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Plants Flashcards

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1
Q

What is epidermal tissue?

A

Covers the leaf

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2
Q

What is the upper epidermis like?

A

Transparent as it allows light energy to get to the palisade cells just underneath

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3
Q

What is the lower epidermis like?

A

Has many stomata and guard cells to allow gases in and out of the leaf

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4
Q

What are palisade cells?

A

Top layer of cells in a leaf

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5
Q

What are palisade cells adapted to do?

A

To absorb as much light as possible, so have many more chloroplasts than any other plant cells

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6
Q

What is the structure of palisade cells?

A
  • They’re long and thinly shaped so many of them can be pushed into the top layer of the leaf -> increases their SA
  • Vacuole push chloroplasts to the edges of the cells to ensure they come into contact with light
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7
Q

What is spongy mesophyll like?

A
  • The layers are not tightly packed together
  • they have lots of air pockets between the cells which allows CO2 to reach the palisade cells for photosynthesis quickly
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8
Q

What does the tissue of spongy mesophyll layer have? How do gases move?

A
  • contains irregular shaped cells with a few chloroplasts

- move by diffusion

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9
Q

What is the stomatas job?

A
  • control gas exchange and water loss
  • They are special pores that let CO2 and O2 in and out
  • Stomata open to let CO2 in and O2 out
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10
Q

Where are stomata usually concentrated?

A

Bottom of the leaf to limit water loss

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11
Q

What are guard cells?

A

They surround each stomata, they open and close the stomata, and control gas exchange and water loss

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12
Q

What is the job of the waxy cuticle?

A

Its the outer thin surface of the leaf, it prevents water loss within the leaf by evaporation

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13
Q

What does xylem do?

A

Transports water and mineral ions from the roots to the stems and leaves.

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14
Q

What does phloem do?

A

Transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage

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15
Q

How does xylem work in the movement of water?

A

1) . Water is absorbed from soil through the root hair cells
2) . Its transported through the xylem vessels up the stem to the leaves
3) . It then evaporates from the leaves

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16
Q

What is meritsm tissue? What are the cells doing?

A

Found in the tip of a root/ shoot, the cells here are dividing or multiplying can differentiate into different types of plant cell

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17
Q

What is photosynthesis?

A

A chemical reaction that occurs in the chloroplasts of a plant cell, the plant uses this reaction to create its own food molecules (glucose) which is used by the plant in several ways

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18
Q

What is the equation for photosynthesis?

A

Carbon dioxide + water -> glucose + oxygen

6CO2 + 6H2O -> C6H12O6 + 6O2

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19
Q

What is an endothermic reaction? How is this connected with plants?

A

The reaction is classed as a reaction that absorbs energy from the surroundings, as plants absorb light energy, photosynthesis is an example of a endothermic reaction

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20
Q

What is the light energy used in photosynthesis as?

A

A power to react carbon dioxide and water together, O2 is released from the plants leaves via stomata and the sugar is used by the plant

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21
Q

What are the 5 conversions of glucose?

A

1) . Into a carbohydrase called starch which is stored in leaves, roots and stem
2) . Into a carbohydrase called celluslose which forms the cell walls
3) . Into fat/oil storage into seeds enables growth
4) . Into amino acids which are used as proteins in the plant
5) . Use for respiration

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22
Q

Why do plants need nitrates?

A

Used in the production of amino acids and thereore proteins

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23
Q

Why do plants need magnesium?

A

Used to make chlorophyll, the green pigment thats absorbs light

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24
Q

What 4 factors affect the rate of photosynthesis?

