Bioenergetics Flashcards
State the balanced symbol equation for photosynthesis
6 CO2 + 6 H2O → C6H12O6 + 6 O2
State the word equation for photosynthesis
light
carbon dioxide + water → glucose + oxygen
Name 5 uses of glucose (for plants)
- Respiration
- Making Cellulose
- Making Amino Acids
- Stored as Oils or Fats
- Stored as Starch
How glucose is used for respiration (in plants)?
Respiration transfers energy from glucose = enables plant to convert rest of glucose into other useful substances
How glucose is used to make cellulose (in plants)?
Glucose is converted into cellulose for making strong plant cell walls
How glucose is stored as oils or fats (in plants)?
Glucose is turned to lipids (fats & oils) for storing in seed
How glucose is used to make amino acids (in plants)?
Glucose combined with nitrate ions (from soil) to make amino acids = made then into proteins
Where is starch stored and why is it stored?
Glucose turned into starch and stored in roots, stems & leaves, ready for use when photosynthesis isn’t happening (like in winter)
Why is starch better for storing than glucose?
Because starch is insoluble - cell with lots of glucose would draw in loads of water and swell up
What is a limiting factor?
Is something that can stop photosynthesis from happening any
Name 4 things the rate of photosynthesis is affected by?
- Temperature
- Intensity of light
- Concentration of carbon dioxide
- Chlorophyll
How can amount of chlorophyll in plant be affected?
Can be affect by disease or environmental stress (lack of nutrients)
How does amount of chlorophyll affect the rate of photosynthesis?
If chloroplasts are damaged or don’t make enough chlorophyll (e.g. due to disease), means rate of photosynthesis decreases as they can’t absorb as much light
In winter, what is usually the limiting factor?
Temperature
At night, what is usually the limiting factor?
Light
When it’s warm enough and bright enough, what is usually the limiting factor?
Carbon dioxide
Why does photosynthesis require light?
Because it provides energy
As the light level is raised, what happens to the rate of photosynthesis?
It increases steadily BUT only up to a certain point
Why might the rate of photosynthesis not increase as the light intensity increases?
Because either temperature or CO2 level is a limiting factor
As the CO2 level is raised, what happens to the rate of photosynthesis?
It increases steadily BUT only up to a certain point
Why does the temperature affect the rate of photosynthesis?
Because it affects enzymes involved
What does it mean if the limiting factor is temperature?
Means the temperature is too low
Why does increasing the temperature make the rate of photosynthesis increases?
Because the collisions between enzymes and substrates occur more frequently
What happens to the rate of photosynthesis when a plant gets too hot and why?
Enzymes become denatured causing photosynthesis to stop completely
Why is respiration important?
It transfers energy that cells needs to do everything - this energy is used for all living processes
What is respiration?
Process of transferring energy from glucose, which goes on in every cell
Name 3 things respiration transfers energy for?
- To build up larger molecules from smaller ones (like proteins from amino acids)
- In animals it’s used to allow the muscles to contract (so they move about)
- In mammals & birds the energy is used to keep their body temperature steady in colder surroundings
What is aerobic respiration?
Respiration using oxygen - most efficient way to transfer energy from glucose
State the word equation for aerobic respiration
glucose + oxygen → carbon dioxide + water
State balanced symbol equation for aerobic respiration
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
When is anaerobic respiration is used?
If there’s not enough oxygen
Why doesn’t anaerobic reposition transfer nearly as much energy as aerobic respiration?
Because glucose isn’t fully oxidised (doesn’t combine with oxygen)
What is anaerobic respiration?
It’s the incomplete breakdown of glucose, making lactic acid
State the word equation for anaerobic respiration (occurs in animals)
glucose → lactic acid
When is anaerobic respiration useful?
Only useful in emergencies
When plants and yeast cells respire without oxygen, what do they produce?
They produce ethanol and carbon dioxide (instead of lactic acid)
What is anaerobic respiration called in yeast cells?
fermentation
In bread-making, what makes bread rise?
The carbon dioxide from fermentation
In beer and wine-making, what produces alcohol?
The fermentation process
State the word equation for anaerobic respiration that occurs in plants and yeast cells
glucose → ethanol + carbon dioxide
Why do muscles need energy from respiration?
To contact
Name 3 things that happens when you exercise (to increase respiration)
- Breathing rate increases
- Breath volume increase
- Heart rate increases
Why does your breathing rate and breath volume increases when you exercise?
To get more oxygen into blood
Why does your heart rate increases when you exercise?
To get this oxygenated blood around body faster & also removes CO2 more quickly at same time
When you do really vigorous exercise (e.g. Sprinting), what happens?
Your body can’t supply oxygen to your muscles quickly enough so they start respiring anaerobically
Why anaerobic respiration not the best way transfer energy from glucose?
Because lactic acid builds up in muscles which gets painful
After resorting to anaerobic respiration, when you stop exercising you’ll have an …
“oxygen debt”`
What is an oxygen debt?
Amount of extra oxygen your body needs to react with build up lactic acid and remove it from cells
When oxygen reacts with lactic acid, what is formed?
(Harmless) CO2 and water
Why do you have to keep breathing hard for a while after you stop exercising?
To get more oxygen into your blood (transported to muscle cells)
When does your pulse and breathing rate stay high?
Whilst there’s high levels of lactic acid and CO2
What the other way your body copes with high levels of lactic acid?
Blood that enters your muscles transports lactic acid to liver. In liver, lactic acid is converted back to glucose.
How can you increase carbon dioxide levels in a greenhouse?
Using paraffin heater = heats & makes CO2 as by-product
What’s the benefit of keeping plants in a greenhouse?
Keep free from pests & diseases
Why does a fitter person have a lower heart rate?
A fitter person’s heart is stronger → can pump more blood in each beat = doesn’t have to work as hard
Name 2 short-term internal effects of exercise
- Glucagon turns glycogen back into glucose for respiration
- Vasodilation
Define heart rate
Beats per min
Define cardiac output
Vol. of blood pumped in a minute
Define stroke volume
Vol. of blood in one beat
How do you calculate cardiac output
Stroke Volume x Heart Rate
