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Cell fractionation is commonly used in biological research to

isolate organelles to examine their biological functions

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?
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whether or not the cell is partitioned by internal membranes

Which of the following correctly describes the pathway taken by a protein destined for secretion from an animal cell?

rough ER →→ transport vesicle →→ Golgi →→ transport vesicle →→ plasma membrane

Active and passive transport of solutes across a membrane typically differ in which of the following ways?

Active transport is always against the concentration gradient of the solute, whereas passive transport is always down the concentration gradient of the solute.

Which of the following molecules would you expect to diffuse through the lipid bilayer of a plasma membrane most rapidly?

O2

The solutions in the two arms of the U-tube shown in the figure are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels are equal, and the solution in side A is

isotonic to the solution in side B.

Which of the following statements about osmosis is correct?

The presence of aquaporins (proteins that form water channels in the membrane) speed up the process of osmosis

Submerging a red blood cell in distilled water will result in

lysis of the cell.

Why are there often so many steps between the original signal event and the cell's response?

Each step in a cascade produces a large number of activated products, causing signal amplification as the cascade progresses.

Why can a signaling molecule cause different responses in different cells?

The transduction process is unique to each cell type; to respond to a signal, different cells require only a similar membrane receptor.

The primary function of G proteins in signal transduction is

transmitting the signal from an activated receptor to the next protein in the pathway.

The primary function of kinases in signal transduction is to

activate protein kinases or other relay molecules in a series.

Which of the following is the greatest advantage of having multiple steps in a transduction pathway?

Having multiple steps provides for greater possible amplification of a signal.

What happens first when a phage infects a bacterial cell and is going to enter a lysogenic cycle?

Linear DNA circularizes.

Why is it ineffective to treat viral disease with antibiotics?

Antibiotics inhibit enzymes specific to bacteria and have no effect on virally encoded enzymes.

Which of the following is the correct sequence of events in the origin of life?

synthesis of organic molecules, synthesis of organic macromolecules, formation of protocells, formation of DNA-based genetic systems

Which of the following traits do archaeans and bacteria share?

presence of plasma membrane

What is a main difference between endotoxins and exotoxins?

Endotoxins are lipopolysaccharides and thus structurally integral to the bacterium, whereas exotoxins are proteins that are secreted by living bacteria.

In general, what is the primary ecological role of prokaryotes?

recycling soil nutrients and breaking down organic matter
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Which of the following is true of secondary endosymbiosis?

An organism containing an endosymbiont is engulfed by another organism and becomes an endosymbiont.

Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells?

the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts

A plant cell placed in a solution with a lower (more negative) water potential will \__________.

lose water and plasmolyze

A plant cell with a ψS of -0.65 MPa maintains a constant volume when bathed in a solution that has a ψS of -0.30 MPa and is in an open container. The cell has a \__________.

ψP of +0.35 MPa

Select the accurate statement about water potential.

Water in a turgid cell has positive pressure potential.

A plant cell is placed in distilled water, as shown in the figure. There is a net uptake of water by osmosis, causing the cell to become turgid. Select the correct statement about this setup, after the cell is fully turgid.

The water potentials (Ψ) of the cell and its surroundings are the same.

Which of the following determines the direction of water movement across the membrane?

a difference in water potential

If isolated plant cells with a water potential averaging -0.5 MPa are placed into a solution with a water potential of -0.3 MPa, which of the following would be the most likely outcome?

The pressure potential of the cells would increase.

The body fluids of an osmoconformer would be \________ with a \________ environment.

isoosmotic; saltwater

Compared to the seawater around them, most marine invertebrates are

isoosmotic

Osmoregulation and excretion are \__________.

mechanisms that maintain volume and composition of body fluids

Which statement about endotherms and ectotherms is correct?

Ectotherms are more abundant and diverse than endotherms.
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Select the correct statement about osmolarity.

Osmolarity measures the moles of solute per liter of solution.

Select the correct statement about osmoregulation.

All osmoconformers are marine animals.

In the process of cellular respiration, what is consumed, and what is produced?

Glucose is consumed, and carbon dioxide is produced.

In an oxidation-reduction reaction, how is the reducing agent changed?

It loses electrons and loses potential energy.

Which of the following describes the result of transferring an electron from a less electronegative atom to a more electronegative atom?

The more electronegative atom is reduced, and energy is released.

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the glucose molecule becomes

oxidized

Which chemical process generates the ATP produced in glycolysis?

substrate-level phosphorylation

Why are carbohydrates and fats considered high-energy foods?

They have a large number of electrons associated with hydrogen.

Which of the following describes the process of glycolysis?

It represents the first stage in the chemical oxidation of glucose by a cell.

