Bio Test 2

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

cellular respiration

The fluid mosaic model describes the plasma membrane as consisting of

diverse proteins embedded in a phospholipid bilayer.

Small, nonpolar, hydrophobic molecules such as fatty acids

easily pass through a membrane's lipid bilayer.

Which of these reactions requires a net input of energy from its surroundings?

endergonic; The products of endergonic reactions have more potential energy than the reactants.

"Conservation of energy" refers to the fact that _____.

energy cannot be created or destroyed but can be converted from one form to another

What is the correct label for "A"?

energy of activation

Identify Structure A.

glycoprotein

You know that this cell is in a(n) _____ solution because it _____.

hypertonic solution ... lost water

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

An enzyme _____.

is an organic catalyst

As a result of its involvement in a reaction, an enzyme _____.

is unchanged

The synthesis of an amino acid follows this pathway: precursor A > intermediate B > amino acid C. Each reaction is catalyzed by a different enzyme. This metabolic pathway is controlled by feedback inhibition with amino acid C inhibiting the conversion of precursor A to intermediate B. Amino acid C acts as a _____ of the first enzyme in the pathway.

noncompetitive inhibitor

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis (Osmosis is the passive transport of water.)

Facilitated diffusion is a type of _____.

passive transport

When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will _____.

remain standing upright

What is the function of Structure E?

stabilization of the phospholipids

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

Structure A in the figure is a(n) _____.

transport protein

Structure B is a _____.

transport protein

Which of these is hydrophobic like the interior of the plasma membrane?

A Lipid soluble molecule

Which statement best describes phagocytosis?

A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.

In cells, what is usually the immediate source of energy for an endergonic reaction?

ATP (adenosine triphosphate); The hydrolysis of ATP provides the energy needed for an endergonic reaction.

Which of the following is an accurate comparison of active transport and facilitated diffusion?

Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.

B ... the diffusion gradient there is steeper

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?

Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site.

The reaction A --> B + C + heat is released in a(n) _____ reaction.

Exergonic Energy has been released.

The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance?

Oxygen and carbon dioxide

Which of these is ATP?

PPP Ribose A

Which of these statements is TRUE with regard to this animation?

Sodium and potassium ions are transported against their concentration gradients.

Which of the following is a typical feature of an ATP-driven active transport mechanism?

The solute moves against the concentration gradient.

Which of these is exhibiting kinetic energy?

a space station orbiting Earth

In this reaction AB+CD---->AC+BD

heat has been released to the environment

This cell is in a(n) _____ solution.

hypertonic

You know that this cell is in a(n) _____ solution because the cell _____.

hypotonic ... swelled

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

isotonic to its environment.

When an enzyme catalyzes a reaction,

it lowers the activation energy of the reaction.

Which of the following enables a cell to pick up and concentrate a specific kind of molecule?

receptor-mediated endocytosis

Enzymes work by _____.

reducing activation energy.

Structure A is a _____.

solute

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?

the difference in water concentration across a selectively permeable membrane

What controls the direction of a molecule, such as oxygen, involved in passive transport?

the direction of the oxygen concentration gradient. The direction material moves in passive transport is determined solely by the material's concentration gradient, with material diffusing from regions of higher concentration to regions of lower concentration.

Fill in

An enzyme is considered a(n) catalyst because it speeds up a chemical reaction without being used up. In a catalyzed reaction, a reactant is often called a(n) substrate . An enzyme is specific because the shape of its active site matches only particular reactants. An enzyme speeds up reactions by lowering the activation energy . The induced fit between an active site and its substrate often strains bonds and helps the reaction proceed. A(n) coenzyme , which is often a vitamin, binds to an enzyme and plays a role in catalysis. High temperatures or changes in pH can denature an enzyme, causing it to lose its shape and biological activity.

Kinetic energy differs from chemical energy in that

Kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules

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

Na+

A group of single cell organisms collected from the ocean was brought into the lab for examination. The lab assistant was concerned that the water had become full of toxic waste products and so added clean water to the culture. All of the organisms died, and when she looked at them under the microscope, all she could see were bits and pieces of them scattered throughout the water. What likely happened?

She added water that was hypotonic to the culture of organisms, and they ruptured.

Which of the following statements is true for all types of passive transport?

The concentration gradient is the driving force.

Fill in the blank

The ideal osmotic environment for an animal cell is a(n) isotonic environment. An animal cell placed in a(n) hypotonic solution will gain water, swell, and possibly burst. There is a net diffusion of water out of an animal cell when it is placed in a(n) hypertonic solution. The ideal osmotic environment for a plant cell is a(n) hypotonic environment. A plant cell placed in a(n) hypertonic solution will lose water and plasmolyze. A plant cell surrounded by a(n) isotonic solution will be flaccid (limp).

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

chemical energy into kinetic energy.

The reaction ADP + P --> ATP is a(n) _____ reaction.

endergonic Energy has been acquired from the surroundings.

The phosphorylation of ADP to form ATP is an _____ reaction that _____ energy.

endergonic ... requires an input of

This graph illustrates a(n) _____ reaction.

endergonic; The products contain more potential energy than the reactants.

Select the INCORRECT association.

exergonic ... uphill

A(n) _____ reaction occurs spontaneously.

exergonic; In exergonic reactions the products have less potential energy than the reactants.

The energy for an endergonic reaction comes from a(n) _____ reaction.

exergonic; The energy released by an exergonic reaction can be used to drive an endergonic reaction.

When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.

exergonic; endergonic

Which of these are by-products of cellular respiration?

heat and water

In the process of osmosis, water displays a net movement from an area of __________ water concentration to an area of __________ water concentration.

high to low

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

hydrolysis

When molecules move down their concentration gradient, they move from where they are----to where they are ---- Diffusion across a biological membrane is called---

less to more and passive transport

A white blood cell engulfing a bacterium is an example of _____.

phagocytosis

The transfer of a phosphate group to a molecule or compound is called

phosphorylation

Chemical energy is a form of _____ energy.

potential

Most enzymes are _____.

proteins

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

proteins.

Cells acquire low-density lipoproteins (LDLs) by

receptor mediated endocytosis

For an enzyme to catalyze a reaction there must be a specific fit between the __________ and the enzyme's __________.

substrate ... active site

The transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when _____.

the concentration of the solute is lower inside the cell than outside it

Plasma membranes are selectively permeable. This means that

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

In this reaction AB+CD---->AC+BD

the products have less potential energy than the reactants

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 is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

It is acquired by a reactant in an endergonic reaction.; By acquiring the phosphate group the reactant acquires energy.

Identify Structure D.

Phospholipid bilayer of membrane

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.

Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.

actively pump water back into their cells to counter its loss due to osmosis