Photosynthesis Flashcards
1
Q
What are the components of a plant?
A
Petals, leaves, stem, and roots
2
Q
What is the petal’s main function?
A
It is the flower of the plant used for reproduction.
3
Q
What is the stem for?
A
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.
4
Q
What is the function of the roots?
A
The roots stabilise the plant, holding it down, while absorbing minerals and water from the soil.
5
Q
What are the functions of the leave?
A
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.
6
Q
How is the exterior of the leaf adapted for photosynthesis?
A
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.
7
Q
What is the word equation for photosynthesis?
A
water + carbon dioxide — sunlight and chlorophyll -> glucose + oxygen
8
Q
What is the chemical equation for photosynthesis?
A
6CO2 + 6H2O —> 6O2 + C6H12O6
9
Q
In which cell does photosynthesis occur?
A
The palisade cell
10
Q
What produces the wax for the waxy cuticle?
A
Cells found in the upper epidermis
11
Q
Waxy cuticle
A
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.
12
Q
Upper epidermis
A
This is a transparent layer, allowing sunlight to diffuse through. It is also thin.
13
Q
Palisade mesophyll
A
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.
14
Q
Spongy mesophyll
A
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.
15
Q
Lower epidermis
A
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.
16
Q
Palisade cells
A
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.
17
Q
Draw the shape of a mitochondria
A
N/a
18
Q
Draw the shape of a chloroplast
A
N/a
19
Q
What are plants?
A
Photoautotrophs, meaning they are organisms capable of synthesising their own food, using light or chemical energy. Green plants, algae and certain bacteria are autotrophs.
20
Q
Stomata
A
- 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
21
Q
Guard cells in the day
A
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.
22
Q
Draw guard cells in the day
A
N/a
23
Q
Guard cells at night
A
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.
24
Q
Tissue levels
A
Organelle < Cell < Tissue < Organ < Organ System
25
Hydro-carbonate indicator
This indicator changes colour based on concentration of carbon dioxide
26
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.
27
Colour of hydrogen-carbonate indicator at normal CO2 level
Red
28
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.
29
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.
30
When do plants respire?
All day, but they only photosynthesise in the day, when there is sunlight
31
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.
32
Draw the apparatus for the pond weed experiment
N/a
33
Limiting factors of photosynthesis
-light intensity - reactant of photosynthesis
-carbon dioxide concentration - reactant of photosynthesis
-temperature - affects enzyme action
34
Why is water not a limiting factor?
Other environmental factors affect water consumption, from the soil.
35
Draw the graph of light intensity and CO2 concentration, labelling where it is or is not a limiting factor
N/a
36
Draw the graph of temperature, labelling where it is or is not a limiting factor
N/a
37
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.
38
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
39
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
40
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
41
Key words in temperature graph explanation
- thermal energy
- kinetic energy
- enzyme-substrate collisions
- denature
- enzyme
42
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
43
How do plants store glucose?
Starch
44
Draw a variegated leaf
N/a
45
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.
46
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
47
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.
48
Nitrate
- Makes protein and DNA
- Deficiency leads to poor growth or repair of tissues, discolouration, no enzymes, and no more cells
49
Phosphate
Makes DNA and cell membranes
- Deficiency leads to no more cells, short roots, and discolouration of leaves
50
Potassium
Makes enzymes
- Deficiency leads to no respiration or photosynthesis, and no energy to have fruits or flowers, as the main priority is survival
51
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
52
Chemical formula of nitrate
NO3(-)
53
Chemical formula of phosphate
PO4(3-)
54
Chemical formula of potassium
K(+)
55
Chemical formula of magnesium
Mg(2+)
56
How do plants cells make protein?
They combine sugars (glucose) and nitrates.
57
How do plants create lipids?
They convert glucose into lipids for storage in their seeds.
58
Draw a graph of photosynthesis and respiration rate of reaction throughout a day
N/a
59
Osmosis
The movement of water (H2O), similar to diffusion, moving from high water potential to low water potential.
