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.