bio exam 2

most of a cell's enzymes are

• carbohydrates

• proteins

• lipids

• amino acids

when two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will

• exhibit a net movement to the side with lower free water concentration

• exhibit a net movement to the side with higher free water concentration

• exhibit an equal movement in both directions across the membrane

• exhibit a net movement to the side with lower solute concentration

diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of

• exocytosis

• endocytosis

• active transport

• passive transport

which process is endergonic?

• the burning of wood

• the synthesis of glucose from carbon dioxide and water

• the breakdown of glucose

• cellular respiration

plasma membranes are selectively permeable. This means that

• glucose cannot enter the cell

• anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy

• the plasma membrane allows some substances to enter or leave a cell more easily than others

• plasma membranes must be very thick

which of the following statements regarding active transport is false?

• active transport can move a solute against its concentration gradient

• active transport requires the cell to expend energy

• active transport uses ATP as an energy source

• active transport is driven by the concentration gradient

most of the functions of a cell membrane, including transport and enzymatic function, are performed by

• proteins

• glycolipids

• cholesterol

• phospholipids

which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

• Na+

• a small, nonpolar molecule such as butane (C4H10)

• CO2

• O2

which of the following statements regarding membrane function is false?

• the plasma membrane plays a role in transferring signals to the cell's interior

• the plasma membrane forms a selective barrier around the cell

• the plasma membrane has receptors for chemical messages

• the plasma membrane is the control center of the cell

heating inactivates enzymes by

• removing phosphate groups from the enzyme

• causing enzyme molecules to stick together

• changing the enzyme's three-dimensional shape

• breaking the covalent bonds that hold the molecule together