Bioenergetics Flashcards
Photosynthesis word equation
carbon dioxide + water ———-> oxygen + glucose sunlight
Photosynthesis symbol equation
6CO₂ + 6H₂O ————> C₆H₁₂O₆+ 6O₂
Photosynthesis reaction type
Endothermic
Plant uses of glucose
- respiration
- making cellulose
- making amino acids
- storing as oils or fats
- storing as starch
How do plants make amino acids
- glucose combined with nitrate ions absorbed from soil
- amino acids made into proteins
How do plants store oils and fats
Glucose turned into lipids and stored in seeds
How is starch stored in plants
- stored in roots, stems, leaves
- used when photosynthesis isn’t happening
How is starch better for plant storage than glucose
- insoluble
- plant with lots of glucose would draw up lots of water and swell up
Photosynthesis limiting factors
- light intensity
- CO₂ concentration
- temperature
- chlorophyll concentration
Photosynthesis limiting factor at night
Light intensity
Photosynthesis limiting factor in winter
Temperature
Photosynthesis limiting factor when warm and bright
CO₂ concentration
What can affect amount of chlorophyll in plant
- disease
- lack of nutrients
How can chlorophyll limit photosynthesis
When chloroplasts are damaged, not enough chlorophyll is made to absorb light for photosynthesis
How does light affect rate of photosynthesis
As light intensity increases, rate of photosynthesis increases to a certain point where it then makes no difference
How does carbon dioxide affect photosynthesis
As amount of CO₂ increases, rate of photosynthesis increases to a point then it makes no difference
How does temperature affect photosynthesis
- as temperature increases, rate of photosynthesis increases to a point where it decreases and stops working
- enzymes for photosynthesis work slower and lower temperatures but are destroyed at around 45°C
Photosynthesis practical
- place LED bulb (doesn’t produce heat) at specific distance from pondweed in water in test tube
- as pondweed photosynthesises, count oxygen bubbles produced for 1 minute
- repeat with light at different distances away to see how that affects rate of photosynthesis (number of bubbles produced)
Inverse square law
Light intensity ∝ 1/distance²
How do greenhouses optimise conditions
- trap heat so temperature doesn’t become limiting
- use shade and ventilation in summer to cool down
- can use artificial light to photosynthesise at night
- paraffin heater can increase CO₂ levels
- protect from pests/disease
Respiration
Process of transferring energy from glucose which goes on in every cell
What type of reaction is respiration
Exothermic
Uses of energy transferred from respiration
- build up larger molecules from smaller ones
- allow muscles to contract and relax
- mammals keep body temperature steady in colder surroundings
Metabolism
Sum of all reactions that happen in a cell or body
More efficient respiration
Aerobic
Where do most aerobic respiration reactions occur
Inside mitochondria
Aerobic respiration word equation
glucose + oxygen —> carbon dioxide + water
Aerobic respiration symbol equation
C₆H₁₂O₆+ 6O₂ —> 6CO₂ + 6H₂O
When is anaerobic respiration used
In addition to aerobic respiration when body can’t supply enough oxygen to muscles
How is lactic acid produced
- through incomplete breakdown of glucose in anaerobic respiration in muscle cells
- bi-product of anaerobic respiration in muscle cells
Word equation of anaerobic respiration in muscle cells
glucose —> lactic acid
Why doesn’t anaerobic respiration in muscle cells not transfer as much energy
Glucose isn’t fully oxidised
Word equation for anaerobic respiration in plants and yeast cells
glucose —> ethanol + carbon dioxide
What type of organism is yeast
Single celled
Name of anaerobic respiration in yeast cells
Fermentation
Uses of yeast fermentation
- making alcohol
- making bread rise
What increases as you exercise
- respiration
- breathing rate
- breathing volume
- heart rate
Why does breathing rate and volume increase when exercising
To get more oxygen into blood for increased respiration
Why does respiration increase when exercising
To supply more energy to muscles for more frequent contraction
Why does heart rate increase when exercising
- get oxygenated blood around body faster
- remove CO₂ faster
Problem with lactic acid
Builds up in muscles which gets painful
What happens to muscles in long periods of exercise
Muscle fatigue
Muscle fatigue
When muscles get tired and stop contracting efficiently
When does oxygen debt occur
After exercising
Oxygen debt
Amount of extra oxygen the body needs to react the buildup of lactic acid and remove it from cells
Why do you keep breathing hard after exercising
To get oxygen into your blood which is transported to muscle cells
What stays high after exercising
- breathing rate
- pulse
Ways of removing lactic acid
- react with oxygen to form CO₂ and water
- blood transports lactic acid to liver to be covered back to glucose
How to investigate effect of exercise on body
- record pulse after 5 mins of sitting, walking, jogging, running
- plot results on bar chart
