Mastering Biology Chapter 5

Which of the following is a difference between active transport and facilitated diffusion?

Active transport requires the6 expenditure of cellular energy, and facilitated diffusion does not.

hypertonic

This cell is in a ________________solution??

a. exocytosis b faciltated diffusion c endocytosis d diffusion e active transport

Label the diagram vocabulary review membrane transport

Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.

The diverse proteins found in and attached to membranes perform many important functions. The diverse proteins found in and attached to membranes perform many important functions. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.

Lactase is essential for digesting lactose in milk. This enzyme is specific for this sugar. Why?

There is a precise compatibility between the active site and the lactose molecule.

hypertonic solution ... lost water

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

hypotonic-swelled

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

In this diagram of the plasma membranes of two adjoining cells, identify the protein indicated by the white arrow, including its function.

a receptor protein that binds with a signaling molecule and relays the message into the cell by activating other molecules inside the cell

Which of these is exhibiting kinetic energy? a space station orbiting Earth b an archer with a flexed bow c the high-energy phosphate bonds of a molecule of ATP d a person sitting on a couch while watching TV e a rock on a mountain ledge

a space station orbiting Earth

Use the graph and your knowledge of enzymes to identify the three true statements about enzymes. a By binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart. b Reactants cannot convert to products without an initial input of energy to start the reaction. c Chemical reactions cannot occur without enzymes. d Enzymes lower the overall energy input needed for a reaction to occur. e Only reactions that are controlled by enzymes require activation energy.

a,b,d

Certain molecules use facilitated diffusion to cross the plasma membrane. 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

An enzyme is specific because the shape of its ________________ matches only particular reactants.

active site

When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This molecule rapidly enters the cell regardless of whether its concentration is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?

active transport

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.

A(n) ______________ , which is often a vitamin, binds to an enzyme and plays a role in catalysis.

coenzyme

Azidothymidine (AZT) is an antiretroviral drug used in the treatment of HIV. It shares a structural similarity to a nucleotide. What might be the mode of action for this drug? feedback inhibition competitive inhibition ixed inhibition noncompetitive inhibition

competitive inhibition

High temperatures or changes in pH can _______________ an enzyme, causing it to lose its shape and biological activity.

denature

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via __________.

endocytosis

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.

Why doesn't the antibiotic penicillin harm humans?

human cells do not have cell walls

A plant cell placed in a(n) _______________ solution will lose water and plasmolyze.

hypertonic

There is a net diffusion of water out of an animal cell when it is placed in a(n) _________________solution.

hypertonic

The ideal osmotic environment for a plant cell is a(n) ______________________ environment

hypotonic

The ideal osmotic environment for an animal cell is a(n)___________________________environment

isontonic

A plant cell surrounded by a(n) ____________________solution will be flaccid (limp).

isotonic

When molecules move down their concentration gradient, they move from where they are _______________________ to where they are _______________________.

more concentrated, less concentrate

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

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 _____.

the diffusion gradient there is steeper

An animal cell placed in a(n) ______________solution will gain water, swell, and possibly burst.

hypotonic

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

phagocytosis

In the figure below, working from the inside out, what would be the order of components observed?

In the figure below, working from the inside out, what would be the order of components observed? A figure shows the water-filled bubble made of phospholipids. water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water

a side with lower concentration of square molecules b transport c energy input from the cell d plasma membrane e side with higher conecntration of square molecules

Label this active transport diagram

Diffusion across a biological membrane is called __________________________.

Passive transport

Facilitated diffusion is a type of _____.

Passive transport

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

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?

the similarity of the drug molecule to other molecules that are transported into the target cells

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

facilitated diffusion

Which of these are by-products of cellular respiration? ATP water heat and water ATP and water glucose and water

heat and water

An enzyme is considered a(n) __________________ because it speeds up a chemical reaction without being used up.

catalyst

Endocytosis moves materials _____ a cell via _____. A) into ... facilitated diffusion B) into ... a transport protein C) out of ... membranous vesicles D) into ... membranous vesicles E) out of ... diffusion

into ... membranous vesicles

Water crosses the plasma membrane

through facilitated diffusion or diffusion

exocytosis and endocytosis

Label the diagram

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

Osmosis is the passive transport of water.

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

Sodium and potassium ions are transported against their concentration gradients.

solute

Structure A is a _____.

transport protein

Structure B is _________

Taq polymerase is an enzyme isolated from the organism Thermophilus aquaticus. This organism has been found living in the hot springs of Yellowstone National Park. This enzyme is used to copy human DNA from crime scenes. Most reactions are performed at ranges similar to those of the human body; however, what considerations should be made for optimum use of this enzyme?

The temperature should be raised.

An enzyme speeds up reactions by lowering the __________________ .

activation energy

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

In a catalyzed reaction, a reactant is often called a(n) _______________

substrate

You can recognize the process of pinocytosis when ____

the cell is engulfing extracellular fluid** "cell drinking*

Aquaporins are proteins that facilitate the transport of _____________across the membrane.

water

Chemical energy is a form of _____ energy. kinetic motion entropic heat potential

potential

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

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP? cellular respiration potentiation digestion anabolism redox

cellular respiration

"Conservation of energy" refers to the fact that a. the net amount of disorder is always increasing b energy cannot be created or destroyed but can be converted from one form to another c if you conserve energy you will not be as tired the entropy of the universe is always increasing d no chemical reaction is 100 percent efficient

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

In active transport

Molecules move across the plasma membrane against their concentration gradient.

The _______________ between an active site and its substrate often strains bonds and helps the reaction proceed.

induced fit