A
  • temperature
  • carbon dioxide concentration
  • light intensity
  • amount of chlorophyll in a plant
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25
How does temperature affect rate of photosynthesis?
The chemical reaction is controlled by enzymes. - if the temperature is too low the enzymes needed for photosynthesis work slower at low temps - if the temperature is too high the enzymes needed for photosynthesis and other reactions will be damaged
26
How does carbon dioxide concentration affect the rate of photosynthesis?
The rate of photosynthesis will increase as the levels of CO2 increase. - However the rate levels off when the rate becomes too high that there is mot enough light to sustain any futher increase or the temperature is too low
27
How does light intensity affect the rate of photosynthesis?
Light provides energy for photosynthesis, so increasing light intensity the rate will also increase at first - eventually when the rate of photosynthesis is high, it will level off as the plant is unable to absorb enough CO2 to continue the increase in rate or because the temperature is too low
28
How does the amount of chlorophyll affect the rate of photosynthesis?
Chlorophyll is needed to absorb sunlight, therefore if the plant has lots of pigment it is able to absorb a lot of available sunlight. - chlorophyll can be affected by disease which would result in a reduction of rate of photosynthesis. Its not a proportionatal relationship
29
How does a thin membrane in leaves increase the ROP?
Provides a short distance for co2 to move by diffusion into the leaf
30
How does chlorophyll increase the ROP?
Absorbs light for energy
31
How do stomata increase the ROP?
Allows co2 ro move by diffusion in a leaf
32
How do xylem and phloem (network of tubes) increase the ROP?
Xylme transports water | Phloem transports food
33
How do long root systems increase the ROP?
Absorbs as much water as possible
34
How do lots of flat leaves increase the ROP?
Increase SA of chlorophyll to ensure lots of light energy is absorbed
35
How does the spongey mesophyll layer increase the ROP?
Enables CO2 to diffuse quickly from stomata to palisade cells
36
How do rows of tight palisade cells increase the ROP?
Gives the layer a big SA & each cell is packed with chloroplasts they absorb as much light as possible
37
Why are greenhouses used?
They eliminate some of the limiting factors and allow photosynthesis to occur at higher than normal rates
38
What are the advantages of greenhouses?
- reduce risk of plants being damaged by pests and diseases | - produce greater harvests of quality produce which can be sold more often which makes money
39
What are the disadvantages of greenhouses?
Expensive to set up and operate
40
What is the inverse square law?
Light intensity ➗ distance (d)2
41
What is the structure of xylem?
- tube made from dead cells - no cell walls between each of the cells -continual column - lignin forms in the cell walls that strengthen the tube and makes it waterproof
42
What does phloem transport and which way?
- Transports sugars ie dissolved sugars from photosynthesis in the leaves and other food substances so they can be used or stored. - food transported in both directions
43
What is an inverse relationship?
For eg in a practical, as distance increases the light intensity will decrease
44
What is the transpiration stream?
Movement of water from the roots of a plant to the leaves from the xylem
45
How does the transpiration stream work?
1. transpiration is caused by the evaporation and diffusion of water from a plant's surface, most happens at the leaves 2. the evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it 3. more water is drawn up from the roots, and so there's a constant stream of water through the plant
46
How does humidity affect the rate of transpiration?
The drier the air around the leaf, faster transpiration happens. Diffusion happens fastest if there's a really high concentration in one place and low in the other
47
How does temperature affect the rate of transpiration?
Increased temperature provides more kinetic energy to the water molecules to evaporate and diffuse out of the stomata
48
How does wind ( air flow) affect the rate of transpiration?
The greater the air flow, greater the transpiration rate - On a windy day, water molecules may be carried away from the stomata at a faster rate, as water is swept away maintaining a low concentration of water outside in the air than in the leaf -> this increases the concentration gradient
49
How does light intensity affect the rate of transpiration?
Brighter the light the greater the transpiration rate | - If it is dark the stomata are closed, so very little water escapes
50
How do co2 levels affect the rate of transpiration?
Also affect whether the stomata are open or closed
51
What is a bubble potometer?
