130 terms

AP Biology Midterm

Which four elements make up appx. 96% of living matter?
Carbon, Oxygen, Hydrogen, Nitrogen
What is a trace element required by humans and other vertebrates?
What indicates the number of protons in an atom's nucleus?
Atomic number
To find the mass number of an element, add _____ and _____.
Protons & neutrons
What is the appx. mass of an atom with 16 neutrons, 15 protons, and 15 electrons?
31 daltons
Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom must have
20 protons
Different atomic forms of an element that contain the same number of protons but a different number of neutrons are called ...
The atomic number of carbon is 6. Carbon-14 is heavier than carbon-12 because the nucleus of carbon-14 contains ______ neutrons.
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 out from the nucleus.
The atomic number of neon is 10. Therefore, what is true about an atom of neon?
It has 8 electrons in its outer shell and is inert.
What does the reactivity of an atom depend on?
the number is unpaired electrons in its valence shell
Atoms whose outer shells contain 8 electrons tend to
be stable and chemically nonreactive, or inert.
What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen?
What is the maximum number of electrons in a 2p orbital of an atom?
A molecule of CO2 is formed when one atom of carbon (atomic number ) is covalently bonded with two atoms of oxygen (atomic number 8). What is the total number of electron pairs that must be shared between the carbon atom and the oxygen atoms in order to complete the outer shell of all three atoms?
Nitrogen is much more electronegative than hydrogen. Which of the following statements is correct about the atoms in ammonia (NH3)?
Each hydrogen has a partial positive charge.
When two atoms are equally electronegative, they will react to form
nonpolar covalent bonds.
What results from an unequal sharing of electrons between atoms?
a polar covalent bond
Which of the following best describes chemical equilibrium?
Forward and reverse reactions continue with no effect on the concentration of the reactants and products.
If your blood pH is 7.8, what is the hydrogen ion concentration in your blood?
1.58 x 10^-8
How many grams of NaOH are needed to produce a 200 mL of a .1 M NaOH solution?
.8 grams NaOH
How do highly electronegative elements affect macromolecules' behavior?
Makes it polar and soluble
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by....
polar covalent bonds
The slight negative charge at one end of one water molecule is attraced to the slight positive charge of another water molecule to form a _____ bond.
What do cohesion, surface tension, and adhesion have in common with reference to water?
All are properties related to hydrogen bonding.
What happens when an ice cube cools a drink?
Kinetic energy in the drink decreases.
Water's high specific heat is mainly a consequence of the...
absorption and release of heat when hydrogen bonds break and form.
Which bonds must be broken for water to vaporize?
hydrogen bonds
Desert rabbits are adapted to the warm climate because their large ears aid in the removal of heat due to the
high heat of vaporization of water
The formation of ice during colder weather helps moderate the seasonal transition to winter. This is because
the formation of hydrogen bonds releases heat
Temperate usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?
the release of heat by the formation of hydrogen bonds
At what temperature is water at its densest?
Hydrophobic substances such as vegetable oil are
nonpolar substances that repel water molecules
How many molecules of glucose (C6H12O6 molecular mass = 180 daltons) would be present in one mole of glucose?
6.02 x 10^23
Recall that when sodium chloride (NaCl) is placed in water the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g, glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest concentration of particles (molecules of ions)?
1.0 M MgCl2
The molecular mass of glucose is 180 g. To make a 1 M solution of glucose, you should do what?
Dissolve 180 g of glucose in water, and then ass more water until the total volume of the solution is 1 L.
Which of the following ionizes completely in solution and is considered to be a strong acid?
Which of the following ionizes completely in solution and is considered to be a strong base?
If the pH of a solution is decreased from 9 to 8, its means that the...
concentration of H+ has increased 10 times what it was at pH 9 and the concentration of OH- has decreased 10 times what it was at pH 9.
Buffers are substances that help resist shifts in pH by
donating H+ to a solution when they've been depleted and accepted H+ when they are in excess.
Who refuted the concept of vitalism?
Miller's experiments with ancient atmospheres
Which properties of the carbon atom give it compatability with a greater number of different elements than any other type of atom?
Carbon has a valence of 4.
What type of bonds does carbon have a tendency to form?
What is the major reason why hydrocarbons are not soluble in water?
The majority of their bonds are nonpolar covalent carbon-hydrogen linkages.
Research suggests that side effects from ritalin may be caused my contamination of enentiomers, or molecules that are
mirror images of one another.
Hydroxyl groups
make molecule polar
What is a carbonyl group?
a carbon atom joined to an oxygen by a double covalent bond
What is a carboxyl group?
a carbon atom double bonded to an Oxygen and single bonded to an OH
Which is a false statement concerning amino groups?
They are nonpolar.
Which two functional groups are always found in amino acids?
carboxyl and amino
Amino acids are acids because they always posess what functional group?
A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so?
Which functional groups can act as acids?
Carboxyl and phosphate
What functional group helps stabilize proteins?
Sulfhydryl (thiol)
What is a hydroxyl group?
-OH (alcohols)
What do phosphate groups do?
transfer energy between organic molecules
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
Which of the following statements correctly describes catabolic pathways?
They release energy as they degrade polymers to monomers.
Which of the following is true of anabolic pathways?
They are highly regulated and consume energy to build polymers from monomers.
Where does the Calvin Cycle take place?
the stroma of the chloroplast
During photosynthesis, visible light has enough energy to..
excite electrons.
Why are the absorption spectrums for photosynthesis different?
Other pigments absorb light in addition to chlorophyll a.
