Topic 4: Bioenergetics Flashcards
What is photosynthesis?
Photosynthesis is the process by which plants make glucose from sunlight.
is photosynthesis an exothermic or endothermic reaction?
It is an endothermic
a reaction where energy is transferred from the environment to the chloroplasts by light.
where does photosynthesis take place
photosynthesis takes place in the leaves of a plant. leaves contain chlorophyll which absorbs light energy
word equation for photosynthesis is:
carbon dioxide + water → glucose + oxygen
balanced symbol equation for photosynthesis
6C02+6H2o→ C6 H12 O6 + 6O2
symbol equation for photosynthesis
CO2+ H2O→ C6 H12 06 + O2
where is photosynthesis made
in the chloroplast
what does photosynthesis produce
glucose + oxygen
Rate of Photosynthesis (graph) - light intensity
- as light intensity increase the rate of photosynthesis increase
- this is because more energy is provided
- so the limiting factor was light intensity
- however, if the light intensity is increased at a certain point the rate of P.S will not increase ( stay the same )
- meaning another factor is limiting the rate of photosynthesis
Rate of Photosynthesis (graph) - temperature
- as the temperature increases the rate of photosynthesis increases
- this is because more energy is provided
- however when the temperature reaches a certain point the enzymes begin to denature
- so fewer collisions between enzymes and substrate
- if the temperature is low less energy is provided therefore the rate of photosynthesis decreases
Rate of Photosynthesis (graph) - LOW temperature
- temperature is low
- kinetic energy of particles is low
- particles move slowly
- less collision
- so rate decreases
Rate of Photosynthesis (graph) - temperature
SECTION A
- the temperature is the lowest
- kinetic energy of the particle is low
- resulting in a fewer collision between enzymes and substrate
- also enzymes move slower due to less energy
Rate of Photosynthesis (graph) - temperature
SECTION B
- the temperature is at the highest
- as a result, the enzymes are at the optimum point
- also photosynthesis can take place without enzymes denaturing
Rate of Photosynthesis (graph) - temperature
SECTION c
- the temperature is still high
- so more kinetic energy is produced
- particles move quicker
- therefore more collision
- but the rate of photosynthesis is low because enzymes denature
- and the active site changes shape so substrate won’t fit
rate of Photosynthesis (graph) - Carbon dioxide concentration
Carbon dioxide concentration increases the rate of photosynthesis
- because CO2 is a reactant and is also needed to make glucose
- above a certain concentration the rate would stay the same
- the limiting factor would no longer be the concentration of co2
rate of Photosynthesis (graph) - Amount of chlorophyll
the more chlorophyll the higher the rate of photosynthesis
-Chlorophyll is a pigment in the leaf that
converts light energy to food for the plant
how are chlorophyll levels are reduced
reduced through a
magnesium deficiency, then the rate of
photosynthesis would decrease.
uses of glucose - r
glucose produced by photosynthesis for respiration
transfers energy from the glucose then the plants convert the rest of the glucose into other useful substances
takes place in the mitochondria
uses of glucose - storage
glucose produced by photosynthesis is used to produce insoluble storage for starch
stored in roots, stems and leaves
uses of glucose - produce
glucose produced by photosynthesis is used to produce fats and oils as storage for energy
uses of glucose - cell
the cellulose is made from the glucose by photosynthesis and is used to strengthen the cell walls
uses of glucose - acid
glucose produced in photosynthesis is used to produce amino acids
to make amino acids from glucose
the plant absorbs nitrate ions from the soil to form amino acids or converted into
proteins
Required Practical 6: Photosynthesis
an experiment measuring the oxygen production of a plant, you can calculate the
rate of photosynthesis.
Describe how you would investigate the
effect of light intensity on the rate of
photosynthesis in an aquatic plant
start by taking a boiling tube and place it at a fixed distance (10cm) away from the light source
fill the boiling tube with sodium hydrogen carbonate solution
place a cut pondweed into the boiling tube and leave it in there for 5 minutes to acclimatise
you should see bubbles of gas being produced. this gas is oxygen which is produced by photosynthesis
you count the number of bubbles produced in one minute using a stopwatch
repeat this serval times at different distance / light intensity
and calculate the mean number of bubbles produced in one min
Why is it best to use an LED light source
rather than a lamp?
