A&p Cell Function Quiz

The statement is true because all of the factors mentioned - charge of a molecule, size, lipid solubility, concentration gradient, and surface membrane area - can indeed affect the rate of diffusion. The charge of a molecule can influence its ability to pass through a membrane, while size can determine how easily it can diffuse through small pores. Lipid solubility affects how well a molecule can dissolve in the lipid bilayer of the membrane. Concentration gradient is the difference in solute concentration on either side of the membrane, and it drives the diffusion process. Finally, the surface membrane area can impact the rate of diffusion by providing more space for molecules to pass through.

Active transport and facilitated diffusion both involve the movement of molecules across the cell membrane with the help of specific carrier proteins. In active transport, molecules are moved against their concentration gradient, requiring energy in the form of ATP. Facilitated diffusion, on the other hand, allows molecules to move down their concentration gradient without the need for energy. In both cases, the carrier proteins play a crucial role in facilitating the transport of molecules across the membrane. Therefore, the statement is true.

Simple diffusion is a passive process where molecules move from an area of higher concentration to an area of lower concentration. It occurs directly through the lipid bilayer of the cell membrane. Large molecules, such as proteins, cannot cross the membrane through simple diffusion because they are too big to fit through the small spaces between the lipid molecules. Similarly, charged or polar molecules cannot pass through the nonpolar lipid bilayer as they are hydrophilic and repelled by the hydrophobic interior of the membrane. Therefore, all of the options mentioned (large molecules, proteins, and charged/polar molecules) cannot cross membranes during simple diffusion.

Osmotic pressure refers to the pressure exerted by a solvent, such as water, as it moves across a semipermeable membrane to equalize the concentration of solutes on both sides. This process tries to make everything even by forcing water to move from areas where there is little dissolved solute to areas where there is a higher concentration of dissolved solute. Therefore, all of the given options are correct as they describe different aspects of osmotic pressure.

Osmosis and simple diffusion are the two processes that match the definition of transport through the membrane that is not carrier mediated. Osmosis is the movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. Simple diffusion, on the other hand, refers to the movement of molecules from an area of higher concentration to an area of lower concentration without the involvement of any carrier proteins. Both osmosis and simple diffusion occur spontaneously and do not require any energy input.

Active transport is the process by which molecules and ions are transported across a cell membrane against their concentration gradients, meaning from areas of lower concentration to higher concentration. This requires the input of energy, usually in the form of ATP, to move substances "uphill" against the natural flow. Therefore, the correct answer is "Lower to higher concentrations."

Primary active transport occurs when the hydrolysis of ATP is directly required for the function of the carriers. These carriers are composed of proteins that span the thickness of the membrane.

During facilitated diffusion, molecules move across a membrane from an area of high concentration to an area of low concentration with the help of transport proteins. These proteins act as channels or carriers, allowing specific molecules to pass through the membrane. Saturation refers to the point at which all available transport proteins are occupied, and no more molecules can be transported. Energy is not required for facilitated diffusion as it is a passive process that relies on the concentration gradient. Therefore, the correct answer is "Transport protein."

Facilitated diffusion is a passive process that allows the movement of molecules across a cell membrane with the help of transport proteins. Unlike active transport, facilitated diffusion does not require energy input from the cell. Instead, it relies on the concentration gradient to drive the movement of molecules from an area of higher concentration to an area of lower concentration. Therefore, the statement that energy is required during facilitated diffusion is false.

Oncotic pressure is specifically related to proteins. Proteins in the blood, such as albumin, exert an osmotic pressure that helps to maintain fluid balance within the blood vessels. These proteins attract water, causing it to remain within the blood vessels and preventing excessive fluid leakage into the surrounding tissues. Therefore, proteins play a crucial role in regulating oncotic pressure and maintaining the overall fluid balance in the body.

Small lipophilic organic compounds are able to easily cross a membrane due to their chemical properties. Lipophilic compounds are soluble in lipids, which make up the cell membrane, allowing them to pass through easily. In contrast, large molecules and polar compounds have difficulty crossing the membrane due to their size and polarity. A concentrated gradient refers to a difference in concentration between two areas, but it does not specifically describe the movement of oxygen from blood into the tissues.

Pinocytosis is a process in which the plasma membrane of a cell invaginates to produce a deep, narrow furrow. This furrow then forms a vesicle that engulfs extracellular fluid and solutes. Unlike phagocytosis, which involves the engulfment of large particles or microorganisms, pinocytosis is the uptake of fluid and small molecules. Active transport is the movement of substances across the cell membrane against their concentration gradient, while simple diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration.