Chapter 3

Question 1

fluid-mosaic model

Answer 1

The phospholipid bilayer has a fluid consistency, similar to oil, allowing lipid molecules the freedom to move; proteins embedded on the outside or within the bilayer form a mosaic pattern

Question 2

glycolipids

Answer 2

Phospholipids that have attached carbohydrate (sugar) chains. Located on the outside of cell membranes

Question 3

glycoproteins

Answer 3

Proteins that have attached carbohydrate (sugar) chains

Question 4

phospholipids

Answer 4

Phospholipids are constructed similar to neutral fats (triglycerides), except a phosphate group takes the place of one of the fatty acids; the main constituent of the plasma membrane; hydrophilic (water-loving) heads of the molecule face the outsides and insides of the cell; hydrophobic (water-fearing) tails face each other in the inner part of the membrane

Question 5

selectively permeable or semipermeable

Answer 5

Describes to the cell membrane because some molecules can through it while others cannot

Question 6

selectively permeable or semipermeable

Answer 6

Describes to the cell membrane because some molecules can through it while others cannot

Question 7

concentration gradient

Answer 7

Small, non-charged molecules, such as carbon dioxide and oxygen, diffuse through a plasma membrane from an area of high concentration to an area of low concentration

Question 8

diffusion

Answer 8

The movement of molecules from an area where the molecule is in high concentration (more solute) to an area of lower concentration (less solute)

Question 9

facilitated diffusion (transport)

Answer 9

the movement of a molecule, with the aid of a protein channel or carrier, from an area of high concentration to an area of lower concentration

Question 10

hypertonic solution

Answer 10

Hyper means ‘more than’ and refers to a solution with more solute (and therefore less water) than found inside a cell; an animal cell placed in a hypertonic solution will shrink or shrivel up due to the movement of water out of the cell

Question 11

hypotonic solution

Answer 11

Hypo means ‘less than’ and refers to a solution with less solute and more water than found inside a cell; a cell placed in this solution will take on water and swell or even burst

Question 12

isotonic solution

Answer 12

The same concentration of solute and water, both inside and outside the cell

Question 13

lysis

Answer 13

Bursting of a cell due to the build-up of pressure

Question 14

osmosis

Answer 14

Diffusion of water through a semi-permeable membrane due to concentration differences; water moves from an area of high water molecule and low solute concentration to an area of low water molecule and high solute concentration

Question 15

osmotic pressure

Answer 15

The force that causes water to move in either direction across a semi-permeable membrane

Question 16

passive transport

Answer 16

Involves diffusion or facilitated transport; no chemical energy is required

Question 17

plasmolysis

Answer 17

Occurs in plants cells placed in a hypertonic solution; cytoplasm is reduced due to osmosis and the plasma membrane pulls away from the cell wall

Question 18

turgor pressure

Answer 18

Occurs in plant cell placed in a hypotonic solution; swelling creates turgor pressure, but the plant cell will not burst because the plasma membrane pushes against the rigid cell wall

Question 19

active transport

Answer 19

By this process, ions and molecules move across the cell’s plasma membrane and accumulate inside or outside the cell; the carrier requires energy to change its shape and transport the molecule to the other side of the membrane

Question 20

endocytosis

Answer 20

Requires the use of a cell’s ATP energy to alter the shape of the membrane surface (called invagination) to allow a macromolecule to be completely surrounded by the membrane, which then pinches together to form an intracellular vesicle inside the cytoplasm of the cell

Question 21

endocytosis

Answer 21

Requires the use of a cell’s ATP energy to alter the shape of the membrane surface (called invagination) to allow a macromolecule to be completely surrounded by the membrane, which then pinches together to form an intracellular vesicle inside the cytoplasm of the cell

Question 22

exocytosis

Answer 22

The movement of materials out of the cytoplasm; ATP energy is needed to create a vesicle or vacuole (large vesicle) that will migrate to the membrane’s inner surface and fuse with the cell membrane

Question 23

phagocytosis

Answer 23

Endocytosis of large particles

Question 24

pinocytosis

Answer 24

Endocytosis of liquid and very small particles

Question 25

surface area

Answer 25

The area of a cell that is exposed to its external environment; if a cell is shaped like a sphere or a ball, the surface area can be calculated by this following equation:surface area = 4&960;r2

Question 26

volume

Answer 26

The volume of a cubical cell can be calculated by the following equation: side length x height x width

Question 27

surface area to volume ratio

Answer 27

A greater surface-area-to-volume ratio makes a cell more efficient; the smallest cells have the greatest surface-area-to-volume ratios and are the most efficient at transporting molecules across the cell membranes