B4 Bioenergetics Flashcards
Word Equation for Photosynthesis
Water + carbon dioxide»_space; oxygen + glucose
Symbol Equation for photosynthesis
6H20 + 6CO2»_space; 6O2 + C6 H12 O6
Where does photosynthesis occur?
Chloroplast
Word Equation Aerobic respiration
Glucose + oxygen»_space; carbon dioxide + water
Symbol equation Aerobic Respiration
C6 H12 O2 + 6O2»_space; 6O2 + 6H2O
Where does aerobic respiration occur?
Mitochondria
Word equation anaerobic respiration in muscles
Glucose»_space; lactic acid
Word equation anaerobic respiration in yeast
Glucose»_space; ethanol + carbon dioxide
Where do both types of anaerobic respiration occur?
Cytoplasm
What happens to oxygen that plants produce?
Diffuses out of stomata as a waste product
Describe how guard cells close stomata
- Ions transported out of guard cells
- Water leaves guard cells by osmosis
- Reduces turgor
- Flaccid guard cells straighten
- Stoma closes
Describe how guard cells open stomata
- Ions transported into guard cells
- Water enters guard cells by osmosis
- Increases turgor
- Turgid guard cells curve
- Stoma opens
Why store glucose as starch?
It is insoluble rather than the soluble glucose that could be lost. Starch can be converted back when needed.
SCARF
5 uses of glucose in a plant
- Starch (as a store)
- Cellulose (for cell walls)
- Amino Acids (to make proteins & grow)
- Respiration (energy for this)
- Fats (as a store)
Limiting factors for photosynthesis
- Light intensity
- Temperature
- Carbon dioxide
- Chlorophyll
What is glucose combined with to make amino acids?
Glucose + NITRATE IONS»_space; amino acids»_space; proteins
Describe how rate of photosynthesis changes with light intensity
At the start, increasing light intensity increases the rate of photosynthesis (ROP)
Eventually, increasing light intensity stops increasing ROP
This means the ROP plateaus. It hasn’t stopped, it just stopped increasing!!
Describe how rate of photosynthesis changes with carbon dioxide concentration
At the start, increasing CO2 concentration increases the rate of photosynthesis (ROP)
Eventually, increasing CO2 concentration stops increasing ROP
This means the ROP plateaus. It hasn’t stopped, it just stopped increasing!!
Describe how rate of photosynthesis changes with temperature
At the start, there is not much
energy to catalyse the reaction
It peaks at the optimum temperature
The enzyme begins to denature and the ROP decreases
How to reduce light as a limiting factor to increase crop yields
- Greenhouses to enable maximum transition of light
- Artificial lighting with increased light intensity to provide optimum wavelength
These mean that the plant’s growing season is lengthened = more profit
These modifications to growing areas are commonly seen in illegal marijuana plants
How to reduce temperature as a limiting factor
- Greenhouses to trap heat inside
- Industrial greenhouses fitted with windows/vents to allow cooling
How to reduce water as a limiting factor
- Irrigation systems used to increase yields
- Plants sprayed with water to keep humidity high
reduces rate of transpiration, minimising water loss
Photosynthesis RPA Method
- Cut pondweed and secure it in a boiling tube, cut end up
- Add 20ml of Sodium Hydrogen Carbonate as a CO2 source
- Put in a beaker of water (heat protection)
- Ruler next to beaker. Lamp at set distance.
- Count bubbles in set time
- Move lamp back set distance and repeat for a mean
Improvements for Photosynthesis RPA
- Use LED bulb (heat not produced)
- Measure volume of oxygen with a gas syringe instead of counting bubbles
Variables for Photosynthesis RPAs
Independent: light intensity (distance from lamp)
Dependent: volume of oxygen (bubbles per minute)
Control: size of pondweed/pondweed species/concentration of sodium hydrogen carbonate
Inverse Square Law
Light intensity is inversely proportional to the square of the distance
Light intensity ∝ 1/distance
Two uses of anaerobic respiration in yeast
- Alcohol production»_space; it produces alcohol that can be used in making beer
- Baking»_space; it produces carbon dioxide that creates air bubbles making bread rise
Which type of respiration releases the most energy
Aerobic
Why would you do anaerobic respiration?
During exercise – when energy demand is greater than oxygen supply.
How does body maximise oxygen supply? (Heart rate)
Blood flows faster
Supplies O2 to cells & removes CO2 from them
How does body maximise oxygen supply? (Breathing rate)
Oxygenates blood faster
Removes CO2 faster
How does body maximise oxygen supply? (Breath volume)
Oxygenates blood faster
Removes CO2 faster
How does body maximise oxygen supply? (Sweating)
Sweat evaporates using body heat
Lowers body temp
What is oxygen debt?
An oxygen debt is the amount of extra oxygen your body needs after exercise.
This means you continue to breathe hard after you stop to ‘pay’ this debt.
You have to ‘repay’ the oxygen that you didn’t get to your muscles during the exercise because your lungs, heart and blood could not meet demand.
What hapoens during long periods of excercise (in terms of respiration & oxygen)
During long periods of vigorous activity:
* The body breaks down glycogen (stores of glucose in muscles + liver) into glucose, eventually causing muscle fatigue.
* Lactic acid levels begin to build up and produce an oxygen debt.
What happens to the oxygen to take in through an oxygen debt?
It is used to complete the breaking down of glucose. Reacts with lactic acid to form carbon dioxide and water
Define metabolism
Sum of all reactions in a cell/organism
What are lipids, where are they stored and what is their use?
Fats/oils
Stored under skin
Have uses in building cell membranes
What are lipids made up of?
A molecule of glycerol and 3 fatty acid molecules
