The mechanical stage upper knob causes the stage to move
Up and down.
Right and left.
Back and forth.
All of the answer choices are correct.
The Correct Answer is B
Choice A rationale: Up and down is incorrect because the mechanical stage upper knob does not control the vertical movement of the stage. The vertical movement of the stage is controlled by the coarse and fine adjustment knobs, which are located on the side of the microscope. The coarse adjustment knob is used to raise or lower the stage quickly, while the fine adjustment knob is used to fine-tune the focus of the specimen.
Choice B rationale: Right and left is correct because the mechanical stage upper knob controls the horizontal movement of the stage along the x-axis. The mechanical stage is a platform that holds the slide and the specimen, and it can be moved by two knobs that are located below the stage. The upper knob moves the stage right or left, while the lower knob moves the stage forward or backward.
Choice C rationale: Back and forth is incorrect because the mechanical stage upper knob does not control the horizontal movement of the stage along the y-axis. The horizontal movement of the stage along the y-axis is controlled by the mechanical stage lower knob, which is located below the stage and next to the upper knob. The lower knob moves the stage forward or backward, while the upper knob moves the stage right or left.
Choice D rationale: All of the answer choices are correct is incorrect because only one of the answer choices is correct. The mechanical stage upper knob only causes the stage to move right or left, not up and down or back and forth. The other movements of the stage are controlled by different knobs.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale: Proteins contain nitrogen, but this is not the reason why they cannot pass through plasma membranes. Nitrogen is a common element in many organic molecules, including nucleic acids and amino acids, which can cross the membrane under certain conditions.
Choice B rationale: Proteins do not cause emulsification, which is the process of breaking down large fat droplets into smaller ones. Emulsification is facilitated by bile salts, which are amphipathic molecules that have both hydrophilic and hydrophobic regions. Proteins are not amphipathic, and they do not interact with fats in this way.
Choice C rationale: The membrane is made of protein, but this does not prevent proteins from passing through it. The membrane is composed of a phospholipid bilayer with embedded proteins, which can act as channels, carriers, receptors, or enzymes for various substances. Some proteins can cross the membrane by using these transport proteins, or by endocytosis or exocytosis.
Choice D rationale: Proteins are very large molecules, and this is the main reason why they cannot pass through plasma membranes. The size of a molecule determines its permeability across the membrane, and proteins are too big to diffuse through the small gaps between the phospholipids or the pores of the transport proteins. Proteins can only cross the membrane by vesicular transport, which requires energy and specific signals.
Choice E rationale: Proteins do not bind to the phospholipids, which are the main components of the membrane. Phospholipids are also amphipathic molecules, with a hydrophilic head and a hydrophobic tail. Proteins are generally hydrophilic, and they do not associate with the hydrophobic core of the membrane. Proteins can bind to other proteins or carbohydrates on the surface of the membrane, but this does not affect their ability to cross it.
Correct Answer is A
Explanation
Choice A rationale: Diffusion is correct because it is the passive movement of molecules from an area of high concentration to an area of low concentration. Small lipid soluble molecules can easily cross the plasma membrane by diffusing through the hydrophobic core of the phospholipid bilayer.
Choice B rationale: Filtration is incorrect because it is the process of separating solid particles from a fluid by passing it through a porous medium. Filtration does not involve the plasma membrane, and it does not depend on the solubility of the molecules.
Choice C rationale: Osmosis is incorrect because it is the diffusion of water across a selectively permeable membrane. Osmosis does not apply to lipid soluble molecules, which are not water molecules.
Choice D rationale: Active transport is incorrect because it is the movement of molecules across a membrane against their concentration gradient, which requires energy and transport proteins. Active transport does not depend on the solubility of the molecules, and it is not a passive process.
Choice E rationale: Pumping is incorrect because it is a type of active transport that involves the use of specific pumps to move ions or molecules across a membrane. Pumping does not apply to lipid soluble molecules, which are not ions or polar molecules.
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