2.1 the transport of substances across the cell

Question 1

passive transport.

Answer 1

Processes that enable substances to move in and out of
cells without an input of energy from the cell

Question 2

concentration gradient

Answer 2

a difference
in concentration
between one side of
a membrane and the
other

Question 3

difusion

Answer 3

the net
movement of ions or
molecules from an area
of higher concentration
to an area of lower
concentration

Question 4

Factors that affect the rate of
di!usion include

Answer 4

1-Molecule size: the larger a molecule is, the more difficult it is for it to diffuse across a membrane. As a result, the rate of diffusion decreases with molecule size.

2-Molecule polarity: Although small polar molecules can cross membranes, their rates of diffusion are generally lower than those of non-polar molecules of the same size.

3-Molecule or ion charge: In general, charged molecules and ions cannot diffuse across a cell membrane.

4-Temperature and pressure also affect the rate of di!usion.

Question 5

osmosis

Answer 5

the movement of water
from an area of
higher concentration
to an area of lower
concentration, across
a semi-permeable
membrane

Question 5

what is the osmatic

Answer 5

isotonic

Question 5

the solution with the lower
concentration of solute

Answer 5

hypotonic (hypo = “less than”).

Question 6

concentrations, the solution with the higher
concentration is

Answer 6

hypertonic (hyper = “more than”).

Question 7

When two solutions have the same osmotic
concentration,

Answer 7

they are isotonic (iso = “equal”).

Question 8

what is the osmatic

Answer 8

hypertonic

Question 8

what is the osmatic

Answer 8

hypotonic

Question 9

what is the osmatic

Answer 9

hypotonic

Question 11

what is the osmatic

Answer 11

hypertonic

Question 11

facilitated diffusion

Answer 11

the transport of ions
or molecules across
a membrane by
means of a membrane
protein along the
concentration gradient
for that ion or molecule

Question 12

active transport

Answer 12

the transport of a solute
across a membrane
against its gradient requires the expenditure of energy, usually from ATP.

Question 13

channel protein

Answer 13

a membrane protein that
forms a channel across
a cell membrane, which
allows specific ions
or molecules to cross
the membrane along
their concentration
gradients

Question 14

carrier protein

Answer 14

a membrane protein that
binds to and transports
one or more particles of
a substance from one
side of a membrane
to the other, along the
concentration gradient
for that substance

Question 15

An ATP
molecule is derived from

Answer 15

an adenosine nucleotide, but it has a triple phosphate group
instead of a single phosphate group. the hydrolysis of the end phosphate group from an
ATP molecule releases energy,

Question 16

what are some of the passive transporters

Answer 16

Difusion, facilitated difusion, and osmosis

Question 17

primary active transport.

Answer 17

A cellular process that uses ATP directly to move molecules or ions from one side of a
membrane to the other

Question 18

ion pumps are
carrier proteins that use ATP to “pump” ions from one side of a membrane to the other, against a concentration gradient. One of the most well-studied examples is

Answer 18

the sodium- potassium pump. “is system transports sodium ions out of the cell while transporting potassium ions into the cell.

Question 19

Secondary Active Transport

Answer 19

Ion pumps create a charge and concentration difference across cell membranes, forming an electrochemical gradient that stores energy. Secondary active transport harnesses this gradient to move molecules or ions across the membrane

Question 20

membrane-assisted
transport

Answer 20

transport
method used to move
materials that are too
large to cross the cell
membrane through
a channel or carrier
protein

Question 21

endocytosis

Answer 21

process by which the cell membrane engulfs extracellular material to bring it inside the cell

Question 22

phagocytosis

Answer 22

If the material the cell takes in is made up of discrete particles, such as an organism or some other fragment of organic matter, the process is called phagocytosis (which literally means “cell-eating”).

Question 23

pinocytosis

Answer 23

If the material the cell takes in is liquid, the process is called pinocytosis (which literally means “cell-drinking”).

Question 24

Receptor-mediated endocytosis

Answer 24

Receptor-mediated endocytosis uses special receptor proteins on a portion of the cell membrane called coated pits. These receptors bind to specific molecules outside the cell. As the pit folds inward, it forms a vesicle containing the bound molecules. The cell can then use or digest the vesicle's contents, and the receptors may be reused by the cell membrane.

Question 25

exocytosis

Answer 25

transport method in which a vacuole fuses with the cell membrane and releases its contents outside the cell