Bio Exam 1 CH 1-4
How many molecules of glucose C6H12O6 molecular mass of 180 daltons) would be present in 90 grams of glucose.
(90/180) X 6.02 X 10^23
Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to complete the valence shell of a fluorine atom.
1
An atom with atomic number 12 would have what type of chemical behavior in bonding with other elements.
Form ions with a +2 charge
Which of the following explains most specifically the attraction of water molecules to one another?
Hydrogen bonds
A .01 M solution of a substance has a PH of 2 What can you conclude about this substance?
Strong acid that ionizes completely in water.
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
The rates of the forward and reverse reactions are equal.
protons =
atomic number
Water molecules are able to form hydrogen bonds with
compounds that have polar covalent bonds
Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to fill the valence shell of a fluorine atom?
1
What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10^-12 M?
2
cells require which of the following to make flagella and cilia
tubulin
Assume that acid rain has lowered the pH of a particular lake to pH 4.0. what is hydroxyl ion concentration of this lake
1 X 10^-10 mol of hydroxyl ion per liter of lake water.
A dietary calorie equals 1 kilocalorie. which of the following statements correctly defines 1 kilocalorie.
1,000 calories or the amount of heat required to raise the temperature of 1 kg of water by 1 degree celsius
Measurements show that the pH of a particular lake is 4.0. what is the hydrogen ion concentration
10 ^-4 M
Slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50L container of cold water. what would be the approximate increase in the temperature of the water?
10 degrees celsius
One liter of a solution of pH 2 has how many more hydrogen ions than 1L of a solution with a pH of 6
10,000
The nutritional info on a cereal box hows that one serving of dry cereal has 200 kilocalories. If one were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature of 20kg of water how many degrees celsius
10.0
Equal volumes 5ml of vinegar from a freshly opened bottle are added to each of the following solutions. After complete mixing, which of the mixtures will have the highest pH?
100 ml of household cleaner containing .5 M ammonia NH4
One liter of solution has a pH of 9 has how many more hydroxyl ions OH- than 1L of a solution of pH 4?
100,000
What is they hydrogen ion H+ concentration of a solution of pH 8?
10^-8
How many molecules of water are needed to completely hydrolyze a polymer that is 12 monomers long.
11
What is the pH of 1-millimolar NaOH solution?
11
A double stranded DNA molecule contains a total of 120 purines and 120 pyrimidines This molecule could be composed of.
120 molecules of cytosine and thymine
The atomic number of each atom is given to the left of each of the following elements. WHich of the following atoms has the same valence as carbon 12
14Si silicon
From its atomic number of 15, it is possible to predict that the phosphorus atom has
15 protons and 15 electrons
One mol of glucose molecular mass= 180 daltons is both
180 grams of glucose and 6.02X10^23 molecules of glucose.
When an ionic compound such as NaCl is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium and chlorine ions Na+ and Cl -. In contrast the atoms of covalently bonded molecules (glucose, sucrose, glycerol) dont dissociate when placed in aqueous solution. which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?
1L of 1.0 M NaCl
An atom has 6 electron sin its outer shell. How may unpaired electrons does it have
2
How many electron pairs are shared between carbon atoms in a molecule that has a formula C2H4
2
How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H4
2
In comparing covalent bonds and ionic bonds, which of the following would you expect? 1) An atom can form covalen bonds with multiple partner atoms, but only single ionic bond with a single partner atom.2) Covalent bonds and ionic bonds occupy opposite ends of a continuous spectrum from nearly equal to completely unequal sharing of electrons. 3) both involve electrical attraction between the electrons of one atom and the nucleus of the other atom
2
Which of these is false. 1) C, H, O, and N are the most abundant elements of living matter. 2) Some trace elements are very abundant on earth. 3)Virtually all organisms require the same elements in the same quantities. 4) Iron is an example of an element needed by all organisms. 5) Other than some trace elements, animals are mostly made up of the same elements as plants, in similar proportions.