Which of the following metabolic processes in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

glycolysis

In addition to ATP, what are the products of glycolysis?

NADH and pyruvate

Glycolysis results in a net production of which of the following molecules from each molecule of glucose?

2 NADH, 2 pyruvate, and 2 ATP

Which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

Yeast cells with defective mitochondria are incapable of cellular respiration. Catabolism of which of the following energy sources would allow these to grow?

glucose

Yeast cells grown anaerobically can obtain energy by fermentation, which results in the production of

ATP, CO2, and ethanol.

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?

to oxidize NADH to NAD+

A mutation in yeast knocks out the ability of cells to convert pyruvate to ethanol. How might this mutation affect these yeast cells?

The mutant yeast will be unable to grow anaerobically.

The nucleus of a nitrogen atom contains 8 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen?

The nitrogen atom has a mass number of 15 and an atomic number of 7.

Hydrogen bonding is most often seen \_____.

when hydrogen is covalently bonded to an electronegative atom

Which bond or interaction would be most difficult to disrupt when compounds are put into water?

covalent bond

Chemical equilibrium is described by which of the following statements?

Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

Which property of water allows a water strider to walk on water?

water's high surface tension

Which property of water allows a paper towel to pick up a puddle of water?

adhesion of water molecules to other kinds of molecules

If a salamander clings to surfaces through hydrogen bonds, it would have the most difficulty clinging to which of the following surfaces?

a surface coated with a thin film of vegetable oil

What is the carbonyl functional group?

C\=O

Which functional group shown in the figure is characteristic of alcohols?

-OH, hydroxyl

sufflhydral

SH

Which of the following statements about functional groups is TRUE?

Amino and carboxyl are functional groups.

Which of the following common chemical groups is hydrophobic?

methyl

A dehydration reaction is the process in which \__________.

water molecules are produced as a polymer is formed from monomers

Which of the following chemical equations describes a dehydration reaction?

monosaccharide + monosaccharide \= disaccharide + H2O

Why are hydrocarbons insoluble in water?

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

Dehydration reactions are responsible for the formation of which of the following?

triacylglycerols

Which of the following are purines?

guanine and adenine

A scientist suspects that food in an ecosystem may have been contaminated by radioactive nitrogen over a period of several months. Which of the following should be isolated from mammals living in the ecosystem and examined for radioactivity in order to test the hypothesis?

hair

Which component in the figure plays an important role in cell-cell recognition?

chloestreol

Which of the following best describes the structure of a biological membrane?

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?

Water will leave the cells, causing them to shrivel and collapse.

Select the statement that correctly distinguishes between relay proteins and second messengers in signal transduction pathways.

Signal transduction pathways are multistep pathways that include relay proteins and small, nonprotein, water-soluble molecules or ions called second messengers.

Anabolic pathways share which of the following characteristics?

They consume energy to synthesize polymers from monomers.

Which of the following reactions release energy?

hydrolysis reactions

Which of the following statements about the combustion of glucose with oxygen to form water and carbon dioxide (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is correct?

The entropy of the products is greater than the entropy of the reactants.

Which of the following statements about a system at chemical equilibrium is true?

The system can do no work.

Which of the following statements about ATP (adenosine triphosphate) is correct?

The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

Enzymes are described as catalysts, which means that they \__________.

increase the rate of a reaction without being consumed by the reaction

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

Nothing; the reaction will stay at equilibrium.

The Haber process is typically carried out at a temperature of approximately 500∘C∘C. What would happen to the rate of the forward reaction if the temperature were lowered to 100∘C∘C?

The reaction rate would decrease.

What would happen to the rate of the forward reaction if the concentration of nitrogen were decreased?

The reaction rate would decrease.

Which of the following would increase the rate of the reverse reaction?

increasing the concentration of ammonia

What will happen to the rates of the forward and reverse reactions when a catalyst is added?

Both forward and reverse rates increase.

How does an enzyme increase the rate of the chemical reaction it catalyzes?

An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes.

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation?

The compound is a competitive inhibitor.

What makes the kink in an unsaturated fat?

Double bonding of the carbon

ionic bond

a bond where electrons are transferred from one atom to another

covalent bond

bond where electrons are shared

hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom.

peptide bond

bond between polymers

adhesion

attraction between molecules of different substances

Cohesion

Attraction between molecules of the same substance

capillary action

tendency of water to rise in a thin tube

Transpiration

Evaporation of water from the leaves of a plant

Osmosis

Diffusion of water through a selectively permeable membrane

water potential

the potential energy of a volume of water, expressed as a pressure

water potential equation

Ψ \= Ψs + Ψp

carbohydrate monomer

monosaccharide

lipid monomer

glycerol and fatty acids

protein monomer

amino acids

nucleic acid monomer

nucleotide