The process through which a plant makes its own food using carbon dioxide and water
Things needed for photosynthesis
Water
Carbon dioxide
Sunlight
Chlorophyll
Photosynthesis
Carbon dioxide + Water → Glucose + Oxygen
Photosynthesis is an endothermic reaction - energy is transferred from the environment to the chloroplasts in the plant
Factors that can limit the rate of photosynthesis
Temperature
CO2
Light
Amount of chlorophyll
Temperature
The best temperature is about 40°C - anything above 30°C will slow photosynthesis right down
this is because temperature gives particles kinetic energy, increasing the chance that reactants bump into each other
CO2
If there is more carbon dioxide, photosynthesis will happen quicker
this is because it is one of the rawproducts required for photosynthesis
increase will continue until maximum efficiency is reached
Light
If there is more light, photosynthesis happens faster
this continues until either maximum productivity is reached or another factor becomes limiting
Amount of chlorophyll
The more chlorophyll, the more photosynthesis
Photosynthesis is controlled by enzymes - these are destroyed at temperatures above 40°C
Calculating intensity
Light intensity = 1/distancesquared
Uses of glucose produced by photosynthesis
Respiration
Making starch
Making cellulose for cell walls
Making amino acids for protein synthesis
Making lipids (fats or oils) to store in seeds
Respiration
The process our bodies use to produce energy, an exothermic reaction
(Aerobic) Respiration
Glucose + Oxygen → Water + Carbon Dioxide + Energy
Uses of energy from respiration
Building up sugars in plants
Building up body tissue
Maintaining a constant body temperature (warm-blooded mammals only)
Building up amino acids and nitrates
movement
active transport
protein synthesis
passage of nerve signals
Anaerobic respiration
Energy is provided without needing oxygen
Anaerobic respiration produces energy much quicker than aerobic respiration but only produces 1/20th as much
Lactic acid
Can build up in muscles causing fatigue and an oxygendebt, which then needs to be repaid by deep breathing to oxidise the lactic acid
Anaerobic respiration in plants and yeast
Glucose → Ethanol + CarbonDioxide
Anaerobic respiration in plants and yeast is called "fermentation" and is widely used in the manufacture of bread and alcoholic drinks
During exercise
Heart rate increases, breathing increases, and arteries supplying muscles dilate - these help muscles get the oxygen and glucose they need
Blood flowing through the muscles transports lactic acid to the liver where it is converted back into glucose. Oxygen debt is the amount of extra oxygen the body needs to break down the lactic acid and remove it.
Metabolism
The sum of all the reactions in a cell or body
Processes included in metabolism
Conversion of glucose to starch, glycogen and cellulose