In the thylakoid membranes, what is the main role of the antenna pigment molecules?
harvest photons and transfer light energy to the reaction center chlorophyll
The reaction center chlorophyll of photosystem I is known as p700 because
this pigment is best at absorbing light w a wavelength of 700 nm
What does not occur in the light reactions of photosynthesis?
Carbon dioxide is incorporated into PGA
Which statement regarding the events of photosystem II is false?
The p680 chlorophyll donates a pair of protons to NADPH
All of the following are directly associated with photosystem II except
NADP+ reductase
What are the products of noncyclic photophosphorylation?
What does cyclic electron flow in the chloroplast product?
Assume a thylakoid is somehow punctured. This damage will have the most direct effect on
the synthesis of ATP (electron transport chain)
What does the chemiosmotic process in chloroplasts involve?
establishment of a proton gradient
Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transderred in the dark to a ph-8 solution. What would be likely to happen?
The isolated chloroplasts will make ATP.
In a plant cell, where are the ATP synthase complexes located?
thylakoid & inner mitochondrial membranes
In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrance space, whereas in chloroplasts, chemiosmosis translocates protons from
the stroma into the thylakoid space
When does the synthesis of ATP by the chemiosmotic mechanism occur?
both photosynthesis and respiration
When does the reduction of oxygen to form water occur?
When does the generation of proton gradients across membranes occur?
both photosynthesis and respiration
What is required in the Calvin Cycle?
What is a chromatid?
a replicated chromosome
If there are 20 chromatids in a cell, how many centromeres are there?
Two centromeres are arranged at opposite poles of the cell.
Centrioles begin to move apart in animal cells
Longest mitotic stage
Centromeres uncouple, sister chromatids are seperated, and two new chromosomes move to opposite poles of the cell
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, which stage will mitosis be arrested?
All of the following occur during prophase of mitosis in animals except:
chromosomes are duplicated
It there are 20 centromeres in a cell at anaphase, how many chromosomes will there be in each daughter cell following cytokinesis?
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
If a cell has 8 chromosomes at metaphase of mitosis, how many will it have during anaphase?
If a cell completed mitosis but not cytokinesis, the result would be a cell with
two nuclei.
How do the daughter cells at the end of mitosis and cyotkinesis compare with their parent cell when it was in G1 of the cell cycle?
The daughter cells have the same number of chromosomes and same amound of DNA.
Which of the following are primarily responsible for cytokinesis in plant cells?
Golgi-derived vesicles
Chromosomes first become visible during _____ of mitosis.
In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?
dinoflagellates & diatoms
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3-6 picograms per nucleus. in which stage of the cell cycle was the nucleus with 6 picograms of DNA?
By examining a karyotype, it is possible to determine
which is a gametophyte/sporophyte and the sex of an animal.
At which stage of mitosis are chromosomes photographed in preparation for a karyotype?
If a liver cells of an animal have 24 chromosomes, how many does its sperm have?
Which of the following is true of a species that has a chromosome number of 2n = 16?
There are 8 homologous pairs.
Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?
a female somatic cell
In animals, meiosis results in gametes, and fertilization results in
Referring to a plant sexual life sycle, which of the following terms describes the process that leads directly to the formation of gametes?
gametophyte mitosis
Which of the following is an example of alternation of generations?
A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain.
Which of the following is missing from the life cycle progression shown below? sporophyte-meiosis-spore-________-gametophyte-mitosis-gametes-fertilization-zygote
After telophase I of meiosis, the chromosomal makeup of each daughter cell is
halpoid, and the chromosomes are composed of two chromatids
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?
they have half the number of chromosomes and 1/4th the DNA
When does the synaptonemal complex disappear?
late prophase of meiosis I
Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?
crossing over
Tetrads of chromosomes are aligned at the center of the cell, independent assortment soon follows.
Metaphase I
Synapsis of homologous pairs occurs, crossing over may occur.
Prophase I
Centromeres of sister chromatids uncouple and chromatids seperate.
Anaphase II
Homologous chromosomes synapse and crossing over occurs.
Prophase I
Which of the following occurs in meiosis but not in mitosis?
synapsis and alignment of tetrads at metaphase plate
When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?
The viral proteins will be radioactive
Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that
the relative proportion of each of the four bases differed among species, and the amount of A=T and C=G
What kind of chemical bond is found between paired bases of the DNA double helix?
Which of the following statements is false when comparing prokaryotes with eukaryotes?
Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.
Which enzyme catalyzes the elongation of a DNA strand in the 5'-3' direction?
DNA polymerase
removed the RNA nucleotides from primer and adds DNA nucleotides to the 3' end of okazaki fragments
DNA polymerase I
seperates the DNA strands during replication
synthesizes short RNA segments
DNA-cutting enzymes used in the repair of DNA damage
The leading/lagging strands differ in that
The leading strang is synthesized in the same direction as the movement of the replication fork, and the lagging strang it synthesized in the opposite direction. the leading strand is also synthesized continuously
What is primer made of?
A eukaryotic cell lacking telomerase would
undergo a reduction in chromosome length.
What is a similarly between DNA and RNA?
nucleotides consisting of a phosphate, sugar, and nitrogenous base
Using RNA as a template for protein synthesis is advantageous because
RNA is an expendable copy, and many mRNA molecules can be transcribed from a single gene
Which of the following are transcribed from DNA
exons & rRNA
Which of the following is not a part of the eukaryotic transcription initiation complex?
RNA polymerase moves along the template strand in the _____ direction and adds nucleotides to the ____ end.
3'---5'; 3'