Photosynthesis Flashcards
What are the components of a plant?
Petals, leaves, stem, and roots
What is the petal’s main function?
It is the flower of the plant used for reproduction.
What is the stem for?
The stems contains vessels to transport substances throughout the plant. The xylem vessel transports water up the plant, while the phloem transports glucose, converted into sucrose for transportation, and amino acids.
What is the function of the roots?
The roots stabilise the plant, holding it down, while absorbing minerals and water from the soil.
What are the functions of the leave?
The leaf is the component used for photosynthesis, adapted to absorb sunlight and diffuse gases, as well as contain chlorophyll or prevent water from evaporating.
How is the exterior of the leaf adapted for photosynthesis?
The leaf has a high surface area to increase diffusion, as well as thin cells walls to decrease diffusion distance. We can also tells that they are packed with chloroplasts as they are green, and chlorophyll emits green light.
What is the word equation for photosynthesis?
water + carbon dioxide — sunlight and chlorophyll -> glucose + oxygen
What is the chemical equation for photosynthesis?
6CO2 + 6H2O —> 6O2 + C6H12O6
In which cell does photosynthesis occur?
The palisade cell
What produces the wax for the waxy cuticle?
Cells found in the upper epidermis
Waxy cuticle
The waxy cuticle, secreted from the upper epidermis, is a thin layer of wax, decreasing diffusion distance, and a waterproof barrier to prevent water from evaporating. It has bumps to increase surface area for diffusion. This allows for the diffusion of sunlight.
Upper epidermis
This is a transparent layer, allowing sunlight to diffuse through. It is also thin.
Palisade mesophyll
This is a layer of tightly-packed palisade cells, trapping sunlight and forcing it to pass through these chloroplast-packed cells, increasing the rate of photosynthesis. It is also close to the surface of the leaf, decreasing diffusion distance of sunlight.
Spongy mesophyll
This is a layer of palisade cells, less packed together, with air spaces, to allow gases, such as oxygen or carbon dioxide, to diffuse faster.
Lower epidermis
The lower epidermis is a layer at the underside of the leaf, containing kidney-shaped guard cells that control the opening and closing of the stomata, depending on the time of day.
Palisade cells
These are specialised plant cells, found in the palisade mesophyll/layer, close to the surface of the leaf. They are packed with chlorophyll, are rectangular, so they can be packed together, and have a high surface area.
Draw the shape of a mitochondria
N/a
Draw the shape of a chloroplast
N/a
What are plants?
Photoautotrophs, meaning they are organisms capable of synthesising their own food, using light or chemical energy. Green plants, algae and certain bacteria are autotrophs.
Stomata
- pores in a leaf, mostly on the undersurface
- each pore is surrounded by a pair of guard cells
- guard cells can change shape to open or close the stomata
Guard cells in the day
In the day, guard cells are swollen or turgid, meaning they have more water, and the stomata is open, to allow carbon dioxide in and water and oxygen out of the leaf.
Draw guard cells in the day
N/a
Guard cells at night
Guard cells are shrunken or flaccid at night, meaning less water, closing the stomata. This is to prevent water loss (leading to being wilted) when photosynthesis does not occur.
Tissue levels
Organelle < Cell < Tissue < Organ < Organ System
Hydro-carbonate indicator
This indicator changes colour based on concentration of carbon dioxide
Carbon dioxide at nighttime
At nighttime, there will be an increase of CO2, as respiration takes place, but not photosynthesis, producing CO2. Hence, the hydrogen-carbonate indicator will be yellow.
Colour of hydrogen-carbonate indicator at normal CO2 level
Red
CO2 in the day
The level of CO2 will reduce, as it is used up, as a reactant of photosynthesis. The hydrogen-carbonate indicator will be purple.
Briefly describe practical involving hydrogen-carbonate indicator
Place closed containers, containing the same volume of pond weed, and hydrogen-carbonate indicator, at different distances from a light source, and record the colour change after a few hours.
When do plants respire?
All day, but they only photosynthesise in the day, when there is sunlight
Pond weed experiment
Set up a beaker, with a funnel and test tube. In the funnel place pond weed. In the whole apparatus, pour in sodium hydrogen carbonate and water, maintaining levels of CO2. Place a light source at different distances from this apparatus, and count the bubbles of oxygen produced at different light intensities.
Draw the apparatus for the pond weed experiment
N/a
Limiting factors of photosynthesis
-light intensity - reactant of photosynthesis
-carbon dioxide concentration - reactant of photosynthesis
-temperature - affects enzyme action
Why is water not a limiting factor?
Other environmental factors affect water consumption, from the soil.
Draw the graph of light intensity and CO2 concentration, labelling where it is or is not a limiting factor
N/a
Draw the graph of temperature, labelling where it is or is not a limiting factor
N/a
Describe the light intensity and CO2 concentration graph
The limiting factor of ______ increases steeply up to a point, where it plateaus, no longer a limiting factor, as it has reached the maximum rate of reaction, and temperature and ______ become the limiting factors.
