B8 Exchange surfaces

Question 1

Define diffusion?

Answer 1

Movement of particles from an area of high concentration to an area of low concentration

Question 2

What are the main factors that affect the rate of diffusion?

Answer 2

Concentration gradient
Temperature
Surface area

Question 3

Describe how the alveoli are adapted for gas exchange

Answer 3

Millions of alveoli - large surface area

Rich blood supply - maintains concentration gradient

Alveoli close to capillaires - short diffusion distance

Thin walls - short diffusion pathway

Ventilation - maintains concentration gradient

Question 4

Name two chemicals that diffuse into all cells.

Answer 4

Glucose
Oxygen

Question 5

Name two chemicals that diffusion out of all cells

Answer 5

Carbon dioxide
Urea

Question 6

How are single celled organisms adapted for diffusion?

Answer 6

Large surface area to volume ratio

Question 7

Why do multi-cellular organisms need a ventilation and cirulation system?

Answer 7

Surface area to volume ratio is too small

Oxygne and glucose coudl not diffuse to each ell in the body without them

Question 8

Define osmosis?

Answer 8

Movement of water from a dilute solution to a concentrated solution

through a selectively permeable membrane

Question 9

What happens to an animal cell if it is placed in water?

Answer 9

Absorbs water by osmosis
Cytoplasm swells
Cell will eventually burst

Question 10

What happens to an animal cell if it is place in very strong salt/sugar solution?

Answer 10

Water is lost by osmosis
Cytoplasm shrinks
Cell becomes crenated

Question 11

What happens to plant cells if they are placed in water?

Answer 11

Absorb water by osmosis
Become turgid
Cell wall prevents bursting

Question 12

What happens to plant cells if they are placed in very strong salt/sugar solution?

Answer 12

Water is lost by osmosis
Cytoplasm shrinks
Cell becomes flaccid

Question 13

Describe how the gills of a fish are adapted for gas exchange

Answer 13

Large surface area
Thin gill walls - short diffusion distance
Good blood supply - maintains concentration gradient

Blood caillries are close to water - shott diffusion distance
Counter current flow - blood and water flow in opposite directions.

Question 14

Describe how the small intestine wall is adapted for rapid diffusion

Answer 14

Villi - increase surface area
Good blood supply - maintains concentration gradient

Close blood supply - short diffusion distance
Thin walls - short diffusion distance

Question 15

How is the surface area to volume ratio of a cube calculated?

Answer 15

Surface area = 6 (width x length)

Volume = length x width x depth

Ratio = surface area / volume

Question 16

What happens to the surface area to volume ratio as an organism gets bigger?

Answer 16

SA:V gets smaller
Organism needs to develop a gas exchange system and circulation system

Question 17

Define active transport

Answer 17

Movemnt of substances from a more dilute solution to a more concentrated solution

Question 18

How is a root hair cell adapted to absorb mineral ions?

Answer 18

Large surface area

Lota of mitocondria to provide energy

Question 19

Name the chemcial absorbed by the roots by active transport

Answer 19

Mineral ions eg nitrate

Question 20

Name a molecule absorbed by active transprot in the gut

Answer 20

Sugar

Question 21

Give a differnece between diffusion and active transport

Answer 21

Active transport requires enregy whereas diffusion does not

Active transprot moves molecules from a low concentration to a higher concentration whereas diffusion moves molecules from a high concentration to a low concentration

Question 22

Give a difference between osmosis and diffusion

Answer 22

Osmoisis is the movment of water whereas diffsuion is the movment of any chemical

Question 23

State the equation for working out percentage change in mass

Answer 23

change in mass x 100

intial mass

Question 24

How is a root hair cell adapated to absorb water?

Answer 24

Large surface area

Question 25

Name the specialised cell shown in the daigram

Answer 25

Root hair cell

Question 26

Name thre strucutre shown in the diagram below

Answer 26

Alveolus

Question 27

How is the alveolus adpated for gas exchange?

Answer 27

Large surface area

Rich blood supply

Cose blood capilliaries

Lung continuous ventilated

Question 28

How is the villus adapted for the absorption of digested food?

Answer 28

Large surface area

Rich blood supply

Close blood capilliaries