6. Plant Nutrition Flashcards
1
Q
Photosynthesis definition
A
the process by which plants manufacture carbohydrates from raw materials using energy from light
2
Q
What are the raw materials for photosynthesis?
A
carbon dioxide and water
3
Q
What is the waste product of photosynthesis?
A
Oxygen
4
Q
Word equation for photosynthesis
A
light
carbon dioxide + water –> glucose + oxygen
chlorophyll
5
Q
Where is water for photosynthesis taken from?
A
Taken up by the roots and transported through the xylem to the leaves
6
Q
Where is carbon dioxide for photosynthesis taken from?
A
Diffuses into the leaf through the stomata
7
Q
What is glucose in plants used for?
A
Used to make substances needed by the plant
- used in respiration as a source of energy
8
Q
What happens to oxygen produced by photosynthesis?
A
Diffuses out of the leaf through the stomata
- used in respiration
9
Q
What is the balanced chemical equation for photosynthesis?
A
6CO2 + 6H2O —> C6H12O6 + 6O2
10
Q
What happens to the light energy during photosynthesis?
A
The light energy is converted into chemical energy in the bonds holding the atoms in the glucose molecules together
11
Q
What substances (that the plant needs) can be made from glucose?
A
They can also convert it into:
starch for storage
into lipids for an energy source in seeds
into cellulose to make cell walls
into amino acids (used to make proteins) when combined with nitrogen and other mineral ions absorbed by roots
12
Q
Why do plants convert glucose into starch, rather than keeping it as glucose?
A
It is insoluble, meaning it won’t affect osmosis in cells
13
Q
What can glucose be converted into to be transported around the plant?
A
converted into sucrose
14
Q
Why can leaves not be tested for glucose?
A
Although plants make glucose in photosynthesis, leaves cannot be tested for its presence as the glucose is quickly used, converted into other substances and transported or stored as starch.
15
Q
Where is starch stored?
A
Starch is stored in chloroplasts where photosynthesis occurs
16
Q
What test can be a reliable indicator of which parts of the leaf are photosynthesising?
A
testing a leaf for starch
17
Q
Procedure for testing leaves for starch
A
A leaf is dropped in boiling water to kill and break down the cell walls
The leaf is left for 5-10 minutes in hot ethanol in a boiling tube. This removes the chlorophyll so colour changes from iodine can be seen more clearly
The leaf is dipped in boiling water to soften it
The leaf is spread out on a white tile and covered with iodine solution
In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
18
Q
How does the results for testing leaves for starch change if the leaf is variegated?
What can this test also be used to test?
A
This method can also be used to test whether chlorophyll is needed for photosynthesis by using a variegated leaf (one that is partially green and partially white)
The white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain chlorophyll stain blue-black
The areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored
19
Q
What safety precautions must be taken into account when testing a leaf for starch?
A
Care must be taken when carrying out this practical as ethanol is extremely flammable, so at that stage of the experiment the Bunsen burner should be turned off.
20
Q
What is the safest way to heat ethanol when testing a leaf for starch?
A
The safest way to heat the ethanol is in an electric water bath rather than using a beaker over a Bunsen burner with an open flame
21
Q
How can the experiment for testing leaves for starch be altered to show the need for light in photosynthesis?
A
Before starting the experiment the plant needs to be destarched by placing in a dark cupboard for 24 hours
This ensures that any starch already present in the leaves will be used up and will not affect the results of the experiment
Following destarching, a leaf of the plant can be partially covered with aluminium foil and the plant placed in sunlight for a day
The leaf can then be removed and tested for starch using iodine
The area of the leaf that was covered with aluminium foil will remain orange-brown as it did not receive any sunlight and could not photosynthesise, while the area exposed to sunlight will turn blue-black
This proves that light is necessary for photosynthesis and the production of starch
22
Q
Procedure for The Need for Carbon Dioxide in Photosynthesis
A
Destarch a plant
Tie a clear bag containing sodium hydroxide, which will absorb carbon dioxide from the surrounding air, around one leaf
Tie a clear bag containing water (control experiment), which will not absorb carbon dioxide from the surrounding air, around another leaf
Place the plant in bright light for several hours.
Test both leaves for starch using iodine
The leaf from the bag containing sodium hydroxide will remain orange-brown as it could not photosynthesise due to lack of carbon dioxide
The leaf from the control bag containing water should turn blue-black as it had all necessary requirements for photosynthesis
23
Q
What plants are usually used to investigate the rate of photosynthesis?
A
The plants usually used are Elodea or Camboba – types of pondweed
24
Q
How is the rate of photosynthesis measured?
A
As photosynthesis occurs, oxygen gas produced is released
As the plant is in water, the oxygen released can be seen as bubbles leaving the cut end of the pondweed
The number of bubbles produced over a minute can be counted to record the rate
The more bubbles produced per minute, the faster the rate of photosynthesis
25
What can be a more accurate way of measuring the rate of photosynthesis rather than counting the number of bubbles produced?
A more accurate version of this experiment is to collect the oxygen released in a test tube inverted over the top of the pondweed over a longer period of time and then measure the volume of oxygen collected
26
What factors can be investigated to see how they influence the rate of photosynthesis?
Investigating the effect of changing light intensity, by moving a lamp different distances away from the beaker containing the pondweed
Investigating the effect of changing temperature, by changing the temperature of the water in the beaker
Investigating the effect of changing carbon dioxide concentration, by dissolving different amounts of sodium hydrogen carbonate in the water in the beaker
27
What precautions must be taken when investigating the rate of photosynthesis?
