respiration and gas exchange 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40B, 2.41B, 2.42B, 2.43B, 2.44B, 2.45B

Question 1

what is aerobic respiration?

Answer 1

use of oxygen to break down glucose and release energy
some energy is released as heat but most is trapped as a useable form of ATP

Question 2

what is the word equation for aerobic respiration?

Answer 2

glucose + oxygen > carbon dioxide + water

Question 3

what is the symbol equation for aerobic respiration?

Answer 3

C6H12O6 + 6O2 > 6CO2 + 6H2O

Question 4

why does aerobic respiration release a lot of ATP?

Answer 4

because it completely oxidises the glucose

Question 5

examples of uses of energy:

Answer 5

cell division
contracting muscle cells
building large molecules
transporting molecule
maintaining body temperature

Question 6

when is photosynthesis faster than respiration in plants?

Answer 6

durning the day, at higher light intensities - there is a net uptake of carbon dioxide and net release of oxygen
oxygen is excreted from the leaves

Question 7

when is respiration faster than photosynthesis?

Answer 7

in the dark, at low light intensities - there would be a net uptake of oxygen and a net release of carbon dioxide
carbon dioxide is excreted from the leaves

Question 8

where does gas exchange occur?

Answer 8

in the airspaces in the leaves and atmosphere
oxygen and carbon dioxide diffuse through the stomata

Question 9

how are guard cells specialised for gas exchange?

Answer 9

the guard cells form the stomata which change shape altering its size

Question 10

how are stomatas specialised for gas exchange?

Answer 10

they close to reduce water loss (and gas exchange) this is when the plant has lost too much water so stomatas turn flaccid
allows gases to diffuse in and out the air spaces in the leaf, providing short diffusion distance to mesophyll cells

Question 11

whats the symbol equation for respiration in plants?

Answer 11

C6H12O6 + 6O2 > 6CO2 + 6H2O

Question 12

what is cell respiration?

Answer 12

the process of breaking down food molecules. to release ATP

Question 13

what’s anaerobic respiration?

Answer 13

respiration without oxygen

glucose is not completely broken down so less ATP and energy is released

produces toxic waste products, which must be excreted or broken down

advantage allows cells to obtain small amount of usable energy when oxygen is limited

Question 14

what does anaerobic respiration in fungi and plants produce?

Answer 14

glucose > ethanol + carbon dioxide

very useful in food production
we use yeast in bread and alcohol production
-co2 forms bubbles in bread dough, causing it to rise
-ethanol provides alcohol content

Question 15

what does anaerobic respiration in animals produce?

Answer 15

glucose > lactic acid

Question 16

what happens when our muscles anaerobically respire?

Answer 16

occurs in muscle cells when shortage of oxygen
-muscles require large quantities of energy, more than provided by aerobic respiration
-glycogen stored in muscle cells is broken down into glucose
-lactic acid builds up causing cramps and diffuses into blood
-high concentration is toxic so transported to liver where it is oxidised

Question 17

what is it called when volume of oxygen needed to oxides lactic acid?

Answer 17

oxygen debt

Question 18

practical: investigating evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms - germinating peas

Answer 18

want to show that only living things respire - control experiment

thermo flasks, dead and alive pea seeds (soaked in Milton solution - preservative and kills bacteria, that would respire affecting results), thermometers

as peas grow they start to respire, releasing heat
thermo flask insulated, heat not transferred to surroundings and we can measure change in temp

only see change in temp of alive peas

use gas delivery tubes to collect gas, gas bubbled through limewater, alive peas gas turn cloudy as co2 is released

Question 19

practical: investigating evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms - hydrogen carbonate indicator and insects

Answer 19

want to show that only living things respire - control experiment

test tubes, insect, support, hydrogen carbonate indicator

yellow: respiration>photosynthesis
CO2>O2

orange: repiration=photosnythesis
CO2=O2

pink: respiration<photosynthesis
CO2<O2

Question 20

practical: investigating anaerobic respiration in yeast

Answer 20

delivery tube, limewater, test tube/boiling tubes, thin layer of oil, glucose and yeast suspension

used to investigate the effect of changing a single variable on the rate of anaerobic respiration of yeast

dependent variable is time taken for limewater to become cloudy
or measure volume of carbon dioxide produced

Question 21

what’s the symbol equation for plants photosynthesising?

Answer 21

6co2 + 6h2o > c6h12o6 + 6o2

Question 22

how to the leaf specialised for gas exchange?

Answer 22

thin so diffusion distance is short
large surface area increasing number of stomata, CO2 diffuse quicker
maximises light absorption

Question 23

list the structure of a leaf from the top, downwards:

Answer 23

cuticle
upper epidermis
palisade cells and mesophyll
xylem and phloem
spongy mesophyll
lower epidermis
stomata and guard cells

Question 24

how is the upper epidermis specialised for photosynthesis?

Answer 24

transparent so light can penetrate the mesophyll

Question 25

how are the palisade cells specialised for photosynthesis?

Answer 25

long, thin and tightly packed
contain large amounts of chloroplasts, maximising the absorption of sunlight energy
palisade mesophyll is the main site of photosynthesis