Which kind of cells have their DNA in a single, circular molecule of DNA devoid of any surrounding membrane or histone proteins?
- flowering plants
Plant cells often have a large membrane-bound sac that is used for storing water and other substances. This organelle is called a
- golgi body
- central vacuole
Membrane-bound organelles that contain powerful digestive enzymes are known as
Flattened sacks of membranes apparently involved in the packaging and export of molecules synthesized elsewhere in the cell are know as
- golgi bodies
- pinocytic vesicles
Mammalian blood contains the equivalent of 0.15M NaCl. Seawater contains the equivalent of 0.45M NaCl. What will happen if red blood cells are transferred to seawater?
- the blood cells will expend ATP for active transport of NaCl into the cytoplasm
- water will leave the cells, causing them to shrivel and collapse
- NaCl will passively diffuse into the red blood cells
- NaCl will be exported from the red blood cells by facilitated diffusion.
- the blood cells will take up water, swell, and eventually burst
water will leave the cells, causing them to shrivel and collapse
Receptor-mediated endocytosis (RME) is different from pinocytosis or phagocytosis because
- phagocytosis takes in only liquid matter, while RME takes in solids
- RME is not specify and takes in any solid matter
- pinocytosis takes in only solid matter, while RME takes in liquid
- phagocytosis is designed to take in only living organisms
- RME depends on specific receptor proteins for specific molecules that trigger endocytosis
RME is not specify and takes in any solid matter
The "powerhouse" organelle involved in the oxygen-requiring process by which the energy in macromolecules is converted/stored into ATP is the
Which of the following are capable of converting light energy to chemical energy (ultimately in the form of carbohydrates)?
- golgi bodies
Lipids are the only class of macromolecules that contain
- amino acids
- nucleic acids
- fatty acids
- phosphate groups
Biological membranes contain bilayers of which of the following lipids?
Prokaryotic cells in the genus Sulfolbus are in the Domain Archaea, and are commonly found in geothermal environments, with an optimum growth temperature of above 80 C. Which of the following features is most likely to allow Archaea to thrive at such temperatures?
- archaea use the heat from their environment to produce ATP
- archaea are not adaptable to changing environmental temperatures
- archaeal membranes contain high concentrations of saturated lipids
- archaeal membranes contain low concentrations of saturated lipids
archaeal membranes contain high concentrations of saturated lipids
The tendency for atom to move from areas of high concentration towards areas of low concentration is called:
- carrier facilited
- active transport
A cell is placed into a beaker containing a sugar solution; water leaves the cell, the cell membrane collapses and shrinks around the cell contents. Which statement best describes the relative solute concentrations in the cell and in the surrounding solution?
- the concentration of solutes inside the cell is the same as the concentration in the outside solution
- the concentration of solutes inside the cell is greater than the concentration in the outside solution
- the concentration of solutes inside the cells is less than the concentration in the outside solution
- none of the above
the concentration of solutes inside the cells is less than the concentration in the outside solution
in the original Star Trek episode, "The Immunity Syndrome", a gigantic single celled space organism destroys planets and ingests the debris of solar systems to gain energy for it's survival. The organism is destroyed by Mr.Spock by exploding a shuttlecraft inside the nucleus of the space organism. Which term best describes the space organism
- prokaryotic, photosynthetic
- prokaryotic, heterotrophic
- eukaryotic, photosynthetic
- eukaryotic, heterotrophic
- prokaryotic, parasitic
Which of the following is true about enzymes?
- enzymes increase the rate of chemical reaction by lowering activation energy barriers.
- enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered
- enzyme function is independent of physical and chemical environmental factors such as pH and temperatures
- enzymes are consumed in reactions and must be replaced as the reaction proceeds
enzymes increase the rate of chemical reaction by lowering activation energy barriers.
A patient is brough to the hospital severely dehydrated. An IV of isotonic saline is started immediately. Why doesn't the doctor order an IV of pure, sterile fresh water?
- an IV of pure, freshwater would cause water to leave the cells, causing them to collapse
- the patient needs the nutrients available in normal saline
- an IV of pure, freshwater would cause blood cells to swell and eventually burst
- normal saline is more economical than pure water
- pure, freshwater may be contaminated by bacteria
an IV of pure, freshwater would cause blood cells to swell and eventually burst
The second law of thermodynamics states that
- energy is not created or destroyed
- disorder in the universe constantly increases
- disorder in the universe constantly decreases
- energy is not created but can be destroyed
- we are all water, same as it ever was
disorder in the universe constantly increases
Which of the following is (are) the major role (s) of proteins in a biological membrane?
