintain the neuronal environment, while microglia function as immune cells in the CNS, participating in immune responses and cellular debris clearance. Therefore, choices A, B, and C are incorrect for myelination of CNS neurons.
Which type of reaction builds larger and more complex molecules from smaller ones, requiring energy?
- A. Catabolic reaction
- B. Anabolic reaction
- C. Exothermic reaction
- D. Hydrolytic reaction
Correct Answer: B
Rationale: The correct answer is 'Anabolic reaction.' Anabolic reactions involve the synthesis of larger and more complex molecules from smaller ones, requiring an input of energy, often in the form of ATP. These reactions are essential for processes like growth, repair, and the building of cellular structures. Catabolic reactions, on the other hand, break down larger molecules into smaller ones, releasing energy. Exothermic reactions release heat, while hydrolytic reactions involve the breakdown of molecules with the addition of water. Therefore, choices A, C, and D are incorrect as they do not describe the process of building larger and more complex molecules from smaller ones with the requirement of energy.