Photosynthesis and Leaf Structure Flashcards
What is the word equation for photosynthesis
Carbon dioxide + water —> glucose + oxygen
What is the balanced equation for photosynthesis
6️⃣CO2 + 6️⃣H2O —> C6H12O6 + 6️⃣O2
What do plants do to the glucose
Convert it into starch and use for respiration
An experiment to show that CO2 is needed for photosynthesis to occur and result
Destarch leaf (place in darkness) Place in CO2 free air Expose to light for 24 hours Iodine test for starch Result: no starch
An experiment to show that light is needed for photosynthesis to occur and result
Destarch plant (leave in darkness so that all starch is converted to glucose due to aerobic respiration)
Expose part of plant to light for 24 hours, part covered in black paper
Iodine test for starch
Exposed: starch present
Covered: no starch
What chemical is used to test for starch and what is the result
Iodine
Positive —> blue/ black
Why will the green parts of a leaf being able to photosynthesise and not the white bits
The green parts of the leaf contain chlorophyll so are able to photosynthesise whereas the white bits don’t
How are leaves adapted to their function (5)
Broad, flat, large surface area to trap light
Palisade cells contain chlorophyll in chloroplasts
Air spaces in spongy mesophyll layer allow gaseous exchange
Transparent epidermis allows light to pass through
Leaf is thin so there is a short diffusion pathway
What is the structure of a leaf (order from top to bottom)
Waxy cuticle Upper epidermis Palisade mesophyll Spongy mesophyll Lower epidermis + guard cells Waxy cuticle
What is the function of the waxy cuticle
Controls loss of water (evaporation)
Protects epidermis
What is the function of the upper epidermis
Let’s light thought to the palisade layer
What is the function of the palisade cells
Contains chloroplasts with chlorophyll so can absorb sunlight for photosynthesis
What is the function of the spongy mesophyll layer
Contains air spaces for gaseous exchange via stomata
What is the function of the guard cells
Opens/ closes stomata so it controls gas exchange and water loss
What is the function of the stomata
Where gaseous exchange takes place
Which two features of the leaf control water loss
Guard cells
Waxy cuticle
How do we test a leaf for starch and results
Boil leaf in boiling water bath to kill it
Put leaf in a test tube of ethanol to remove chlorophyll
Rinse leaf with cold water to get ride of the rest of the chlorophyll
Iodine - blue/black if starch is present
What are the uses of glucose in a plant (4)
Stored as starch
Respiration to release energy
Converted to proteins for growth
Cellulose for cell walls
What factors affect the rate of photosynthesis
Concentration of CO2
Temperature
Light intensity
What is the useful product from photosynthesis and what is it use for
Glucose is used as a source of energy
Which long chain molecules can glucose convert into and. What are their uses
Starch - stores energy
Cellulose - cell walls
Which element is needed to make protein and not to make carbohydrates
Nitrogen
Which gases enter and leave plants during photosynthesis
Carbon dioxide enters
Oxygen leaves
Which gases enter and leave during respiration in plants
Oxygen enters
Carbon dioxide leaves
What affects the rate of photosynthesis
Light intensity
Amount of CO2
Varying temperature
How does light intensity affect photosynthesis
Increasing light intensity increases photosynthesis as plants need light to photosynthesise. After a certain point the rate will reach its maximum as there will be another limiting factor
How does increasing the concentration of Co2 increase the rate of photosynthesis
Increasing the concentration will increase the rate of photosynthesis as plants need CO2 to photosynthesise. After a certain point the rate will reach its maximum as there will be another limiting factor
How does increasing the temperature increase the rate of photosynthesis
Rate of photosynthesis has an optimum temperature so too hot and photosynthesis will decrease, too cold and photosynthesis will also decrease. At a certain point the rate will reach its maximum as there will be another limiting factor
Which 4 minerals do plants need to thrive
Nitrate
Potassium
Phosphate
Magnesium
Why do plants need nitrates and what will happen if there is a deficiency
Makes amino acids, proteins, DNA, chlorophyll
Stunted growth
Older leaves turn yellow
Why do plants need potassium and what happens if there is a deficiency
For enzymes for respiration
Needed for photosynthesis to work
Leaves turn yellow with dead spots
Why do plants need phosphate and what will happen if there is a deficiency
Makes DNA and compounds in cell membrane
Younger leaves turn purple
Poor root growth
Why do plants need magnesium and what happens if there is a deficiency
Part of the chlorophyll molecule
Leaves turn yellow
What are the advantages of hydroponic cultivation of vegetables (3)
Clean
Disease/ pest control
Efficient/ controlled
What are the disadvantages of hydroponic cultivation of vegetables (3)
Expensive to set up
High maintenance
Diseases can spread easily