Care must be taken when investigating a condition to keep all other variables constant in order to ensure a fair test
28
Why does a glass tank need to be used when when investigating changing light intensity?
When investigating changing light intensity, a glass tank should be placed in between the lamp and the beaker to absorb heat from the lamp and so avoid changing the temperature of the water as well as the light intensity
29
What is the rate of photosynthesis limited by?
limited by whatever factor is the lowest at that time
30
What factors affect the rate of photosynthesis?
light intensity
carbon dioxide concentration
temperature
31
Limiting factor definition
something present in the environment in such short supply that it restricts life processes
32
Why is water not considered a limiting factor?
Although water is necessary for photosynthesis, it is not considered a limiting factor as the amount needed is relatively small compared to the amount of water transpired from a plant so there is hardly ever a situation where there is not enough water for photosynthesis
33
How does temperature affect the rate of photosynthesis?
As temperature increases the rate of photosynthesis increases as the reaction is controlled by enzymes
However, as the reaction is controlled by enzymes, this trend only continues up to a certain temperature beyond which the enzymes begin to denature and the rate of reaction decreases
34
How does light intensity affect the rate of photosynthesis?
The more light a plant receives, the faster the rate of photosynthesis
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
35
How does carbon dioxide concentration affect the rate of photosynthesis?
Carbon dioxide is one of the raw materials required for photosynthesis
This means the more carbon dioxide that is present, the faster the reaction can occur
This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short sup
36
When can the knowledge of limiting factors be useful and why?
The knowledge about limiting factors and how they affect the rate of photosynthesis can be used to help control factors in glass houses to ensure maximum crop yields for farmers
37
Why is it better for farmer to grow crops inside a green house rather than outside?
Growing crops outside does not allow farmers to control any of these factors to increase growth of plants
In a glass house, several conditions can be manipulated to increase the rate of photosynthesis
38
What conditions can be manipulated to increase the rate of photosynthesis in a greenhouse?
artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temperatures – only used in temperature countries such as the UK)
artificial lighting (plants can photosynthesise for longer)
increasing carbon dioxide content of the air inside (plants can photosynthesise quicker)
regular watering
39
What is one problem with green houses for farmers?
When considering the use of glasshouses and manipulating conditions like this, farmers need to balance the extra cost of providing heating, lighting and carbon dioxide against the increased income
40
What is one problem with green houses for farmers?
When considering the use of glasshouses and manipulating conditions like this, farmers need to balance the extra cost of providing heating, lighting and carbon dioxide against the increased income
41
What problem can occur in green houses in tropical countries?
they may need to be ventilated to release hot air and avoid temperatures rising too high, which could cause the denaturation of the enzymes controlling the photosynthesis reaction
42
When do plants respire and what do they take in/out?
Plants are respiring all the time and so plant cells are taking in oxygen and releasing carbon dioxide as a result of aerobic respiration
43
When do plants photosynthesise and what do they take in/out?
Plants also photosynthesise during daylight hours, for which they need to take in carbon dioxide and release the oxygen made in photosynthesis
44
Where can chloroplasts be found in a leaf?
palisade mesophyll cells
spongy mesophyll cells
guard cells (around stomata)
45
During the day, what is the difference between the rate of photosynthesis and respiration?
During the day, especially when the sun is bright, plants are photosynthesising at a faster rate than they are respiring, so there is a net intake of carbon dioxide and a net output of oxygen
46
What is used to investigate the effect of light on the net gas exchange?
a pH indicator such as hydrogencarbonate indicator
47
Why is a pH indicator suitable to measure net gas exchange?
This is possible because carbon dioxide is an acidic gas when dissolved in water
48
What does a hydrogen carbonate indicator show?
Hydrogencarbonate indicator shows the carbon dioxide concentration in solution
49
What colour is hydrogen carbonate indicator at highest conc of CO2?
yellow
50
What colour is hydrogen carbonate indicator at higher (than atmospheric level) conc of CO2?
orange
51
What colour is hydrogen carbonate indicator at atmospheric level conc of CO2?
red
52
What colour is hydrogen carbonate indicator at lower (than atmospheric level) conc of CO2?
magenta
53
What colour is hydrogen carbonate indicator at lowest conc of CO2?
purple
54
What are the conditions in a plant when the hydrogen carbonate indicator is yellow or orange?
More respiration than photosynthesis
- lower pH - more acidic
55
What are the conditions in a plant when the hydrogen carbonate indicator is red?
photosynthesis is occurring at an equal rate to respiration
56
What are the conditions in a plant when the hydrogen carbonate indicator is magenta or purple?
more photosynthesis than respiration
- higher pH - more alkaline
57
How can a plant be tested for net gas exchange?
Several leaves from the same plant are placed in stoppered boiling tubes containing some hydrogen-carbonate indicator
The effect of light can then be investigated over a period of a few hours
58
What conclusion can be made if the indicator turns purple?
There is a net intake of oxygen by a leaf in light
59
What conclusion can be made if the indicator turns yellow?
