🌿 Photosynthesis 🌿 Flashcards
Endothermic
(of a reaction or process) accompanied by or requiring the absorption of heat
Where photosynthesis takes place
In chloroplasts
How many simple substances photosynthesis involves combining
Two
- water
- carbon dioxide
Where is the water from in photosynthesis?
Soil
Where is the CO2 from in photosynthesis?
The air
What water and CO2 form
Sugar (glucose)
What are the by-products of photosynthesis?
Sugar (glucose) + oxygen
Where does the energy required for photosynthesis come from?
Sunlight
What traps sunlight?
Green pigment chlorophyll contained within chloroplasts
What is contained within chloroplasts?
Chlorophyll
Is photosynthesis endothermic
Yes
Photosynthesis word equation
CO2 + H2O —-> glucose + O
light
Chemical equation for photosynthesis
6CO2 + 6H2O ———> C6H12O6 + 6O2
How glucose produced in photosynthesis is used by the plant
- respiration 🫁
- storage 📦
- made into different substances
How glucose produced by photosynthesis is used for respiration
Broken down 🧱 in respiration produce energy 🏃♀️
How glucose produced in photosynthesis is used for storage
Converted into starch and stored in the leaves
How glucose produced by photosynthesis is made into useful substances
Converted into cellulose for cell walls, chlorophyll and protein for growth
How protein is used by plants
Growth
What much of the sugar produced by photosynthesis is converted to
Starch for storage 📦 in leaves 🍃
Test for starch
Iodine
Positive starch, Iodine colour change
Orange to blue– black
What does the presence of starch in a leaf indicate?
Photosynthesis has taken place
Why is the leaf initially place in boiling water in the starch test?
- kills the leaf
- stops chemical reactions
Why is the leaf in the starch test transferred to boiling ethanol?
Remove chlorophyll
How do you de-starch a leaf?
By leaving the plant in the dark for at least two days
Why do you de-starch leaves before any experiments?
- To ensure any starch already in the leaves is used up before the experiment
- Therefore it’s a starch test at the end of the investigation is positive starch present must’ve been produced during the investigation
- fair test
What is the aim of the light experiment?
To discover if the light is needed for photosynthesis
Results for light experiment
- positive result for starch = carried out photosynthesis
- no colour changed in covered part of leaf = no starch = no photosynthesis
- light = essential to photosynthesis
What is the control for the light experiment?
The covered part of the leaf
Aim of the chlorophyll experiment
To discover of chlorophyll is needed for photosynthesis
Results for chlorophyll experiment
- When variegated leaf was tested for starch;
- green =black
- white = orange (colour of iodine)
What do the results for the chlorophyll experiment prove?
Chlorophyll is essential for the process of photosynthesis
Why is chlorophyll essential for the process of photosynthesis?
Absorbs light = makes energy available for photosynthesis
What is the control for the chlorophyll experiment?
White part of leaf
Variegated
• Botany (of a plant or foliage) having or consisting of leaves that are edged or patterned in a second colour, especially white as well as green: the variegated form of philadelphus | variegated foliage.
Where does the process of photosynthesis take place in most plants?
In the leaves
What are leaves adapted for to help with photosynthesis
- Light absorption
- Gas exchange
Way leaves are arranged
Ensures each leaf can absorb as much light as possible
Cell wall function
- acts as physical defence
- transparent allowing light through
Why is the cell wall transparent
To allow light through
Palisade mesophyll
Tightly packed with many chloroplasts to increase photosynthetic
Spongy mesophyll
Tightly packed with many chloroplasts to increase photosynthesis
Stomata
Allows gases to diffuse in and out of leaf
Waxy cuticle
- Physical defence
- transparent
- allows light through
- barrier to disease causing microbes
Xylem
Carries water
Phloem
Carries sugar
Air spaces purpose
Circulation
Large surface area leaf adaptation, maximum light absorption
Maximises area for light to be absorbed
Finley leave adaptation, maximum light absorption
Short distance allows cells to receive light
Thin, transparent cuticle adaptation, maximum light absorption
- Reduces water loss by evaporation
- doesn’t stop light entering leaf 
Lots of chloroplasts leaf adaptation, maximum light absorption
Pigment chlorophyll, absorbs light
Tightly packed, palisade mesophyll
Ensures many cells rich and chloroplasts are packed together near upper surface
Leaf adaptation maximum gas exchange stomata
- Allow CO2 and O2 to enter and leave leaf
- pores found on lower leaf surface
- each one surrounded by guard cells
Guard cell function
Regulate stomatas opening and closing
Leaf adaptation, maximum gas exchange, intracellular air spaces
- Allow O2 leave and CO2 enter photosynthesising cells in palisade layer
- allows gases to circulate around photosynthesising cells
Factors affecting photosynthesis
- Levels of light and CO2
- Water
- Temperature
What is the rate of photosynthesis occur in depend on?
Availability of raw materials and energy needed for process 
Temperature photosynthesis
Affects rate of all reactions influence rate at which photosynthesis occurs
Limiting factors of photosynthesis
Raw materials in short supply
How does photosynthesis take place at its maximum rate
All environmental factors must be present at optimum levels
Limits photosynthesis
One or more factors in short supply
Effects of light intensity on photosynthesis
light intensity increase = photosynthesis increase
Limiting factor
Environmental factor limits rate of photosynthesis due to factor being present in too small an amount
