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Biology Gcse Full 25-26 > B8-Photosynthesis > Flashcards

B8-Photosynthesis Flashcards

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1
Q

What is an endothermic reaction?

A

a reaction that requires a transfer of energy from the environment

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2
Q

What is glucose

A

A simple sugar

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3
Q

What are limiting factors?

A

factors that limit the rate of a reaction

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4
Q

What is the word equation for Photosynthesis?

A

Carbon Dioxide + water —(light)—> glucose + oxygen

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5
Q

What is the balanced symbol equation for photosynthesis?

A

6H₂O + 6CO₂ —(light)—> C₆H₁₂O₆ + 6O₂

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6
Q

What part of the leaf absorbs the energy from the sun?

A

The chlorophyll in the chloroplasts

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7
Q

What type of reaction is photosynthesis and why?

A

Photosynthesis is an endothermic reaction, this is because energy is transferred from the environment when the light is absorbed by the chlorophyll

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8
Q

What is the formula of glucose?

A

C₆H₁₂O₆

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9
Q

What happens to the glucose produced during photosynthesis?

A

Some of the glucose is immediately used by the plant cells for respiration, however much of it is converted into insoluble starch and is stored.

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10
Q

Explain the process of photosynthesis

A

Photosynthesis is an endothermic reaction used by plants to make their own food. Energy is required in the form of light from the sun. Light energy is absorbed by the chlorophyll in the chloroplasts in the leaf. This energy is then used to convert Carbon Dioxide (absorbed from the air through the stomata) and water (absorbed from the ground through the roots) into glucose. This chemical reaction also produces oxygen as a by-product. The oxygen is released into the air

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11
Q

What leaf adaptations are there to make photosynthesis more efficient?

A

Most leaves are broad

Most leaves are thin

They contain chlorophyll within chloroplasts

They contain veins

They contain air spaces

They have guard cells

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12
Q

How does having broad leaves make photosynthesis more efficient?

A

Broader leaves means that there is more surface area for the light to fall on

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13
Q

How does having thin leaves make photosynthesis more efficient?

A

Thinner leaves means that the diffusion distances for the gases are short

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14
Q

How does containing chlorophyll in chloroplasts make photosynthesis more efficient?

A

Chlorophyll within the chloroplasts absorbs the light which is needed to provide energy for photosynthesis

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15
Q

How does having veins make photosynthesis more efficient?

A

Leaf veins contain xylem and phloem in vascular bundles. The xylem brings in plenty of water to the cells of the leaves and the phloem removes the products of photosynthesis (Glucose)

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16
Q

How does having air spaces make photosynthesis more efficient?

A

Having air spaces in a leaf means that carbon dioxide can diffuse into the cells, and oxygen can diffuse out of the cells

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17
Q

How does having guard cells make photosynthesis more efficient?

A

Guard cells open and close the stomata to regulate gas exchange

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18
Q

How is algae adapted for photosynthesis

A

Algae is aquatic so they have a large surface area and can absorb carbon dioxide dissolved in the water around them, they also release the oxygen that they produce which dissolves into the water

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19
Q

State 4 limiting factors of photosynthesis:

A

Light*
Temperature*
Carbon Dioxide Concentration*
Chlorophyll levels in the leaf

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20
Q

Explain how light is a limiting factor

A

If there is plenty of light then lots of photosynthesis can take place, if there a lack of light, photosynthesis would slow down. If there is no light, photosynthesis would stop. This is because light transfers the energy needed for the process. Even on sunny days, light may be limited due to shade from other plants or buildings. For most plants, the brighter and more intense the light is, the faster the rate of photosynthesis

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21
Q

Explain how temperature is a limiting factor

A

Temperature affects all chemical reactions, including photosynthesis. Photosynthesis is controlled by enzymes, if it is too cold the reactant particles will not have much kinetic energy, reducing the number of collisions, the enzymes will also not work as effectively. As temperature increases, the rate of photosynthesis speeds up as the particles gain more kinetic energy and there is more collision between reactants and enzymes. However, if the temperature continues to rise, the enzymes will become denatured at around 40-50*C, this will cause the rate of photosynthesis to fall eventually to 0.

