Exam 1 Quiz Questions

How are temperature and fluidity of the cell membrane related?

Across a broad temperature range, fluidity of the cell membrane decreases as temperature decreases.

Why does the cell membrane's fluidity change with its composition?

? Don't know the right answer, can be: A) The non-covalent interactions between the molecules that make up the cell membrane change B) The cell membrane becomes more or less permeable to water, depending on its composition. C) Depending on its composition, the cell membrane's ability to absorb fluids into its structure changes.

Which of the following changes would make a cell membrane more fluid?

? Can be: A) Decrease the degree of unsaturation in the fatty acids in its phospholipids. B) Lower the temperature. C) Lower the cholesterol content in the cell membrane.

A species of fish spends part of its life cycle under conditions of moderate temperatures and part of its life cycle under extremely cold conditions. What change in the cell membranes of this fish might be expected to occur as conditions shift from moderate to extremely cold temperatures?

The fish's cells would slow production of cholesterol and increase production of unsaturated, short chain fatty acids.

Increased synthesis of phosphodiesterase would lead to

decreased concentration of cyclic AMP.

How could you distinguish between a signal transduction pathway that leads to an alteration in gene expression and a pathway that leads to an alteration in enzyme activity?

Look at the timing of the cellular response to signal molecules to determine whether the response is very fast or relatively slow.

If a person is being treated for shock and receives an injection of epinephrine to aid recovery, you would not expect to see

increased conversion of cAMP to ATP in liver cells.

(Fig 1)
The figure above shows the signal transduction pathway initiated by the binding of an odorant molecule to an olfactory receptor of an olfactory neuron in the human nose. Information will be sent to the brain because of changes in ion concentrations within the neuron. What specific event is most directly responsible for the change in intracellular ion concentrations?

cAMP binding to its gated channel

Phosphodiesterase is the enzyme that catalyzes the degradation of cAMP in cells. Phosphodiesterase inhibitors have been synthesized and used as drugs in the treatment of several human diseases and disorders. Based on the role of cAMP in the signal transduction pathway shown above, you would expect these drugs to

?: A) slow epinephrine's activity to produce the same amount of glucose over a longer period of time. B) enhance the effects of epinephrine to shift the production of glucose to increased amounts. C) replace the effects of epinephrine to maintain a steady balance of glucose. D)speed up epinephrine's activity to produce the same amount of glucose over a shorter time.

The process of random movement of molecules toward a state of equilibrium is called _______.

diffusion

A solution in which the solute molecules are uniformly distributed is said to be at _______.

equilibrium

The effectiveness of many anesthetics in reducing feeling or sensation is directly related to their___

Solubility in membrane lipids

The ability of membranes to allow some substances to pass through, but not others, is called _______.

selective permeability

Primary active transport involves the direct hydrolysis of _______.

ATP

Any transport of a relatively small uncharged molecule down its concentration gradient, either through the phospholipid bilayer or through a protein will be:

passive transport

The glucose transporter is a _______ protein that allows glucose to enter the cell at a faster rate than would be possible by simple diffusion.

carrier

One reason cancer therapy often fails is that the targeted cells become resistant to the drugs that are supposed to kill them. Which of the following is the most likely mechanism of this resistance?

Membrane proteins actively transport the drugs out of the cancer cells.

Which statement about ligands and receptors is true?

For most ligand-receptor complexes, binding is favored. Ligand-receptor interactions are reversible. Many drugs that alter human behavior prevent the binding of receptors' specific ligands. Ligand-receptor interactions often induce conformational changes in membrane channels.

Which process does not involve the uptake of materials into the cell?

Which process does not involve the uptake of materials into the cell?

You are doing a summer internship in a cell biology lab. Your supervisor asks you to change the medium on some cells she is growing. You do so and then examine the cells under a microscope. To your dismay, you can't find any cells and see only what looks like cell debris. What most likely happened to your cells and why?

The cells burst because the new medium was hypotonic to the cells.

Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?

Cyclic AMP

Many signal transduction pathways cause

alterations in gene expression. upregulation of genes. the switching off of genes. an alteration of the abundance of enzymes.

Plant cells transport sucrose across the vacuole membrane against its concentration gradient by a process known as

active transport

Vitamin A is a relatively small, lipid-soluble molecule that can behave as a hormone. Most likely its receptor

is not connected to the cell membrane.

Which of the following is the driving force for active transport?

ATP hydrolysis

Which statement does not correctly describe the processes by which materials are taken up by the cell?

Vesicles touch the cell membrane and release their contents through a pore.

ncreased synthesis of phosphodiesterase would lead to

decreased concentration of cyclic AMP.

How do the cell membranes of a hibernating animal change in colder temperatures?

Unsaturated fatty acids make up more of the lipid composition.

Which statement about peripheral membrane proteins is true?
A) They have hydrophobic regions within the lipid portion of the bilayer.
B) They have hydrophilic regions that protrude in aqueous environments on both sides of the membrane.
C) They frequently flip from one side of the bilayer to the other.
D) They control the rate of simple diffusion.
E) Their polar regions interact with complementary regions of integral membrane proteins.

E) Their polar regions interact with complementary regions of integral membrane proteins.

After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters

an effector protein.

What is the membrane property that helps ensure the diffusion of glucose into a cell that has a high energy need?

A high number of carrier proteins specific for glucose

. Phagocytosis refers to

the specific import of relatively large particles

A benefit of the many steps involved in a protein kinase cascade is that they allow for

activation or inhibition of many enzymes. amplification of the signal. distribution of the signal throughout the inside of the cell. variation in the response.

A protein that forms an ion channel through a membrane is most likely

a transmembrane protein.

True or False? Protein kinase receptors are a type of cytoplasmic receptor.

False

True or False? Simple diffusion depends upon specific carrier proteins.

False

Which one of the following reactions is not an oxidation-reduction reaction?

R—CH=CH—CH3 + H2O ↔ RCH2—CH(OH)—CH3

Which of the following statements about ATP is false?

The phosphate bond energy of ATP is used to power catabolic metabolism.

The mitochondrial electron transport chain

oxidizes the intermediate electron carriers, NADH and FADH2.

In green plant photosynthesis, water (H2O) is

oxidized to oxygen gas (O2) in the light.

Fermentation

results in the formation of lactic acid or ethanol.

In photosynthesis, NADPH is used for the

reduction of 3-phosphoglycerate (3PG).

Glycolysis

is an oxidation-reduction process.

Cyanide inhibits the enzyme (cytochrome C oxidase) in the mitochondrial electron transport chain that reduces O2 to water; i.e., O2 cannot be used in glucose catabolism. Suppose that you add cyanide to a suspension of muscle cells from a rat. Which statement given below is the most accurate with respect to the effects of cyanide on glucose catabolism?

The citric acid cycle would be inhibited, but glycolysis would not; and lactic acid would accumulate.