- transporter of ions or large molecules
- adhesion between adjacent cells
- receptor for enzymes or other info. at the cells surface
- attachment to the cytoskeleton
- all of the above
all of the above
The hydrolysis of sucrose to glucose and fructose is exergonic. However, if you dissolve sucrose in water and keep the solution overnight room temperature, there is no detectable conversion to glucose and fructose in the morning. Why?
- the change in free energy of the reaction is neutral
- the activation energy is high enough to prevent the reaction from occurring very often in the solution
- the change in free energy of the reaction is positive
- this is a condensation reaction
- this free energy of the product is higher than the free energy of the reactants
the activation energy is high enough to prevent the reaction from occurring very often in the solution
facilitated diffusion is an important method for cells in obtaining necessary molecules and removing other ones. Requirements for facilitated diffusion include which of the following?
- the carrier molecule must be specific to the molecule that is transported. the direction of movement is always with the concentration gradient, never against the gradient
- the carrier molecule is nonspecific to the molecule that is transported. the direction of movement is always with the concentration gradient, never against the gradient
- the carrier molecule is non specific to the molecule that is transported. the direction of movement is always against the concentration gradient, never with the gradient.
the carrier molecule must be specific to the molecule that is transported. the direction of movement is always with the concentration gradient, never against the gradient
Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism?
Glucose is a six-carbon sugar that diffuses slowly through artificial membranes. The cells lining the small intestine, however, rapidly move glucose from the the gut into their cytoplasm. This occurs even when the gut concentrations of glucose are lower than the glucose concentrations in intestinal cell cytoplasm. Using this information, which transport mechanism described by this situation is most likely responsible for the glucose transport in cells?
- active transport
- simple diffusion
- facilitated diffusion
An organism with a cell wall would most likely be unable to take in materials through
- facilitated diffusion
- active transport
An enzyme is
- an organic (protein) catalyst
- lipid catalyst
- a metal ion catalyst
- a detergent
- a phospholipid
an organic (protein) catalyst
When the size of a cell increases, the surface area/volume ratio
- decreases initially and then begins to increase
- remains the same
- increases initially and then begins to decrease
Whenever energy is transformed, for example from gasoline to kinetic energy of a speeding car, there is always an increase in
- free energy of the system
- enthalpy the universe
- car accidents
- free energy of the universe
Which of the following metabolic process can occur without a net influx of energy from some other process?
- APD + Pi -> ATP+H2O
- 6 CO2+ 6 H20 -> C6H12O6+ 6 O2
- glucose+fructose -> sucrose
- C6H12O6+6 O2 -> 6 CO2+6 H2O
- amino acids -> protein
C6H12O6+6 O2 -> 6 CO2+6 H2O
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier knowns as the reactions
- equilibrium point
- free-energy content
- endothermic level
- activation energy
An enzyme is __ when it loses it's native conformation and it's biological activity; it can happen due to changes in temperature or pH.
Which of the following is a statement of the first law of thermodynamics?
- kinetic energy is stored energy that results from the specific arrangements of matter
- the entropy of the universe is decreasing
- energy cannot be created or destroyed
- the entropy of the universe is constant
- energy cannot be transferred of transformed
energy cannot be created or destroyed
Which of these is exhibiting kinetic energy?
- a rock on a mountain ledge
- a person sitting on a couch while watching tv
- the high-energy phosphate bonds of a molecule of ATP
- an archer with a flexed bow
- a space station orbiting Earth
a space station orbiting earth
Which of the following is an example of potential rather than kinetic energy?
- water rushing over Niagara Falls
- the muscle contractions of a person mowing grass
- a molecule of glucose
- the flight of an insect foraging for food
- light flashes emitted by a firefly
a molecule of glucose
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
- it is transported to specific organs such as the brain
- it is used to generate ADP from nucleotide precursors
- it is used to power yet more cellular work
- it is used to store energy as more ATP
- it is lost to the environment as increased kinetic energy in molecules
it is lost to the environment as increased kinetic energy in molecules
Which of the following is (are) true for anabolic pathways?
- they are usually highly spontaneous chemical reactions
- they release energy as the degrade polymers to monomers
- they do not depend on enzymes
- they consume energy to increase the entropy of the organism and it's environment
- they consume energy to build up polymers from monomers
they consume energy to build up polymers from monomers
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At high temperatures, these regions
- are less fluid than the surrounding membrane
- have higher rates of lateral diffusion of lipids and proteins into and out of these regions
- are more fluid than the surrounding membrane
- detach from the plasma membrane and clog arteries
- are able to flip from inside to outside
are less fluid than the surrounding membrane