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22
Q

Explain how Carbon Dioxide concentration is a limiting factor

A

Plants need Carbon Dioxide to perform photosynthesis. However, the atmosphere is only about 0.04% carbon dioxide. This means that carbon dioxide often limits the rate of photosynthesis. Increasing the carbon dioxide concentration will increase the rate of photosynthesis

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23
Q

Explain how Chlorophyll levels in the leaf is a limiting factor

A

If the amount of chlorophyll in a leaf is limited in any way, less photosynthesis will take place. The leaves on some ornamental plants have white, chlorophyll-free areas. This reduces the rate of photosynthesis, causing the plants to grow less vigorously than plants with all green leaves. This is because chlorophyll in chloroplasts absorb the light that transfers the energy needed for the process.

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24
Q

Required practical:Describe the method for how the rate of photosynthesis is effected by light intensity:

A

1) Cut a piece of pondweed 8-10cm long. Place it in a boiling tube of water with the cut end uppermost

2) Use the thermometer to measure the temperature of the water in the boiling tube

3) Place the boiling tube in the large beaker of water, making sure that the top of the boiling tube is floating above the surface of the water in the beakerPlace the lamp 15cm from the boiling tube. Place the large beaker of water between the lamp and the boiling tube

4) Wait until there is a steady flow of bubbles from the cut end of the pondweed. Count the number of bubbles in 2 minutes. Record this in your results table.

5) Measure the temperature of the water in the boiling tube to make sure it has not changed.

6) Repeat steps 1-5 four more times but in step 3 increase the distance between the lamp and boiling tube by 2cm each time

7) Repeat the whole investigation (steps 1-6) two more times and record your results

8) Calculate the mean number of bubbles for each distance, leaving out any anomalous results.
9) Record data in appropriate table/graph

