The positive control for the iodine test was the

Choice A rationale: The solute concentration of the cytoplasm inside the cell is correct because tonicity is a measure of how the solution affects the movement of water across the cell membrane by osmosis. Osmosis is the process by which water moves from a region of high water concentration to a region of low water concentration. The water concentration of a solution is determined by the solute concentration of the solution. The higher the solute concentration, the lower the water concentration, and vice versa. Therefore, tonicity compares the solute concentration of the solution outside the cell to the solute concentration of the cytoplasm inside the cell.

Choice B rationale: The permeability of the cell membrane is incorrect because permeability is a property of the cell membrane that determines how easily molecules can pass through it, not a measure of tonicity. The cell membrane is selectively permeable, meaning that it allows some molecules to cross, but not others. The cell membrane is permeable to water, but not to most solutes.

Choice C rationale: The swelling of the cell is incorrect because swelling is a result of tonicity, not a measure of it. Swelling occurs when a cell is placed in a hypotonic solution, which has a higher concentration of water and lower concentration of solute than the cell. In a hypotonic solution, water moves into the cell and out of the solution by osmosis, causing the cell to swell.

Choice D rationale: The number of cell fragments inside the cell is incorrect because cell fragments are pieces of broken cells that have no relation to tonicity. Cell fragments can be produced by mechanical damage, apoptosis, or necrosis, but they do not affect the solute concentration of the cytoplasm or the solution.

Choice E rationale: The presence of a cell wall is incorrect because the cell wall is a structure that surrounds the cell membrane in some cells, such as plant cells, but it does not affect tonicity. The cell wall is made of cellulose, a polysaccharide that is resistant to water. The cell wall provides mechanical support and prevents the cell from bursting in a hypotonic solution, but it does not change the solute concentration of the cytoplasm or the solution.

Choice A rationale: Movable is correct because motile is an adjective that describes the ability of an organism or a cell to move by itself, using some form of locomotion, such as flagella, cilia, or pseudopodia. For example, some bacteria, protists, and sperm cells are motile.

Choice B rationale: Fixed is incorrect because fixed is the opposite of motile. Fixed is an adjective that describes the inability of an organism or a cell to move by itself, due to being attached to a substrate or a surface. For example, some plants, fungi, and coral are fixed.

Choice C rationale: Magnification is incorrect because magnification is not related to motility. Magnification is a measure of how much larger an image appears compared to the actual size of the object. Magnification is used in microscopy to observe small objects, such as cells.

Choice D rationale: Solid is incorrect because solid is not related to motility. Solid is a state of matter that has a definite shape and volume, due to the strong attraction between the molecules. Solid is contrasted with liquid and gas, which have no definite shape and can flow.