The immediate source of energy for ATP synthesis in chloroplasts is

the electrochemical proton gradient.

In the complete oxidation of glucose, 6 CO2 molecules are formed per glucose molecule oxidized. The numbers of CO2 molecules per molecule of glucose that is released during glycolysis is _____ , during pyruvate oxidation is ________ , and during the citric acid cycle is ______ .

0;2;4

The mitochondrial ATP synthase

makes ATP at the expense of the proton gradient established by electron transport.

The major product of photosynthesis that is exported from the leaves to the rest of the plant is

sucrose

The conversion of malate to oxaloacetate in the citric acid cycle takes place with the conversion of NAD+ to NADH. In this reaction, NAD+ is

both b and c. (the oxidizing agent. reduced to NADH. )

The ultimate source of energy for ATP synthesis in chloroplasts is

light

Triglycerides are major energy storage molecules. Which statement about the complete oxidation of triglycerides to CO2 and water, and the oxidation of glucose to two molecules of pyruvate is correct?

Glucose oxidation to pyruvate and triglyceride oxidation use glycolysis.

Which statement given below best characterizes the properties of a photosystem?

A photosystem is a complex of pigments, proteins, and reaction center chlorophyll.

Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should over the short term

inhibit mitochondrial ATP synthesis.

Which of the statements below about the citric acid cycle is false?

The cycle releases less energy than glycolysis.

To be metabolized, glucose first must be converted to glucose 6-phosphate. This _______________ ATP, and thus this step is ______________. Overall glycolysis is ________________ , and _______________ ATP, and NADH.

consumes; endergonic; exergonic; produces

The end products of glycolysis are

pyruvate, ATP, and NADH.

The following is an example of a(n) ______________. Male frog eggs exposed to 0.1ppb of atrazine will have abnormal testes.

experimental prediction

Which of the following processes is not dependent on interactions of plants with other organisms (including other plants)?
Obtaining nutrients, Producing fertile seeds , Dispersing seeds, Regulating the internal environment, or Competing for water

regulating the internal environment

A community differs from a population in that:

a community consists of many species.

T or F? Histograms are a useful way to visualize categorical data

True

T or F? Continuous data cannot be shown using a histogram or pie chart

False

T or F? Scatterplots are useful for showing the relationship between two continuous variables

True

T or F? All graphs should have axes, captions, and units clearly labeled.

True

T or F? Frequency distributions can be shown using a bar chart, histogram, or pie chart.

True

____________ explanations consider the immediate genetic, or physiological processes that explain an organism possessing a trait.

Proximate

The advantage of controlled experiments is that

all variables are held constant except for one.

Scientists observed that frogs with expanded toe pads live in trees, not in water. They stated "expanded toe pads are an adaptation to life in trees." This statement is an example of a(n)

hypothesis

A scientific theory, such evolution or gravity, is a body of scientific work that

has been rigorously tested and is testable. results from the understanding of several related processes. provides an explanatory framework for observations. could be refutable with sufficient evidence.

What cannot increase the power of a statistical test?

Selecting a higher a-value

Suppose we are interested in whether or not dung beetles are a major (i.e., greater than 50%) prey item for a local population of Mediterranean House Geckos. You initially collect 5 geckos and induce them to vomit so you can examine their stomach contents. You find that 4 have beetle bits in their stomachs, indicating beetles are a major component (80%) of the gecko diet. Later you expand your sample to 25 and find that only 10 have eaten beetles, indicating that beetles are not a major component (40%) of the gecko diet. Select the truest statement below given this scenario.

The results of the first sample (5 geckos) were a false positive.

____________________ variables have a natural ordering to them.

Ordinal

Earth is approximately _______ years old.

4-5 billion

An organism

may be one or more cells. is either a prokaryote or a eukaryote. can do biological work. contains genetic information.

Organisms that produced oxygen gas in the early Earth's atmosphere paved the way for a new type of metabolism used by larger organisms, and this new type of metabolism is called _______ metabolism.

aerobic

Of the characteristics that all of life share, viruses

have genetic material that can mutate

Recently, ____________ data has greatly contributed to our understanding of the evolutionary relationships between living organisms.

genomic

Scientists use statistics because it helps us

avoid drawing the wrong conclusions. describe patterns in data. determine if a pattern could have occurred by chance alone. plan our experiments and comparisons.

All cells in a multicellular organism

contain the same genome

The P-value

is mathematically calculated from a statistical test.

Positive feedback occurs when a product of a system

accelerates an earlier process in the system.

In the scientific method, a hypothesis

is the basis for making predictions

What are the molecules that govern the chemical reactions within a cell?

proteins

Oceans were a good environment for early organisms because they

shielded organisms from ultraviolet light

Genomes are

the sum of genetic information in a cell

Scientific explanations for a natural phenomenon

are testable and have the potential to be refuted by experiments

In terms organization, the order of parts of a multicellular organism is

molecule, cell, tissue, organ, organ system

a cell

is the fundamental unit of life

two samples with the same range

will likely have different standard deviations

The main purpose of any single experiment is to

test a prediction that is based on a hypothesis

A biologist hypothesizes that the sounds made by lions at night in the Serengeti are territoriality calls and predicts that two lions inhabiting the same territory will roar even louder. She selects an area inhabited by one lion, records its calls, and plays them back in the same area. She records her observations, and notes that the lion does indeed roar more often as a result of this experiment. What would be the next step in the hypothesis-prediction method?

asking new questions

A scientist walking by a pristine stream, and then a polluted pond below a mill, observes that fish are present in the stream but not in the pond. The scientist then says, "polluted water kills fish." This statement is an example of

a hypothesis

A statistical test starts with

a null hypothesis

What is a null hypothesis?

A prediction about what will happen to a control group

A comparative experiment

starts with the prediction that there will be a difference between groups or samples

Scientific explanations for a natural phenomenon

are based on reproducible and quantifiable observations

Many possible applications of scientific knowledge raise ethical issues for some people. Which application, however, would be rejected by all responsible scientists?

using scientific knowledge to dictate how the world ought to be

a scientific hypothesis

is based on observations

The binding of a substrate to an enzyme

may involve hydrogen bonds and van der Waals interactions

For a covalent bond to be polar, the two atoms that form the bond must have

different electronegativities

Quaternary structure of proteins refers to

the number and king of polypeptide subunits the protein has

The reactivity of an atom arises primarily from the

existence of unpaired electrons in the outermost shell

Which interactin between atoms is the strongest?

Covalent bonds

An element that contains ten protons and ten electrons is likely to

be chemically inert (stable)

Oils and Fats

are triglycerides

Complementary base pairing

takes place between purine and pyrimidine bases

Physical properties of water that benefit life?

Cohesiveness, high heat capacity, high heat of evaporation, and hydrogen bonds

The synthesis of complex molecules _______ energy, whereas their degradation _______ energy. Synthesis occurs with _______ in entropy.

requires; releases; a decrease

If rainbow trout were transferred from warm water to near freezing water (2°C), what changes in the trout would occur in the trout's nervous system in the colder water?

The trout would produce a new isozyme of acetylcholinesterase that has a lower optimal temperature, allowing the fish's nervous system to perform normally in the colder water.

Nucleotides

are the monomers of DNA and RNA

DNA differs from RNA in that DNA

contains deoxyribose

DNA with a higher G + C content is more stable at high temperatures than DNA with a high A + T content. Why?

G and C form three hydrogen bonds between antiparallel strands and A and T, just two

A yeast is cultured in the presence of radioactive phosphate, and the following biological molecules are purified. Which molecule should be most radioactive?

RNA

Replication, transcription, and translation

refer to RNA synthesis, DNA synthesis, and protein synthesis, respectively

T or F? The properties of starch are very similar to those of cellulose

False

Table salt, NaCl, is neutral. When dissolved in water, NaCl

separates to form Na+ and Cl- ions that interact with water molecules

Covalent bond formation depends on the ability of atoms to

share electrons with other atoms

The "building blocks" of polysaccharides are _______, and the blocks are covalently linked together by _______.

monosaccharides; glycosidic linkages

Fatty acids are

carboxylic acids with long hydrocarbon tails

Replication is the synthesis of _______ and transcription is the synthesis of _______.

an exact copy of DNA; an RNA copy of DNA

A competitive inhibitor of an enzyme-catalyzed reaction

is usually structurally similar to the substrate

In a reaction catalyzed by an enzyme,

the enzyme does not affect the equilibrium constant for the reaction

Enzymes

may be subject to feedback inhibition

Entropy

is related to the disorder or randomness of a system

Noncovalent binding of a substrate to the active site of an enzyme is

reversible

Enzymes are highly sensitive to pH and temperature because

changes in temperature and pH readily break their hydrogen bonds and can alter the enzyme shape.

he addition of the competitive inhibitor mevinolin slows the reaction HMG-CoA -> mevalonate, which is catalyzed by the enzyme HMG-CoA reductase. The effects of mevinolin would be overcome and the rate of the reaction increased by

adding more HMG-CoA

Which type of inhibitor can be overcome by the addition of more substrate?

Competitive

How to competitive and noncompetitive enzyme inhibitors differ?

Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors may change the shape of the active site

In the biosynthetic pathway for folic acid, the compound PABA is the normal substrate for an enzyme in the pathway. The antibiotic sulfanilamide is very similar in structure to PABA and will act as a(n) _______ of the enzyme that acts on PABA.

competitive inhibitor

The rate of a chemical reaction in a cell is the measure of how

quickly the substrates are converted to product

When an egg is exposed to extreme heat it turns from a liquid substance into a solid substance. Even when the egg is allowed to cool, these changes are not reversible for a number of reasons. Which is not one of those reasons?

Fats in the egg have become saturated and less fluid

The Quaternary structure of a protein

consists of exactly four subunits, hence the name Quarternary

Lipids are

- insoluble in water - important for energy storage - hydrophobic - important constituents of biological membranes

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

The activation energy of the reaction is high

What type of amino acid side chains would you expect to find on the surface of a protein embedded in the lipid-rich environment of a cell membrane?

Hydrophobic

An atom with _____ has an atomic mass of 14.

7 neutrons and 7 protons

What accounts for the stability of the double-stranded DNA molecule?

The hydrogen bonds between purines and pyrimidines

Which characteristic allows cells to control their internal environment?

Their ability to control the synthesis of an enzyme and the activity of an enzyme

Which condition or component was not likely to have been present on Earth during the formation of the first biologically relevant molecules?

High atmospheric oxygen levels

T or F? Condensation reactions consume water as a reactant.

False

How does the second law of thermodynamics apply to organisms?

The potential energy of chemical bonds can be converted to kinetic energy

You have duplicated the threonine to isoleucine metabolic pathway and want to determine the saturation level of threonine. You slowly add increasing amounts of threonine and observe that the reaction rate initially increases slowly and then decreases. You also note that increasing the amount of isoleucine decreases the rate of the reaction. You determine that the pathway is thus regulated by

feedback inhibition

Some proteins that are on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by _______ and the sugars added in the _______.

Rough ER; GA

The extracellular matrix of animal cells

is involved in chemical signaling between cells, helps filter materials passing between tissues, contains proteglycans, and contains collagen

Amoeba proteus is injected with a drug that inhibits the formation of microtubules. What effect does this have on the organism's movement?

It continues to move with no effect

The presence of ___________ means that substances must pass through, rather than between, the epithelial cells that form the lining of the small intestine.

tight junctions

The endomembrane system

includes the GA and the ER

Which structure occupies the largest volume in a mature plant cell?

the vacuole

Nucleic acids are not found in

plant vacoules

Prokarytes

are surrounded by a plasma membrane

Cilia and eukaryotic flagella

must have a motor protein that uses the energy of ATP hydrolysis to power movement.

Liver cells are exposed to radioactive amino acids; all proteins synthesized during this time are radioactive. The cells are then removed at 5-minute intervals and fractionated. Where in the cells is the radioactively labeled enzyme lipase performing its intracellular digestion?

In lysosomes

Cells are the _____________ unit of life, and the principles that underlie the structure and function of a bacterial cell are ________________ to those governing the cells in a human body.

fundamental; similar

Which of the following is not an important role served by the cell membrane?

Carbohydrates protruding from it allow binding and adhering to adjacent cells

The organelles and biomolecules present in homogenized cells can be separated by centrifugation. Which of the following would be found at the top of a centrifugation gradient?

ATP molecules

Which of the following proteins powers the movement of both cilia and vesicles within a cell?

Dyein

Which of the following organelles is involved in energy conversions?

Chloroplasts

Which of the following organelles are found only in plants?

Glyoxysomes

The proteins that make up the cytoskeleton of bacteria are similar to _______ in eukaryotic cells.

actin

Which of the following structures is directly involved with the movement of organelles within a cell?

Microtubules

Plastids are

present in nearly all plant cells

T or F? The nucleus is the site of protein synthesis

False

Lysosomes are important to eukaryotic cells because they contain

digestive enzymes

A secondary lysosome

is used to break down macromolecules through hydrolysis

In autophagy

lysosomes engulf cell components and digest them

The substances that enter the GA arrive packaged within __________ from the ____________.

vesicles; rough ER

The movement of the proteins through the GA is _____ to _______ to _______.

cis, medial, trans

What happens to proteins as they pass through the Golgi apparatus?

proteins are modified by having carbohydrates attached or removed

Besides the proteins being processed for distribution, what other components could be expected to be found inside the GA?

Enzymes

If you had a problem with your heart whereby signals were not being conducted adequately through the heart muscle, which structures would likely be a cause for this malfunction?

Gap junctions

A prokaryotic cell has _______ but does not have _______.

DNA; membrane-bound organelles

Example of a motor protein

kinesin

The cell membrane

helps maintain a constant internal environment

If a cell lacked ribosomes, it would not be able to

make proteins

Which structure(s) is/are involved with maintaining the position of organelles within a cell?

intermediate filaments

A protein that is meant to be exported from the cell is synthesized by ribosomes

on the rough endoplasmic reticulum

You find a previously unknown single-celled organism in a water sample. While studying it, you find that the organism is photosynthetic and has a cell membrane surrounded by a layer of peptidoglycan (carbohydrates linked to peptides). The organism contains DNA and RNA, but you see no nuclear membrane. This organism most likely belongs to which group?

Bacteria

Plants are able to distribute hormones and nutrients to neighboring cells through _______; in animal tissues _______ has/have a similar function.

cell membrane-lined channels extending through the cell wall; gap junctions

Which organelle is generated by the cell membrane and contains macromolecules?

Phagosome

After a protein is made, what is one of the ways in which it can get to a specific location in a cell?

A carbohydrate group is added in the RER that tags the protein for a specific location

Prokaryotic cells generally are smaller than eukaryotic cells. Which of the following is the most likely explanation for this difference?

Eukaryotes have compartmentalization, which allows them to be structurally and functionally more complex.

If a cell needed to increase its surface area without changing its volume in order to carry out cellular processes more efficiently, it could do this most effectively

by creating deep invaginations in the cell membrane

If you forget to water a potted plant, its leaves wilt. A likely reason for this wiliting is that

vacuoles lose water, reducing the turgor pressure in the cells.

Which organelle contains special enzymes to safely break down toxic by-products of oxidation?

Peroxisome

Suppose the concentration of epinephrine in the blood stream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.

decrease; adenylyl cyclase; decrease

Phospholipids spontaneously form bilayer structures, but oils form small droplets. Why do oils not form bilayers?

Oils do not have the polar head group that phospholipids have.

Hormones are chemical signals that

are circulating signals, and bind to the receptors of distant cells.

In facilitated diffusion

specific integral membrane proteins mediate transport along the concentration gradient.

What would happen if a suspension of red blood cells, in an isotonic NaCl solution, was suddenly diluted with pure water by a factor of 10?

The cells would swell and lyse (burst).

Receptor-mediated endocytosis

sults in the formation of clathrin-coated vesicles.

Adenylyl cyclase

makes cAMP from ATP with the liberation of pyrophosphate (PPi).

The activation of a receptor by a signal, and the subsequent transduction and amplification of a signal, can lead to

downregulation of a specific enzyme. upregulation of a specific gene. changes in the electrical potential across the cellular membrane. changes in the function of brain cells.

In animals, cell recognition

involves proteins in plasma membranes.

The phosphorylation of proteins by ATP

is catalyzed by enzymes known as "protein kinases."

he sodium-potassium pump (or Na+-K+ pump)

results in the formation of Na+ concentration gradient across the plasma membrane.

A universal feature of receptors is that they

undergo structural (shape) changes when the signal molecule is bound.

Chemical signal transduction pathways

involve binding of the signal molecule to receptors.

In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.

carbohydrates; glycoproteins; glycolipids

Caffeine

binds to a receptor on nerve cells in the brain.

T or F? Hydrophilic regions of integral membrane proteins are in contact witht the interior of the bilayer

false

Osmosis is

the movement of water across membranes

T or F? cAMP binds noncovalently to protein kinase A, and changes shape of the protein.

True

T or F? Both receptors and enzymes may be integral membrane proteins.

True

What processes of cellular respiration occur in the mitochondrial matrix?

Pyruvate oxidation and citric acid cycle

What would happen to pyruvate is O2 is not present?

will enter a fermentation pathway to produce NAD+ to keep the CAC going

In the electron transport/ATP synthesis in mitochondria, what is the immediate source of electrons for the electron transport chain?

NADH and FADH2

Why is oxygen so important to electron transport chain in ATP synthesis?

It acts as the final elecctron acceptor

If excessive ATP begins to accumulate, which enzymes are inhibited?

Phosphofructokinase, citrate synthase, isocitrate dehydrogenase, citrate synthase and isocitrate dehydrogenase

ADP or AMP activates which enzyme?

Phosphofructokinase

The oxygen produces by photosynthesis comes from

water

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide. Most of the carbon dioxide comes from

citric acid cycle

The light energy absorbed by the P680 reaction center

oxidizes water

In the conversion of pyruvate to acetyl CoA, hydrogen atoms are transferred to NAD+. The conversion of pyruvate to acetyl CoA is an example of

a redox reaction

What is the balanced equation for the generation of sugar from sunlight, water, and CO2?

6 CO2 + 6 H2O ----> C6H12O6 + 6 O2

Plants are green because

chlorophylls absorb blue and orange-red wavelengths of light and reflect green light.

How does the reduction of pyruvate to lactic acid during fermentation allow glycolysis to continue in the absence of oxygen?

This reaction is coupled to the oxidation of NADH to NAD+.

The NADPH required for 3PG reduction is formed

during the light reactions

The O2 gas produced during photosynthesis is derived from

water

Which of the following do photosynthesis and respiration have in common?

ATP synthesis in both processes relies on the chemiosmotic mechanism.

How is the Calvin cycle connected to the light reactions?

The light-induced pH changes activate rubisco. The light-induced electron flow changes the shape of four Calvin cycle enzymes. The Calvin cycle needs the ATP produced in the light reactions. The Calvin cycle needs an NADPH produced in the light reactions.

For the citric acid cycle to proceed, it is necessary for

an acetyl group to bind to oxaloacetate.

When acetyl CoA builds up in the cell, it increases the activity of the enzyme that synthesizes oxaloacetate. In this case, acetyl CoA is acting as a(n)

allosteric activator

The component of aerobic respiration that produces the most ATP per mole of glucose is

oxidative phosphoryation and chemiosmosis.

A person on a dangerously severe diet will eventually suffer from malnutrition and even starvation. If a person does not eat enough to fuel sufficient ATP and NADH production for biological activities, energy sources will be depleted. Which of the following represents the correct order in which this depletion takes place?

Glycogen, fats, proteins

During the first step of the citric acid cycle, energy stored in acetyl CoA is used to

drive the reaction oxaloacetate to citric acid

During the fermentation of one molecule of glucose, the net production of ATP is _______ molecule(s).

2

When CO2 is added to RuBP, the first stable product synthesized is

3PG

T or F? Each metabolic pathway is regulated by specific enzymes.

True

The light reactions of photosynthesis provide the Calvin cycle with

ATP and NADPH

In the first step of glycolysis, the hydrolysis of ATP to ADP is exergonic, whereas the phosphorylation of glucose to glucose 6-phosphate is endergonic. The two reactions are therefore said to be

coupled

Exam 1 Quiz Questions - Subjecto.com

Exam 1 Quiz Questions

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How are temperature and fluidity of the cell membrane related?

Across a broad temperature range, fluidity of the cell membrane decreases as temperature decreases.

Why does the cell membrane’s fluidity change with its composition?

? Don’t know the right answer, can be: A) The non-covalent interactions between the molecules that make up the cell membrane change B) The cell membrane becomes more or less permeable to water, depending on its composition. C) Depending on its composition, the cell membrane’s ability to absorb fluids into its structure changes.

Which of the following changes would make a cell membrane more fluid?

? Can be: A) Decrease the degree of unsaturation in the fatty acids in its phospholipids. B) Lower the temperature. C) Lower the cholesterol content in the cell membrane.

A species of fish spends part of its life cycle under conditions of moderate temperatures and part of its life cycle under extremely cold conditions. What change in the cell membranes of this fish might be expected to occur as conditions shift from moderate to extremely cold temperatures?

The fish’s cells would slow production of cholesterol and increase production of unsaturated, short chain fatty acids.

Increased synthesis of phosphodiesterase would lead to

decreased concentration of cyclic AMP.

How could you distinguish between a signal transduction pathway that leads to an alteration in gene expression and a pathway that leads to an alteration in enzyme activity?

Look at the timing of the cellular response to signal molecules to determine whether the response is very fast or relatively slow.

If a person is being treated for shock and receives an injection of epinephrine to aid recovery, you would not expect to see

increased conversion of cAMP to ATP in liver cells.

(Fig 1)
The figure above shows the signal transduction pathway initiated by the binding of an odorant molecule to an olfactory receptor of an olfactory neuron in the human nose. Information will be sent to the brain because of changes in ion concentrations within the neuron. What specific event is most directly responsible for the change in intracellular ion concentrations?

cAMP binding to its gated channel

Phosphodiesterase is the enzyme that catalyzes the degradation of cAMP in cells. Phosphodiesterase inhibitors have been synthesized and used as drugs in the treatment of several human diseases and disorders. Based on the role of cAMP in the signal transduction pathway shown above, you would expect these drugs to

?: A) slow epinephrine’s activity to produce the same amount of glucose over a longer period of time. B) enhance the effects of epinephrine to shift the production of glucose to increased amounts. C) replace the effects of epinephrine to maintain a steady balance of glucose. D)speed up epinephrine’s activity to produce the same amount of glucose over a shorter time.

The process of random movement of molecules toward a state of equilibrium is called _______.

diffusion

A solution in which the solute molecules are uniformly distributed is said to be at _______.

equilibrium

The effectiveness of many anesthetics in reducing feeling or sensation is directly related to their___

Solubility in membrane lipids

The ability of membranes to allow some substances to pass through, but not others, is called _______.

selective permeability

Primary active transport involves the direct hydrolysis of _______.

ATP

Any transport of a relatively small uncharged molecule down its concentration gradient, either through the phospholipid bilayer or through a protein will be:

passive transport

The glucose transporter is a _______ protein that allows glucose to enter the cell at a faster rate than would be possible by simple diffusion.

carrier

One reason cancer therapy often fails is that the targeted cells become resistant to the drugs that are supposed to kill them. Which of the following is the most likely mechanism of this resistance?

Membrane proteins actively transport the drugs out of the cancer cells.

Which statement about ligands and receptors is true?

For most ligand-receptor complexes, binding is favored. Ligand-receptor interactions are reversible. Many drugs that alter human behavior prevent the binding of receptors’ specific ligands. Ligand-receptor interactions often induce conformational changes in membrane channels.

Which process does not involve the uptake of materials into the cell?

Which process does not involve the uptake of materials into the cell?

You are doing a summer internship in a cell biology lab. Your supervisor asks you to change the medium on some cells she is growing. You do so and then examine the cells under a microscope. To your dismay, you can’t find any cells and see only what looks like cell debris. What most likely happened to your cells and why?

The cells burst because the new medium was hypotonic to the cells.

Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?

Cyclic AMP

Many signal transduction pathways cause

alterations in gene expression. upregulation of genes. the switching off of genes. an alteration of the abundance of enzymes.

Plant cells transport sucrose across the vacuole membrane against its concentration gradient by a process known as

active transport

Vitamin A is a relatively small, lipid-soluble molecule that can behave as a hormone. Most likely its receptor

is not connected to the cell membrane.

Which of the following is the driving force for active transport?

ATP hydrolysis

Which statement does not correctly describe the processes by which materials are taken up by the cell?

Vesicles touch the cell membrane and release their contents through a pore.

ncreased synthesis of phosphodiesterase would lead to

decreased concentration of cyclic AMP.

How do the cell membranes of a hibernating animal change in colder temperatures?

Unsaturated fatty acids make up more of the lipid composition.

Which statement about peripheral membrane proteins is true?
A) They have hydrophobic regions within the lipid portion of the bilayer.
B) They have hydrophilic regions that protrude in aqueous environments on both sides of the membrane.
C) They frequently flip from one side of the bilayer to the other.
D) They control the rate of simple diffusion.
E) Their polar regions interact with complementary regions of integral membrane proteins.

E) Their polar regions interact with complementary regions of integral membrane proteins.

After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters

an effector protein.

What is the membrane property that helps ensure the diffusion of glucose into a cell that has a high energy need?

A high number of carrier proteins specific for glucose

. Phagocytosis refers to

the specific import of relatively large particles

A benefit of the many steps involved in a protein kinase cascade is that they allow for

activation or inhibition of many enzymes. amplification of the signal. distribution of the signal throughout the inside of the cell. variation in the response.

A protein that forms an ion channel through a membrane is most likely

a transmembrane protein.

True or False? Protein kinase receptors are a type of cytoplasmic receptor.

False

True or False? Simple diffusion depends upon specific carrier proteins.

False

Which one of the following reactions is not an oxidation-reduction reaction?

R—CH=CH—CH3 + H2O ↔ RCH2—CH(OH)—CH3

Which of the following statements about ATP is false?

The phosphate bond energy of ATP is used to power catabolic metabolism.

The mitochondrial electron transport chain

oxidizes the intermediate electron carriers, NADH and FADH2.

In green plant photosynthesis, water (H2O) is

oxidized to oxygen gas (O2) in the light.

Fermentation

results in the formation of lactic acid or ethanol.

In photosynthesis, NADPH is used for the

reduction of 3-phosphoglycerate (3PG).

Glycolysis

is an oxidation-reduction process.

Cyanide inhibits the enzyme (cytochrome C oxidase) in the mitochondrial electron transport chain that reduces O2 to water; i.e., O2 cannot be used in glucose catabolism. Suppose that you add cyanide to a suspension of muscle cells from a rat. Which statement given below is the most accurate with respect to the effects of cyanide on glucose catabolism?

The citric acid cycle would be inhibited, but glycolysis would not; and lactic acid would accumulate.