There is a net intake of carbon dioxide by a leaf in the dark
60
wax cuticle description
protective layer on top of the lead, prevents water from evaporating
61
upper epidermis description
thin and transparent to allow light to enter palisade mesophyll layer underneath it
62
palisade mesophyll description
column shaped cells tightly packed with chloroplasts to absorb more light, maximising photosynthesis
63
spongy mesophyll description
contains internal air spaces that increase the surface area to volume ratio for the diffusion of gases mainly carbon dioxide
64
lower epidermis description
contains guard cells and stomata
65
guard cell description
absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out
66
stomata description
where gas exchange takes place; opens during the day, closes during the night. Evaporation of water also takes place from here. in most plants, found in much greater concentration on the underside of the leaf to reduce water loss
67
vascular bundle description
contains xylem and phloem to transport substances to and from the leaf
68
xylem description
transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
69
phloem description
transports sucrose and amino acids around the plant
70
large surface area (leaf) adaptation
increases surface area for the diffusion of carbon dioxide and absorption of light for photosynthesis
71
thin (leaf) adaptation
allows carbon dioxide to diffuse to palisade mesophyll cells quickly
72
chlorophyll adaptation
absorbs light energy so that photosynthesis can take place
73
network of veins adaptation
allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis (water for photosynthesis, carbohydrates as a products of photosynthesis)
74
stomata adaptation
allows carbon dioxide to diffuse into the lead and oxygen to diffuse out
75
epidermis is thin and transparent adaptation
allows more light to reach the (photosynthesising) palisade cells
76
thin cuticle made of wax adaptation
to protect the lead without blocking sunlight
77
palisade cell layer at top of leaf adaptation
maximises the absorption of light as it will hit chloroplasts in the cells directly
78
spongy layer adaptation
air spaces allow carbon dioxide to diffuse through the leaf, increasing the surface area
79
vascular bundles adaptation
thick cell walls of the tissue in the bundles help to support the stem and leaf
80
What type of biological molecules do plants contain?
carbohydrates
proteins
lipids
nucleic acid (DNA)
81
What elements do carbohydrates contain?
What element do proteins also contain
Carbohydrates contain the elements carbon, hydrogen and oxygen
- nitrogen (and certain amino acids contain other elements too)
82
What elements does chlorophyll also contain
magnesium and nitrogen
83
Where do plants get elements from?
Plants obtain these elements in the form of mineral ions actively absorbed from the soil by root hair cells
84
What is a mineral?
Mineral’ is a term used to describe any naturally occurring inorganic substance
85
magnesium function
magnesium is needed to make chlorophyll
86
signs of magnesium deficiency
causes yellowing between the veins of leaves (CHLOROSIS)
87
nitrate function
nitrates are a source of nitrogen needed to make amino acids ( to build proteins)
88
signs of nitrate deficiency
causes stunted growth and yellowing of leaves
89
What is photosynthesis?
The process by which plants synthesise carbohydrates from raw materials using energy from light.
90
What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen.
In the presence of light and chlorophyll.
91
What does the photosynthesis reaction require and what is it obtained from?
The reaction requires light energy which is obtained by the green pigment chlorophyll in the chloroplasts that traps light energy and transfers it to chemical energy for the synthesis of carbohydrates.
92
What is the chemical equation for photosyntheis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
93
Minerals are taken up actively by root hair cells and have a variety of important roles in the plant. Name the two most important minerals.
Nitrate ions.
- Magnesium ions.
94
What is the use of nitrate ions in plants?
Nitrate ions are used in the plant to build amino acids, and thus proteins and enzymes.
95
What would happen to a plant without nitrate ions?
Without nitrate ions, the plant would not be able to grow or repair itself.
96
What is the use of magnesium ions in plants?
Magnesium ions are used to make chlorophyll.
97
What would happen to a plant without magnesium ions?
A lack of magnesium ions will lead to a lack of chlorophyll, meaning that photosynthesis cannot occur. This means that sugars cannot be formed through photosynthesis, therefore the plant will not have a sufficient enough energy source to grow and repair itself.
98
What would happen to a plant if there were no magnesium and nitrate ions?
The lack of either of these ions leads to yellow leaves and poor growth, eventually leading to the plant’s death.
99
Describe the test for starch production (5).
A leaf is dropped in boiling water.
The leaf is left in hot ethanol in a boiling tube.
The leaf is dipped in boiling water to soften it.
The leaf is spread out on a white tile and covered with iodine solution.
RESULT: In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf.
100
Describe the test that shows leaves need for chlorophyll for photosynthesis.
A destarched variegated leaf is dropped in boiling water.
The leaf is left in hot ethanol in a boiling tube.
The leaf is dipped in boiling water to soften it.
The leaf is spread out on a white tile and covered with iodine solution.
RESULTS: The white parts of the leaf contain no chlorophyll so no photosynthesis takes place and the iodine solution remains orange. The green part of the leaf contains chlorophyll which is needed for photosynthesis to make starch and the iodine solution turns blue-black.
101
A leaf is dropped in boiling water for the starch experiment. Why?
To kill the cells and break down the cell membranes.
102
The leaf is left in hot ethanol in a boiling tube for the starch experiment. Why?
This removes the chlorophyll so colour changes from iodine can be seen more clearly.
103
Why is the Bunsen burner be turned off after boiling the leaf?
Ethanol is extremely flammable, so at that stage of the experiment, the Bunsen burner should be turned off.
104
Describe the test that shows leaves need for light in photosynthesis (4).
Before starting the experiment the plant needs to be destarched by placing in a dark cupboard for 24 hours.
A leaf of the plant can be partially covered with aluminum foil and the plant placed in sunlight for a day.
