Topic 4- Photosynthesis Flashcards
What is photosynthesis?
the process by which plants synthesise glucose using light energy from the sun.
light energy is converted into chemical energy
Where does photosynthesis take place?
within chloroplasts in leaf palisade cells. They contain chlorophyll, a pigment which absorbs light energy
State the equation for photosynthesis (words and symbol)
word: carbon dioxide + water = (light) glucose + oxygen
Symbol: 6CO2 + 6H2O =(light) C6H12O6 + 6O2
Is photosynthesis an endothermic or exothermic reaction and why?
endothermic- energy is transferred from the environment to chloroplasts by light
How can you show that a plant gives off oxygen during photosynthesis?
using a water plant (eg Elodea), collect gas bubbles produced during photosynthesis. The gas will relight a glowing splint as it contains oxygen
Give examples of leaf adaptations which maximise the rate of photosynthesis
broad leaves- maximise surface area
thin leaves- short diffusion distance
chlorophyll present- trap light energy
veins- transport water to leaves via xylem, remove photosynthesis products via phloem
Air spaces- allow C02 to enter and O2 to leave
Guard cells- control opening of stomata for gaseous exchange and prevent water loss
What are the four main factors that affect the rate of photosynthesis
Temperature
light intensity
carbon dioxide concentration
amount of chlorophyll
How does temperature affect the rate of photosynthesis?
increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased. The rate decreases past a certain temperature as enzymes become denatured
How does light intensity affect the rate of photosynthesis
increasing the light intensity increases the rate of photosynthesis until another factor becomes limiting
How does carbon dioxide concentration affect the rate of photosynthesis?
increasing the carbon dioxide concentration increases the rate of photosynthesis (until another factor becomes limiting) as CO2 is required to make glucose
How does the amount of chlorophyll affect the rate of photosynthesis?
decreasing the amount of chlorophyll decreases the rate of photosynthesis as chlorophyll is required to absorb light energy
What is limits factor?
An environmental factor which can restrict the rate of photosynthesis
explain how you can calculate the rate of photosynthesis by measuring oxygen production
set up bubble photometer apparatus (pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe)
oxygen gas produced causes the bubble in the capillary tube to move. The distance moved by the bubble is used to calculate the volume of oxygen produced
How can farmers use their knowledge of limiting factors to increase their profits
they can control temperature, light intensity and CO2 concentration to achieve the faster possible rate of photosynthesis, leading to a greater yield
State the law which describes the relationship between the distance of a light source from a plant and light intensity
inverse square law - light intensity §1 / distance^2
