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IGCSE edexcel Biology > Plant Nutrition > Flashcards

Plant Nutrition Flashcards

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1
Q

What is the word equation for photosynthesis?

A

Carbon dioxide +water ➯ (using chlorophyll and light) glucose + oxygen

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2
Q

What is the chemical equation for photosynthesis?

A

6CO2 + 6H2O ➯ C6H12O6 + 6O2

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3
Q

How do you test the requirement for light?

A
  • cover part of the leaf w foil or card
  • leave another part uncovered
  • after being left in sun, test with iodine
  • covered section should remain brown, as no sun, so no PS or starch
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4
Q

How do you test the requirement of chlorophyll?

A
  • take a variegated leaf, and test with iodine
  • draw pattern of chlorophyll and compare results
  • the white sections should stay brown, as they have no chlorophyll for PS, so not starch
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5
Q

How do you test for the production of starch?

A
  • boil leaf in boiling water to denature enzymes in leaf to kill it
  • then, using a water bath, boil leaf in boiling ethanol to remove colour
  • wash the leaf
  • test leaf with iodine. If starch present, goes from brown to blue/black
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6
Q

How do you test the production of oxygen?

A
  • place elodea in a beaker of water, with a test tube on top to catch the oxygen.
  • place a funnel around the elodea into the test tube to catch all the oxygen
  • as PS append, bubble can be seen and collected
  • prove it is oxygen by relighting a glowing splint
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7
Q

How is the leaf adapted for photosynthesis?

A
  • palisade cells have many chloroplasts and are tightly packed, as chlorophyll needed (generally called mesophyll tissue)
  • xylem delivers water, as it is needed
  • lower epidermis has stomata to allow gas exchange, for CO2 and O2
  • phloem transports glucose produced, as sucrose, around plant
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8
Q

Why do plants need nitrogen?

A
  • needed for amino acids, which make proteins needed for growth.
  • plant growth stunted, and leaves yellow without
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9
Q

Why do plants need magnesium?

A
  • needed to make chlorophyll, which is needed for PS

* chlorophyll green ∴ leaves look yellow without it

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10
Q

What are possible limiting factors on a plant?

A

Shortage of water, low light, low temperature, shortage of CO2.

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11
Q

How does light affect photosynthesis?

A
  • when there is not enough light, there will be less photosynthesis
  • when light levels have increased, another factor will be the limiting factor
  • although PS is higher than before, it is not at peak level
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12
Q

How does CO2 affect photosynthesis?

A
  • at first, when CO2 levels are low, it will be the limiting factor
  • when CO2 levels increase, PS will increase, but then another factor will be the limiting factor
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13
Q

How does temperature affect photosynthesis?

A
  • at first photosynthesis increases, as there is more kinetic energy
  • if the temperature excedes 40 °C, the enzymes denaturate, so PS rates drop
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14
Q

How do water and minerals reach the xylem?

A
  • water from soil taken in via osmosis in root hair cells
  • minerals taken in via active transport in root hair cells, as there are minerals inside the cells, so energy is needed to bring them against the concentration gradient
  • water and minerals diffuse to xylem
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15
Q

How is the root hair cell adapted?

A
  • many mitochondria for energy, for active transport of minerals
  • long extension, to increase SA, so more osmosis and active transport
  • 1 cell thick cell membrane ∴ shorter diffusion distance
  • large vacuole for storage
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16
Q

How does water get from the roots to the leaves?

A

Through the xylem, which uses capillary action.

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17
Q

How do the water molecules get from the xylem to the air?

A
  • water molecules leave xylem vessels
  • diffuse through spongy cell layer
  • they then evaporate from the stomata into the air
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18
Q

What is transpiration?

A

Evaporation of water through the stomata

19
Q

What is a transpiration stream?

A

Uninterrupted stream of water taken up at the roots and transported in the xylem to the leaves where it evaporates

20
Q

Pros/cons of open and closed stomata

A 
Open:
➯ allows gas exchange and transpiration
➯ can lead to dehydration
Closed:
➯ reduces water loss
➯ reduces CO2 levels(less PS), and plant can overheat
21
Q

When do the stomata open?

A

When water moves into the guard cells by osmosis

22
Q

What causes the stomata to open?

A
  • lots of light
  • high temp
  • lots of water
23
Q

What causes the stomata to close?

A
  • little light
  • low temp
  • not much water
24
Q

How does light affect transpiration?

A

• increases it
• more PS
∴ stomata open for CO2

25
Q

How does temperature affect transpiration?

A
  • increases it

* evaporation increases

26
Q

How does humidity affect transpiration?

A

• decreases it
• lower concentration gradient
∴ less evaporation

27
Q

How does wind speed affect transpiration?

A
  • increases it
  • faster air movement removing water vapour
  • higher concentration gradient
28
Q

How do plants prevent water loss?

A
  • Stomata only on one side of leaf
  • wilting reduces SA for water loss
  • close stomata
  • waxy cuticle
29
Q

How does a potometer work?

A
  • shoot placed in open end of potometer tube
  • bung made airtight to prevent evaporation from potometer
  • as water moves through planta and evaporates from stomata , air bubble moves along scale
  • over time, this gives you the transpiration rate
  • you could test the plant with different factors to see how they affect transpiration
30
Q

What is glucose transported as, and where?

A

Transported as sucrose, through the phloem

31
Q

What is glucose stored as? Why?

A

Starch, as it is insoluble, so osmosis won’t take place, so it wont escape from the cells

32
Q

What is glucose used for?

A
  • respiration
  • lipids, stored in seeds, to make membranes
  • amino acids, to make proteins for growth
  • cellulose, to make cell walls
33
Q

What is a tropism?

A

A growth response in the plant towards a directional stimulus

34
Q

How do plants bend towards light?

A
  • they have auxin, a hormone required for growth
  • this is produced in the tip, and diffuses to shoot
  • destroyed by light, so it accumulates on shady side, cause cell elongation to take place
35
Q

What is phototropism?

A
  • shoots grow towards light source(positive phototropism)

* roots grow away from light source(negative phototropism)

36
Q

What is geotropism?

A
  • shoots grow away from gravity(negative geotropism)

* roots grow towards gravity(positive geotropism)

37
Q

What is hydrotropism?

A
  • none for shoots

* some roots grow towards direction of water

38
Q

What is thigmotropism?

A
  • some shoots grow towards and bend around support(positive thigmotropism)
  • roots grow away from object
39
Q

What are the benefits of geotropism?

A
  • shoot grows away front gravity towards light, for more light, for more PS, for more respiration
  • root grows towards gravity to find water and minerals needed in PS and growth, and for anchorage
40
Q

What are the benefits of phototropism?

A
  • shoots grow towards light, so they get more light for PS, ∴ more glucose, ∴ more PS
  • roots grow towards soil for water and mineral ions
41
Q

What are some benefits of greenhouses?

A

• increases crop yields
➯ can control temps. + temps mean more KE ∴ more PS ∴ more respiration
➯ control CO2 levels. More CO2 means more PS, as stomata open, so more gas exchange
➯ increase light, so increase PS
➯ fewer pests

42
Q

Why are fertilisers good?

A
  • increase crop yields, as provides more minerals

* e.g. Nitrogen, which makes plant proteins, so is needed for plant growth

43
Q

How do you test for the requirement of carbon dioxide?

A

Fill jar with air but put soda lime at top, which absorbs CO₂ from air ∴ no CO₂ for PS ∴ leaf stays brown

IGCSE edexcel Biology (10 decks)

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