Chapter 3:movement in and out of cells

Question 1

Definition of diffusion

Answer 1

the net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient,as a result of their random movement

Question 2

Where does energy for diffusion come from?

Answer 2

Kinetic energY of random movement of molecules and ions.

Question 3

Where does diffusion take place

Answer 3

In cell membranes as it’s partially permeable meaning some molecules can diffuse while some can’t

Question 4

Name 4 molecules which can diffuse

Answer 4

-glucose
-amino acids
-water
-oxygen

Question 5

Name two molecules which do not diffuse

Answer 5

-starch
-protein

Question 6

name examples of diffusion in organisms

Answer 6

-in respirating cells
-plants need carbon dioxide for photosynthesis

Question 7

How does diffusion in respirating cell happen

Answer 7

-oxygen dissolved in the cytoplasm is constantly being used up,producing a low concentration of oxygen inside the cell and higher concentration outside the cell.oxygen therefore diffused down the concentration gradient into cells through cell membranes

Question 8

what’s re the factors which affect the rate of diffusion

Answer 8

-surface area
-temperature
-distance
Concentration gradient

Question 9

What is active transport

Answer 9

the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration against a concentration gradient,using energy from respiration

Question 10

How is the energy provided for active transport

Answer 10

By aerobic respiration

Question 11

How does active transport happen

Answer 11

1.the ion enters the carrier protein
2.the carrier protein changed shape.the energy needed for it to do is provided by respiration in cells
3.the change of shape of the carrier protein pushes the nitrate ion into the cell

Question 12

Definition of osmosis

Answer 12

The net movement of water molecules from a region of higher water potential to a region of lower water potential through partially permeable membrane

Question 13

Where can osmosis happen through

Answer 13

-cell membrane
-dialysis tube

Question 14

Examples of osmosis

Answer 14

1-substances are transported around the body dissolved in water to form urine
2-the water from the soil into the root cell
3-movement of water across the cell
4-the kidneys excrete urea dissolved in water

Question 15

What happens when the plant cell is in pure water?

Answer 15

-the cell will absorb water by osmosis
-the cell swells
-cytoplasm pushes against the cell wall
-gets turgid

Question 16

What happens when plant cells are placed in a concentration solution

Answer 16

-loses water by osmosis
-the cytoplasm and vacuole shrink
-the cell wall stays in position
-becomes flaccid

Question 17

what does plasmolysed mean

Answer 17

When the cell membrane tears away from the cell wall

Question 18

What happens in a plasmolysed cell

Answer 18

-the cell contents shrink
-the cell embrace and cytoplasm split away from the cell wall and gaps appear between the membrane and cell wall

Question 19

What happens to animal cells in pure water

Answer 19

-water diffuses into the cell
-as more and more water enters it swells

Question 20

What happens to animal cells in concentrated solution

Answer 20

-the cell loses water by osmosis
-shrinks