Mastering Bio exam two

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

isotonic

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

isotonic

A scientist wants to study the enzymes of the citric acid cycle in eukaryotic cells. What part of the cell would she use as a source of these enzymes?

mitochondrial matrix

What organelle is indicated by the letter C?

mitochondrion

In active transport,

molecules move across the plasma membrane against their concentration gradient.

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.

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.

When molecules move down their concentration gradient, they move from where they _______ are to where they are _______. Diffusion across a biological membrane is called_____ .

more concentrated, less concentrated, 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

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

osmosis

In cellular respiration, glucose becomes_____ to carbon dioxide (CO2) as it loses electrons (in hydrogen atoms).

oxidized

NADH delivers electrons to an electron transport chain, which passes the electrons through carrier molecules in a series of redox reactions to the final electron acceptor,

oxygen

What molecule is indicated by the letter D?

oxygen Oxygen is the final electron acceptor of cellular respiration.

Facilitated diffusion is a type of _____.

passive transport

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

phagocytosis

What process occurs in structure H?

photosynthesis Chloroplasts are the sites of photosynthesis.

Chemical energy is a form of _____ energy.

potential 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 eukaryotes, most of the high-energy electrons released from glucose by cellular respiration __________.

reduce NAD+ to NADH, which then delivers them to the electron transport chain

. In cellular respiration, oxygen becomes ______ to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose.

reduced

Structure A is a _____.

solute

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

substrate

How many NADH are produced by glycolysis?

Two NADH molecules are produced by glycolysis.

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

In glycolysis there is a net gain of _____ ATP.

2 It takes 2 ATP to produce 4 ATP.

In glycolysis, ATP molecules are produced by _____.

A phosphate group is transferred from glyceraldehyde phosphate to ADP.

In glycolysis, what starts the process of glucose breakdown?

ATP

The energy released from the redox reactions in the electron transport chain is used by the cell to make

ATP

Which energy-rich molecule produced by cellular respiration directly powers cell work?

ATP

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

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

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

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

Which of these is NOT a product of glycolysis?

FADH2 (It is a product of the citric acid cycle.)

Why doesn't the antibiotic penicillin harm humans?

Human cells do not have cell walls.

Given the relatively modest number of calories burned by anything but the most vigorous activities, why can people consume over 2,000 kilocalories a day, yet maintain a healthy body weight?

Most of the energy consumed in food is spent maintaining the body's functions, so only a fraction of food energy needs to be burned in exercise.

In cellular respiration, organic molecules become oxidized as picks up electrons and H+and becomes reduced to NADH.

NAD+

An enzyme speeds up reactions by lowering the

activation energy

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

active sites

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

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

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

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

Sodium and potassium ions are transported against their concentration gradients.

In an experiment, mice were fed glucose (C6H12O6) containing a small amount of radioactive carbon. The mice were closely monitored, and in a few minutes, radioactive carbon atoms showed up in __________.

carbon dioxide

What molecules belong in spaces E and F?

carbon dioxide and water

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

catalyst

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

cellular respiration

The O2 required for __________ is supplied by __________.

cellular respiration ... breathing

Most NADH molecules generated during cellular respiration are produced during __________.

citric acid cycle

What process occurs within Box B?

citric acid cycle

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?

competitive inhibition

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

denature

The transfer of _______ from one molecule to another is an oxidation-reduction reaction, or redox reaction.

electrons

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.

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

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

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

1) Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. 2) The diverse proteins found in and attached to membranes perform many important functions. 3)The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.

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.

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 the following molecules is broken down in cellular respiration, providing fuel for the cell?

glucose

What molecules belong in space A and B?

glucose and oxygen (Photosynthesis produces glucose and releases oxygen into the atmosphere)

In the equation shown below, during cellular respiration __________ is oxidized and __________ is reduced.

glucose.....oxygen

What process occurs in Box A?

glycolysis, Glycolysis occurs in the cytosol.

Which of these are by-products of cellular respiration?

heat and water

Water crosses the plasma membrane

hrough facilitated diffusion or diffusion.

A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to treat people with bacterial infections. However, he can't do this because _____.

human cells also perform glycolysis; the drug might also poison them

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

This cell is in a(n) _____ solution.

hypertonic (greater amount outside of cell)

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

hypertonic ... lost water

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

hypotonic

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

hypotonic

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

hypotonic ... swelled

Structure B is a _____.

transport protein

Aquaporins are proteins that facilitate the transport of __________ across the membrane.

water

We inhale O2 and we exhale CO2. Carbon dioxide is produced __________.

in the reaction that creates acetyl CoA (coenzyme A) from pyruvate

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

induced fit

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

water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles