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WorksheetsBiology Unit 1
Total questions: 99
Worksheet time: 50mins
A single bacterium divides into two bacteria that are identical to, but smaller than, the original bacterium. Which characteristic of life does this best describe?
Conversion of molecules
Response to stimulus
Replication and reproduction
Complexity and organization
Why the did evolution of photosynthesis in the ancient ocean allow organisms to colonize land?
Photosynthesis is more efficient in land plants
Oxygenation of the atmosphere formed protective ozone
Cells no longer required water with aerobic metabolism
More water vapors formed as oxygen increased in the atmosphere
True/False
Organization (e.g., building molecules, constructing tissues) in life requires energy inputs.
True
False
True/ False
You hypothesize that increased light levels will enhance growth of your houseplants. You test this hypothesis, moving the plants to an area in your home with more light. Over several weeks, and you find that the plants begins to look fuller and healthier. This result proves your original hypothesis.
True
False
An atom with _______ has an atomic number of 14.
7 neutrons and 7 protons
14 protons
14 neutrons
. 7 neutrons and 7 electrons
What determines if a molecule is polar or nonpolar?
The differences in the electronegativities between the atoms
The number of atoms in the molecule
The ionic charges between atoms
The number of bonds in the molecule
Small molecules containing several hydroxyl groups are typically
Soluble in water
Not very stable
Ionic
Nonpolar
Which of these molecules contains only nonpolar bonds?
O2
CH3-OH
CH3-NH2
H2O
An atom has an atomic number of 12. Assuming neutrality, how many valence electrons does it have?
8
10
1
2
Which factor defines whether a reaction is endergonic?
Entropy
Delta G
The laws of thermodynamics
Activation energy
During a typical hydrolysis reaction in cells, the energy required to break bonds in the substrates is _______________ the energy released when bonds are formed in the products.
Greater than (endergonic)
Less than (exergonic)
Equal to
Gibbs free energy is negative for _________________ reactions, which are typically associated with a ________________ change in enthalpy and a _______________ change in entropy.
exergonic; positive; negative
endergonic; negative; positive
exergonic; negative; positive
endergonic; positive, negative
True/False
Energy can be transformed during metabolic reactions
True
False
True/False
For each reaction in a metabolic pathway, a small amount of energy disappears due to the increase in entropy
True
False
True/False
Endergonic and exergonic reactions can both involve breaking of bonds.
True
False
Which of the following relationships are not accurate?
Hydrolysis – water is required (reactant)
Anabolic – synthesis of biomolecules
Entropy – disorder
Endergonic – negative delta G
Margarine is a butter substitute that is solid at room temperature. It is made from vegetable oils (often soybean or canola oil). The label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. Which statement below best explains this?
The margarine is less likely to clog arteries compared to vegetable oil, because the triglycerides in vegetable oils contain unsaturated fatty acids.
The margarine stays solid at room temperature because the fatty acids in the triglycerides are saturated.
The margarine has more "kinks" in the fatty acid chains, compared to vegetable oil, causing it to be solid at room temperature.
Margarine has a lower melting point than vegetable oil.
Maltose, or malt sugar, is composed of two glucose molecules bound by a glycosidic linkage. How can maltose be classified? Choose all that apply.
as a monosaccharide
as a disaccharide
as a hexose
as a polysaccharide
as a starch
Put the correct word in the blanks:
First blank
_____________ bonds are formed during anabolic reactions in the synthesis of macromolecules. In lipids there are ____________ bonds, whereas in carbohydrates there are ____________ bonds.
covalent
glycosidic
hydrogen
ionic
ester
Put the correct word in the blanks:
Second blank
_____________ bonds are formed during anabolic reactions in the synthesis of macromolecules. In lipids there are ____________ bonds, whereas in carbohydrates there are ____________ bonds.
ester
covalent
hydrogen
carboxylic
Put the correct word in the blanks:
Final blank
_____________ bonds are formed during anabolic reactions in the synthesis of macromolecules. In lipids there are ____________ bonds, whereas in carbohydrates there are ____________ bonds.
Glycosidic
Carboxylic
Ester
Covalent
In order to maintain an ideal membrane fluidity, cells of a fish can make chemical modifications to their membranes to deal with changes in temperature. How might you expect the lipids in a fish from warmer water to compare to those in a fish from colder water?
Lipids will have fatty acids with more glycerol in the water water fish.
Lipids will have more saturated fatty acids in the warmer water fish.
Lipids will have less saturated fatty acids in the warmer water fish.
True/False
All carbohydrates are polymers
True
False
In an alpha helix, the coiling is stabilized by
the hydrophobic nature of the R chains, which causes the chain to coil with the R groups inward.
hydrogen bonding of the N—H groups on one amino acid and the C=O groups on another.
repulsion of the R chains from each other, causing the coil to form with the R groups on the outside.
disulfide bond formation between cysteines that are regularly spaced along peptide chains.
. the N—C—C repeat of the peptide backbone, allowing for regularly spaced peptide bonds between chain segments.
Which of the following is matched correctly with its building block?
Polysaccharides – amino acids
Proteins – glucose
Lipids – glycerol and fatty acids
Nucleic acids – monosaccharides
Nucleotides in RNA are connected to one another in the polynucleotide chain by
covalent bonds between bases.
covalent bonds between sugar and base.
covalent bonds between sugar and phosphate
hydrogen bonds between purines.
hydrogen bonds between any bases.
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Arg+Lys
Van der Waals interactions
Ionic bond
Hydrogen bond
Disulfide bridge
None of these interactions are likely
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Asp+Lys
van der Waals interaction
Ionic bond
Hydrogen bond
Disulfide bridge
None of these are likely
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Gln+Ser
van der Waals
Ionic
Hydrogen
Disulfide
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Leu+Ile
van der Waals
Ionic bond
Hydrogen bond
Disulfide bridge
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Cys+Cys
van der Waals
Ionic
Hydrogen
Disulfide bridges
Match the amino acid pairs with the type of bond/interaction they would have in the tertiary structure of a protein
Ala+Thr
van der Waals interactions
Ionic bond
Hydrogen bond
Disulfide bridge
None of these interactions are likely
In a properly folded, active protein that is found in the aqueous environment of a cell, where would you expect to find isoleucine and valine residues?
In the interior of the protein with nonpolar side chains
In the interior of the protein with polar side chains
On the exterior of the protein
In the interior of the protein in contact with water
On either the interior or the exterior of the protein
True/False
Bonding between A-T is stronger than G-C in double stranded DNA.
True
False
Ascorbic acid, which is found in citrus fruits, acts as an inhibitor to catecholase, the enzyme responsible for the browning reaction in fruits such as apples, peaches, and pears.
One explanation for the inhibiting function of ascorbic acid could be its similarity, in terms of size and shape, to catechol, the substrate of the browning reaction. If this explanation is correct, then this inhibition is most likely an example of _______ inhibition.
competitive
indirect
noncompetitive
allosteric
feedback
Cyclooxygenase catalyzes a step in the metabolic pathways that produce Prostaglandins involved in inflammation and pain. Aspirin covalently binds to and inhibits the enzyme cyclooxygenase. What kind of regulation is this?
Allosteric inhibition
Feedback inhibition
Reversible inhibition
Irreversible inhibition
True/False
An enzyme can lower the activation energy of a reaction by inducing physical strain on the chemical bonds in the substrate(s).
True
False
Enzymes
may be subject to allosteric inhibition
change the value of ΔG for a reaction
always require cofactors.
have no effect on the activation energy barrier of a reaction
are permanently changed by the reactions they facilitate
A competitive inhibitor of an enzyme-catalyzed reaction:
always interferes with product release
cannot bind to the active site
binds to an allosteric site
is usually structurally similar to the substrate
In hibernating animals, during the cold months of winter,
signal transduction pathways cease.
saturated fatty acids are replaced with unsaturated fatty acids
membranes harden as more saturated fatty acids accumulate in them
there are no changes in lipid composition
integral proteins shrink as temperatures fall
When placed in water, wilted plants ‘perk up’ and lose their limpness because of
active transport of salts from the water into the plant cells.
active transport of salts into the water from the plant cells.
osmosis of water into the plant cells.
osmosis of water out of the plant cells.
diffusion of water out of the plant cells.
Suppose the inside of a cell has a total solute concentration of 4 M. Which of the following solutes outside of the cell would require active transport into the cell?
2.5 M CO2
4.2 M Cl-
6 M fructose
3 M Na+
4.5 M K+
When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because
many proteins can move around within the bilayer
all proteins are anchored within the membrane
proteins are asymmetrically distributed within the membrane
all proteins in the plasma membrane are peripheral
different membranes contain different proteins
When you eat fruits and vegetables, your body breaks down carbohydrates into many sugar monomers through ___________ reactions. Then the monomers move across the membrane of intestinal cells against their concentration gradient by ________________.
Hydrolysis; facilitated diffusion
Condensation; active transport
Hydrolysis; active transport
Condensation; simple diffusion
The process of primary active transport ________ the input of energy because it involves the movement of substances________ their concentration gradients, via _______ proteins.
requires; down; channel
does not require; down; carrier
requires; against; carrier
does not require; against; channel
requires; against; channel
What determines whether an atom will form a chemical bond with another atom?
The stability of the atom's nucleus
The number of protons in the atom's nucleus
The state of the atom's outermost electron shell
The number of filled electron shells in the atom
The reactivity of an atom arises primarily from
sum of the potential energies of all electron shells
energy difference between the electron shells
existence of fewer than eight electrons in the outermost shell
average distance of outermost shell from the nucleus
potential energy of the outermost shell
An atom that contains ten portons and ten electorns is likely to
be chemically inert (stable)
form covalent bons with another aotm
be toxic
form ionic bons woitj another atom
be readioactive
van der Waals interactions are weak interactions that occur between nonpolar covalent bonds
true
false
Covalent bond formation depends on the ability of atoms to
capture electrons from gases
receive electrons from other atoms
share electrons with other atoms
donate electorns to other atkms
If an organism takes in 1,000 kilojoules of energy in the form of food, how much of this energy still exists after the organism has used the energy to build new cells, repair damaged cells, pump its heart, and run from a predator?
all of the energy remains
only the energy used to build new cells remains
only the energy used to build new cells, repair damaged cells, and pump its heart remains.
No energy remains
Only the energy used to build new cells and repair damaged cells remains
Which statement is false with regards to the first and second laws of thermodynamics?
Chemical energy may be converted to light energy
Living organisms can change the form taken by energy
The total energy of a system is available to do work
Some organisms obtain energy from the sun
Kinetic energy may be used to do work.
Entropy
is free energy
is related to the disorder or randomness of a system.
is the total energy in a system.
tends to decrease the total energy in the universe.
when multiplied by the absolute temperature, is the usable energy in a system
Condensation reactions are typically
endergonic
both
exergonic
The synthesis of complex molecules _______ energy, whereas their degradation _______ energy. The synthesis of complex molecules occurs with _______ in entropy.
requires; releases; a decrease
requires; releases; no change
requires; releases; an increase
releases; requires; no change
releases; requires; an increase
Which of the following would decrease the rate of a chemical reaction?
Adding more reactants
Squeezing the reactants into a smaller volume
Stirring the reaction more vigorously
Raising the activation energy
Increasing the temperature
Table salt, NaCl, is neutral. When dissolved in water, NaCl
emains as NaCl (does not dissociate).
dissociates to form Na– and Cl+ molecules.
dissociates to form Na+ and Cl– ions that interact with water molecules.
dissociates to form Na+ and Cl– ions that do not interact with water molecules.
does not dissociate, but interacts with water molecules
A solution with a pH of 9 contains
no OH– ions
only H– ions.
the same number of OH– ions and H+ ions
more OH– ions than H+ ions.
more H+ ions than OH– ions.
_______ capacity is a term used to describe the ability of a solution to prevent large changes in pH with the addition of a base or acid
Cohesive
Buffering
Freezing
Heat
Vaporization
Phospholipids differ from triglycerides in that phospholipids
do not contain fatty acids
are amphipathic
are not derivatives of glycerol
are used to store energy for the cell
do not have both hydrophilic and hydrophobic components
Olive oil melts at a lower temperature than beef fat because
oils contain glycerol, whereas fats do not
oils are made by plants, whereas fats are made by animals.
fats contain more unsaturated fatty acids than oils do
fats contain more saturated fatty acids than oils do.
All carbohydrates
are polymers
are found in biological membranes
are more soluble in nonpolar solvents than in water
have the general structure (C1H2O1)n or CnH2nOn
are simple sugars
DNA with a higher G and C content is more stable at high temperatures than DNA with a high A and T content. Why?
The two DNA strands assume a parallel orientation when the A and T content is higher.
Each G-C pair forms three hydrogen bonds between antiparallel strands, whereas each A-T pair forms just two.
The negative charge on the phosphates in the backbone of DNA strands is partially neutralized with a higher G and C content.
The hydrophobic interactions between G and C are stronger than those between A and T.
G and C fit together better than A and T do.
Complementary base pairing
results in the formation of the double helix of RNA
takes place between purine and pyrimidine bases.
does not take place in RNA
takes place between two purine bases
takes place between the bases and the phosphates in the backbone of the nucleic acid chain
Replication is the synthesis of _______, and transcription is the synthesis of _______.
an identical copy of RNA; an identical copy of DNA
an RNA copy of DNA; an identical copy of DNA
an identical copy of DNA; proteins
an identical copy of DNA; an RNA copy of DNA
proteins; an RNA copy of DNA
When incorporated into a polypeptide chain not at the N or C terminus, _______ would make the charge of the polypeptide more positive.
cysteine
serine
alanine
glutamic acid
arginine
Where would the leucine side chain most likely be found in a protein dissolved in water?
On either the interior or the exterior of the protein
In the interior of the protein in contact with nonpolar side chains
In the interior of the protein in contact with water
In the interior of the protein in contact with polar side chains
On the exterior of the protein
The primary structure of proteins is the _______. The primary structure contains the information necessary for the formation of secondary structure, including the _______ and the _______. Secondary structure of proteins is stabilized by the formation of _______ bonds.
β pleated sheet; α helix; amino acid sequence; hydrogen
amino acid sequence; α helix; β pleated sheet; hydrogen
α helix; amino acid sequence; β pleated sheet; hydrophobic
amino acid sequence; α helix; β pleated sheet; peptide
amino acid sequence; β pleated sheet; α helix; disulfide
Tertiary structure of proteins involves bonding between amino acid R groups. What kind of bond would form between the R groups of Leu, Phe, and Val?
no kind of bond is possible between these amino acid R groups
ionic bond
hydrogen bond
van der Waals interactions
disulfide bond
How should the lettered parts be labeled?
A = cholesterol, B = oligosaccharide, C = glycolipid, D = transmembrane protein
A = glycolipid, B = glycoprotein, C = cholesterol, D = phospholipid bilayer
A = glycolipid, B = integral protein, C = oligosaccharide, D = phospholipid bilayer
A = glycoprotein, B = peripheral protein, C = cholesterol, D = phospholipid bilayer
A = glycoprotein, B = peripheral protein, C = glycolipid, D = fatty acid tails
Which statement about diffusion is false?
Facilitated diffusion does not require ATP.
Molecules move from areas of greater concentration to areas of lesser concentration.
The rate of transport depends on the concentration of the molecule transported
Simple diffusion depends on channel proteins
Diffusion occurs as the result of the random movement of molecules.
A unicellular organism adapted to living in salt water is placed in a freshwater tank. What is the likely outcome?
Water moves out of the cell, causing it to shrivel.
Water moves into the cell until the organism can adapt.
Water moves out of the cell until the organism can adapt.
Water and salt move in opposite directions until the organism can adapt.
Water moves into the cell, causing it to burst.
Lactose is transported via secondary active transport into bacterial cells. Which of the following would be absent from a diagram illustrating the mechanism of this transport system?
Diffusion of a substance in the same direction as its concentration gradient
The formation of a concentration gradient
A channel protein used to create an ion gradient
The movement of lactose against its concentration gradient
Coupling of lactose transport to transport of another substance
Which structure(s) is/are directly involved in the movement of organelles within a cell?
Intermediate filaments
Cell wall
Microtubules
Golgi apparatus
Endoplasmic reticulum
Which type of cell junction would be used to pass ions from one cell to an adjacent cell?
desmosome
tight junction
channel protein
gap junction
Tight junctions are a type of cell junction that still allows materials to move around in the extracellular matrix between cells.
true
false
Suppose you are analyzing a newly discovered unicellular organism to determine whether it should be classified as a prokaryote or eukaryote. Which approach should you take?
Determine the types of compartmentalization of functions within the cytoplasm.
Analyze the metabolic reactions taking place in the cytoplasm.
Determine whether the organism uses cytoskeletal proteins to provide structure within its cell.
Determine whether the organism is capable of respiration
Some proteins on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by _______ and the carbohydrates are added in the _______.
Golgi apparatus; rough endoplasmic reticulum
cytoplasmic ribosomes; smooth endoplasmic reticulum
cytoplasmic ribosomes; cell membrane
the rough endoplasmic reticulum; Golgi apparatus
Which type of metabolic reaction is an example of a process that does not require coupling to ATP hydrolysis?
β-oxidation of fatty acids
Active transport of sodium ions against their concentration gradient
Condensation of amino acids to form proteins
Condensation of glucose units to form glycogen
During photosynthesis in green plants, water is
used to hydrolyze ATP.
oxidized to O2 in the light.
reduced to hydrogen gas.
an electron acceptor.
oxidized to O2 in the dark.
The energy currency of cells is
light
nucleic acids
heat
ATP
glucose
Metabolic pathways can be controlled through the availability of enzymes and modulation of their catalytic activities. Enzyme availability can be regulated via _______, while enzyme activity is commonly regulated via _______.
covalent modification; proteolytic breakdown
proteolytic breakdown; gene expression
gene expression; allosteric activation and inhibition
gene expression; covalent modification
Triglycerides are major energy storage molecules. Which statement about the complete oxidation of triglycerides to CO2 and water and the oxidation of glucose to CO2 and water is true?
ATP is hydrolyzed at some point in both pathways.
Glucose oxidation and triglyceride oxidation use glycolysis.
They are both endergonic.
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
reduced
oxidized
unchanged
Which statement about the citric acid cycle is true?
It requires FAD but not NAD+.
It takes place in the mitochondrial matrix
CO2 is absorbed during operation of the cycle.
It releases less energy than glycolysis.
At which catabolic step is the greatest quantity of ATP produced?
Citric acid cycle
Oxidative phosphorylation
Glycolysis
Pyruvate oxidation
Which molecule has the high-energy chemical bonds that can be oxidized to release enough energy to drive NADH and ATP synthesis from NAD+ and ADP?
CH2O2
CO2
H2O
C5H10O2
According to the chemiosmotic mechanism, what is the direct source of the energy used to synthesize ATP from ADP in chloroplasts and in mitochondria?
electrons
proton gradient
glucose
water
Which is the correct order of the steps in a generalized signal transduction pathway?
Signal molecule enters nucleus, signal molecule binds to DNA, transcription of specific genes occurs
Signal molecule binds to extracellular region of receptor, signal molecule diffuses through cell membrane, signal is transduced to nucleus where specific genes are turned on or off
Signal molecule activates target cell, target cell binds to receptor, receptor is activated
Signal molecule is secreted by nearby cell, signal molecule enters cell, signal activates receptor
Signal molecule binds to receptor, molecules within cell transduce signal, cell responds
Which statement about intracellular receptors in a signal transduction pathway is true?
Ligands do not have to enter the cell to activate intracellular receptors
Ligands bind first to membrane receptors, then enter the cell and bind to intracellular receptors.
Ligands bind irreversibly to intracellular receptors
Intracellular receptors undergo a conformational change when activated
Intracellular receptors bind to hydrophilic ligands.
Protein kinase receptors phosphorylate themselves and/or other proteins when activated, resulting in a(n)
change in the ligand binding specificity.
decrease in ligand–receptor binding.
inhibition of further transduction of the signal.
change in shape and function of the proteins.
Oxytocin stimulates a G protein-coupled signal transduction pathway. During signal transduction in this pathway, a G protein becomes activated. Which three molecules does G protein interact with in this pathway?
Ligand, GDP, and GTP
G protein-linked receptor, GTP, and effector protein
GTP, cytoplasmic receptor, and transcription factor
G protein-coupled receptor, ATP, and enzyme
How would administering a non-hydrolyzable form of GTP to a cell affect its G protein-coupled signal transduction pathways?
The pathways would never turn off.
The pathways would become nonresponsive to stimuli.
The pathways would become hypersensitive to stimuli.
he pathways would respond in unpredictable ways
Some drugs function as ligands to bind to a natural receptor site in the body and elicit the signal transduction pathway associated with that receptor. In designing a drug to function in the human body, a pharmaceutical chemist would focus on mimicking which aspect of the natural ligand?
number of chemical bonds
density
orientation of functional groups
number of atoms
A previously unknown chemical signal is discovered in mice. Five observations about this signal are listed. Which observation would serve as evidence in distinguishing whether this chemical signal should be classified as a juxtacrine or a paracrine signal?
Cells producing the signal are not affected by the signal molecule.
The signal molecule is a protein.
The signal molecule is not present in blood.
The signal molecule is not present in extracellular fluid.
A protein kinase can phosphorylate an enzyme and activate it by
increasing the number of enzyme molecules.
increasing transcription of the enzyme.
changing the shape of the enzyme to expose an active site
changing the enzyme's function.
decreasing the number of enzyme inhibitors.
This is an example of
Protein kinase receptor
Ligand-gated ion channel
G protein-coupled receptor
This is an example of
Ligand-gated ion channel
G protein-coupled receptor
Protein kinase receptor
This is example of
Ligand gated ion channel
G protein-coupled receptor
Protein kinase receptor