To calculate rate using a BP you would obseve and record the movement of a bubble in the tubing over severla minutes and divide the distance travelled by the bubble by the time taken
52
What is a mass potometer?
To calculate a rate you would obseve and record the change in mass of a plant over several minutes and divide the total mass by the total time taken
53
How does translocation work?
1) . Sucrose is produced by the palisade cells during photosynthesis and move by diffusion into the phloem tubes 2) . Sucrose is then transported in a liquid called sap to other cells that absorb the sugar and use it for respiration 3) . Sugar is transported quickly to ensure that all cells can produce enough enegy to stay alive
54
What is translocation?
Uses phloem to Transport sugars eg glucose from leaves to respiring cells
55
What do plant hormones do?
Coordinate and control the growth and response to light and gravity
56
What is auxin?
A plant hormone that is produced in the TIP of roots and shoots It controlls the growth where they diffuse back along the root/shoot causing cells to elongate
57
What is phototropism and how does it work?
The shoots and leaves of a plant will follow the sun during the day -> phototropism 1) . Sunlight breaks down auxins, when a tip of a shoot is exposed to light, auxins will accumulate on the side thats in the shade 2) . This makes the cells elongate faster on the shaded side, so the shoot bends towards light
58
Wha happens when the tip of the shoot is removed?
No auxin is available and the shoot may stop growing
59
What affect does gravitropism/geotropism have on shoots?
1) . When a shoot is growing sideways, gravitt produces an unequal distribution of auxin in the tip, with more auxin on the lower side 2) . This causes the lower side to grow faster, bending the shoot upwards
60
What affect does gravitropism/geotropism have on roots?
1) . A root growing sideways will also have more auxin on its lower side 2) . But in a root the extra auxin inhibits growth, this means the cells on top elongate faster and the root bends downwards
61
How are auxins used in weed killer?
Selective weed killers have been developed to attack broad leaved plants (weeds) instead of crops; they cause them to grow quicker, the weed killer then is a strong in larger quantities by the weeds than the plants
62
How are auxins used in rooting powders?
If you add rooting poweder which has auxins to cutting in soils, they will produce roots rapidly and start growing as new plants. The grower is able to produce many clones of a plant very quickly
63
How are auxins used in promoting growth in tissue cultures?
Tissue culture can be used to grow clones of plants, by adding hormones eg auxins it stimulates cells to divide and form roots and shoots which forms a clone!
64
How is gibberellin used to end seed dormancy?
Most seeds only germinate in specific conditions, seeds can be treated sith gibberellin to alter dormancy and make them germinate all year round
65
How is gibberellin used to promote flowering?
Flowers also tend to grow with specific conditions eg longer days, temperature but by adding gibberellin, they will flower all year round without a need for change in environment; often producing larger flowers
66
How is gibberellin used to increase fruit size?
Seedless variaties of fruit eg grapes dont grow as large as seeded fruit, but if gibberellin is added they'll grow larger to match the normal types
67
What is ethene?
A gas produced by aging parts of a plant, it stimulates enzymes that cause fruit to ripen
68
How does ethene work in ripening fruit?
1) . Fruit can be picked while its unripe so its firm and hard to damage 2) . The gas is added during transport to the shop 3) . The fruit is ripe and ready on arrival!
69
How can you delay ripening of fruit?
Adding chemicals that block ethenes effect on the fruit or remove it from the atmosphere
70
What is phloem composed of?
Tubes if englongated cells, cell sap can move from one phloem cell to the next through pores in the end walls
71
What are root hair cells?
Adapted for the efficient uptake of water by osmosis, and mineral ion by active transport
71
What is xylem composed of?
Hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream
72
why does water escape from the leaves by diffusion?
because there's more water inside the plant than outside in the air
73
what happens when the guard cells have lots of water?
they fill with it and go plump and turgid which makes the stomata open so gases can be exchanged for PHS
74
what happens when the plant becomes short of water?
the guard cells lose water and become flaccid, making the stomata close. this helps too much water from escaping
75
what do guard cells have?
- thin outer walls and thickened inner walls make the opening and closing work - they are also sensitive to light and close at night to save water without losing out on PHS

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