Describe the temperature graph
- increases steeply
- reaches optimum, no longer limiting factor, instead CO2 concentration and light intensity are the limiting factors
- decreases steeply up to
Explain the carbon dioxide graph
- as conc. increases, so does the rate of reaction, as CO2 is a reactant of photosynthesis
- more CO2 increases potential for photosynthesis
- eventually plateaus, no longer a limiting factor of photosynthesis
- limiting factors become temp. and light intensity
Explain light intensity graph
- directly proportional as it is a reactant of photosynthesis (absorbed by chlorophyll)
- more is needed
- eventually plateaus, no longer limiting factor, limiting factors become temp, and CO2 concentration
Key words in temperature graph explanation
- thermal energy
- kinetic energy
- enzyme-substrate collisions
- denature
- enzyme
What is the role of chlorophyll?
- absorbs the light energy
- found in the chloroplasts, made by magnesium
- reflects green light, as it is not very good at absorbing it, hence plants tend to be green, this is due to the fact it absorbs all wavelengths of the visible light spectrum, except it reflects green light wavelengths
- where there us chlorophyll, there is more photosynthesis
How do plants store glucose?
Starch
Draw a variegated leaf
N/a
What is a variegated leaf?
A variegated leaf is a leaf with a green section, where we can assume chlorophyll is present and photosynthesis occurs, and a white section where we can assume there is no chlorophyll and no photosynthesis occurs.
Leaf starch experiment
Equipment: leaves, beakers, ethanol (removes chlorophyll to see the colour change more clearly) , white tile, tweezers (move leaf) , and hot water.
Method:
1. Place the leaves in a beaker of boiling water (denature, no processes) for 1 minute.
2. Half fill a boiling tube with ethanol (goes green, due to chlorophyll, very important) and place the 2 leaves in it using the forceps.
3. Place this boiling tube in the beaker of hot water and leave it for a further 5 minutes
4. Take the leaves out of the boiling tube and wash them with water (to remove ethanol)
5. Place the leaves on a Petri dish or white tile and add 5 drops of iodine solution to each leaf - if a blue/black colour appears then starch is present
Conclusion of starch leaf experiment
Only the green parts of the leaf went blue-black when iodine was added. The green parts show the presence of chlorophyll. Iodine shows the presence of starch. Plants store glucose as starch. Glucose is produced in photosynthesis. Therefore, for photosynthesis to occur, chlorophyll must be present.
Nitrate
- Makes protein and DNA
- Deficiency leads to poor growth or repair of tissues, discolouration, no enzymes, and no more cells
Phosphate
Makes DNA and cell membranes
- Deficiency leads to no more cells, short roots, and discolouration of leaves
Potassium
Makes enzymes
- Deficiency leads to no respiration or photosynthesis, and no energy to have fruits or flowers, as the main priority is survival
Magnesium
Makes up part of the chlorophyll molecule
- Deficiency leads to no chlorophyll, so no sunlight absorption, so no photosynthesis, so no glucose, so no respiration, so no energy, and lack of green
Chemical formula of nitrate
NO3(-)
Chemical formula of phosphate
PO4(3-)
Chemical formula of potassium
K(+)
Chemical formula of magnesium
Mg(2+)
How do plants cells make protein?
They combine sugars (glucose) and nitrates.
How do plants create lipids?
They convert glucose into lipids for storage in their seeds.
Draw a graph of photosynthesis and respiration rate of reaction throughout a day
N/a
Osmosis
The movement of water (H2O), similar to diffusion, moving from high water potential to low water potential.
Active transport
The movement of molecules from an area of low to high concentration, requiring energy in the form of ATP, from respiration
Root hair cells
- specialised plant cells
- absorb mineral ions (eg. Mg(2+)) and water
- have a high surface area
Draw a root hair cell
N/a
Explain how plants absorb water and minerals from the soil
- Mineral ions are dissolved into the water in the soil
- Mineral ions and water get taken into the plant via the root hair cells
- Water moves by osmosis into the plant from the soil
- Mineral ions move by active transport into the plant from the soil
Explain how plants transport water and mineral ions up the plant
- Water and the dissolved mineral ions move from the roots to the leaf by the process of transpiration
- Transpiration involves water moving up the xylem (adhesion and cohesion)
- Water moves due to the transpirational pull caused by the evaporation of water from the stomata on the underside of the leaf, lowering the overall temperature of the plant for enzyme action
What is waterlogged soil?
Soil containing no oxygen
Suggest why plants do not grow in waterlogged soil
No oxygen -> No aerobic respiration -> No energy -> No active transport -> No mineral ions -> No nitrate or phosphate -> Stunts plant growth
The xylem vessel
- contains water and minerals (water keeps the cells turgid or upright, while being a reactant of photosynthesis)
- battles the force of gravity for transportation of water and mineral ions
- continuous and hollow tube with only water and minerals
- one way only from soil to leaf
- made of dead cells
- walls have lignin, a substance keeping the tube waterproof, strong and upright
Adhesion
The attraction of water to the side/wall of the xylem
Cohesion
The attraction between water molecules, being very strong, such that, if one molecule moves, so does the rest
Transpirational pull
Umbrella term for evaporation, adhesion and cohesion
Evaporation
Water transported up the xylem to the leaf, is then lost through the stomata due to evaporation, resulting in constant low water potential in the leaf, for continuous replacement. Additionally, the evaporation results in thermal energy being lost to the water particles, lowering the overall temperature of the plant for enzyme action.
The phloem
The vessel that carries sucrose, converted from glucose, from the leaf to the rest of the plant