3) Virtually all organisms require the same elements int he same quantities.
Which of the following statements is true about buffer solutions? 1)they maintain a constant pH when bases are added to them but not when acids are added to them 2) they maintain a constant pH when acids are added to them but not when bases are added to them 3) they maintain a relativley constant pH of approximately 7 when acids or bases are added to them 4) they maintain a relatively constant pH when either acids or bases are added to them 5) they are found only in living systems and biological fluids
4 maintain relatively constant pH when either acids or bases are added to them
The molecular weight of water is 18 daltons. What is the molarity of 1L of pure water?
55.6M
What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms.
6
You have a freshly prepared 1M solution of glucose in water. You carefully pour out a 100ml sample of that solution. How many glucose molecules are included in that 100 ml sample?
6.022X 10^22
You have a freshly prepared .1M solution of glucose in water. Each liter of this solution contains how many glucose molecules.
6.02X10^22
How many molecules of glycerol molecular mass 92 would be present in 1 L of a 1M glycerol solution?
6.02X10^23 molecules in 1 L
You have two beakers. One contains a solution of HCl ph=1. The other contains a solution of NaOH at ph=13. Into a third beaker you slowly pour 20 ml of HCl and 20 ml of NaOH after stirring the pH of the mixture will be
7
The atomic number of nitrogen is 7. Nitrogen 15 is heavier than nitrogen 14 because the atomic nucleus of nitrogen 15 contains how many neutrons.
8
We can represent atoms by listing the number of protons neutrons and electrons for example, 2p+; 2n0;; 2e- for helium. which of the folloiwng represents 18 O isotope of oxygen?
8p+, 10n 0, 8e-
How many molecules of glucose C6H12O6 molecular mass 180 daltons would be present in 90 grams of glucose?
90/180 X 6.02 X 10^23
Upon chemical analysis a particular polypeptide ws found to contain 100 amino acids. How many peptide bonds are present in this protein
99
A given solution contains .0001)10^-4) moles of hydrogen ions H+ per liter. Which of the following best describes this solution?
Acidic: will give H+ to weak acids. but accept H+ from strong acids
How would acidification of seawater affect marine organisms?
Acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell building animals
Oxygen has an atomic number of 8 and a mass number of 16. thus what is the atomic mass of an oxygen atom.
Approximately 16 daltons
Which of the following types of cells utilize DNA as their genetic material but dont have their DNA encased in a nuclear envelope
Archae
Carbon dioxide CO2 is readily soluble in water, according to the equation CO2 + H2O <> H2CO3. Carbonic acid is a weak acid. respiring cells release CO2 into bloodstream. What will be the effect on pH of blood as the blood first comes in contact with respiring cells?
Blood pH will decrease slightly
What factors are most important in determining which elements are most common in living matter?
Both relative abundances of the elements and the emergent properties of the compounds made from these elements.
About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter.
Carbon. Hydrogen, Nitrogen, and Oxygen
Which two functional groups are always found in amino acids
Carboxyl and amino
A carbon atom is most likely to form which of the folloiwng bonds with other atoms
Covalent bond
The molar mass of glucose is 180g/mol. Which of the following procedures should you carry out to make a 1 M solution of glucose.
Dissolve 180g of glucose in .8L of water and then add more water until the total volume of the solution is 1L
The molar mass of glucose is 180g/mol. Which of the following procedures should you carry out to make a 0.5M solution of glucose.
Dissolve 90g of glucose in small volume of water and then add more water until the total volume of water is 1L.
Why is each element unique and different from other elements in chemical properties?
Each element has a unique number of protons in its nucleus.
Which of the following correctly describes chemical equilibrium?
Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.
Which of the following produces and modifies polysaccharides that will be secreted.
