biology - exchange & transport in animals (8.1 - 8.12)

8.1 why must substances be removed from organisms? (general)

all chemical reactions in body (metabolism) produce waste

must be excreted - can cause problems

8.1 is oxygen transported into/out of organisms?

into

8.1 why is oxygen transported into organisms?

for aerobic respiration

8.1 is CO₂ transported into/out of organisms?

out of

8.1 why is CO₂ transported out of organisms?

produced in aerobic respiration

8.1 is water transported into/out of organisms?

both

8.1 are dissolved food molecules transported into/out of organisms?

into

8.1 why are dissolved food molecules transported into organisms?

e.g. glucose - for aerobic respiration

e.g. glucose, amino acids - produce new substances for body

8.1 are mineral ions transported into/out of organisms?

into

8.1 why are mineral ions transported into organisms?

produce new substances for body

8.1 is urea transported into/out of organisms?

out of

8.1 why is urea transported out of organisms?

poison produced by breaking down amino acids

(removed by kidneys)

8.2 why are there exchange surfaces in multicellular organisms?

many substances move into & out of body by diffusion

ensure a lot of particles diffuse quickly, exchange surfaces:

• thin - short diffusion distance for particles

• large surface area - more room for particles to diffuse

8.2 why are there transport systems in multicellular organisms?

too long for materials to diffuse through cells on outside of tissue to reach cells on inside

e.g. in humans, capillaries in circulatory system use blood to transport substances to & from cells

8.2 surface area:volume ratio calculation

8.3 how are alveoli adapted for gas exchange by diffusion between air in lungs & blood in capillaries?

lungs have lots of alveoli - increase SA so increase speed & amount of gas exchange

1. blood enters from rest of body - higher CO₂ conc. & lower O₂ conc.

2. CO₂: capillary → alveolus & O₂: alveolus → capillary

   • alveolus - higher O₂ conc. & lower CO₂ conc. than blood

   • alveolus shape - large SA

   • alveolus & capillary - one-cell thick wall

3. blood leaves to rest of body - lower CO₂ conc. & higher O₂ conc.

8.4 SA affect on rate of diffusion

small particles pass through membranes

increased SA = increased rate of diffusion - more space for particles to pass

rate of diffusion ∝ surface area

conc. gradient definition

difference between 2 concs.

bigger difference = steeper conc. gradient

8.4 conc. gradient affect on rate of diffusion

particles in solution move randomly in all directions

net movement of solute particles - high conc. → low conc.

conc. equal - no net movement (particles still moving)

steeper conc. gradient = increased rate of diffusion

rate of diffusion ∝ concentration difference

8.4 diffusion distance affect on rate of diffusion

increased diffusion distance = decreased rate of diffusion - particles have to diffuse further

rate of diffusion ∝ 1/thickness of membrane

8.5 rate of diffusion - Fick’s law

8.6 structure & function of RBCs (erythrocytes)

lots of haemoglobin - binds with oxygen in lungs & releases it in tissues

no nucleus - more space for haemoglobin

biconcave shape - large SA:volume ratio for oxygen to diffuse in & out

8.6 structure & function of WBCs (phagocytes & lymphocytes)

remove foreign cells inside body

lymphocytes - produce antibodies that stick to foreign cells & help destroy them

phagocytes - surround foreign cells & digest them

8.6 structure & function of plasma

carries dissolved substances (e.g. glucose, CO₂ & urea)

8.6 structure & function of platelets

tiny fragments of cells

no nuclei

produce substances needed to clot blood at injury site

8.7 structure & function of arteries

take blood away from heart

thick walls - withstand blood pressure, stretching & contracting makes blood flow more smoothly

narrow tube

8.7 structure & function of veins

carry blood back to heart

thin, flexible wall - low blood pressure, muscles help push blood along

wide tube

valves - prevent blood flowing wrong way

8.7 structure & function of capillaries

wall only 1 cell thick - faster diffusion of substances in & out

very narrow tube

8.8 structure & function of heart & circulatory system - major blood vessels

superior/inferior vena cava: upper/lower body → right atrium

pulmonary vein: lungs → left atrium

pulmonary artery: right ventricle → lungs

aorta: left ventricle → body

8.8 structure & function of heart & circulatory system - valves

stop blood flowing wrong way

8.8 structure & function of heart & circulatory system - relative thickness of chamber walls

left ventricle wall more muscle & thicker than right

(needs more force to pump blood to body (vs lungs))

8.9 cellular respiration

exothermic reaction - some energy transferred out cells by heating (keeps animals warm)

occurs continuously in living cells - releases energy for metabolic processes (e.g. aerobic & anaerobic resp.)

8.10 aerobic respiration

glucose + oxygen → carbon dioxide + water

requires O₂

occurs in mitochondria

8.10 anaerobic respiration

glucose → lactic acid

doesn’t require O₂

releases less energy from glucose than aerobic resp.

releases sudden bursts of energy without sudden increase in O₂ supply

(8.10) anaerobic respiration during exercise

muscles need more energy so rate of aerobic resp. increases - muscle cells take more O₂ & glucose from blood

heart rate increases - more blood to muscle cells

breathe faster & deeper - increase amount of O₂ diffusing into blood in lungs, excrete more CO₂

O₂ used up faster than replaced

amount of anaerobic resp. in cytoplasm of cells greatly increases

releases sudden bursts of energy without sudden increase in O₂ supply

heart & breathing rates remain high after - O₂ needed to replace O₂ lost from blood & muscles & to release extra energy to get rid of lactic acid

8.11 practical: rate of respiration in living organisms

1. get tube with soda lime held in place with cotton wool

   • soda lime: absorbs CO₂; corrosive

   • cotton wool: protect you & organisms

2. collect some of small organisms in weighing boat

3. gently shake organisms out of container & into tube

4. insert bung & capillary tube

5. set up control tube

6. place both tubes into rack in water bath at set temp.

7. wait for 5 mins to let organisms adjust to temp.

8. hold beaker of coloured liquid to ends of capillary tubes so liquid enters

9. mark position of coloured liquid in tube & time 5 mins

10. mark position of coloured liquid again & measure distance travelled

11. repeat at diff. temps.

8.12 calculate heart rate, stroke volume & cardiac output

cardiac output (litres/min) = stroke volume (litres/beat) x heart rate (beats/min)

heart rate = number of heart beats per min

stroke volume = volume of blood pushed into aorta each beat

cardiac output = volume of blood pushed into aorta per min