Chapter 3

Question 1

Name the 3 major parts of a cell

Answer 1

cell membrane, nucleus, cytoplasm

Question 2

What is the function of the cell membrane?

Answer 2

encloses the cell

Question 3

What is the function of the nucleus?

Answer 3

contains genetic material and controls activities

Question 4

What is the function of the cytoplasm?

Answer 4

fills out the cells shape

Question 5

Discuss cell membrane structure

Answer 5

• each cells membrane is extremely thin and delicate
• able to stretch to varying degrees
• usually tiny folds on the surface to help increase surface area

Question 6

The cell membrane only allows certain substances to enter or leave each cell, what is this called?

Answer 6

selective permeability

Question 7

Name the two types of cell membrane permeability

Answer 7

deferentially permeable or semipermeable

Question 8

What does a semipermeable membrane do?

Answer 8

allows certain elements to pass through but not others

Question 9

What is the cell membrane also known as?

Answer 9

plasma membrane

Question 10

What are the functions of the cell membrane? (6 points)

Answer 10

• controls movement of substances into and out of the cell
• allows selective communication between intracellular and extracellular components whilst aiding cellular movement
• gives the cell form
• where most of the cells biological activities are conducted
• molecules in the cell membrane form pathways that allow the signals from outside the cell to be detected and transmitted inside
• when cells form tissues the cell membrane assists by adheering the cell to other cells

Question 11

How does the cell membrance control which substances enter and leave?

Answer 11

active and passive mechanisms

Question 12

Which mechanism does NOT require cellular energy?

Answer 12

Passive mechanisms

Question 13

Which mechanisms DO require cellular energy?

Answer 13

Active mechanisms

Question 14

Define diffusion

Answer 14

Diffusion is the process where substances spontaneously move from HIGH concentration to LOW concentration.

speed is influenced by kinetic energy, molecular size and temperature

Question 15

What influences the speed of diffusion? (3)

Answer 15

kinetic energy
molecular size
temperature

Question 16

Define active transport

Answer 16

Active transport is the movement of particles through membranes from LOW concentration to HIGH concentration

Question 17

Define osmosis

Answer 17

Osmosis is a special type of diffusion that occurs when WATER molecules diffuse from HIGH WATER concentration to LOW WATER concentration

Question 18

Define endocytosis

Answer 18

involves secretion from the cell membrane moving particles too LARGE to enter the cell by processes within a vesicle of the cell

Question 19

Define filtration

Answer 19

forces molecules through membranes

Question 20

Define Exocytosis

Answer 20

OPPOSITE of endocytosis, in which a substance is stored in a vesicle is secreted from the cell

Question 21

Name the 3 passive mechanisms

Answer 21

Diffusion, osmosis, filtration

Question 22

Name the 3 active mechanisms

Answer 22

Active transport, endocytosis, exocytosis

Question 23

What is diffusion also known as?

Answer 23

simple diffusion

Question 24

what is the process of moving from a high to low concentration called?

Answer 24

concentration gradient

Question 25

In diffusion do particles move very quickly or very slowly?

Answer 25

very quickly + collide with other particles

Question 26

Once particles have diffused, what have they achieved?

Answer 26

equilibrium

Question 27

Why does o2 diffuse from blood to tissues/cells?

Answer 27

because its concentration is always higher in the blood

Question 28

Why does CO2 diffuse into the blood?

Answer 28

because co2 is higher in the tissues/cells than the blood

Question 29

What type of membrane does osmosis require?

Answer 29

semi - permeable

Question 30

What is osmotic pressure?

Answer 30

the ability of osmosis to create enough pressure to raise a volume of water

Question 31

Via osmosis, water equilibrates throughout the body so the concentration of intracelluar and extracellular fluids is....

Answer 31

nearly the same

Question 32

Water is highly polar and passes via osmosis through what?

Answer 32

the lipid bilayer

Question 33

Filtration is commonly used to....

Answer 33

separate solids from water

Question 34

Which active mechanism requires carrier proteins which combine with transported substances both specifically and reversibly?

Answer 34

active transport

Question 35

Name the two types of active transport

Answer 35

primary and secondary

Question 36

What is the name of the energy that active transport requires?

Answer 36

ATP

Question 37

Why does active transport require ATP?

Answer 37

Because it is moving against the concentration gradient

Question 38

What does active transport move across cell membranes? (6)

Answer 38

sugar, amino acids, sodium, potassium, calcium, hydrogen particles

Question 39

Despite being opposites, what doe endocytosis and exocytosis have in common?

Answer 39

They both use energy from the cell to move substances into or out of the cell without crossing the cell membrane