Golgi apparatus
If an atom of sulfur atomic number 16 were allowed to react with atoms of hydrogen atomic number 1, which of the following molecules would be formed
H-S-H
Which of the following molecules contains the most polar covalent bond? H2 O2 CO2 H20 CH4
H20
Which of the following would be regarded as compounds? H20, O2 and CH4 H20 and O2 O2 and CH4 CH4 and O2 but NOT H20 H20 and CH4 but NOT O2
H20 and CH4 NOT O2
Know what a carbonyl functional group looks like
H2CO
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to forma compound hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.
H2S
Which type of bond must be broken for water to vaporize
HYDROGEN
Which type of interaction stabilizes the alpha helix of the beta pleated sheet structures of proteins?
HYDROGEN BONDS
Why does ice float in liquid water?
Hydrogen bonds stabilize and keep the molecules of ice farther apart than molecules of liquid water.
Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element thats required by humans and other vertebrates but not by other organisms such as bacteria or plants?
Iodine
The atomic number of neon is 10. Therefore which of the following is most correct about an atom of neon?
It has 8 electrons in its outer electron shell and it is inert
Which of the following takes place as an ice cube cools a drink
Kinetic energy in the drink decreases
The atomic number of chlorine is 17. The atomic number of magnesium is 12. What formula for magnesium chloride.
MgCl2
Molybdenum has an atomic number of 42. Several common isotopes exist with mass numbers of 92,94,95,96,97,98,100. Therefore which of the following can be true.
Molybdenum atoms can have between 50 and 58 neutrons.
what functional groups are present in all amino acids
NH2 CO2H
In Ammonium Chloride NH4Cl the anion is a single Chloride ion What is the cation of NH4Cl
NH4 with a charge of positive 1+
Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S will
NOT form hydrogen bonds with eachother
You have two beakers. One contains pure water, the other contains pure methanol. The covalent bonds of methanol molecules are nonpolar so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt into each beaker. Predict what will happen.
NaCl crystals will dissolve in water but not in methanol
Which of the following ionizes completely in solution and is considered to be a strong base.
NaOH
What results form an unequal sharing of electrons between atoms?
Polar covalent bonds
mass number =
Protons + neutrons
In what way are the elements in the same column of the periodic table the same?
Same number of electrons in their valence shell
Carbon 12 is the most common isotope of carbon and has an atomic mass of 12 daltons. A mole of carbon in naturally occurring coal weighs slightly more than 12 grams. why?
Some carbon atoms in nature have more neutrons
If a salamander relied on hydrogen bonds to cling to surfaces, what type of surface would cause the most problems for this animal?
Surface made with carbon and hydrogen atoms covalently bonded together.
Which statement is true of all atoms that are anions?
The atom has more electrons than protons
The precise weight of a mole of some pure elements like Si can vary slightly from the standart atomic mass, or even from sample to sample, WHy?
The element may have multiple isotopes and the isotopic composition may vary from sample to sample.`
The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen?
The nitrogen atom has mass number of 14 and atomic mass of 14 daltons.
Knowing just the atomic mass of an element allows inferences about which of the following.
The number of protons plus neutrons in the element.
A beaker contains 100 ml of NaOH solution at pH 13. A technician carefully pours into the beaker 10 ml of HCl at ph 1. Which of the folloiwng statements correctly describes the results of this mixing.
The pH of the beakers contents will decrease
Which of the following effects is produced by the high surface tension of water.
Water strider can walk across the surface of a small pond
Liquid water's high specific heat is mainly a consequence of the
absorption and release of heat when hydrogen bonds break
Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature.
absorption of heat by breaking hydrogen bonds
Which of the following is true for this reaction? 3H2 + N2 >< 2NH3
ammonia is being formed and decomposed
Electrons exist only at fixed levels of potential energy. However if an atom absorbs sufficient energy a possible result is that
an electron may move to an electron shell farther away from the nucleus.
which of these individuals is likely to be most successful in an evolutionary sense
an organism that dies after five days of life but leaves 10 offspring , all of whom survive to reproduce
A water sample from a hot thermal vent contained a single celled organism that had a cell wall but lacked a nucleus. What is its classification
archae
which of the following statements concerning cells of bacteria and archae is correct
archaea contain small membrane enclosed organelles Bacteria do not.