The leaf can then be removed and tested for starch using iodine.
RESULT: The area of the leaf that was covered with aluminium foil will remain orange-brown as it did not receive any sunlight and could not photosynthesise, while the area exposed to sunlight will turn blue-black.
105
Why do we destarch leaves?
This ensures that any starch already present in the leaves will be used up and will not affect the results of the experiment.
106
Describe the test that shows leaves need for carbon dioxide in photosynthesis.
Destarch a plant.
Tie a clear bag containing soda lime, which will absorb carbon dioxide from the surrounding air.
Place the plant in bright light for several hours.
Test both leaves for starch using iodine.
RESULT: The leaf from the bag containing sodium hydroxide will remain orange-brown as it could not photosynthesise due to lack of carbon dioxide.
The leaf from the control bag containing water should turn blue-black as it had all necessary requirements for photosynthesis.
107
There are three main factors which limit the rate of photosynthesis: What are they?
There are three main factors which limit the rate of photosynthesis:
Temperature
Light intensity
Carbon dioxide concentration
108
What is the effect of a higher temperature for photosynthesis?
As temperature increases the rate of photosynthesis increases as the reaction is controlled by enzymes. However, as the reaction is controlled by enzymes, this trend only continues up to a certain temperature beyond which the enzymes begin to denature and the rate of reaction decreases.
109
What is the effect of an increased light energy for a plant?
The more light a plant receives, the faster the rate of photosynthesis.
LIMITING FACTORS: This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply.
The factors which could be limiting the rate when the line on the graph is horizontal include temperature not being high enough or not enough carbon dioxide.
110
What is the effect of more carbon dioxide for a plant?
This means the more carbon dioxide that is present, the faster the reaction can occur.
LIMITING FACTORS: This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply.
The factors which could be limiting the rate when the line on the graph is horizontal include temperature not being high enough or not enough light.
111
In a green house or in general, several conditions can be manipulated to increase the rate of photosynthesis, including:
artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temperatures).
artificial lighting.
increasing carbon dioxide content of the air inside (plants can photosynthesise quicker).
regular watering.
112
What do plants do at night?
At night, plants do not photosynthesise but they continue to respire, meaning they take in oxygen and give out carbon dioxide.
113
When do plants respire?
Plants are respiring all the time and so plant cells are taking in oxygen and releasing carbon dioxide as a result of aerobic respiration.
114
When do plant photosynthesis?
Plants photosynthesise during daylight hours, for which they need to take in carbon dioxide and release the oxygen made in photosynthesis.
115
Give 6 uses for glucose in a plant.
starch as an energy store.
cellulose to build cell walls.
glucose used in respiration to provide energy.
sucrose for transport in the phloem.
nectar to attract insects for pollination.
some sugars are converted to fats for energy store.
116
Give the description of the wax cuticle?
Protective layer on the top of the leaf, prevents water from evaporating.
117
Give the description for the upper epidermis?
Thin and transparent to allow light to enter palisade mesophyll layer underneath it.
118
Give the description for the palisade mesophyll?
Column-shaped cells tightly packed with chloroplasts to absorb more light, maximizing photosynthesis.
119
Give the description for the spongy mesophyll?
Contains internal air spaces that increase the surface area to volume ratio for the diffusion of gases.
120
Give the description for the lower epidermis?
Contains guard cells and stomata.
121
Give the description for the guard cells?
Absorbs and loses water to open and close the stomata to allow carbon dioxide to diffuse in, oxygen to diffuse out.
122
Give the description for the xylem?
Transports water into the leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata.
123
Give the description for the phloem?
Transports sucrose and amino acids around the plant.
124
Give the description for the stomata.
Where gas exchange takes place; opens during the day, and closes during the night. Evaporation of water also takes place here. Found on the underside of the leaf to prevent water loss.
125
Why do leaves have a large surface area?
Increase surface area for the diffusion of carbon dioxide and absorption of light for phtotosynthesis.
126
Why are leaves thin?
Allows carbon dioxide to diffuse to palisade mesophyll cells quickly.
127
Why do leaves have chlorophyll?
Absorbs light energy so that photosynthesis can take place.
128
Why do leaves have stomata?
Allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out.
129
Why is the epidermis thin and transparent?
Allows more light to reach the palisade cells.
130
Why do leaves have a thin cuticle made of wax?
To protect the leaf without blocking sunlight.
131
Why do leaves have the palisade layer at the top of the leaf?
Maximises the absoprtion of light as it will hit chloroplasts in the cells directly.
132
Why do leaves have a vascular bundle?
Thick cell walls of the tissue in the bundles help to support the stem and leaf.
133
Why do leaves have a spongy layer?
Air spaces allow carbon dioxide to diffuse through the leaf, increasing the surface area.
134
Why do leaves have a network of veins?
Allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis.
135
Describe the test for oxygen.
The plants used are aquatic plants.
As photosynthesis occurs, oxygen gas produced is released.
As the plant is in water, the oxygen released can be seen as bubbles leaving the cut end of the aquatic plant into the inverted test tube.
To test if the gas released is oxygen, place a glowing splint in the test tube and if it relights, oxygen is the gas present.
CORE INFORMATION FOR RESULTS - The number of bubbles produced over a minute can be counted to record the rate.
The more bubbles produced per minute, the faster the rate of photosynthesis.
136
Diagrams:
Photosynthesis experiment diagrams.
Leaf structure.
