Which of these classes of biological molecules does NOT include polymers?
nucleic acids
proteins
carbohydrates
lipids
What is the difference between an aldose sugar and a ketose sugar?
the position of the carbonyl group
the number of carbons
the position of the hydroxyl groups
one is a ring form, the other is a linear chain
What is the major structural difference between starch and glycogen?
The amount of branching that occurs in the molecule
the types of monosaccharide subunits in the molecules
the types of glycosidic linkages in the molecule
whether glucose is in the alpha or beta form
Which polysaccharide is an important component in the structure of many animals and fungi?
cellulose
chitin
amylose
amylopectin
What does the term insoluble fiber refer to on food packages?
polypeptides
starch
A molecule with the chemical formula C6H12O6 is probably a _____.
polysaccharide
fatty acid
hexose
monosaccharide
Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
polysacchardie
disaccharide
Starch and cellulose ____.
used for energy storage in plants
are cis-trans isomers of each other
are structural components of the plant cell wall
are polymers of glucose
Phospholipids and triglycerides both ____.
Have three fatty acids
have a phosphate
contain serine or some other organic compound
have a glycerol backbone
Which of the following is the best explanation for why vegetable oil is a liquid at room temperature while animal fats are solid?
animal fats have no amphipathic character
vegetable oil has longer fatty-acid tails than animal fats have
vegetable oil has fewer double bonds than animal fats
vegetable oil has more double bonds than animal fats
Saturated fatty acids ____.
have double bonds between carbon atoms of the fatty acids
are the principal molecules of lard and butter
are usually liquid at room temperature
are usually produced by plants
Steroids are considered to be lipids because they _____.
contribute to atherosclerosis
are essential components of cell membranes
are not soluble in water
are made of fatty acids
The molecule illustrated in the accompanying figure ____.
Will be liquid at room temperature
is a carbohydrate
stores genetic information
is a saturated fatty acid
A glycosidic linkage is analogous to which of the following proteins?
an amino group
beta-pleated sheet
a peptide bond
a disulfide bond
Which one of the following is NOT a component of each monomer used to make proteins?
phosphorus atom, P
side chain, R
amino functional group, NH2
carboxyl group, COOH
What component of amino acid structure varies among dfifferent amino acids?
the components of the R-group
the presence of a central C atom
the long carbon-hydrogen tails of the molecule
the glycerol molecule that forms the backbone of the amino acid
You disrupt all hydrogen bonds in a protein. What level of structure will be preserved?
primary structure
secondary structure
tertiary structure
quaternary structure
All of the following contain amino acids EXCEPT ____.
hemoglobin
enzymes
insulin
cholesterol
Which level of protein structure do the α-helix and the β-pleated sheet represent?
primary
secondary
tertiary
quaternary
Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides?
diabetes mellitus only
Parkinson's only
Alzheimer's only
Alzheimer's and Parkinson's only
What is the term used for a protein molecule that assists in the proper folding of other proteins?
denaturing protein
chaperonin
renaturing protein
tertiary protein
Nucleic acids are polymers made up of which of the following monomers?
sugars
amino acids
nitrogenous bases
nucleotides
Which of the following includes all of the pyrimidines found in RNA and DNA?
cytosine, uracil, and guanine
cytosine and uracil
cytosine, uracil, and thymine
cytosine and thymine
One of the primary functions of RNA molecules is to _____.
transmit genetic information to offspring
make a copy of itself, thus ensuring genetic continuity
function in the synthesis of proteins
act as a pattern or blueprint to form DNA
Which of the following descriptions best fits the class of molecules known as nucleotides?
a nitrogenous base, a phosphate group, and a sugar
a nitrogenous base and a sugar
a nitrogenous base and a phosphate group
a sugar and a purine or pyrimidine
The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is a _____.
ribosome
microfilament
mitochondrion
microtubule
The advantage of light microscopy over electron microscopy is that _____.
light microscopy provides for higher resolving power than electron microscopy
light microscopy provides higher contrast than electron microscopy
light microscopy allows one to view dynamic processes in living cells
light microscopy provides for higher magnification than electron microscopy
What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?
transmission electron microscopy
standard light microscopy
scanning electron microscopy
A newspaper ad for a local toy store indicates that an inexpensive toy microscope available for a small child is able to magnify specimens nearly as much as the more costly microscope available in your college lab. What is the primary reason for the price difference?
The toy microscope does not have the same fine control for focus of the specimen.
The college microscope produces greater contrast in the specimens.
The toy microscope usually uses a different wavelength of light source.
The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images.