Atoms whose outer electron shells contain 8 electrons tend to
be both chemically inert and gaseous at room temperature
One idea to mitigate the effects of burning fossil fuels on atmospheric CO2 concentrations to pipe liquid CO2 into the ocean depths of 2500 feet or greater. At the high pressures at such depths CO2 is heavier that water. What potential effects might result from implementing such a scheme.
both increased acidity of the deep waters and changes in growth of bottom dwelling organisms with calcium carbonate shells.
About 25 of the 92 natural elements are known to be essential to life. Which 4 of these 25 elements make up approximately 96% of living matter.
carbon hydrogen nitrogen oxygen
On food packages to what does the term INSOLUBLE FIBER refer to
cellulose
A group of molecular biologists is trying to synthesize a new artificial compound to mimic the effects of a known hormone that influences sexual behavior. They have turned to you for advice. Which of the following compounds is most likely to mimic the effects of the hormone?
compound with the same 3D shape as part of the hormone
If the pH of a solution is decreased from 9 to 8 it meants that the
concentration of H+ has increased tenfold 10X and the concentration of OH- has decreased to one tenth what they were at pH 9.
What causes the shape of molecules of carbon and hydrogen
configuration of sp hybrid orbitals of electrons shared between the carbon and hydrogen atoms
Which bond or interaction would be difficult to disrupt when compounds are put into water?
covalent bonds
Which of the following is not considered to be a weak molecular interaction?
covalent bonds
What is the difference between covalent bonds and ionic bonds?
covalent bonds involve sharing of electrons between atoms. ionic bonds involve the electrical attraction between atoms
One of the buffers that contributes to pH stability in human blood is carbonic acid. H2CO3. Carbonic acid is a weak acid that dissociated into bicarbonate HCO3- and a hydrogen ion H+ thus, H3Co3 <> HCO3- + H+ If the pH of blood increases, one would expect?
decrease of concentration of H2CO3 and an increase in concentration of HCO3-.
Research indicates that acid precipitation can damage certain marine organisms by
decreasing the concentration of carbonate ions in oceans.
Buffers are substances that help resist shifts in pH by
donating H+ to a solution when bases are added and accepting H+ when acid are added.
Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia? NH3
each atom has a partial positive charge; the nitrogen atom has a partial negative charge.
why is each element unique and different from other elements with respect to its chemical properties
each element has a unique number of protons
What is the reason that a modern electron microscope TEM can resolve biological images to the subnanometer level, as opposed to the tens of nanometers achievable for the best super resolution light microscope?
electron beams have much shorter wavelengths than visible light
Van Der Waals interactions result when
electrons arent symmetrically distributed in a molecule
protons=
electrons or atomic number
The evolution of eukaryotic cells most likely involved
endosymbiosis of an aerobic bacterium in a larger host cell that embo-symbiont evolved into mitochondria
Which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH?
gastric juices with a pH of 2
Humans can digest starch but not cellulose because
humans have enzymes that can hydrolyze the alpha glycosidic linkages of starch but not glycosidic linkages of cellulose
In the methane molecule shown in the figure above, bonds have formed that include both the s orbital valence electrons of hydrogen atoms and the p orbital valence electrons of the carbon,. the electron orbitals in these bonds are said to be
hybrid orbitals
A strong acid like HCl
ionizes completely in an aqueous solution
Molybdenum has an atomic number of 42. Several common isotopes exist with mass numbers of 92,94,96,97,97, and 100. Therefore which of the following is true?
isotopes of molybdenum have between 50 and 58 neutrons and have different electron configurations.