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25
What is the equation for light intensity?
Light intensity = 1 / (distance²)
26
How do plants use glucose produced during photosynthesis?
For respiration To convert into insoluble starch To produce fats and oils To produce cellulose To produce amino acids
27
Why do plants use glucose produced in photosynthesis for respiration?
Plant and algal cells, like all other living cells, need to respire all the time. They use some of the glucose produced during photosynthesis as they respire. The glucose is broken down using oxygen to provide energy for the cells. Carbon dioxide and water are waste products of the reaction. Chemically, respiration is the reverse of photosynthesis
28
Why do plants convert glucose produced in photosynthesis into insoluble starch?
Plants convert some glucose produced in photosynthesis into starch to be stored. Glucose is soluble in water. If it were stored in plant cells, it could affect the way water moved in and out of the cells by osmosis. Lots of glucose could affect the water balance of the whole plant. Starch is insoluble in water, this means that it has no effect on the water balance of the plant so plants can store large amounts of starch in their cells. Starch is the main energy store in plants and it is found in cells all over a plant: Starch is often stored in the cells of the leaves. It provides an energy store for when it is dark or when light levels are low Starch is also kept in special storage areas of a plant. For example, many plants produce tubers and bulbs that are full of stored starch to help them survive through the winter
29
Why do plants use glucose produced in photosynthesis to produce lipids?
Plants and algae use some of the glucose from photosynthesis and energy transferred from respiration to build up fats and oils. These may be used in the cells as an energy store. They are sometimes used in the cell walls to make them stronger. In addition, plants often use fats or oils as an energy store in their seeds. Seeds provide food for the new plant to respire as it germinates.
30
Why do plants use glucose produced in photosynthesis to produce cellulose?
Energy transferred in respiration may be used to build smaller molecules into bigger molecules. For example, plants build up glucose into complex carbohydrates such as cellulose. They use this to strengthen their cell wall.
31
Why do plants use glucose produced in photosynthesis to produce amino acids?
Plants use some of the glucose from photosynthesis to make amino acids. They do this by combining sugars with nitrate ions and other mineral ions from the soil. These amino acids are then used for protein synthesis to make proteins. These proteins can then be used in the plant in many ways, including making enzymes. This uses energy from respiration. For this, the plant must be able to absorb nitrates and other minerals from the soil
32
Can plants photosynthesise at night and why?
Plants cannot photosynthesise at night as there is no light, this means that photosynthesises stops
33
Can plants respire at night and why?
Plants can respire 24 hours a day as they do not need light to respire, unlike photosynthesis
34
What is the rate of photosynthesis compared to the rate of respiration of a plant in a completely dark room?
Photosynthesis stops but respiration continues
35
What is the rate of photosynthesis compared to the rate of respiration of a plant in a dim light?
Photosynthesis rate = respiration rate
36
What is the rate of photosynthesis compared to the rate of respiration of a plant in a bright light?
Photosynthesis rate > respiration rate
37
What happens to the gas exchange in a plant at night and why?
Oxygen is taken in and Carbon Dioxide is given out, this is because respiration continues but photosynthesis stops
38
What happens to the gas exchange in a plant under a dim light and why?
The net amount of oxygen in and out and Carbon dioxide in and out is 0, this is because the rate of photosynthesis is equal to the rate of respiration
39
What happens to the gas exchange in a plant under a bright light and why?
More Carbon dioxide is taken in and more oxygen is given out, this is because the rate of photosynthesis is more than the rate of respiration.
40
How are some carnivorous plants adapted to live in nitrate-poor soil such as bogs?
Some carnivorous plants, such as pitcher plants or Venus fly traps, are adapted to live in nitrate-poor soil. They can survive because they obtain most their nutrients from the animals, such as insects, that they catch. The plants produce enzymes to digest the insects they trap. They then use nitrates and other minerals from the digested bodies of their victims in place of nutrients they cannot get from the poor soil that they grow in
41
What happens if a plant begins to photosynthesise faster?
It grows faster and creates more biomass
42
How do farmers increase the yield of their crop?
They can use greenhouses or huge plastic polytunnels to try and remove limiting factors
43
How do greenhouses or huge plastic polytunnels increase the yield of a crop?