The immediate source of energy for ATP synthesis in chloroplasts is

the electrochemical proton gradient.

In the complete oxidation of glucose, 6 CO2 molecules are formed per glucose molecule oxidized. The numbers of CO2 molecules per molecule of glucose that is released during glycolysis is _____ , during pyruvate oxidation is ________ , and during the citric acid cycle is ______ .

0;2;4

The mitochondrial ATP synthase

makes ATP at the expense of the proton gradient established by electron transport.

The major product of photosynthesis that is exported from the leaves to the rest of the plant is

sucrose

The conversion of malate to oxaloacetate in the citric acid cycle takes place with the conversion of NAD+ to NADH. In this reaction, NAD+ is

both b and c. (the oxidizing agent. reduced to NADH. )

The ultimate source of energy for ATP synthesis in chloroplasts is

light

Triglycerides are major energy storage molecules. Which statement about the complete oxidation of triglycerides to CO2 and water, and the oxidation of glucose to two molecules of pyruvate is correct?

Glucose oxidation to pyruvate and triglyceride oxidation use glycolysis.

Which statement given below best characterizes the properties of a photosystem?

A photosystem is a complex of pigments, proteins, and reaction center chlorophyll.

Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should over the short term

inhibit mitochondrial ATP synthesis.

Which of the statements below about the citric acid cycle is false?

The cycle releases less energy than glycolysis.

To be metabolized, glucose first must be converted to glucose 6-phosphate. This _______________ ATP, and thus this step is ______________. Overall glycolysis is ________________ , and _______________ ATP, and NADH.

consumes; endergonic; exergonic; produces

The end products of glycolysis are

pyruvate, ATP, and NADH.

The following is an example of a(n) ______________. Male frog eggs exposed to 0.1ppb of atrazine will have abnormal testes.

experimental prediction

Which of the following processes is not dependent on interactions of plants with other organisms (including other plants)?
Obtaining nutrients, Producing fertile seeds , Dispersing seeds, Regulating the internal environment, or Competing for water

regulating the internal environment

A community differs from a population in that:

a community consists of many species.

T or F? Histograms are a useful way to visualize categorical data

True

T or F? Continuous data cannot be shown using a histogram or pie chart

False

T or F? Scatterplots are useful for showing the relationship between two continuous variables

True

T or F? All graphs should have axes, captions, and units clearly labeled.

True

T or F? Frequency distributions can be shown using a bar chart, histogram, or pie chart.

True

____________ explanations consider the immediate genetic, or physiological processes that explain an organism possessing a trait.

Proximate

The advantage of controlled experiments is that

all variables are held constant except for one.

Scientists observed that frogs with expanded toe pads live in trees, not in water. They stated "expanded toe pads are an adaptation to life in trees." This statement is an example of a(n)

hypothesis

A scientific theory, such evolution or gravity, is a body of scientific work that

has been rigorously tested and is testable. results from the understanding of several related processes. provides an explanatory framework for observations. could be refutable with sufficient evidence.

What cannot increase the power of a statistical test?

Selecting a higher a-value

Suppose we are interested in whether or not dung beetles are a major (i.e., greater than 50%) prey item for a local population of Mediterranean House Geckos. You initially collect 5 geckos and induce them to vomit so you can examine their stomach contents. You find that 4 have beetle bits in their stomachs, indicating beetles are a major component (80%) of the gecko diet. Later you expand your sample to 25 and find that only 10 have eaten beetles, indicating that beetles are not a major component (40%) of the gecko diet. Select the truest statement below given this scenario.

The results of the first sample (5 geckos) were a false positive.

____________________ variables have a natural ordering to them.

Ordinal

Earth is approximately _______ years old.

4-5 billion

An organism

may be one or more cells. is either a prokaryote or a eukaryote. can do biological work. contains genetic information.

Organisms that produced oxygen gas in the early Earth’s atmosphere paved the way for a new type of metabolism used by larger organisms, and this new type of metabolism is called _______ metabolism.

aerobic

Of the characteristics that all of life share, viruses

have genetic material that can mutate

Recently, ____________ data has greatly contributed to our understanding of the evolutionary relationships between living organisms.

genomic

Scientists use statistics because it helps us

avoid drawing the wrong conclusions. describe patterns in data. determine if a pattern could have occurred by chance alone. plan our experiments and comparisons.

All cells in a multicellular organism

contain the same genome

The P-value

is mathematically calculated from a statistical test.

Positive feedback occurs when a product of a system

accelerates an earlier process in the system.

In the scientific method, a hypothesis

is the basis for making predictions

What are the molecules that govern the chemical reactions within a cell?

proteins

Oceans were a good environment for early organisms because they

shielded organisms from ultraviolet light

Genomes are

the sum of genetic information in a cell

Scientific explanations for a natural phenomenon

are testable and have the potential to be refuted by experiments

In terms organization, the order of parts of a multicellular organism is

molecule, cell, tissue, organ, organ system

a cell

is the fundamental unit of life

two samples with the same range

will likely have different standard deviations

The main purpose of any single experiment is to

test a prediction that is based on a hypothesis

A biologist hypothesizes that the sounds made by lions at night in the Serengeti are territoriality calls and predicts that two lions inhabiting the same territory will roar even louder. She selects an area inhabited by one lion, records its calls, and plays them back in the same area. She records her observations, and notes that the lion does indeed roar more often as a result of this experiment. What would be the next step in the hypothesis-prediction method?

asking new questions

A scientist walking by a pristine stream, and then a polluted pond below a mill, observes that fish are present in the stream but not in the pond. The scientist then says, "polluted water kills fish." This statement is an example of

a hypothesis

A statistical test starts with

a null hypothesis

What is a null hypothesis?

A prediction about what will happen to a control group

A comparative experiment

starts with the prediction that there will be a difference between groups or samples

Scientific explanations for a natural phenomenon

are based on reproducible and quantifiable observations

Many possible applications of scientific knowledge raise ethical issues for some people. Which application, however, would be rejected by all responsible scientists?

using scientific knowledge to dictate how the world ought to be

a scientific hypothesis

is based on observations

The binding of a substrate to an enzyme

may involve hydrogen bonds and van der Waals interactions

For a covalent bond to be polar, the two atoms that form the bond must have

different electronegativities

Quaternary structure of proteins refers to

the number and king of polypeptide subunits the protein has

The reactivity of an atom arises primarily from the

existence of unpaired electrons in the outermost shell

Which interactin between atoms is the strongest?

Covalent bonds

An element that contains ten protons and ten electrons is likely to

be chemically inert (stable)

Oils and Fats

are triglycerides

Complementary base pairing

takes place between purine and pyrimidine bases

Physical properties of water that benefit life?

