Bioenergetics Flashcards
What do plants use as a source of energy?
Light from the sun
What is the name of the reaction that traps energy for plants
Photosynthesis
What type of reaction is photosynthesis?
Endothermic because it takes in energy
Where does photosynthesis take place in?
The leaf
How does photosynthesis occur?
Plant takes in carbon dioxide and water
The chlorophyll in chloroplasts absorb light energy
Light energy used in reaction to concert CO2 and H2O into glucose and oxygen
Photosynthesis word equation
Carbon dioxide + water ——> Glucose + Oxygen
Photosynthesis symbol equation (unbalanced)
CO₂ + H₂O ——> C₆H₁₂O₆ + O₂
Limiting factor in photosynthesis
When a factor lowers the rate of photosynthesis
So if you increase it the rate of photosynthesis will increase
But eventually rate stops increasing as something else becomes limiting factor
What could be a limiting factor?
Light intensity
Carbon dioxide level
Amount of chlorophyll
Temperature
Amount of chlorophyll as a limiting factor
The leaf will trap less light if there are low levels of chlorophyll in the leaf
Making it a limiting factor
How are limiting factors shown on a graph for photosynthesis
(CO2, chlorophyll, light intensity)?
The rate will increase as the factor increases showing it couldn’t have increased before as there wasn’t enough
It straightens off when it no longer is a limiting factor
Temperature as a limiting factor
Increasing it will increase rate of reaction
But if you increase it over the enzymes optimum it will denature and rate will fall
How is temperature limiting factor graph shown?
Rate increase as temperature increases
But falls to 0 as it reaches optimum temperature
What can plants use glucose from photosynthesis for?
For respiration to release energy
Starch
Fats and oils
Cellulose
Amino acids
Why do plants store glucose as starch?
It is insoluble
So can be stored and then converted back into glucose if they need it for respiration
Because at night time they cannot make more glucose with no photosynthesis so they can use the stored starch instead
Why do plants convert glucose to fats and oils?
As a storage form of energy
Why do plants make cellulose from glucose?
Because it strengthens the cell wall which keeps it from bursting
Why do plants make amino acids from glucose?
Amino acids are needed for protein synthesis
How do plants make amino acids from glucose?
From nitrate ions
How can we determine what the limiting factor is?
Increase the amount of another factor and record the rate of photosynthesis
If the rate increases then that was the limiting factor
If not repeat with another factor
Why do farmers want to increase the rate of photosynthesis
It increases yield of crops they want to produce
How do farmers increase the rate of photosynthesis?
Oil burners = increase heat and carbon dioxide
Greenhouse = light heat and carbon dioxide increase
Problem with increasing yield
Methods of increasing yield are expensive so the yield has to be justified
What do humans need energy
Movement
Maintain body temperature
Chemical reactions to build larger molecules
How do humans get energy
Respiration
What type of reaction is respiration
Exothermic because it releases energy
Aerobic respiration word equation
Glucose + oxygen ——> carbon dioxide + water + (energy)
Why does aerobic respiration release a lot of energy?
Because the glucose molecule has been fully oxidised
Aeróbic symbol equation
C₆H₁₂O₆ + O₂ ——> CO₂ + H₂O
Anaerobic respiration
Happens when not enough oxygen is present
Anaerobic respiration word equation in muscles
Glucose ——> Lactic acid+ (energy)
Why does anaerobic respiration not release as much evidence?
Because the glucose molecule has not been fully oxidised
Anaerobic respiration in plant/yeast cells
Glucose ——> ethanol + carbon dioxide
Uses of yeast anaerobic respiration
Can make alcoholic drinks like beer
Can make bread as the carbon dioxide causes bubbles in the dough = rise
Name for yeast anaerobic respiration
Fermentation
Why do we need more energy during exercise?
For muscle contraction
What changes with the body cells during exercise?
Increase in aerobic respiration
Therefore body cells demand more oxygen
If the body cells demand more oxygen, what do we do?
Breathing rate and volume increases (more frequent deeper breaths)
To get more oxygen in blood stream
So heart rate increases to bump the oxygenated blood around
What is the problem with exercising?
Not enough oxygen can be supplied to muscles especially if exercise is too vigorous
So we can’t aeróbically respire
What do we do once we don’t have enough oxygen for aerobic respiration?
Respire anaerobically
But the oxidation of glucose incomplete = lactic acid builds up
What happens when lactic acid builds up?
If we do a lot of vigorous activity = lactic acid makes muscles fatigued
So stop contracting efficiently
What do we do when muscle fatigue happens?
We need to remove the lactic acid by oxidising it
Therefore enter a condition called oxygen debt
How is lactic acid removed from muscles?
Transported out in the blood to the liver
Converted back to glucose in chemical reactions using oxygen
Oxygen debt
The oxygen required to convert the lactic acid that has built up back to glucose
Metabolism
The sun of all chemical reactions in a cell or the body
How is metabolism and respiration linked?
Respiration releases energy
Which is used by enzymes to synthesise new molecules in a cell in chemical reactions
Metabolism = sum of these reactions
Uses of glucose in plants
Cellulose = strengthens cell wall
Starch = storage form of glucose
Reacts with nitrate ions = amino acids = protein synthesis
Converted to fats and oils = storage form of energy
Uses of glucose in humans
Glycogen = storage form released if blood sugar levels fall too low
Aerobic respiration
Metabolism reaction for lipid
1 glycerol molecules
3 fatty acid molecules
Where are lipids found?
In the cell membrane
Metabolism reaction involving excess protein
Excess protein —> urea —> excreted