Graphs showing the effect of increasing light intensity, carbon dioxide concentration and temperature.
137
What is the definition of photosynthesis?
Process in which plants manufacture carbohydrates from raw materials using energy from light
138
What is the chemical equation for photosynthesis?
6CO2 + 12H20 => C6H12O6 + 6O2
139
What are 3 requirements for photosynthesis?
light
chlorophyll
carbon dioxide
140
What happens if you covered a part of the leaf and added iodine? Why?
Parts that were covered did not turn blue black
In the parts that were covered there wasn’t starch
141
What happens if there isn’t chlorophyll present and then iodine was added? Why?
White parts turned brown
Green parts turned black/blue
The white part didn’t have chlorophyll and the green part did so that means photosynthesis took place
142
What does soda lime(sodium hydroxide) do?
Absorbs carbon dioxide
143
What does sodium hydrogen carbonate do?
Releases carbon dioxide
144
What happens when soda lime is placed near a plant when iodine is added? Why?
Parts stay brown
starch is not present as there is no carbon dioxide
145
What happens when sodium hydrogen carbonate is placed near a pant when added iodine? Why?
Parts turn black blue
carbon dioxide is present so it is able to photosynthesis
146
Where does photosynthesis occur?
It occurs in specialized double- membraned organelles called chloroplasts which contain the light absorbing green pigment called chlorophyll
147
What does chlorophyll do?
Chlorophyll transfers light energy into chemical energy in molecules for the synthesis of carbohydrates
148
List the order of the structure of the leaf
Waxy cuticle
upper epidermis
palisade mesophyll layer
spongy mesophyll layer
xylem
phloem
lower epidermis
guard cell (stoma)
149
Where are chloroplasts concentrated? Why?
Chloroplasts are concentrated in the cells near the top of the leaf in order to receive the most sunlight
150
What are the cells near the top of the leaf called?
palisade cells
151
What are the spongy mesophyll cells?
Layer of loosely packed cells with some chloroplasts that are also able to photosynthesis.
152
Where are air spaces and what do they do?
Air spaces are in the spongy mesophyll layer and they are in this layer where gases can build up as they enter and leave the leaf.
153
How is water brought into the leaf?
Water is brought in by veins
154
What does the cuticle do and where is it found?
upper epidermis
prevents water loss
155
Where are stomata found?
lower epidermis
156
What do stomata do?
Control gaseous exchange needed for photosynthesis
157
When do stomata open?
during the day when there is high carbon dioxide uptake
158
What is produced by photosynthesis and how does it leave the leaf?
oxygen
by diffusion through the open stomata
159
How could excessive water loss and wilted plants happen?
Some of the water coming into the leaf via veins also evaporates and diffuses out of the leaf via stomata
160
What happens if water loss in excessive?
Plants are forced to close their stomata during the day which decreases the rate of photosynthesis.
161
What is a limiting factor?
If any factors are in short supply the rate of photosynthesis will be less than its maximum possible rate
162
How can increasing temperature increase photosynthesis?
Increasing molecular collisions due to kinetic energy leads to an increase in the rate of photosynthesis.
163
What is optimal temperature?
Maximum rate of photosynthesis reached
164
How can high temperatures decrease the rate of photosyntheis?
Breaking of bonds in enzymes structure leads to a change in shape of the active site( denaturing)
165
When does the rate of photosynthesis increase due to carbon dioxide concentration?
Rate of photosynthesis increases until all substrate molecules are being used up
166
How can you increase the rate of concentration if the carbon dioxide concentration has become constant?
increase temperature or light intensity
167
What causes light intensity to become constant?
a factor becomes a short supply
168
What 4 conditions can be set up in greenhouses to reduce the effects of limiting factors on the rate of photosynthesis?
Greenhouse to be constructed from glass to enable maximum transmission of light
Artificial lighting systems can be sued to lengthen a plants growing season
Heat is used in greenhouses
Paraffin heaters in small scale to increase concentration of co2
169
What is the chemical equation for respiration?
6CO2 +C6H12O6 => 6H20 + 6CO2 + energy
170
What is the compensation point?
Compensation point is the point where teh rate of photosynthesis and respiration point are balanced and there is no net uptake or loss of carbon dioxide or oxygen.
171
When does photosynthesis not occur? Why?
At night. There is no sunlight
172
When is the rate of photosynthesis highest?
During the day
173
What is the indicator that shows carbon dioxide concentration in solution?
hydrogencarbonate indicator
174
What does orange in hydrogencarbonate indicator indicate?
an average amount of co2
175
What does yellow in hydrogencarbonate indicator indicate?
A lot of co2
176
What does purple in hydrogencarbonate indicator indicate?
A little co2
177
What happens if you boil a leaf?
there are no living cells
178
What are minerals needed for?
Are needed for healthy growth
179
How do minerals enter the plant?
They are absorbed through the roots by active transport as mineral ions dissolved in the soil water
180
What are the 4 most important minerals needed by plants? What are their ions called?
nitrogen nitrates
phosphorus phosphates
potassium potassium ions
magnesium magnesium ions
181
What is nitrate needed for?
to make proteins
182
What happens in nitrate deficiency?
The amount of chlorophyll in leaves reduces
This reduces the plant is ability to photosynthesis and grow properly
183
How can you tell if a plant has a nitrate deficiency?
upper leaves are green but lower leaves are yellow
184
How can you increase nitrate levels?
add chemicals or natural fertilisers such as manure
185
What do plants need magnesium ion for?
