Topic 4 - Bioenergetics Flashcards
(41 cards)
Photosynthesis equation
Carbon dioxide +water —— (with light) = glucose +oxygen
6CO2 + 6H2O ————- (with light) C6H12O6 + 6O2
What does photosynthesis do?
Uses energy to change carbon dioxide and water into glucose and oxygen
Where does photosynthesis take place?
In the chloroplasts in the green plant cells which contain pigments like chlorophyll that absorbs light
Is photosynthesis endothermic or exothermic?
Photosynthesis is endothermic- energy is transferred from the environment.
What are the five ways plants use glucose?
1 - RESPIRATION - transfers energy from glucose which enables the plant to convert the rest of the glucose into various other useful substances
2 - MAKING CELLULOSE - glucose is converted into cellulose for making cell walls
3 - MAKING AMINO ACIDS - glucose combined with a nitrate ions (from soil) to make amino acids to make proteins
4 - STORES OF FAT AND OIL - glucose is turned into lipids for storing in seeds
5 - STORED AS STARCH - glucose is stored as starch in the roots, steams and leaves. Starch =insoluble =better for storing than Glucose.
Limiting factors in photosynthesis
Light
Co2
Temperature
(Sometimes) chlorophyll
Amount of chlorophyll can be affected by disease , environmental stress.
Rates of photosynthesis (graphs need to be looked up) p.g 58
Light provides energy needed for photosynthesis.as light lever increases rate of photosynthesis increases steadily only to a CERTAIN POINT. Then something else become the limiting factor.
Carbon dioxide is needed. The rate of photosynthesis will only increase up to a point then the graph flattens and something else is the limiting factor
Light and carbon dioxide graph goes from 0 then steadily up and flattens out.
Temperature- too low = enzymes slow too high= enzymes denatured. Denatures from 45degrees
SPECIAL POINT ABOUT STARCH
as starch is insoluble and is stored in cells. This prevents water from moving into the cell via osmosis. This is because starch does doesn’t affect osmosis as its insoluble. Sugar would effect it as it is a soluble thing so if it’s put into water then it lowers the concentration. However starch isn’t solvable so it doesn’t affect it it doesn’t lower or higher the concentration of water.
Equation for the rate of photosynthesis
Light intensity is directly proportional to one over distance squared.
So: light intensity (proportion symbol) to 1/d^2
How can you artificially create the ideal conditions for farming?
Using a greenhouse to create ideal conditions
How do greenhouses help?
1)They trap the suns heat and make sure that the temperature doesn’t become Limiting.
In winter they may use a heater to make sure temp isn’t limiting. In summer they may use shades and ventilators.
2) They supply artificial light so photosynthesis can continue after sunset.
3) enclosing plants- helps keep pests and diseases out.
Farmers can also use fertilisers to the soil to provide all the minerals for healthy growth.
Advantages and disadvantages of a greenhouse:
Disadvantage- All of the perfect conditions cost money.
Advantage - However if the farmer keeps conditions good for photosynthesis the plants can grow which means a BIGGER YIELD in LESS TIME.
Farmers need to be careful of the amounts of everything e.g temp can denature enzymes. Or they could waste money
Definition of respiration:
Respiration is the process of TRANSFERRING ENERGY FROM GLUCOSE, which goes on in EVERY CELL.
Is respiration exothermic or endothermic?
It is exothermic as it transfers energy to the environment.
Do plants respire?
Yes. All living things do. It transfers energy to the environment.
How often does respiration happen?
CONTINUOUSLY
respiration is the process if transferring energy from the breakdown of glucose and it happens in every cell continuously
Give three examples of how respiration is used:
1) to build up larger molecules from smaller ones e.g proteins from amino acids
2) in animals it’s used to allow muscles to contract
3) In mammals and birds the energy is used to keep their body temperature steady.
What is metabolism?
It is the sum of all reactions that happen in a cell or the body is called metabolism.
The chain of things to form bigger reactions:
Reactant ——>(with enzyme) —> product ——> (with enzyme) product ——>(with enzyme) product
In a cell there are lots of chemical reactions happening all the time which are controlled by enzymes. Many of which are linked together to form these bigger reactions(above)
Examples of metabolism:
- Lots of small glucose molecules are joined up together in reactions to form starch (in plants), glycogen (in animal cells), cellulose (plant cell walls)
- Lipids made up from one molecule of glycerol and 3 fatty acids
- Glucose is combined with nitrate ions to make amino acids then made into proteins
- Glucose is broken down in respiration. Respiration transfers energy to power all reactions in the body that makes molecules
- Excess protein is broken down in a reaction to produce urea. Urea is excreted in the urine
What are the two types of respiration?
Aerobic and anaerobic respiration
What is the most efficient way to transfer energy from glucose?
Aerobic respiration
Where do the reactions in aerobic respiration happen?
Most of the reactions in Andropov respiration happen Inside the mitochondria
Aerobic respiration requires….
Using oxygen.
It goes on all the time in plants and animals.
