Biology Midterm Chapter 5

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

NA+

Aquaporins

allow water to cross the plasma membrane with the concentration gradient

A cell that has neither a net gain of water nor net loss of water when it is immersed in a solution must be

isotonic to its environment

Which of the following statements regarding active transport is false? -Active transport uses ATP as an energy source -Active transport can move a solute against its concentration gradient -Active transport requires the cell to expend energy -Active transport is driven by the concentration gradient

Active transport is driven by the concentration gradient

Which of the following statements regarding enzyme function is false? -Enzymes are very specific for certain substrates -Enzymes emerge unchanged from the reaction they catalyze -An enzyme's function depends on its three-dimensional shape -Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction

Enzymes are used up when the catalyze a chemical reaction so must be synthesized for each new chemical reaction

Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing

chemical energy into kinetic energy

Osmosis can be defined as

diffusion of water

The fluid mosaic model describes the plasma membrane as consisting of

diverse proteins embedded in a phospholipid bilayer

phagocytosis is eating as pinocytosis is to

drinking

The cholesterol associated with animal cell membranes

helps to keep phospholipids from being too close to one another

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

passive transport

Oxygen crosses a plasma membrane by

passive transport

Which not the following processes is classified as a metabolic pathway

protein synthesis

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

proteins

According to ___, energy cannot be created or destroyed

the first law of thermodynamics

The active site of an enzyme is

the region of an enzyme that attaches to a substrate

If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference

the relative inelasticity and strength the plant cell wall

Facilitated diffusion across a biological membrane requires ____ and moves a substance ___ its concentration gradient

transport proteins; down