All of the following are part of a prokaryotic cell EXCEPT _____.
a cell wall
an endoplasmic reticulum
a plasma membrane
ribosomes
Cell size is limited by _____.
the size of the endomembrane system
the surface area of mitochondria in the cytoplasm
the number of proteins within the plasma membrane
surface to volume ratios
Which of the following is a major difference between prokaryotic cells and eukaryotic cells?
Prokaryotes have cells while eukaryotes do not.
Eukaryotic cells have more intracellular organelles than prokaryotes.
Prokaryotes are not able to carry out aerobic respiration, relying instead on anaerobic metabolism.
Prokaryotes are generally larger than eukaryotes.
Prokaryotes are classified as belonging to two different domains. What are the domains?
Bacteria and Protista
Bacteria and Archaea
Bacteria and Eukarya
Archaea and Protista
Which structure is common to plant and animal cells?
central vacuole
centriole
chloroplast
Which of the following is present in a prokaryotic cell?
ER
Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?
mRNA
DNA
phospholipids
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
glycogen
A cell with a predominance of free ribosomes is most likely _____.
enlarging its vacuole
primarily producing proteins for secretion
constructing an extensive cell wall or extracellular matrix
primarily producing proteins in the cytosol
Which organelle often takes up much of the volume of a plant cell?
vacuole
lysosome
peroxisome
Golgi apparatus
A cell with an extensive area of smooth endoplasmic reticulum is specialized to _____.
import and export protein molecules
synthesize large quantities of lipids
play a role in storage
actively export protein molecules
Which structure is NOT part of the endomembrane system?
plasma membrane
nuclear envelope
Which structure is the site of the synthesis of proteins that may be exported from the cell?
plasmodesmata
free cytoplasmic ribosomes
Golgi vesicles
rough ER
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 the following produces and modifies polysaccharides that will be secreted?
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
Golgi → ER → lysosome
ER → Golgi → nucleus
ER → lysosomes → vesicles that fuse with plasma membrane
ER → Golgi → vesicles that fuse with plasma membrane
Which organelle is the primary site of ATP synthesis in eukaryotic cells?
Thylakoids, DNA, and ribosomes are all components found in _____.
lysosomes
mitochondria
nuclei
chloroplasts
Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely involved in this disease?
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?
cellulose fibers in the cell wall
free ribosomes and ribosomes attached to the ER
components of the cytoskeleton
membrane proteins of the inner nuclear envelope
Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to _____.
migrate by amoeboid movement
form cleavage furrows during cell division
separate chromosomes during cell division
maintain the shape of the nucleus
For a protein to be an integral membrane protein, it would have to be _____.
exposed on only one surface of the membrane
hydrophobic
amphipathic, with at least one hydrophobic region
hydrophilic
According to the fluid mosaic model of cell membranes, phospholipids _____.
frequently flip-flop from one side of the membrane to the other
can move laterally along the plane of the membrane
have hydrophilic tails in the interior of the membrane
occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane
The membranes of winter wheat are able to remain fluid when it is extremely cold by _____.
cotransport of glucose and hydrogen
decreasing the number of hydrophobic proteins in the membrane
increasing the percentage of cholesterol molecules in the membrane
increasing the percentage of unsaturated phospholipids in the membrane
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At higher temperatures, these regions _____.
are more fluid than the surrounding membrane
have higher rates of lateral diffusion of lipids and proteins into and out of these regions
are less fluid than the surrounding membrane
detach from the plasma membrane and clog arteries
An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
attaching the plasma membrane to the cytoskeleton
transporting ions against an electrochemical gradient
establishing a diffusion barrier to charged molecules
cell-cell recognition
Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all?
peripheral proteins
integral proteins
transmembrane proteins
All of these are embedded in the hydrophobic portion of the lipid bilayer.
Which component is a peripheral protein?
A
B
C
D
Which component is cholesterol?
E
Which component is a protein fiber of the extracellular matrix?
Which component is a microfilament (actin filament) of the cytoskeleton?
Which component is a glycolipid?
The presence of cholesterol in the plasma membranes
enables the membrane to stay fluid more easily when cell temperature drops
enables the membrane to stay more rigid when cell temperature increases (or body temperature)
enables the cell to add hydrogen atoms to unsaturated phospholipids
a and b
What kinds of molecules pass through a cell membrane most easily?
large and hydrophobic
large polar
small and hydrophobic
ionic
Which of the following most accurately describes selective permeability?
Only certain molecules can cross a cell membrane.
There must be a concentration gradient for molecules to pass through a membrane.
Lipid-soluble molecules pass through a membrane.
An input of energy is required for transport.
Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
glucose
an amino acid
CO2
K+
Which of the following allows water to move much faster across cell membranes?