LED lights source don’t release very much heat energy this can affect the rate of photosynthesis
if you do use a normal light bulb what should you do?
place a beaker of water between the light and boiling tube to absorb the heat
Why is sodium hydrogen carbonate solution used
during this experiment?
It releases CO2
, which is needed for photosynthesis
why should you leave the pondweed for 5 minutes?
leave it to acclimatise
How can the measurement of oxygen
production be made more accurate?
we can measure the volume of oxygen produced rather than counting the bubbles
place the pondweed under a funnel and catch the bubbles in a measuring cylinder
what are the problems with this experiment?
- bubbles too fast to count accurately
- bubbles are not all the same size
Why can the number of bubbles produced to be used
to calculate the rate of photosynthesis?
Oxygen bubbles are formed as a product during
photosynthesis. The number of bubbles
produced in a given time is proportional to the
rate of photosynthesis
What is the relationship between the distance
from a light source and light intensity?
Inverse-square law - light intensity∝1 /
distance2
as distance doubles the light intensity decreases by a factor of 4 so as the distance halves the light intensity increases by a factor of 4
to workout inverse law
double the distance
light intensity divide by 4
why do farmers increase the rate of photosynthesis
increases the yield of crops, therefore, more money for them
how do farmers increase light intensity
use artificial light
glass windows trap the sunlight
how do farmers increase co2/temperature
paraffin heater to heat the greenhouse gas and the paraffin heater burns co2 as a by-product
how do farmers increase the temperature
greenhouse traps suns head during winter use
how do farmers decrease the temperature
use shades to block the sunlight
or ventilation
benefits of greenhouse
protection from dieses and pests
is respiration an Exo or endo
It is exothermic as energy is transferred to the environment
where does respiration take place
occurs in every cell in the body,
aerobic respiration - equation
glucose + oxygen → carbon dioxide + water
aerobic respiration - oxygen or no oxygen
respiration in which glucose is broken down in the presence of oxygen
respiration is made in the
mitochondria
aerobic respiration release a great or less deal of energy
it yields the most energy
symbol equation for
C6 H12O6+ O2—> CO2 + H2O
anaerobic respiration- oxygen or no oxygen
occurs when there is not much oxygen
anaerobic respiration - in muscle equation
glucose —> lactic acid
anaerobic respiration - release a great or less deal of energy
does not yield much energy
incomplete oxidation
the incomplete oxidation of glucose causes build up of lactic acid . this causes oxygen debt , this results in the muscles tiring and not contracting properly . blood flowing through the muscles transport lactic acid to the liver where it converts to glucose
anaerobic reaction In plant and yeast cells it is called
fermentation-equation
Glucose (C6 H12O6) —> Ethanol + Carbon dioxide (CO2)
what does this reaction produce
c6 H12O6 —> Ethanol + Carbon dioxide (CO2)
the glucose is converted to ethanol and carbon dioxide
overview of anaerobic respiration
respiration in which glucose is broken down in the absence of oxygen
to release lactic acid and co2
dose does not yield much energy
less energy as oxidation of glucose is incomplete
occurs in cytoplasm
overview of aerobic respiration
respiration in which glucose is broken down in with oxygen
glucose is completely oxidised
takes place in most organism
releases co2, h20
occurs in mitochondria
During exercise…
more energy is needed in order for the muscles to contract. This means
respiration has to occur faster, and therefore more oxygen needs to be supplied to cells (and more
CO2 removed).
to provide more oxygen
● Heart rate increasing
● Breathing rate increasing
● Breath volume increasing
oxygen debt
Oxygen debt is the
amount of extra oxygen the body needs after exercise to react with the accumulated lactic
acid and remove it from the cells. This results in the muscles tiring and not contracting properly.
Blood flowing through the muscles transports the lactic acid to the liver where it is
converted back to glucose.
define Metabolism
is the sum of all the reactions in a cell or the body.
Examples of metabolic reactions:
1.Glucose molecules being converted to starch, glycogen and cellulose by being joined
together
2. A glycerol molecule and three molecules of fatty acids forming a lipid molecule
3. Glucose and nitrate ions forming amino acids, which are used to form proteins
4. The reactions in respiration
5. Urea forming from the breakdown of proteins for excretion
Suggest two ways the method could be improved to measure the rate of
photosynthesis more accurately.
measure the volume of gas released rather than counting the bubbles by measuring the volume of gas released
increase length of time
repeat the measurement
at each distance several times
and calculate a mean
