Unit 5 Flashcards
The process of a white blood cell engulfing a bacterium is
phagocytosis
In the lab, you use a special balloon that is permeable to water but not sucrose to make an “artificial cell.” The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur?
Water will leave the balloon.
Which part of the ATP molecule breaks free of the rest when an ATP molecule is used for energy?
part D
(the 3rd P molecule)
Which of the following statements is true for all types of passive transport?
The concentration gradient is the driving force.
Which curve shows the course of the reaction in the presence of an enzyme–the black curve or the red curve? Which line represents the activation energy for that reaction–a, b, or c?
red curve; line b
Use the graph and your knowledge of enzymes to identify the three true statements about enzymes.
- Reactants cannot convert to products without an initial input of energy to start the reaction.
- Enzymes lower the overall energy input needed for a reaction to occur.
- By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart.
In a hypotonic solution, an animal cell will
lyse
The phosphorylation of ADP to form ATP is an _____ reaction that _____ energy.
endergonic … requires an input of
When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will _____.
remain standing upright
Which figure depicts an animal cell placed in a solution hypotonic to the cell?
cell A
The cholesterol associated with animal cell membranes
helps to keep phospholipids from being too close to one another.
Oxygen crosses a plasma membrane by
passive transport.
The molecules responsible for membrane transport are
proteins
Which of the following is a coenzyme?
vitamin B6
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 of the plant cell wall
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
This cell is in a(n) _____ solution.
hypertonic
You know that this cell is in a(n) _____ solution because the cell _____.
hypotonic … swelled
You know that this cell is in a(n) _____ solution because it _____.
hypertonic solution … lost water
The first law of thermodynamics _____.
states that energy is neither created nor destroyed
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
receptor-mediated endocytosis
Osmosis can be defined as
the diffusion of water.
Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of
passive transport.
The active site of an enzyme is
the region of an enzyme that attaches to a substrate.
Which of the following statements is true about passive transport?
Passive transport requires no expenditure of cellular energy.
When molecules move down their concentration gradient, they move from where they are ________ to where they are _________.
more concentrated, less concentrated
Diffusion across a biological membrane is called
passive transport
An enzyme is considered a(n) _______ because it speeds up a chemical reaction without being used up.
catalyst
In a catalyzed reaction, a reactant is often called a(n)
substrate
An enzyme is specific because the shape of its ____________
matches only particular reactants.
active site
An enzyme speeds up reactions by lowering the_______
activation energy
The _________ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
A(n) _______, which is often a vitamin, binds to an enzyme and plays a role in catalysis.
coenzyme
High temperatures or changes in pH can ______
an enzyme, causing it to lose its shape and biological activity.
denature
When an enzyme catalyzes a reaction,
it lowers the activation energy of the reaction.
Most of the functions of a cell membrane, including transport and enzymatic function, are performed by
proteins
Plasma membranes are selectively permeable. This means that
the plasma membrane allows some substances to enter or leave a cell more easily than others.
Which of the following processes can move a solute against its concentration gradient?
active transport
What is the basic difference between exergonic and endergonic reactions?
Exergonic reactions release energy; endergonic reactions absorb it.
Cellular respiration is an example of __________.
an exergonic process
The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance?
oxygen and carbon dioxide
Anything that prevents ATP formation will most likely
result in cell death.
What substance is transported by aquaporins?
water
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
a hypertonic sucrose solution
In the lab, you use a special balloon that is permeable to water but not sucrose to make an “artificial cell.” The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is ________ relative to the solution in the beaker.
hypotonic
The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____.
diffusion
ATP can be used as the cell’s energy exchange mechanism because
endergonic reactions can be fueled by coupling them with the hydrolysis of high-energy phosphate bonds in ATP.
Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.
transport proteins; down
