Correct Answer: B

Rationale: The correct answer is the Cell Membrane. The cell membrane acts as a barrier that controls the passage of substances into and out of the cell. It is selectively permeable, allowing only certain molecules to pass through. Vacuole (Choice A), Nuclear Membrane (Choice C), and Cytoplasm (Choice D) do not primarily regulate the passage of substances in and out of the cell. Vacuoles are responsible for storage, the nuclear membrane surrounds the nucleus providing protection, and the cytoplasm is the fluid where organelles are suspended.

Correct Answer: B

Rationale: Passive transport refers to the movement of substances across cell membranes without the need for energy input. In contrast, active transport, choice A, requires energy to move substances against their concentration gradient. Diffusion, choice C, is a type of passive transport where substances move from an area of high concentration to low concentration. Osmosis, choice D, specifically refers to the movement of water molecules across a selectively permeable membrane.

Correct Answer: B

Rationale: Osmosis is the process specifically involving the movement of water molecules through a selectively permeable membrane, from an area of higher water concentration to an area of lower water concentration. This process helps balance concentrations on both sides of the membrane. Choice A, Diffusion, refers to the movement of particles from an area of higher concentration to an area of lower concentration, not specific to water. Choice C, Active Transport, requires energy to move substances against their concentration gradient, unlike osmosis. Choice D, Facilitated Diffusion, involves the use of transport proteins to move specific substances across membranes, not limited to water molecules.

Correct Answer: B

Rationale: Microtubules are the cellular structures responsible for cell movement and propulsion. Microtubules are part of the cytoskeleton and play a crucial role in various cellular processes, including cell motility and intracellular transport. While microfilaments also contribute to cell movement by enabling muscle contraction and cell shape changes, they are not primarily responsible for propelling the cell. Flagella and cilia are cellular appendages involved in cell movement, but they are composed of microtubules, making them the structures that move due to the actions of microtubules.

Correct Answer: B

Rationale: The correct answer is B: Water. Blood plasma is composed mostly of water, which acts as a solvent for various nutrients and substances. Choices A, C, and D are incorrect. Proteins are indeed present in blood plasma but are not the main component. Red blood cells and platelets are cellular components of blood, not the main component of blood plasma.