60
Active transport
The movement of molecules from an area of low to high concentration, requiring energy in the form of ATP, from respiration
61
Root hair cells
- specialised plant cells
- absorb mineral ions (eg. Mg(2+)) and water
- have a high surface area
62
Draw a root hair cell
N/a
63
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
64
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
65
What is waterlogged soil?
Soil containing no oxygen
66
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
67
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
68
Adhesion
The attraction of water to the side/wall of the xylem
69
Cohesion
The attraction between water molecules, being very strong, such that, if one molecule moves, so does the rest
70
Transpirational pull
Umbrella term for evaporation, adhesion and cohesion
71
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.
72
The phloem
The vessel that carries sucrose, converted from glucose, from the leaf to the rest of the plant
73
Active transport always takes place…
Through a membrane, requiring special proteins to take place
74
Draw active transport, with the special proteins
N/a
75
Draw diffusion
N/a
76
NPK fertiliser
Has nitrate, potassium, magnesium and phosphate
77
Cellulose is made of…
Carbon
78
Apart from mineral ions, what elements do plants need?
Carbon, hydrogen and oxygen (which they get through water and carbon dioxide)
79
Osmosis must be the diffusion of water through a…
Semi-permeable membrane
80
Culture solution
A liquid that contains water and all minerals a plant needs
81
What minerals does culture solution have?
- calcium nitrate
- magnesium sulfate
- potassium nitrate
- iron phosphate
- potassium dihydrogenphosphate
82
Hydroponic plants
Plant that do not grow in soil, but in culture solution
83
Draw an open stomata
N/a
84
Draw a closed stomata
N/a
85
What is water used for in a plant?
- turgid cells (stabilise the plant and keep cells upright)
- reactant of photosynthesis
- reduce plant overall temperature
- movement of substances
86
Draw a root croos-section, labelling everything you can
N/a
87
Draw a stem cross-section, labelling all you can
N/a
88
Sugar is used for…
Growth and repair
89
In the night…
Sugar goes up the plant for respiration
90
In the day…
Sugar goes down the plant for storage and active transport
91
Water always…
Goes up the plant
92
What transpirational pull happens in the leaf?
The xylem brings water to the leaves, that moves into the leaf by osmosis, due to the low water potential, diffusing out of the plant through the stomata in the day. Some of the water goes to the palisade cells for photosynthesis. The water loss through the stomata is due to evaporation, meaning the liquid particles require more energy to escape the leaf, and are given this energy, bring down the overall temperature of the plant. This cooling effect aids enzyme action. Finally, the continuous replacement of water, that has been lost, by the xylem maintains a high concentration gradient.
93
The phloem functions and adaptations
- transports sucrose and amino acids, using active transport or translocation
- has two-way movement, or is multidirectional, as it carried substances needed by all cells
- has end walls (sieve plates), that phloem SAP travels through
- made of organic molecules
- cells are living but need support from neighbouring companion cells, as they provide ATP needed for active transport
94
The source of sucrose is…
Where it is converted, that has a low concentration of sucrose
95
The sink of sucrose…
Is where it ends up, with a high concentration of sucrose
96
The sucrose travels from…
The source (with low concentration) to the sink (with high concentration), through active transport, hence the phloem requires neighbouring cells to provide energy in the form of ATP for this process
97
Xylem is always on the…
Inside
98
Factors influencing transpiration, causing the rate to increase
- higher temperature
- increased light intensity
- increased air movement
Hence, a hot, bright, windy day is perfect for the rate of transpiration.
99
High temperature effect on transpiration
This leads to more evaporation due to increased particle movement, as they have more energy to overcome the inter-molecular forces between their particles, evaporating into water vapour, and increasing the rate of transpiration.
100
Increased air movement effect on transpiration
The air carries the water vapour diffused from the plants away from the plant, lowering the water concentration outside the plant, increasing the concentration gradient, allowing the water vapour to diffuse out of the stomata at a faster rate, increasing the rate of transpiration.
101
Increased light intensity effect on transpiration
Light stimulates the opening of the stomata wider for photosynthesis, meaning more water leaves in the atmosphere through evaporation, increasing the rate of transpiration.
