BIOENERGETICS

Question 1

word equation and chemical equation for photosynthesis

Answer 1

6CO2 + 6H2O → C6H12O6 + 6O2
Carbon dioxide + water (+light) —> glucose + oxygen

Question 2

-plants get energy from
-What happens in photosynthesis
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-is it exo/ endo thermic
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-where does photosynthesis take place- explain

Answer 2

light
-plant takes in CO2 and water
-energy transferred from environment to chloroplasts by light
- light energy used to turn carbon dioxide and water into glucose + oxygen
-endo thermic, takes in light energy

• in leaves of plant
  -leaves have chloroplasts-
  -chlorophlasts contain green pigment-chlorophyll
  -chlorophyll absorb light energy

Question 3

LIGHT INTENSITY and rate of photosynthesis

-no light
-increase
-if we increase light intensity and rate of photosynthesis increases, what does it tell us
-when we increase light intensity- rate X increase
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-graph for CO2 concentration and rate of photosynthesis

Answer 3

• x photosynthesis- rate = 0

-rate increases-more light energy to carry out photosynthesis

-light intensity is limiting factor- rate wasn’t as fast bcse X enough
- +ve gradient on graph

-light intensity X longer limiting factor
-graph rises to a point, then levels off

-same as graph for light intensity

Question 4

4 things that affect rate of photosynthesis and be limiting factor

Answer 4

temp- in winter
light intensity- night
co2 con. - if its warm + bright enough
amount of chlorophyll in leaf

Question 5

what happens to leaves w/ low amount of chlorophyll

What can affect chlorophyll amount

Answer 5

-leaves trap less light energy, have lower rate of photosynthesis than normal leaves

-disease
-environmental stress eg lack nutrients

Question 6

TEMP and rate of photosynthesis
- increase temp
-keep increasing
-what temp causes this

Answer 6

rate increases- enzymes work faster
-enzymes denature- rate falls
-around 45 *

Question 7

how would you get the graph for light intensity-

Answer 7

if u plot distance of lamp from plant- don’t get the specific graph u know
-need to MEASURE light intensity w/ LIGHT METER(or do math w/ results)

Question 8

uses of glucose from photosynthesis x 5

Answer 8

-for respiration
-converted into insoluble starch for storage
-used to produce fat/ oil for storage
-used to produce cellulose- strengthens cell wall
-used to produce amino acids for protein synthesis

Question 9

What does resporation do

-why’s glucose converted into starch x3
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why is glucose stored as fats./ oils (lipids)
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how is glucose used in cell wall
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-how is glucose used in terms of protien synthesis

Answer 9

-respiration transfers energy from glucose

-to convert back when photosynthesis isn’t happening eg in winter/ at night
-starch is insoluble- better for storing than glucose
-cell w/ lots of glucose would draw in lots of water and swell up

-to be stored in seeds
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glucose converted into cellulose which gives cell wall strength
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-glucose combined with nitrate ions absorbed from soil to produce amino acids
-amino acids synthesise protiens

Question 10

RP 6- rate of photosynthesis-
-steps x7 by counting bubbles
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different steps using capillary tube-x4
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-what type of light is used-why

-what if we use normal light bulb

Answer 10

1)put boiling tube 10 cm away from source of WHITE LIGHT -led light
2)fill boiling tube w/ sodium hydrogencarbonate solution- release co2 needed
3)put pondweed in tube,below level of solution, cut end diagonally(steady stream of O2 bubbles)
4)leave for 5 mins- pondweed can acclimatise to conditions in tube + start photosynthesising
5)start stop watch- count no. bubbles from cut end in 1 min
6)repeat a total of 3 times and get a mean no. of bubbles
7)do whole experiment again at 20 cm 30cm, so on

-bubbles will collect in capillary tube.
-use syringe to draw gas up tube alongside a ruler
-measure length of gas bubble
-this is proportional to vol of O2 produced

-led light- X give off much heat-change in heat affect rate
-if we use normal light bulb, place beaker of water btwn light and tube- absorb heat produced by bulb

Question 11

RP 6 - photosynthesis
-problems x2
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-what’s the independant variable in OG RP
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-dependant variables x3
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-control variables- x3
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how do you make sure no other light effects the practical-

Answer 11

-no. of bubbles too fast to count accurately
-assumed every bubble has same O2 volume- bubbles not all same size