ATP
the sodium-potassium pump
aquaporins
Diffusion _____.
is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
requires an expenditure of energy by the cell
is very rapid over long distances
requires integral proteins in the cell membrane
Which of the following processes includes all others?
osmosis
facilitated diffusion
passive transport
transport of an ion down its electrochemical gradient
Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water_____.
is hypertonic and the salt solution is hypotonic to the cells of the celery stalks
and the salt solution are both hypertonic to the cells of the celery stalks
is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
is isotonic and the salt solution is hypertonic to the cells of the celery stalks
What will happen to a red blood cell (RBC), which has an internal ion concentration of about 0.9 percent, if it is placed into a beaker of pure water?
The cell will remain the same size because the solution outside the cell is isotonic.
The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.
The cell would shrink because the water in the beaker is hypertonic relative to the cytoplasm of the RBC.
The cell would shrink because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.
The sodium-potassium pump is called an electrogenic pump because it _____.
ionizes sodium and potassium atoms
is used to drive the transport of other molecules against a concentration gradient
contributes to the membrane potential
pumps equal quantities of Na+ and K+ across the membrane
The voltage across a membrane is called the _____.
membrane potential
chemical gradient
electrochemical gradient
osmotic potential
Ions diffuse across membranes through specific ion channels down _____.
their chemical gradients
their electrochemical gradients
the electrical gradients
their concentration gradients
Which of the following would increase the electrochemical gradient across a membrane?
a proton pump
a sucrose-proton cotransporter
a potassium channel
both a proton pump and a potassium channel
The force driving simple diffusion is _____, while the energy source for active transport is _____.
phosphorylated protein carriers; ATP
the concentration gradient; ADP
transmembrane pumps; electron transport
the concentration gradient; ATP
In eukaryotic cells, chromosomes are composed of _____.
DNA and RNA
DNA only
DNA and phospholipids
DNA and proteins
What is the final result of mitosis in a human?
genetically different 2n somatic cells
genetically identical 2n somatic cells
genetically identical 2n gamete cells
genetically identical 1n somatic cells
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
32
64
16
8
If there are 20 duplicated chromosomes in a cell, how many centromeres are there?
30
20
40
10
Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5 times more DNA than G1 phase cells. The cells of this group are _____.
in the G2 phase of the cell cycle
in the S phase of the cell cycle
between the G1 and S phases in the cell cycle
in the M phase of the cell cycle
The first gap in the cell cycle (G1) corresponds to _____.
normal growth and cell function
the phase between DNA replication and the M phase
the beginning of mitosis
the phase in which DNA is being replicated
The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the _____.
centrosome
microtubulere
kinetochore
centromere
The mitotic spindle is a microtubular structure that is involved in _____.
separation of sister chromatids
dissolving the nuclear membrane
triggering the compaction and condensation of chromosomes
splitting of the cell (cytokinesis) following mitosis
Metaphase is characterized by _____.
splitting of the centromeres
cytokinesis
aligning of chromosomes on the equator
At which phase are centrioles beginning to move apart in animal cells?
prophase
metaphase
prometaphase
anaphase
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____.
chromatid assembly
the structure of the mitotic spindle
formation of the centrioles
The beginning of anaphase is indicated by which of the following?
Spindle microtubules begin to polymerize.
Cohesin attaches the sister chromatids to each other.
Chromatids lose their kinetochores.
Cohesin is cleaved enzymatically.
During which phase of mitosis do the chromatids become chromosomes?
telophase
Which of the following does NOT occur during mitosis?
separation of the spindle poles
condensation of the chromosomes
spindle formation
replication of the DNA
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
cell elongation during anaphase
spindle attachment to kinetochores
Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?
a microtubule-organizing center
intact centromeres
synthesis of cohesin
ATP as an energy source
Neurons and some other specialized cells divide infrequently because they _____.
can no longer bind Cdk to cyclin
no longer have active nuclei
show a drop in MPF concentration
have entered into G0
MPF is a dimer consisting of _____.
ATP synthetase and a protease
cyclin and tubulin
a growth factor and mitotic factor
cyclin and a cyclin-dependent kinase
What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells enter mitosis.
Cell differentiation is triggered.
Nothing happens.
The cells undergo meiosis.
The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.
Which of the following is released by platelets in the vicinity of an injury?
PDGF
MPF
cyclin
Cdk
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
Which of the following is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active?
The cyclin component of MPF is destroyed toward the end of which phase?
G2
M
S
G1
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?
lack of appropriate cell death
changes in the order of cell cycle stages
inability to form spindles
inability of chromosomes to meet at the metaphase plate
Bitte warte - es wird geladen…