To make chlorophyll in the leaves
186
What happens is the plant has magnesium ion deficiency?
the plant is limited in terms of its photosynthetic ability and the plant growth is compromised
187
How can you tell if a plant has magnesium ion deficiency?
Upper leaves are green lower leaves pale green or yellow
188
What is eutrophication?
Eutrophication happens when excess nitrate enters rivers or lakes from fields. This can lead to the death of fish and other aquatic animals.
189
Explain using details how this can heavily affect the ecosystem.
This happens when fertilisers are washed in rivers or lakes. Algae feed off of nutrients and create a green covering of the lake. This is called algae bloom which covers the water source not allowing any light to penetrate. Bacteria then eat the dead matter releasing more nutrients and consume oxygen making the lake anoxic. This causes for plants and animals to die due to lack of oxygen.
190
How are plants adapted for the process of photosynthesis?
they are broad and thin with many chloroplasts n their cells
191
What are raw materials of photosynthesis?
water and carbon dioxide
192
List three uses of carbohydrate in plants
creates the cell walls
stores available energy
primary fuel in cells
193
Explain how atmospheric carbon dioxide concentrations contribute to global warming.
they contribute as co2 creates a thick blanket around the atmosphere
light and heat cannot escape the atmosphere
co2 is a greenhouse gas contributing to the greenhouse effect
194
What are energy transducers?
Chloroplasts act as energy transducers converting light energy into chemical energy
195
Chemical equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 + 6O2
196
How is glucose used for storage?
Glucose is soluble in water and if it were stored as glucose in plant cells it would dissolve and affect the water balance of the plant. Instead it is converted into starch which is not soluble.
197
How is glucose used in respiration
Glucose is broken down using oxygen to provide energy for cells.
198
How is glucose used to create the necessary amino acids for plants
Glucose combines with Nitrates and other mineral ions from the soil to form amino acids which are the built up into proteins.
199
How is glucose used to strengthen cell walls
Plants and algae build up glucose into more complex carbohydrates (like cellulose) which are used to strengthen the cell walls
200
How is glucose used to create energy stores
Glucose can be used to build up fats and oils (lipids) which act as energy stores and can be used in seeds to give them the energy they need to germinate
201
Word and chemical equation for respiration
Oxygen + glucose -> carbon dioxide+ water vapour + energy (ATP)
6O2 + C6H12O6 -> 6CO2 +6H2O + energy(ATP)
202
Why do you destarch leaves before testing them for starch?
So you don’t test already present starch
203
How do you test for starch in a leaf
Boil the leaf and then dip it in ethanol to stop metabolic reactions and remove chlorophyl. Dip the leaf back into hot water to soften it, then lay out the leaf on a white tile. Cover the leaf in iodine solution. If starch is present it goes blue black if there is no starch it will stay yellowy orange
204
Hydrogen carbonate indicator shows the presence of what?
Carbon dioxide
205
What colour does hydrogen carbonate indicator go when showing positive and negative results?
Yellow if there is more co2 stays red if there is still an atmospheric level of co2 and goes purple if there is less co2
206
Word equation for photosynthesis
Carbon dioxide + water -sunlight trapped as chlorophyl–> glucose + oxygen
207
What solution removes co2
Potassium hydroxide
208
Why do plants need nitrate ions and what does a deficiency of nitrate ions cause?
Building proteins and growth
Deficiency: poor growth and yellow leaves
209
What do plants use magnesium ions for and what does a deficiency of magnesium ions cause?
Used for photosynthesis (magnesium is what makes chlorophyll green and is in chlorophyll)
Deficiency: yellow leaves
210
What are stomata?
Small holes in the epidermis of leaves where gas exchange happens
211
What does the xylem transport?
Water
212
What is water used for in plants
Photosynthesis
Germination
Keeping cells turgid
Transport
213
Why does water evaporate (by diffusion) from the leaf surface? (Transpiration)
To set up a concentration gradient
214
Describe the transpiration stream
Water moves out of roots and into xylem by osmosis. The water then moves up the xylem due to the tension due to water loss and the cohesion and capillarity of water. Water then moves from the xylem into the pal aside cells by osmosis.
215
What is capillarity?
The adhesion(sticking) of water to the walls of a small tube
216
How does humidity affect transpiration?
Low humidity = high transpiration as there is a higher water potential difference.
217
How does temperature affect transpiration?
High temp = high transpiration as water molecules have more kinetic energy
218
How does wind speed affect transpiration?
High wind speed = high transpiration because it blows humidity and water away from leaf to increase water gradient
219
What is the xylem made up of?
Dead cells and rings of lignin which strengthens/thickens the xylem wall
220
Why does an airtight seal need to be made when using a potometer
Because otherwise the transpiration pull and cohesion between water molecules is broken
221
What does the phloem transport?
Sucrose and other organic compounds. It flows up and down.
222
What are the cell walls of the phloem made up of?
Cellulose
223
If you shine light from one direction onto a plant where will the auxin go?
To the dark side
224
What is auxin?
A plant hormone for plant growth regulation. Responsible for geotropism. It causes cell elongation
225
In a shoot a high concentration of auxin causes
Cell elongation
226
In roots a high concentration of auxin does what?
Stops cell elongation
227
What is phototropism?
A response to light (positive response is growth towards stimuli, negative is growth away)
228
What is geotropism or gravitropism?
