B8 Photosynthesis Flashcards
Photosynthesis
Process when plants and some other organisms convert light energy into chemical energy in the form of glucose
Word equation for photosynthesis
light
Carbon dioxide + water —————–> glucose + oxygen
Symbol equation for photosynthesis
light
6CO2 + 6H2O —————–> C6H12O6 + 6O2
Describe process of photosynthesis
Photosynthesis uses energy to convert carbon dioxide and water into glucose and oxygen
Where does photosynthesis take place
In chloroplasts in green plant cells
How is energy transferred to the chloroplasts from the environment
By light
How plants get the materials they need for growth
From air and water
Describe how the leaf is adapted for photosynthesis
A leaf usually has a large surface area, so that it can absorb a lot of light
Contains palisade cell to absorb light
How adaptations of the leaf make photosynthesis efficient
Light provides energy needed for photosynthesis
As light level is raised rate of photosynthesis increases
Why do plants need light for photosynthesis
To convert carbon dioxide and water into carbohydrates
Describe an experiment to prove that plants carry out photosynthesis when exposed to light
Place boiling tube so pondweed is 10 cm away from light source
Allow boiling tube to stand for five minutes
Count number of bubbles emerging from the cut end of the stems in one minute
Repeat the count five times and record your results
Why chlorophyll is needed for photosynthesis
To absorb light
What is amount of chlorophyll in a plant be affected by
Disease or environmental stress such as lack of nutrients
These factors can damage chloroplasts or not make enough chlorophyll
Why would photosynthesis be reduced if there isn’t enough chlorophyll
They can’t absorb as much light
List the factors that affect the rate of photosynthesis
Temperature
Carbon dioxide concentration
Light intensity
Amount of chlorophyll
How does temperature affect the rate of photosynthesis
As temperature increases the number of collisions between enzymes and substrate increases, so rate of photosynthesis increases
What happens to enzymes at high temperatures
Denatured
How does carbon dioxide concentration affect the rate of photosynthesis
As CO2 increases the plant can use more of the available light and water to photosynthesis
If concentration of carbon dioxide is increased, the rate of photosynthesis will increase
How does light intensity affect the rate of photosynthesis
Increased light intensity means more energy is available to drive the light-dependent reactions
What is photoinhibition
If light intensity continues to increase beyond saturation point it can lead to photoinhibition where rate of photosynthesis decreases
Why low temperature limits rate of photosynthesis
If its too low the enzymes needed for photosynthesis work more slowly at low temperatures
Why shortage of carbon dioxide limits rate of photosynthesis
When there is a shortage of CO2 there isn’t enough carbon available to produce glucose
Why shortage of light intensity limits rate of photosynthesis
Without enough light, a plant cannot photosynthesise very quickly
how the rate of photosynthesis will be affected with more than one limiting factor
Any change in the level of a limiting factor will affect the rate of reaction
How to tell where on a graph there is a limiting factor
Where there is a straight line on the graph
List ways in which plants use glucose
Respiration
Making cellulose and amino acids
Stored as starch, oil or fats
How is glucose used for making cellulose and amino acids
Converted into cellulose for making strong plant cell walls
Glucose is combined with nitrate ions to make amino acids which then made to proteins
How is glucose stored as oil, fats, starch
Glucose turned into lipids
Glucose turned into starch and stored in roots for storage and long-term energy usage
Explain how carnivorous plants are adapted to their environment
Have adaptations to provide additional nutrients by consuming insects
How to test a leaf for starch
Dip leaf in water to soften it
Spread leaf on white tile
Add iodine
A chemical reagent, which changes from yellow-brown to blue-black in the presence of starch
Safety rules for testing leaf for starch
Ensure ethanol is kept away from naked flames
Students should wear eye protection
Risks involved in starch test
Ethanol is highly flammable
Why greenhouses increases plant growth
Warmth and humidity promote plant growth
How using greenhouses can help control limiting factors and increase the rate of photosynthesis
Paraffin lamps inside a greenhouse increases rate of photosynthesis as burning paraffin produces CO2 and heat
Cost-effectiveness of adding heat greenhouses
Use of alternative energy sources (solar, geothermal) are cheaper to use
Cost-effectiveness of adding light to greenhouses
LED lights have longer lifespan and is cheaper
Cost-effectiveness of adding carbon dioxide to greenhouses
CO2 enrichment is highly cost effective when other conditions are optimal
What are hydroponics
Technique of growing plants using a water-based nutrient solution rather than soil
Benefits of hydroponics
Conserves water
Crops grow faster
Produce higher yields
Economic value of hydroponics
Promoting cost savings for growers
Reduces labour costs and risks
Economic value of greenhouses
Increase crop production
Reduces the dependency on seasonal cycles
Enables year-round production
Photosynthesis is ENDOTHERMIC reaction because…
Needs more input of energy from environment