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition.
lysosome
which of the following contains hydrolytic enzymes
lysosome
Which organelle is the primary site of ATP synthesis in eukaryotic cells
mitochondrion
which plant organelle cell holds its own dna and ribosomes
mitochondrion
Two atoms appear to have the same mass number. These atoms
must have the same number of protons + neutrons
Which of these provides evidence of the common ancestry of all life?
near universality of the genetic code
A solution contains .0000001(10^-7) moles of hydroxl ions (OH-) per liter. Which of the following best describes this solution?
neutral
Which of the following descriptions best fits the class of molecules known as nucleotides?
nitrogenous base and a phosphate group
When two atoms are equally electroneative they will interact to form what kind of bond
nonpolar covalent bonds
When two atoms are equally electronegative they will interact to form
nonpolar covalent bonds
Hydrophobic substances like vegetable oil are
nonpolar substances that repel water molecules
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules
Compared with 31P the radioactive isotope 32P has
one more neutron
Covalent bond is likely to be polar when
one of the atoms sharing electrons is much more electronegative than the other atom
A covalent chemical bond is one in which
outer-shell electrons of two atoms are shared to satisfactorily fill the outer electron shells of both atoms
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules
proteins.
Which of the following correctly describes any reaction that has reached chemical equilibrium?
rate of the forward reaction is equal to the rate of the reverse reaction
The bonding of two amino acid molecules to form a larger molecule requires the
release of a water molecule
Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?
release of heat by the formation of hydrogen bonds
Increased atmospheric CO2 concentrations might have what effect on seawater?
seawater will become more acidic and carbonate concentrations will decrease
the liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?
smooth ER
Which of these systems is least likely to be at chemical equilibrium
test tube of living cells
One of the buffers that contributes to pH stability in human blood is carbonic acid. H2CO3. Carbonic acid is a weak acid that dissociated into bicarbonate HCO3- and a hydrogen ion H+ thus, H3Co3 <> HCO3- + H+ If the pH of blood drops, one would expect?
the HCO3- to act as a base and remove the H+ ions withing the formation of H2CO3-.
If a solution has a pH of 7 this means that
the concentration of H+ ions in the water equals the concentration of OH- ions in the water
If the cytoplasm of a cell is at pH7 and the mitochondrial matrix is at pH 8 this means that
the concentration of H+ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix.
If the pH solution increased from 5 to 7 it means that
the concentration of OH- is 100 times greater than it was at the pH of 5
Consider two solutions; solution X has a pH of 4; solution Y has a pH of 7; From this information we can reasonably conclude that
the concentration of hydrogen ions in solution X is 1000 times as great as the concentration of hydrogen ions in solution Y
The partial negative charge in a molecule of water occurs because
the electrons shared between the oxygen and hydrogen atoms spend more time aroun oxygen atom's nucleus than around hydrogen atom's nucleus
In the term trace, the modifier trace means that
the element is required in very small amounts
Organisms interact with their environments, exchanging matter and energy. For example, plant, chloroplasts covert the energy of sunlight.
the energy of motion.
The reactivity of a atom arises from
the existence of unpaired electrons in the valence shell
the reactivity of an atom arises from
the existence of unpaired electrons in the valence shell
In the fractionation of homogenized cells using centrifugation, the primary factor that determines wether a specific cellular component ends up in the supernatant or the pellet is ?
the size and weight of the component
In what way are elements in the same column of the periodic the same.
they have the same number of electrons in their valence shell.
One difference between Carbon-12 and Carbon- 14 is that carbon -14 has
two more NEUTRONS than carbon 12
One difference between carbon 12 is that carbon 14 has
two more neutrons than carbon 12
What bonding or interaction is most likely to occur among a broad array of molecules of various types (polar, nonpolar, hydrophilic, hydrophobic)?
van der waals interactions
carbon skeleton is covalently bonded to both an amino acid group and a carboxyl group. When placed in water it.?
would function as both an acid and a base.