Response to gravity. (Positive is growth towards stimuli and negative is growth away.)
229
What is asexual reproduction
Only having one parent. Cells make copies of themselves and all genes are passed on. The offspring is identical to its parent (clone)
230
What is a zygote?
The first cell after fertilisation when the diploid number has been restored
231
Half a diploid is a….
Haploid
232
What is a disadvantage of asexual reproduction?
It reduces the gene pool
233
What does a zygote undergo to become and embryo, and what does an embryo undergo to become the offspring?
Mitosis
234
What do plants use nitrate ions for?
Building proteins and growth, all amino acids contain nitrogen and amino acids build proteins.
235
What do plants use phosphate ions for?
Respiration and growth as phosphate ions are in components of DNA molecule and cell membranes
236
What do plants use potassium ions for
Respiration and photosynthesis as they must be present for photosynthesis and respiration enzymes to work
237
What do plants use magnesium ions for
Photosynthesis as chlorophyll molecules contain magnesium.
238
What does a deficiency of nitrate ions cause
Poor growth and yellow leaves
239
What does a phosphate deficiency cause
Poor root growth and discoloured leaves
240
What does a potassium deficiency cause
Poor flower and fruit growth and discoloured leaves
241
What does a magnesium deficiency cause
Yellow leaves
242
Describe colour change in hydrogencarbonate indicator
At atmospheric CO2 level it is red
When there is increasing CO2 it turns orange then yellow
When there is decreasing CO2 it turns magenta then purple
243
When does respiration happen
During the day and night.
244
What does the net exchange of CO2 and oxygen depend on?
Light intensity
245
What is the function of the upper epidermis
Is protects the plant whilst letting the sun shine in as it is thin and transparent
246
What is the palisade mesophyll
A layer of palisade cells which absorb light. They are near the surface so light can get to them easily and palisade cells are filled with chloroplasts
247
What is the xylem
It is made from dead cells and lignin. It moves water through the plant from the roots to the leaves via the stem.
248
What is the phloem
It is made from living cells and moves dissolved sugars from photosynthesis and other soluble food molecules from the leaves to growing and storing tissues
249
What is the spongy mesophyll
It is filled with air spaces to allow CO2 to diffuse from the stomata tot he photosynthesising cells. It provides a large internal sa:v
250
What is the lower epidermis
The lower epidermis is at the bottom of the leaf. It contains guard cells that open and close the stomata where gas exchange happens, water vapour is also lost through the stomata during transpiration
251
What is the cuticle
A thin waxy protective layer on top of the leaf. It reduces water loss by evaporation and prevents entry of pathogens
252
Photosynthesis
process by which plants manufacture carbohydrates from raw materials using energy from light
253
raw materials for photosynthesis
carbon dioxide and water
254
requirements for photosynthesis
Radient energy from light and chlorophyll
255
light energy is absorbed by
chlorophyll ( found in chloroplast )
256
The energy from light is transferred by
chlorophyll into
chemical energy to drive the reactions that form carbohydrates from water and carbon
dioxide
257
Energy is used to split water into
hydrogen ions and oxygen
258
The H ions are used to reduce
CO 2
to C 6 H 12 O 6 so light energy absorbed by chlorophyll becomes the chemical bond energy in the simple
sugars that are produced, and O 2 is released as a byproduct
259
light provides
energy for the process
260
chlorophyll traps
light energy
261
co2 in photosynthesis
diffuses into leaves from the air
262
water in photosynthesis
absorbed by roots of the plant
263
TESTING A LEAF FOR STARCH
● Place in boiling water
● Place in ethanol
● Place in a water bath
● Remove and wash in cold water
● Spread leaf on a tile and starch test it
264
IMPORTANCE OF CO 2 ( investigation )
● Leave a destarched plant in a bag with soda
lime under sunlight for few hours
● Test for starch - should be a negative test
265
importance of chlorophyll ( investigation)
● Starch test one normal leaf, and one
variegated leaf
● Normal leaf - fully positive
● Variegated leaf - negative where white
266
importance of light ( investigation)
● Cover a destarched leaf with a stencil and leaf
in light for a few hours
● Test for starch - covered part should be -ve
267
Uses of glucose as a product of photosynthesis
● Respiration
● Changed into starch and stored in stem tubers and chloroplasts
● Converted to cellulose which makes up cell walls
● Converted to sucrose for translocation
● Glucose forms proteins along with amino acids - growth and repair
● Sugars converted to oils - efficient way of storage in seeds
268
Carbondioxide + water (in presence of sunlight and chlorophyll)→
glucose + oxygen
269
Limiting Factor
Something present in the environment in such a short supply that it restricts life process
270
factors that affect photosynthesis
1) light
2) co2 concentration
3) temperature
271
how does light affect rate of reaction
With increasing light intensity, the rate of photosynthesis rises
to a point where it becomes constant as other limiting factors
such as CO2 and temperature are stalling a quicker rate of
photosynthesis. As the light intensity increases, stomata open
wider, allowing more light to enter the plant
272
how does carbon dioxide concentration affect rate of reaction
With increasing carbon dioxide concentration, the rate of
photosynthesis rises to a point where it becomes constant as
other limiting factors such as light intensity and temperature are
stalling a quicker rate of photosynthesis
273
how does temperature affect rate of reaction
Up to an optimum temperature for enzyme activity, the rate of
photosynthesis rises. However, after this temperature, enzymes
denature and the rate of photosynthesis falls quickly. To explain
refer to enzymes, and how optimum temperature affects their
activity. Greater kinetic energy increases the rate of reaction.
