Exchange and Transport

Question 1

How to measure ease of substance exchange

Answer 1

Surface area to volume ratio

Question 2

How to work out surface area to volume ratio

Answer 2

Work out surface area
Work out volume
Put into ratio
Simplify

Question 3

Why multicellular organisms need exchange surfaces

Answer 3

Have smaller surface areas to volume

More difficult to exchange enough substances to supply entire volume with outside surface alone

Question 4

Factors of rate of diffusion

Answer 4

Distance
Concentration difference
Surface area

Question 5

Alveoli exchange method

Answer 5

Deoxygenated blood from heart arrived (min O2, max CO2)

Due to high concentration differences, O2 gases diffuses from alveoli to blood and CO2 from blood to alveoli

Question 6

Adaptations of alveoli

Answer 6

Moist lining for dissolving gases
Good blood supply to maintain concentration differences of gases
Very thin walls
Enormous surface area

Question 7

Fick’s Law

Answer 7

rate of diffusion is proportional to surface area x concentration difference / thickness of membrane

Question 8

Red blood cell adaptations and function

Answer 8

Carry oxygen to all cells in the body
Biconcave disc structure to increase surface area
No nucleus (more oxygen space)
Haemoglobin used to carry blood to cells in body (oxyhaemoglobin breaks down and releases oxygen in cells)

Question 9

Blood contents

Answer 9

Red blood cells
White blood cells
Platelets
Plasma

Question 10

Phagocytes facts

Answer 10

White blood cells

Change shape to engulf unwelcome microorganisms (phagocytosis)

Question 11

Lymphocytes facts

Answer 11

White blood cells
Produces antibodies against microorganisms
Can produce antitoxins to neutralise toxins made by microorganisms

Question 12

White blood cell facts

Answer 12

Has nucleus (unlike red blood cell)
Fights against infections (immune system)
Multiplies rapidly when infection is present

Question 13

Platelets facts

Answer 13

Small fragments of cells

Bundle up and clot at a wound to prevent microorganisms from entering blood stream

Question 14

Plasma facts

Answer 14

Pale, straw-coloured liquid 
Carries lots of things e.g. :
red and white blood cells
platelets
nutrients (glucose and amino acids)
carbon dioxide
urea
hormones
proteins
antibodies and antitoxins

Question 15

3 types of blood vessel

Answer 15

Capillaries (exchanges materials at tissues)
Arteries (carries blood away from the heart)
Veins (carried blood towards the heart)

Question 16

Artery adaptations

Answer 16

Blood is pumped at high pressure so:
Walls are thick
Walls contain layers of muscle to make them strong and elastic fibres so they can stretch and spring back

Question 17

Capillary adaptations

Answer 17

Exchange of materials at tissues so:
They are narrow so they can squeeze between cells (narrows distance of diffusion)
Permeable walls so diffusion can occur
Walls are one cell thick (less distance of diffusion)

Question 18

Veins adaptations

Answer 18

Blood is at low pressure so:
Walls don’t have to be as thick as the arteries
Bigger lumen than arrives to help blood low despite lower pressure
Valves to prevent blood from flowing in the wrong direction

Question 19

Double circulatory system meaning

Answer 19

2 circuits for full circulation 
Heart pumps deoxygenated blood to lungs
Oxygenated blood returns to heart
Heart pumps oxygenated blood to rest of body
Deoxygenated blood returns to heart

Question 20

Single circulatory system meaning

Answer 20

Only 1 circuit e.g. fish

Deoxygenated blood travels to heart right round body (but passes gills along the way)

Question 21

How heart pumps blood

Answer 21

Right atrium receives deoxygenated blood from body (via vena cava)
Right ventricle pumps blood to lungs (via pulmonary artery)
Left atrium receives oxygenated blood from lungs (via pulmonary vein)
Left ventricle pumps blood to rest of body (via aorta)

Question 22

Heart adaptations

Answer 22

Left ventricle’s wall is thicker than right as needs more muscle to pump blood at greater distance, needing higher pressure
Valves prevent backflow of blood
Septum prevented mixing of deoxygenated and oxygenated blood

Question 23

Cardiac output formula

Answer 23

cardiac output (cm^3 min^-1) = heart rate (bpm) x stroke volume (cm^3)

Question 24

Respiration facts

Answer 24

Process of transferring (releasing) energy from the break down of organic compounds (glucose)
Exothermic reaction 
2 types (aerobic and anaerobic)

Question 25

Uses of energy released through respiration

Answer 25

Metabolic processes (break / synthesising molecules)
Contracting muscles (in animals)
Maintains steady body temperature (in mammals and birds)

Question 26

Aerobic respiration formula

Answer 26

glucose + oxygen -> carbon dioxide and water

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Question 27

Aerobic respiration facts

Answer 27

Done when plenty of oxygen is available

Most efficient way to transfer energy from glucose

Question 28

Anaerobic respiration in animals formula

Answer 28

glucose -> lactic acid

Question 29

Anaerobic respiration in plants formula

Answer 29

glucose -> ethanol + carbon dioxide

Question 30

Anaerobic respiration facts

Answer 30

Done when not enough oxygen is enough for aerobic respiration
Also when energy demand is too much for aerobic respiration to match
Less efficient than aerobic respiration and releases less energy
Glucose is only partially broken down
Leads to build up of lactic acid (causes pain and cramps)