Cohesiveness, high heat capacity, high heat of evaporation, and hydrogen bonds

The synthesis of complex molecules _______ energy, whereas their degradation _______ energy. Synthesis occurs with _______ in entropy.

requires; releases; a decrease

If rainbow trout were transferred from warm water to near freezing water (2°C), what changes in the trout would occur in the trout’s nervous system in the colder water?

The trout would produce a new isozyme of acetylcholinesterase that has a lower optimal temperature, allowing the fish’s nervous system to perform normally in the colder water.

Nucleotides

are the monomers of DNA and RNA

DNA differs from RNA in that DNA

contains deoxyribose

DNA with a higher G + C content is more stable at high temperatures than DNA with a high A + T content. Why?

G and C form three hydrogen bonds between antiparallel strands and A and T, just two

A yeast is cultured in the presence of radioactive phosphate, and the following biological molecules are purified. Which molecule should be most radioactive?

RNA

Replication, transcription, and translation

refer to RNA synthesis, DNA synthesis, and protein synthesis, respectively

T or F? The properties of starch are very similar to those of cellulose

False

Table salt, NaCl, is neutral. When dissolved in water, NaCl

separates to form Na+ and Cl- ions that interact with water molecules

Covalent bond formation depends on the ability of atoms to

share electrons with other atoms

The "building blocks" of polysaccharides are _______, and the blocks are covalently linked together by _______.

monosaccharides; glycosidic linkages

Fatty acids are

carboxylic acids with long hydrocarbon tails

Replication is the synthesis of _______ and transcription is the synthesis of _______.

an exact copy of DNA; an RNA copy of DNA

A competitive inhibitor of an enzyme-catalyzed reaction

is usually structurally similar to the substrate

In a reaction catalyzed by an enzyme,

the enzyme does not affect the equilibrium constant for the reaction

Enzymes

may be subject to feedback inhibition

Entropy

is related to the disorder or randomness of a system

Noncovalent binding of a substrate to the active site of an enzyme is

reversible

Enzymes are highly sensitive to pH and temperature because

changes in temperature and pH readily break their hydrogen bonds and can alter the enzyme shape.

he addition of the competitive inhibitor mevinolin slows the reaction HMG-CoA -> mevalonate, which is catalyzed by the enzyme HMG-CoA reductase. The effects of mevinolin would be overcome and the rate of the reaction increased by

adding more HMG-CoA

Which type of inhibitor can be overcome by the addition of more substrate?

Competitive

How to competitive and noncompetitive enzyme inhibitors differ?

Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors may change the shape of the active site

In the biosynthetic pathway for folic acid, the compound PABA is the normal substrate for an enzyme in the pathway. The antibiotic sulfanilamide is very similar in structure to PABA and will act as a(n) _______ of the enzyme that acts on PABA.

competitive inhibitor

The rate of a chemical reaction in a cell is the measure of how

quickly the substrates are converted to product

When an egg is exposed to extreme heat it turns from a liquid substance into a solid substance. Even when the egg is allowed to cool, these changes are not reversible for a number of reasons. Which is not one of those reasons?

Fats in the egg have become saturated and less fluid

The Quaternary structure of a protein

consists of exactly four subunits, hence the name Quarternary

Lipids are

– insoluble in water – important for energy storage – hydrophobic – important constituents of biological membranes

The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?

The activation energy of the reaction is high

What type of amino acid side chains would you expect to find on the surface of a protein embedded in the lipid-rich environment of a cell membrane?

Hydrophobic

An atom with _____ has an atomic mass of 14.

7 neutrons and 7 protons

What accounts for the stability of the double-stranded DNA molecule?

The hydrogen bonds between purines and pyrimidines

Which characteristic allows cells to control their internal environment?

Their ability to control the synthesis of an enzyme and the activity of an enzyme

Which condition or component was not likely to have been present on Earth during the formation of the first biologically relevant molecules?

High atmospheric oxygen levels

T or F? Condensation reactions consume water as a reactant.

False

How does the second law of thermodynamics apply to organisms?

The potential energy of chemical bonds can be converted to kinetic energy

You have duplicated the threonine to isoleucine metabolic pathway and want to determine the saturation level of threonine. You slowly add increasing amounts of threonine and observe that the reaction rate initially increases slowly and then decreases. You also note that increasing the amount of isoleucine decreases the rate of the reaction. You determine that the pathway is thus regulated by

feedback inhibition

Some proteins that are on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by _______ and the sugars added in the _______.

Rough ER; GA

The extracellular matrix of animal cells

is involved in chemical signaling between cells, helps filter materials passing between tissues, contains proteglycans, and contains collagen

Amoeba proteus is injected with a drug that inhibits the formation of microtubules. What effect does this have on the organism’s movement?

It continues to move with no effect

The presence of ___________ means that substances must pass through, rather than between, the epithelial cells that form the lining of the small intestine.

tight junctions

The endomembrane system

includes the GA and the ER

Which structure occupies the largest volume in a mature plant cell?

the vacuole

Nucleic acids are not found in

plant vacoules

Prokarytes

are surrounded by a plasma membrane

Cilia and eukaryotic flagella

must have a motor protein that uses the energy of ATP hydrolysis to power movement.

Liver cells are exposed to radioactive amino acids; all proteins synthesized during this time are radioactive. The cells are then removed at 5-minute intervals and fractionated. Where in the cells is the radioactively labeled enzyme lipase performing its intracellular digestion?

In lysosomes

Cells are the _____________ unit of life, and the principles that underlie the structure and function of a bacterial cell are ________________ to those governing the cells in a human body.

fundamental; similar

Which of the following is not an important role served by the cell membrane?

Carbohydrates protruding from it allow binding and adhering to adjacent cells

The organelles and biomolecules present in homogenized cells can be separated by centrifugation. Which of the following would be found at the top of a centrifugation gradient?

ATP molecules

Which of the following proteins powers the movement of both cilia and vesicles within a cell?

Dyein

Which of the following organelles is involved in energy conversions?

Chloroplasts

Which of the following organelles are found only in plants?

Glyoxysomes

The proteins that make up the cytoskeleton of bacteria are similar to _______ in eukaryotic cells.

actin

Which of the following structures is directly involved with the movement of organelles within a cell?

Microtubules

Plastids are

present in nearly all plant cells

T or F? The nucleus is the site of protein synthesis

False

Lysosomes are important to eukaryotic cells because they contain

digestive enzymes

A secondary lysosome

is used to break down macromolecules through hydrolysis

In autophagy

lysosomes engulf cell components and digest them

The substances that enter the GA arrive packaged within __________ from the ____________.

vesicles; rough ER

The movement of the proteins through the GA is _____ to _______ to _______.

cis, medial, trans

What happens to proteins as they pass through the Golgi apparatus?

proteins are modified by having carbohydrates attached or removed

Besides the proteins being processed for distribution, what other components could be expected to be found inside the GA?

Enzymes

If you had a problem with your heart whereby signals were not being conducted adequately through the heart muscle, which structures would likely be a cause for this malfunction?