274
The optimum conditions for plant survival can be provided in a
glasshouse
275
Plant/Animal/Both (Dark)
Only respiration - CO 2 which
reacts with water to form
carbonic acid, indicator goes
yellow
276
(Plant + Animal)(Normal)
Both plant and animal respire
and release CO 2 , but some taken
by the plant, so orange.
277
Plant (normal conditions)
CO 2 taken out of the water, less
carbonic acid, indicator goes
purple
278
Cuticle
Waterproof layer that also cuts down the water lost by evaporation
279
Upper epidermis
A single layer of cells with no chloroplasts. Light goes straight through
280
Palisade mesophyll
● Contain lots of chloroplasts - most photosynthesis occurs here
● Packed very close together to maximize light absorption
281
spongy mesohyll
Many air spaces (makes it easier for CO2 to diffuse) in between
282
Vascular bundle
Xylem and phloem transport respective substances around the plant
283
Lower epidermis
No thick cuticle. Lots of stomata on surface - allow gases in and out
284
Role of stomata
and/or out of the leaf
● O 2
● CO 2
● H 2 O vapor
285
Role of gaurd cells
Guard cells open in the morning for CO 2 to
diffuse into the plant. They close at night to
minimize water loss. In the morning water
moves by osmosis into guard cells forcing them
open. This water moves out at night and so the
guard cells close.
286
The plant uses nitrates for
the production of amino acids that are built into proteins . Proteins are used
for the growth and repair of cells. A deficiency of nitrate ions results in stunted growth, weak stems,
yellow dying lower leaves and upper leaves turn pale green
287
The plant requires magnesium to make
chlorophyll . A lack of chlorophyll results in leaves turning yellow
due to a lack of chlorophyll. Also as no photosynthesis takes place, plant growth is harmed.
288
Photosynthesis
the process by which plants synthesize carbohydrates from raw materials using energy from light.
289
Photosynthesis reaction
Carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll)
290
Chlorophyll
green pigment that is found in chloroplasts.
291
Chlorophyll transfers energy from light into
in chemicals, for the synthesis of carbohydrates.
292
Uses of glucose:
glucose used in respiration to provide energy
293
Protein contains not only carbon, hydrogen, oxygen, but also
nitrogen
294
Therefore, in
order to make amino acids plants need a source of
nitrogen, and they get this nitrogen from nitrite ions. They use this nitrate ion to make amino acids and use this amino acid to make protein which is used for growth. If the plant cannot get enough nitrate ions, it will not be able to synthesize protein effectively. And so will not grow quickly or strongly.
295
Chlorophyll is not a protein, but it contains
nitrogen. It also contains magnesium
296
a plant needs magnesium ions as well as nitrite ions to make
chlorophyll.Without these ions, the plant will look yellow and not green, suggesting that there are not plenty of chlorophylls present. If the plant cannot make lots of chlorophyll, it will not be able to photosynthesize well, and will therefore not grow well.
297
Limiting factors for photosynthesis are
1) light intensity
2) carbon dioxide concentration
3) temperature
298
Light intensity.
As the light intensity increase, the rate of photosynthesis increase until the the plant is photosynthesizing as fast as it can.
299
Carbon dioxide concentration.
The more carbon dioxide a plant is given the faster it can photosynthesis. But once the carbon dioxide concentration reaches a certain level, there is no further increase in the rate of photosynthesis.
300
Temperature.
As the temperature increase, the rate of photosynthesis is also increased. But after the optimum temperature, the rate of reaction decreases.
301
Stomata
Carbon dioxide diffuses into the leaf through the stomata. If the stomata are closed, photosynthesis cannot take place because the plant lacks one of its raw materials - carbon dioxide. Stomata are often closed during hot weather to prevent water loss. This means that on a really hot or bright day,photosynthesis may slow down.
302
Leaves have large surface area and are thin
This large surface area allows a large amount of sunlight to fall onto the leaves. The large surface area also increases the rate at which carbon dioxide can diffuse into the leaf from the air. Being thin means that sunlight can pass right through the leaf, allowing many cells inside it to photosynthesise. The thinness also helps carbon dioxide to reach all the cells quite quickly by diffusion
303
upper epidermis
-Cells are tightly packed together to reduce water loss.
-No chloroplast, so can not photosynthesis.
-Secretes a waxy substance, which forms a thin, transparent, waterproof covering called the cuticle.
-Transparent to let the light through easily, to reach the palisade mesophyll cells.
304
Palisade mesophyll
-Tightly packed
-Column shape.
-Large number of chloroplasts.
-Close to the top to get plenty of sunlight.
305
Spongy mesophyll:
-Not many chloroplast.
-Loosely packed.
-There are air spaces between them.
-They allow diffusion of carbon dioxide and oxygen between the air and the cells inside the leaf.
-this space also allows water vapour to move out of the leaf.
306
Lower epidermis
-On some leave this tissue makes a cuticle But usually, it does not because the the underside of the leaf does not get as hot as the upper side.
-Stomata are present. Each stomata is surrounded by a pair of guard cells.
- Stomata is a small opening that allows diffusion of carbon dioxide, oxygen, and water vapor.
307
starch use
as an energy store
308
cellulose
to build cell walls
309
sucrose use
for transport in the phloem
310
nectar use
to attract insects for pollination