102
What influences the rate of transpiration negatively?
Increased humidity
103
Humidity effect on transpiration
Humidity increases the water concentration in the air (eg. rainforest), lowering the concentration gradient for diffusion of water vapour out of the stomata, hence the rate of transpiration decreases.
104
Cactus adaptation for transpiration
1) No leaves, stems photosynthesise
2) Fat stem (low surface area : volume ratio)
3) Stomata only open at night, to avoid water loss, in the desert
105
Marram Grass Leaf Adaptations
1) Rolled Leaves, lower surface area for evaporation
2) Pitted stomata, decrease surface area, meaning less evaporation, as they are less exposed
106
Other factors affecting transpiration
Water Availability - Less water in the soil = less uptake = reduced transpiration to prevent wilting.
Type and Number of Stomata - More stomata or open stomata = higher transpiration.
Leaf Surface Area - Bigger leaf area = more stomata and surface for water loss = increased transpiration.
Cuticle Thickness - Thicker waxy cuticle = reduced transpiration.
Leaf Folding or Rolling - Some plants fold or roll their leaves (like in dry conditions) to trap moist air and reduce the exposed surface area, leading to lower transpiration.
Guard Cell Function - Guard cells control the opening and closing of stomata.
• When they’re turgid (full of water), stomata open = transpiration increases.
• When they’re flaccid, stomata close = transpiration decreases.
107
Draw a mass potometer, labelling everything
N/a
108
Draw a bubble potometer, labelling all
N/a
109
Advantages of mass potometer
• Very accurate: Measures actual water loss by mass.
• Simple setup: Easy to monitor changes over time using a balance.
• Good for long-term experiments.
110
Disadvantages of mass potometer
• Can’t show rate of uptake—only loss from leaves.
• Water lost might include non-transpiration losses (e.g. evaporation from soil surface).
• Less immediate than a bubble potometer.
111
Advantages of bubble potometer
• Quick results: Shows changes in real-time.
• Measures rate of water uptake, which is often used as a proxy for transpiration.
• Useful for comparing effects of different variables (e.g. light, wind, etc.).
112
Disadvantages of bubble potometer
• Can be tricky to set up without air bubbles or leaks.
• Assumes water uptake = transpiration, which isn’t always true.
• Fragile and can be disrupted by small air leaks or vibrations.
113
Using a mass potometer
The plant is placed in a sealed container, and the whole setup is placed on a balance. As the plant loses water through transpiration, the mass gradually decreases. The change in mass over time reflects water lost.
114
Using a bubble potometer
The plant is connected to a capillary tube filled with water. An air bubble is introduced into the tube. As the plant takes up water, the bubble moves along the tube. The distance moved over time shows the rate of water uptake, which is usually linked to transpiration rate.
115
What do we assume with a volume or bubble potometer?
That all other factors of transpiration remain constant. We also assume that all water is used for transpiration.
116
Stomata Nail Polish Experiment
1. Select a healthy leaf and label the top (adaxial) and bottom (abaxial) sides.
2. Apply a thin layer of clear nail polish to a small area on the top surface of the leaf.
3. Repeat on the underside in a separate spot.
4. Allow both areas to dry fully (about 5–10 minutes).
5. Place a piece of clear sticky tape over each dried polish patch.
6. Gently peel off the tape, lifting the clear nail polish imprint.
7. Stick each tape peel onto a separate microscope slide, clearly labelling them “Top” and “Bottom”.
8. View each slide under a light microscope at low and high power.
9. Count the stomata in several fields of view and calculate an average stomatal density for each side.
10. Compare the two sides—most leaves have more stomata on the underside to reduce water loss.
117
Cobalt chloride paper is…
Pink when moist and blue when dry
118
If cobalt chloride paper is not deep blue before the start of the experiment, …
Place it on the warm shade of a bench lamp (switched on) for a few seconds
119
There are more open stomata on the…
Underside of the leaf, as it has less light, that can possibly obstruct water evaporation, and does not have a waxy cuticle, that would prevent water loss.
