Practice Quiz #2
In humans, the diploid number of chromosomes is
46
If we inspect most cell membranes in a living human body, we would find a nearly continuous flow of substances back and forth across the plasma membrane. Which of the following explains this continuous flow?
Cell metabolism is constantly using up oxygen and raw materials; this lowers their concentration, so more will diffuse into the cell.
The chromatids are held together at a region called
Centromere
Which of the following molecules add stiffness and strength to the plasma membrane?
Cholesterol
Which of the following molecules is an enzyme?
Lipase
Which statement is true concerning movement of molecules across the cell membrane?
Lipid molecules pass through easily.
In which stage of mitosis do the chromosomes line up in the center of the cell?
Metaphase
In a coupled reaction, some of the energy released in one reaction is used to drive another reaction forward.
True
Less energy is needed to bring about a reaction when an enzyme is present.
True
Which is a correct example of tonicity?
Turgor pressure is created when a plant cell swells in a hypotonic solution.
ATP contains
an adenine base, a ribose sugar, and three phosphate groups.
During which phases of mitosis do the chromosomes look like Xs?
prophase, metaphase
Most enzymes are
protein molecules
According to the fluid-mosaic model of membrane structure
proteins float inside or within the phospholipid bilayer.
Which of the following is a correct association?
sister chromatids-two identical chromosome strands still attached at the centromere
If the total number of chromosomes in a cell is six, then after mitosis there will be
six chromosomes in each daughter cell.
The reason an increase in substrate concentration does not increase the reaction rate indefinitely is because
the active site will become saturated with substrate and the enzyme will not be able to go any faster.
Permeability refers to
the extent to which a membrane allows a substance to pass through.
Dead plants seen alongside a salted roadway died because the salt solution caused the cells to
undergo plasmolysis.
A cell placed in a hypotonic solution will
Gain water
If you have a 10% sugar solution and a 35% sugar solution, the 10% solution is _____________ compared to the 35% solution.
Hypotonic
During which stage of the cell cycle do the chromosomes duplicate?
Interphase
Macrophages, a type of white blood cells, are able to remove bacteria from our bloodstream and tissues by
phagocytosis.
Which of the following are functions of the plasma membrane? Select all that apply.
-It separates the internal environment of the cell from the external environment. -It regulates the entrance and exit of molecules to and from the cell. -It serves as a site for protein synthesis. -It serves as the site for photosynthesis in plant cells.
The various uses of ATP include
-moving substances into a cell. -transport work -mechanical work -chemical work
In the emergency room, saline solutions are often run into a person's vein. The saline solution must be
0.9% NaCl.
If 0.9% NaCl were isotonic to a cell, then
1.0% would be hypertonic to the cell.
Which of the following refers to materials only leaving the cell?
Exocytosis
ATP can be broken down into
ADP plus phosphate plus energy.
When a substance moves from an area of low concentration to an area of high concentration while using energy, the process is termed
Active Transport
While eating a container of yogurt, you have to leave, so you store the yogurt in the refrigerator. A day later you return and find the surface of the yogurt is no longer smooth but has broken into several liquified products. You correctly guess that enzymes from your saliva, via the spoon, have continued digesting the yogurt in your absence. What will happen over time?
As long as the enzyme is not denatured by environmental conditions, the reaction will continue until all of the substrate is used up.
Which of the following is an example of chemical work within a cell?
Building a protein
A student sitting in the back row opened a bottle of foul-smelling perfume and dabbed it on her wrists. One by one (beginning from the back of the room), the students began to cough due to the foul smell. This phenomenon was due to
Diffusion
Which of the following statements is true concerning enzymatic activity?
Enzyme activity increases as substrate concentration increases until the maximum rate is achieved.
The pressure that is generated when water flows through a differentially permeable membrane is termed
Osmotic Pressure
During what stage of mitosis does the nuclear envelope disappear and the chromosomes become distinct?
Prophase
The nuclear membrane reappears in mitosis during
Telophase
How does cell division differ between animal and plant cells?
The cell plate is the final partitioning of plant cells.
During an enzymatic reaction, what happens to the enzyme?
The enzyme and the substrate form a temporary complex.
The high energy bond in ATP is found in or between
The phosphate groups
Kidney dialysis relies on diffusion of various dissolved waste molecules (solutes) across a non-living semipermeable membrane. If the concentration of solutes in the blood increases over time before dialysis is administered, what will happen to the rate of dialysis when it occurs?
The rate will speed up since the concentration gradient is higher.
A semipermeable membrane sac filled with water and large molecules of starch is suspended in a beaker of distilled water. What will happen?
Water will enter the sac and it will swell.
Of the following conditions, which is absolutely necessary for diffusion to take place?
a concentration difference
Oxygen diffuses into the capillaries of the lungs because there is
a higher concentration of O2 in the alveoli than the capillaries.
The term hypertonic means
a higher solute concentration.
Carrier molecules are required for
both facilitated diffusion AND active transport.
Energy flows...
but chemicals cycle through living things
Which of the following will increase enzyme activity?
change to optimum pH for the reaction
The definition of osmosis is the
diffusion of water across a selectively permeable membrane.
Chemical reactions that require the input of energy are
endergonic reactions.
An isotonic solution means that the solute concentration outside the cell
is the same as inside the cell.