Gap junctions

A prokaryotic cell has _______ but does not have _______.

DNA; membrane-bound organelles

Example of a motor protein

kinesin

The cell membrane

helps maintain a constant internal environment

If a cell lacked ribosomes, it would not be able to

make proteins

Which structure(s) is/are involved with maintaining the position of organelles within a cell?

intermediate filaments

A protein that is meant to be exported from the cell is synthesized by ribosomes

on the rough endoplasmic reticulum

You find a previously unknown single-celled organism in a water sample. While studying it, you find that the organism is photosynthetic and has a cell membrane surrounded by a layer of peptidoglycan (carbohydrates linked to peptides). The organism contains DNA and RNA, but you see no nuclear membrane. This organism most likely belongs to which group?

Bacteria

Plants are able to distribute hormones and nutrients to neighboring cells through _______; in animal tissues _______ has/have a similar function.

cell membrane-lined channels extending through the cell wall; gap junctions

Which organelle is generated by the cell membrane and contains macromolecules?

Phagosome

After a protein is made, what is one of the ways in which it can get to a specific location in a cell?

A carbohydrate group is added in the RER that tags the protein for a specific location

Prokaryotic cells generally are smaller than eukaryotic cells. Which of the following is the most likely explanation for this difference?

Eukaryotes have compartmentalization, which allows them to be structurally and functionally more complex.

If a cell needed to increase its surface area without changing its volume in order to carry out cellular processes more efficiently, it could do this most effectively

by creating deep invaginations in the cell membrane

If you forget to water a potted plant, its leaves wilt. A likely reason for this wiliting is that

vacuoles lose water, reducing the turgor pressure in the cells.

Which organelle contains special enzymes to safely break down toxic by-products of oxidation?

Peroxisome

Suppose the concentration of epinephrine in the blood stream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.

decrease; adenylyl cyclase; decrease

Phospholipids spontaneously form bilayer structures, but oils form small droplets. Why do oils not form bilayers?

Oils do not have the polar head group that phospholipids have.

Hormones are chemical signals that

are circulating signals, and bind to the receptors of distant cells.

In facilitated diffusion

specific integral membrane proteins mediate transport along the concentration gradient.

What would happen if a suspension of red blood cells, in an isotonic NaCl solution, was suddenly diluted with pure water by a factor of 10?

The cells would swell and lyse (burst).

Receptor-mediated endocytosis

sults in the formation of clathrin-coated vesicles.

Adenylyl cyclase

makes cAMP from ATP with the liberation of pyrophosphate (PPi).

The activation of a receptor by a signal, and the subsequent transduction and amplification of a signal, can lead to

downregulation of a specific enzyme. upregulation of a specific gene. changes in the electrical potential across the cellular membrane. changes in the function of brain cells.

In animals, cell recognition

involves proteins in plasma membranes.

The phosphorylation of proteins by ATP

is catalyzed by enzymes known as "protein kinases."

he sodium-potassium pump (or Na+-K+ pump)

results in the formation of Na+ concentration gradient across the plasma membrane.

A universal feature of receptors is that they

undergo structural (shape) changes when the signal molecule is bound.

Chemical signal transduction pathways

involve binding of the signal molecule to receptors.

In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.

carbohydrates; glycoproteins; glycolipids

Caffeine

binds to a receptor on nerve cells in the brain.

T or F? Hydrophilic regions of integral membrane proteins are in contact witht the interior of the bilayer

false

Osmosis is

the movement of water across membranes

T or F? cAMP binds noncovalently to protein kinase A, and changes shape of the protein.

True

T or F? Both receptors and enzymes may be integral membrane proteins.

True

What processes of cellular respiration occur in the mitochondrial matrix?

Pyruvate oxidation and citric acid cycle

What would happen to pyruvate is O2 is not present?

will enter a fermentation pathway to produce NAD+ to keep the CAC going

In the electron transport/ATP synthesis in mitochondria, what is the immediate source of electrons for the electron transport chain?

NADH and FADH2

Why is oxygen so important to electron transport chain in ATP synthesis?

It acts as the final elecctron acceptor

If excessive ATP begins to accumulate, which enzymes are inhibited?

Phosphofructokinase, citrate synthase, isocitrate dehydrogenase, citrate synthase and isocitrate dehydrogenase

ADP or AMP activates which enzyme?

Phosphofructokinase

The oxygen produces by photosynthesis comes from

water

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide. Most of the carbon dioxide comes from

citric acid cycle

The light energy absorbed by the P680 reaction center

oxidizes water

In the conversion of pyruvate to acetyl CoA, hydrogen atoms are transferred to NAD+. The conversion of pyruvate to acetyl CoA is an example of

a redox reaction

What is the balanced equation for the generation of sugar from sunlight, water, and CO2?

6 CO2 + 6 H2O —-> C6H12O6 + 6 O2

Plants are green because

chlorophylls absorb blue and orange-red wavelengths of light and reflect green light.

How does the reduction of pyruvate to lactic acid during fermentation allow glycolysis to continue in the absence of oxygen?

This reaction is coupled to the oxidation of NADH to NAD+.

The NADPH required for 3PG reduction is formed

during the light reactions

The O2 gas produced during photosynthesis is derived from

water

Which of the following do photosynthesis and respiration have in common?

ATP synthesis in both processes relies on the chemiosmotic mechanism.

How is the Calvin cycle connected to the light reactions?

The light-induced pH changes activate rubisco. The light-induced electron flow changes the shape of four Calvin cycle enzymes. The Calvin cycle needs the ATP produced in the light reactions. The Calvin cycle needs an NADPH produced in the light reactions.

For the citric acid cycle to proceed, it is necessary for

an acetyl group to bind to oxaloacetate.

When acetyl CoA builds up in the cell, it increases the activity of the enzyme that synthesizes oxaloacetate. In this case, acetyl CoA is acting as a(n)

allosteric activator

The component of aerobic respiration that produces the most ATP per mole of glucose is

oxidative phosphoryation and chemiosmosis.

A person on a dangerously severe diet will eventually suffer from malnutrition and even starvation. If a person does not eat enough to fuel sufficient ATP and NADH production for biological activities, energy sources will be depleted. Which of the following represents the correct order in which this depletion takes place?

Glycogen, fats, proteins

During the first step of the citric acid cycle, energy stored in acetyl CoA is used to

drive the reaction oxaloacetate to citric acid

During the fermentation of one molecule of glucose, the net production of ATP is _______ molecule(s).

2

When CO2 is added to RuBP, the first stable product synthesized is

3PG

T or F? Each metabolic pathway is regulated by specific enzymes.

True

The light reactions of photosynthesis provide the Calvin cycle with

ATP and NADPH

In the first step of glycolysis, the hydrolysis of ATP to ADP is exergonic, whereas the phosphorylation of glucose to glucose 6-phosphate is endergonic. The two reactions are therefore said to be

coupled

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