The glass or plastic building means that the environment is much more controllable than in an ordinary garden or field. This means that farmers can try and eliminate limiting factors as much as possible: The temperature is maintained at the optimum temperature for enzyme activity Carbon dioxide levels are increased so they do not become a limiting factor Artificial lighting can be used to extend the hours of the day, and months of the year when plants can photosynthesise Plants can be grown in a mineral solution with a perfect balance of nutrients, such as nitrate ions, instead of soil to ensure optimum growth. This is called hydroponics This increases the rate of photosynthesis and therefore the rate of growth of the plants.
44
What is hydroponics?
Hydroponics is when soil is replaced by a mineral solution pumped around the plant roots instead of soil. Removing the soil means there’s no risk of soil organisms causing disease. Monitoring and adjusting the concentrations of minerals in the solution enable the farmer to optimise growth. Hydroponics allows crops to be grown in regions where there’s infertile or poor soil. Due to the costs involved, hydroponics is used only for high-value crops.
45
Explain the economics of using a greenhouse to optimise photosynthesis:
Using a greenhouse and keeping the conditions just right can be very costly. Electricity and gas are used to maintain the lighting and temperatures and to control the carbon dioxide levels. Expensive monitoring systems are needed to maintain the conditions within the greenhouse. However, less staff are needed as much of it is automated, the time from seed to harvest is much shorter, and the final crop is larger and cleaner. The higher yields also help to increase profits
46
In which cell organelle does photosynthesis take place?
Chloroplasts
47
Which chemical in the leaves is required for photosynthesis?
Chlorophyll
48
What is the compensation point in a plant?
When the rate of photosynthesis is equal to the rate of respiration
49
In which layer of the leaf does the most photosynthesis take place?
Palisade mesophyll layer
50
Where is starch stored in a plant?
Starch is the main energy store in plants and it is found in cells all over a plant: Starch is often stored in the cells of the leaves. It provides an energy store for when it is dark or when light levels are low Starch is also kept in special storage areas of a plant. For example, many plants produce tubers and bulbs that are full of stored starch to help them survive through the winter
51
Why may plants have a difference in the rate of water loss?
One plant may have more stomata One plant may have more leaves One plant may have bigger leaves
52
Explain the relationship between the temperature and the rate of photosynthesis
The rate of photosynthesis initially increases as the temperature increases as temperature is a limiting factor between A and B and is required for the reaction to take place. From B to C, the temperature passes its optimum, causing the enzymes involved in the reaction of photosynthesis to become denatured, deforming the active site, therefore disabling the active site from binding to the substrate and ultimately decreasing the rate of photosynthesis rapidly
53
In the testing a leaf for starch test, how will covering the leaf effect the concentration of starch?
The leaf that is covered with foil or card will not receive light meaning that the plant cannot photosynthesise in these areas, meaning that no glucose in produced and therefore no starch is stored.
54
Briefly describe photosynthesis
Light energy is harnessed by the chloroplasts. The light energy is used to convert carbon dioxide and water into glucose. This essentially converts light energy into chemical energy in the form of glucose. Oxygen is released as a by-product. Because this requires an input of energy, it is classed as an endothermic reaction
55
What is the energy transfer in photoysnthesis?
Light energy is converted to chemical energy (in glucose).
56
Why are leaves very thin?
This allows for a short diffusion pathway for the exchange of gases.
57
Which substances does the plant tissue xylem transport?
Water molecules and dissolved minerals
58
Why are there air spaces in the spongy mesophyll layer?
For faster exchange of gases
59
What is the chemical test for starch?
Add 2-3 drops of iodine to the sample, if the colour changes from red/orange to blue-black starch is present.
60
What is meant by the ‘rate of photosynthesis’?
The rate of photosynthesis is how quickly photosynthesis takes place (or how quickly a plant converts water and carbon dioxide to glucose and oxygen)
61
Name 3 ways a student could measure the rate of photosynthesis?
Measure: 1) the rate of oxygen output 2) the rate of carbon dioxide uptake 3) the rate of carbohydrate production
62
What is meant by an ‘inverse relationship’ between two variables.
As one variable increases the other decreases. For e.g. in the photosynthesis experiment as the distance of the light source from the plant increases, the light intensity decreases.
63
Which variable gets plotted on the x axis?
Independent
64
Which variable gets plotted on the y axis?
Dependent
65
How might farmers increase the carbon dioxide concentration in a greenhouse?
