Mastering Biology Chapter 5 Homework

Calories are units of __________.

energy _______________________________________________________________________________ A calorie is the amount of energy required to increase the temperature of 1 gram of water by 1 degree C. Calories can refer to any type of energy, not just heat.

Activation energy can be described as __________.

energy that must be invested to start a reaction ------------------------------ For a chemical reaction to begin, chemical bonds in the reactant molecules must be broken, and this process requires that the molecules absorb energy from their surroundings.

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

1. The ideal osmotic environment for an animal cell is a(n) environment. 2. An animal cell placed in a(n) solution will gain water, swell, and possibly burst. 3. There is a net diffusion of water out of an animal cell when it is placed in a(n) solution. 4. The ideal osmotic environment for a plant cell is a(n) environment. 5. A plant cell placed in a(n) solution will lose water and plasmolyze. 6. A plant cell surrounded by a(n) solution will be flaccid (limp).

1) isotonic 2) hypotonic 3) hypertonic 4) hypotonic 5) hypertonic 6) isotonic

Cells use this molecule to store the chemical energy released by the breakdown of food molecules during cellular respiration.

ATP ______________________________________ A molecule called ATP is responsible for fueling most energy-requiring reactions in cells.

Can you match the processes involved in membrane transport to their descriptions? ------------------------------- Vocabulary review Drag the labels onto the chart to match each process with its description.

Exocytosis Facilitated Diffusion Endocytosis Diffusion Active Transport

Some large molecules move into or out of cells by exocytosis or endocytosis. ------------------------------- Exocytosis and endocytosis Drag the correct label under each diagram.

Exocytosis endocytosis

Which of the following is an example of potential energy?

a bowling ball placed on the top shelf of a closet _______________________________________________________________________________Lifting the bowling ball into place required energy, which is now stored in the ball because of its location. Thus, this is an example of potential energy.

"The use of energy to move molecules across a membrane" is the definition of __________.

active transport ------------------------------ Cellular energy is used to drive a transport protein that pumps a solute against a gradient.

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of

active transport. ----------------- The sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. This requires energy and is an example of active transport.

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of

endocytosis ----------------- In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

In osmosis, water moves across a selectively permeable membrane toward the __________ solution; that is, toward the solution with the __________ solute concentration.

hypertonic ... greater ------------------------------ There will be a net movement of water by osmosis from the hypotonic solution toward the hypertonic solution.

In active transport,

molecules move across the plasma membrane against their concentration gradient. ----------------- Molecules move against their concentration gradient in active transport.

Which one of the following terms is sometimes called "cell eating"?

phagocytosis ------------------------------ In phagocytosis, a cell engulfs a particle and packages it within a food vacuole.

Water crosses the plasma membrane

through facilitated diffusion or diffusion. ----------------- Water can cross the plasma membrane through the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.

What are the components of a molecule of ATP?

an organic molecule called adenosine plus three phosphate groups ------------------------------ This is the primary structure of adenosine triphosphate.

Entropy means that __________.

the quantity of usable energy declines with each energy transformation _______________________________________________________________________________In almost all situations, a significant percentage of the energy involved in a transformation is converted to heat.

ATP drives work in cells by __________.

transferring its phosphate group to other cell molecules ----------------- Addition of a phosphate group from ATP can energize other molecules to help the cell perform work. Return to Assignment

Certain molecules cross the plasma membrane through the process of active transport. Active transport requires an input of energy and moves molecules against their concentration gradient. ------------------------------- Drag the labels to their appropriate locations on the diagram.

A) Side with lower concentration of square molecules B) Transport protein C) Energy input from the cell D) Plasma membrane E) Side with higher concentration of square molecules

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

facilitated diffusion. ----------------- In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.

Use the graph and your knowledge of enzymes to identify the three true statements about enzymes.

1) Enzymes lower the overall energy input needed for a reaction to occur. 2) Reactants cannot convert to products without an initial input of energy to start the reaction. 3) By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart. _____________________________________________________________________________ For a chemical reaction to begin, chemical bonds in the reactant molecules must be broken. This process requires that the molecules absorb energy from their surroundings. The energy that must be invested to start a reaction is called activation energy because it activates the reactants and triggers the chemical reaction. Enzymes enable metabolism to occur by reducing the amount of activation energy required to break the bonds of reactant molecules.

Certain molecules use facilitated diffusion to cross the plasma membrane. ------------------------------- Facilitated diffusion Drag the labels to their appropriate locations on the diagram.

A) plasma membrane B) side with higher concentration of molecules C) side with lower concentration of molecules D) facilitated diffusion causes a net movement of molecules down their concentration gradient E) transport protein

Certain molecules use diffusion to cross the plasma membrane. ---------------------------------------------- Diffusion Drag the labels to their appropriate locations on the diagram.

A) side with higher concentration of molecules B) plasma membrane C) side with lower concentration of molecules D) diffusion causes a net movement of molecules down their concentration gradient.

Certain molecules cross the plasma membrane through the process of active transport. Active transport requires an input of energy and moves molecules against their concentration gradient. ---------------------------------------------- Drag the labels to their appropriate locations on the diagram.

A) side with lower concentration of square molecules B) transport protein C) energy input from the cell D) plasma membrane E) side with high concentration square molecules

Which one of the following is an example of osmosis?

Water enters a plant by passing through the root cell membranes. ------------------------------ The passive transport of water across a selectively permeable membrane is called osmosis.

Molecules of food have a form of potential energy called __________.

chemical energy _______________________________________________________________________________Food molecules contain energy in the arrangement of atoms.