-light intensity

-rate
-no. of bubbles
-vol of gas
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-carbon dioxide conc.
-temp
-type of plant

-turn over head lights off, only light is from lamp

Question 12

different steps using a funnel

-what do you control on RP6 photosynthesis- x4
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-what if you wanted to discover effect of:
CO2 and
temp on Photosynthesis

Answer 12

-place pondweed under funnel and catch bubbles in measuring cylinder filled w/ water
-use measuring cylinder to measure vol of Oxygen produced

-temp
-time
(+ co2 conc by using same concentration of hydrogen carbonate solution )
-use same length of pondweed and same species

-For testing effect of CO2-
different concentrations of sodium hydrogencarbonate solution

-for testing effect of temp-
put pondweed in water bath at set temp- repeat w/ different temps

Question 13

RP 6 photosynthesis and light intensity-
what would potentially be plotted on graph x3 options
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-what happens if we double distance of pondweed from light

-what is the relationship btwn light intensity and distance

-equation to show this-

use inverse square law to work out light intensity when distance is 10 cm

Answer 13

Y-axis:
*bubbles per min- when counting

*vol of oxygen per min- with funnel

*length of bubble per min- w/ capillary tub

X-axis:
distance from light source

-distance doubled- number of bubbles falls by factor of 4

-inversely proportional-
DISTANCE INcrease
LIGHT intensity DEcrease

• light intensity ∝ 1/ d²

light intensity ∝ 1/ 10²
= 1/ 100 = 0.01 (a.u= arbitrary units)

Question 14

what happens to light intensity:
if you do distance/2
if you do distance/3
if you do distance x2
if you do distance x3

A plant is moved from 15cm to 5cm away from led light.
-prove that light intensity becomes 9 times greater

Answer 14

light intensity = x4
light intensity= x9
light intensity= /4
light intensity= /9
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1/ 15² = 0.004444…
1/ 5² = 0.04

0.04 / 0.004444…
= 9

Question 15

why do farmers control temp, light intensity and co2 concentration in a greenhouse

-how do farmers control:
-temp x3
-light intensity
-co² conc.

-another pro of a greenhouse- x1
-what else farmers do to improve growth x1

Answer 15

• to increase rate of photosynthesis- to increase yield-

-Temp
*greenhouses trap sun’s heat so its X limiting
*use a heater to keep ideal temp
* use shades + ventilation if too hot

Light intensity
-supply artificial light eg at night- more time to photosynthesise

CO₂ conc.
-paraffin heater/ oil burner- give off heat AND also CO₂ as by product

-easier to keep plants free from pests + disease
-farmers can add fertiliser to soil- provide minerals

Question 16

consideration when using a green house- x3

Answer 16

-must enhance conditions to get max rate of photosynthesis while maintaining profit
-extra cost should be justified by increase in yield
-eg don’t provide more light/ heat ect than plant needs otherwise money is wasted.

Question 17

-how do we get energy- what process-
-is this exo/ endo thermic
-where does it occur

-what happens in aerobic respiration

-why is it important

Answer 17

• cellular respiration

-exothermic- releases energy

-all living cells

-glucose + O₂= CO₂ and water
and energy is released

-the energy transferred in respiration supplies all the energy needed for living processes

Question 18

respiration transfers energy due to the….

-what happens to the glucose molecule

Answer 18

breakdown of glucose

-fully oxidised- which is why alot of energy is released

Question 19

where in a cell does aerobic respiration happen

-word equation for anaerobic respiration in muscles
-what do muscle cells neede energy for
-is energy given off in anaerobic respiration- how much
-why

Answer 19

in mitrochondria
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glucose—>lactic acid
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contraction
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yes-much less than aerobic
-because in anaerobic respiration, oxidation of glucose is INCOMPLETE

Question 20

why can anaerobic respiration happen in muscle cells

Answer 20

vigorous excercise- body can’t supply enough oxygen to muscles

Question 21

3 places anaerobic respiration takes place

Answer 21

plant cells
yeast cells
muscle cells

Question 22

word equation for anaerobic respiration in plant/yeast cells

-anaerobic respiration in yeast cells is called-
-why is this important

Answer 22

glucose —> ethanol + carbon dioxide
-energy given off

-fermentation
-has economic importance in manufacture of bread and alcoholic drinks

Question 23

-how is fermentation important in:

-alcoholic drinks

-in bread

-is yeast uni/multicellular

Answer 23

the alcohol in the drinks is the ethanol produced by fermentation

-carbon dioxide produced by fermentation creates bubbles in dough-make bread rise

-single celled organisms

Question 24

what do organisms need energy for x3

Answer 24

-chemical reactions to build larger molecules (eg protiens from amino acids)
-movement- allow muscle cells to contract
-keeping warm-mammals and birds keep body temp steady in colder surroundings

Question 25

during excercise the body reacts to the…….
explain why-

Answer 25

increased demand for energy-

-muscles need energy from respiration to contract
-muscles contract more than normal
- need more energy

Question 26

what 3 things increase when exercising
-overall why
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and specifically why for each thing
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why does anaerobic respiration increase-

Answer 26

-heart rate,
-breathing rate,
-breath volume
* to supply muscles w/ more oxygenated blood

-breathing rate, breathing volume increase(more frequent breathing and deeper breaths)
*more oxygen in blood stream
-heart rate increases
*to pump oxygenated blood around body faster

-anaerobic respiration increases bcse body cells need more oxygen

Question 27

faster heart rate gets o2 blood around body faster but also…..

-why does anaerobic respiration happen in humans- 3 points

Answer 27

removes CO2 quicker

-if insufficient oxygen is supplied to muscles
-normally during vigorous exercise
- anaerobic respiration takes place in muscles

Question 28

-what does anaerobic respiration cause- 3 points

Answer 28

-The incomplete oxidation of glucose
-causes a build up of lactic acid
-and creates an oxygen debt

Question 29

-what happens to our muscles during long periods of vigorous exercise

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-what is the oxygen debt

Answer 29

lactic acid causes muscles to become fatigued AND so they stop contracting efficiently

(After resorting to anaerobic respiration and u stop exercising, you’ll have an oxygen debt)

-oxygen debt is amount of extra O2 body needs after exercise to react with accumulated lactic acid and remove it from cells

Question 30

-what happens to lactic acid in muscles after you’ve finished exercising- 3 points

Answer 30

-blood flowing through muscles
-transports lactic acid to liver
-where it’s converted back into glucose

Question 31

2 ways your body deals with lactic acid build up

Answer 31

-blood transports lactic acid to liver where it’s converted into glucose

-you ‘repay’ the oxygen- breath hard after exercise to get more o2 in blood- o2 reacts w/ lactic acid in muscle cells to form CO2 and water

Question 32

how do you measure:
breathing rate
heart rate

• why does pulse rate increase the more intense exercise is-

-how can you reduce random errors when plotting a bar graph on pulse rate/breath count and type of exercise-

Answer 32

-count breaths
-taking the pulse
(2 fingers on inside of wrist/neck-count no. of pulses in 1 min)

-body needs to get more oxygen to muscles and take more CO2 away

(-co2 is in muscles because it is a product of aerobic respiration)

-do as a group and plot the average

Question 33

5 chemical reactions involved in metabolism

Answer 33

-conversion of glucose to starch/glycogen/cellulose

-formation of lipid molecules from 1 glycerol + 3 fatty acids

-glucose and nitrate ions form amino acids which synthesise protiens

-respiration

-breakdown of excess protein to form urea for excretion

Question 34

metabolism is..
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energy released by respiration is used by…..
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-the chemical reactions that occur in our bodies are controlled by…

Answer 34

the sum of all the reactions in a cell/ the body

-energy released by respiration is used by enzymes to synthesise new molecules in the cell

-enzymes

Question 35

why is glucose important x2
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how is glucose used in only plants-x3
these are included in metabolism

Answer 35

-starting point for many new chemicals
-energy released from glucose in respiration

-glucose molecules converted into starch- a storage form of glucose

-glycose reacts w/ nitrate ions to form amino acids-
amino acids used to synthesis protiens

-glucose converted into cellulose-

Question 36

how is glucose used in only animals x1

-other reactions involved in metabolism x3

Answer 36

glucose converted into Glycogen- storage form glucose

*1 molecule of glycerol reacted w/ 3 molecules of fatty acids to form a lipid molecules- found in cell membrane

*excess protiens broken down into urea which is excreted in urine by kidneys

*glucose broken down in respiration to transfer energy