Use paraffin heaters on a small scale. On a larger scale, use carbon dioxide wastes from industrial processes that has been cleaned up before use. Can use liquid carbon dioxide, applied through pipes, though this can be expensive.
66
Which type of microorganism can be used to increase CO2 concentrations in greenhouses?
Fungi can be used, grown as amyceliumin bags around the greenhouse, that add carbon dioxide through their respiration.
67
Explain 2 ways water volume could be increased in commercial plant greenhouses.
Irrigation systems. - Plants are sometimes grown in liquid systems called hydroponics.
68
Compare the normal concentration of atmospheric carbon dioxide to carbon dioxide in a greenhouse.
The normal concentration for atmospheric carbon dioxide varies between 0.03 % and 0.04 %. The concentration of carbon dioxide in greenhouses is often kept at around 0.1 per cent
69
Give an advantage of growing crops in a commercial greenhouse.
Much higher yields of crops can be obtained. - Plants can be grown all year round.
70
Give an disadvantage of growing crops in a commercial greenhouse.
Manipulating the conditions can be very expensive. - Very time consuming and workers need to be trained.
71
What makes starch a useful long term storage molecule?
Its insoluble to water Its compact It can easily be broken down when needed
72
Examples of the inverse square law
If you double the distance from a light source, the light intensity becomes four times smaller. If you halve the distance, light intensity becomes four times greater
73
Why does photosynthesis slow down at very high temperatures?
Enzymes involved denature, reducing the rate of reaction.
74
Why do farmers control limiting factors in greenhouses?
To increase the rate of photosynthesis and maximise crop yield while balancing costs for maximum profit.
75
How does a greenhouse work
A greenhouse traps the sun’s radiation as heat inside the greenhouse, so that temperature is not a limiting factor for the rate of photosynthesis.
76
Worked example of inverse square law
Worked example: If the light source is 10cm from a plant, calculate the light intensity reaching the plant. 1 ÷ (distance²) 1 ÷ (0.10 × 0.10) 1 ÷ 0.01 = 100 arbitrary units
77
Advantages of hydroponics-general
Higher Yield in Smaller Space Water Conservation Faster Plant Growth No Need for Soil Fewer Pests and Diseases
78
Disadvantages of hydroponics-general
High Initial Setup Costs • * Technical Knowledge Required • X Energy Costs • X Market Dependency
79
Advantages of greenhouses-Economics
Increased yield.Extended growing seasons.Reduced transportation cost
80
Disadvantages of greenhouses-economics
High inital cost,operating costs
81
describe how plants get the materials they need for growth.
Mineral ions-roots Chlorophyll in leaves-light Water-by the roots Co2-from the leaves
82
explain how carnivorous plants are adapted to their environment
Traps - Special leaves catch insects (e.g., Venus flytrap snaps shut, pitcher plants have deep traps). 2. Digestive Enzymes - Break down insects to absorb nutrients. 3. Bright Colors & Nectar - Attract insects. 4. Sticky Hairs or Slippery Surfaces - Help trap prey. 5. Survive in Poor Soil - Get nutrients from insects instead of the ground.
83
Advantages and Disadvantages of hydroponics-economics
✅Space effiency,water efficiency,faster growth ❌High start up costs,specialized knowledge,energy costs
84
General advantages and disasvantages of greenhouses
Extended Growing Seasons • V Controlled Environment • Protection from Pests and Weather • V Water Efficiency • V Reduced Transport Costs • X High Initial Setup Costs • X Ongoing Operational Costs • X Limited Crop Variety • X Complexity in Climate Control
85
Why add heat to a greenhouse?
To keep enzymes at their optimum temperature and speed up photosynthesis.
86
Is adding heat to a greenhouse cost-effective?
Only if the increased plant growth leads to enough profit to cover heating costs. Too much heat = wasted money.
87
Why add artificial light to a greenhouse?
So plants can photosynthesise for longer, especially in winter or at night
88
Is adding artificial light to a greenhouse cost effective
Yes, if used efficiently (e.g. LED lights on timers). Too much lighting increases electricity bills.
89
Why increase CO₂ in a greenhouse?
A: More carbon dioxide means a higher rate of photosynthesis (if other factors are not limiting).
90
Is adding co2 cost effective
It can be, but only up to a certain concentration. After that, it has little effect, so extra CO₂ is wasted.
91
Define nitrate ions
Minerals absorbed from the soil that plants use with glucose to make amino acids (for protein synthesis)
92
Define amino acids
Building blocks of proteins made in plants from glucose and nitrate ions.
93
Define lipids
Fats and oils made by plants from glucose, used for energy storage in seeds.
94
Define cellulose
A carbohydrate made from glucose, used to strengthen plant cell walls.
95
Define respiration(in plants)
The process by which plants break down glucose to release energy.
96
What is photosynthesis
A chemical process where plants use light energy to convert carbon dioxide and water into glucose and oxygen

Biology Gcse Full 25-26 (12 decks)

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