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IGCSEs > Biology πŸƒ | Plant Nutrition | 6 > Flashcards

Biology πŸƒ | Plant Nutrition | 6 Flashcards

1
Q

What is the photosynthesis word equation?

A

Carbon dioxide + water -> glucose + oxygen, needs light energy.

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2
Q

In the night, plants _ because _

A

In the night, plants respire because there is little light energy.

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3
Q

How does temperature increase speed of speed germination and photosynthesis?

A

High temperature-more motion-more collisions-faster reactions-photosynthesis.

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4
Q

Define photosynthesis.

A

The process by which plants manufacture carbohydrates from raw materials using energy from light.

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5
Q

What carbohydrate is first produced in photosynthesis?

A

Glucose.

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6
Q

What can glucose be used to make in plants, and why is it useful?

A

Sucrose for transport in phoelem
Cellulose for building cell walls
Nectar to attract insects for pollination
Starch for energy store

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7
Q

What is the BALANCED chemical equation for photosynthesis?

A

6COβ‚‚+6Hβ‚‚O->C₆H₁₂O₆+6Oβ‚‚

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8
Q

What is chlorophyll?

A

The pigment in chloroplasts that allows photosynthesis to occur by absorbing sunlight

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9
Q

What colors do chlorophyll absorb and reflect.

A

Absorbs red and blue, reflects green.

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10
Q

What do plants use nitrate for?

A

To produce amino acids (proteins)

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11
Q

What do plants use magnesium for?

A

To create chlorophyll and cell walls

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12
Q

What are the factors influencing photosynthesis?

A
  • Temperature
  • Light intensity
  • Humidity
  • Carbon dioxide levels
  • Minerals in soil
  • Chlorophyll count
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13
Q

Why is a high temperature needed in photosynthesis?

A

It helps increase reaction rate

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14
Q

Why is light intensity needed for photosynthesis?

A

Chlorophyll traps light and transfers energy into chemical energy for photosynthesis.

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15
Q

What is a limiting factor?

A

Something present in the environment in such short supply that it restricts life processes.

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16
Q

How do you know there is a limiting factor?

A

A graph for photosynthesis rate with one factor plateaus

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17
Q

Why doesn’t the graph for temperature’s relationship with photosynthesis follow the same pattern as the others?

A

Enzymes denature at such a high temperature.

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18
Q

What is a sign of magnesium deficiency in plants?

A

Yellowing between veins.

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19
Q

What is a sign of nitrogen deficiency in plants?

A

Weak growth and yellow leaves

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20
Q

What is the lamina?

A

The broad, flat main part of the leaf

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21
Q

How is the lamina connected to the rest of the plant?

A

By the petiole: the leaf stalk.

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22
Q

What are vascular bundles?

A

A vein in a plant containing xylem vessels and phloem tubes for the carrying of substances to and from the leaf.

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23
Q

What is the epidermis?

A

It is a layer of closely fitting cells that covers the top and bottom of the leaf.

24
Q

What are the characteristics of the upper epidermis?

A
  • No chloroplasts
  • Cells of the upper epidermis excrete a waxy substance called the cuticle, helping to stop water evaporating and sometimes on the underside
25
Q

What is the function of the upper epidermis?

A

To protect the inner layers of the leaf’s cells

26
Q

What are the characteristics of the lower epidermis?

A
  • Has small openings called stomata

- Stomata is surrounded by a pair of sausage shaped guard cells which open and close at the hole

27
Q

What are the two layers of mesophyll?

A

Palisade mesophyll layer and Spongy mesophyll layer.

28
Q

What are xylem vessels?

A

Thick walled tissue, for carrying water.

29
Q

What are phloem tubes?

A

Smaller than xylem vessels, thin-walled, to carry away sucrose and other substances made.

30
Q

How are the ingredients for photosynthesis given from the atmosphere to chloroplasts?

A

Carbon dioxide diffuses through stomata from atmosphere, through air spaces into the chloroplast. Water is brought from the roots in xylem vessels, and to chloroplasts by osmosis. Sunlight can travel to the chloroplasts through the transparent upper epidermis.

31
Q

Why do leaves have a large surface area?

A

To expose a large area to the sunlight and air.

32
Q

Why are leaves thin?

A

To allow sunlight to penetrate to all cells and increases rate of diffusion for carbon dioxide in and oxygen out.

33
Q

Why are there air spaces in spongy mesophyll?

A

To allow diffusion of carbon dioxide and oxygen through and from cells.

34
Q

Why arent there chloroplast in epidermal cells?

A

The epidermal cells are for protection; It is transparent for the light to enter chloroplasts in palisade mesophyll.

35
Q

Why is glucose poor for the storage of energy?

A

As glucose is a simple sugar, it is soluble in water, and quite a reactive substance. With high reactivity. it can be involved in unwanted chemical reactions. As it is soluble, it would dissolve in water and around the plant cells, being lost from the cell, as well as increase the concentration of the solution in the cell disrupting osmosis.

36
Q

Why do plants use starch to store energy?

A

Starch is a polysaccharide, made of many glucose molecules joined together - which makes it not very reactive or soluble. Therefore, it can be made into granules that can easily be stored in chloroplasts.

37
Q

Why can’t plants use the nitrogen in the air for amino acids?

A

It is very unreactive, so the plants need to be supplied nitrogen in a more reactive form: nitrate ions.

38
Q

How do plants get nitrate ions?

A

They absorb the ions from the soil, through their root hairs by diffusion and active transport.

39
Q

What solution do we use to test leaves for starch?

A

Iodine solution.

40
Q

What is inaccurate about testing for starch in a leaf without other steps?

A

The starch is in the chloroplasts in the cell so the iodine cannot get through the cell membranes to reach the starch and react with it. In addition, the brown negative result of the iodine test combined with the green colour of the leaf can look black and be a false positive result.

41
Q

How do we break down cell membranes in a leaf when testing for starch?

A

We boil the leaf in water over a bunsen burner.

42
Q

How do we remove chlorophyll in a leaf when testing for starch?

A

Dissolve it out with water.

43
Q

What is the method of testing a leaf for starch?

A
  1. Take a leaf from a healthy plant and drop it into boiling water in a water bath. Leave it for about 30s. Turn out the Bunsen flame. (Breaking down cell walls)
  2. Remove the leaf, which will be very soft and drop it into a tube of alcohol in the water bath, leaving it until all the chlorophyll has come out of the leaf
  3. The leaf, now brittle, should be removed from the alcohol and dipped into hot water to be softened.
  4. Spread the leaf out on a white tile and cover it with iodine solution. A blue-black colour shows that the leaf contains starch.
44
Q

When testing whether a factor is needed for photosynthesis, what is a β€œcontrol”

A

The control is the part of the leaf that has all the substances it needs to be compared to the experimental plant - which is lacking only one substance.

45
Q

Why is a control in an experiment important?

A

Both the control and the experiment can be tested the exact same way. By comparing them, you will be able to find out necessary factors.

46
Q

Why do we destarch a plant before testing?

A

The leaves should not have starch in them at the beginning of the investigation because if they did, and still had starch at the end of the investigation you couldnt be able to tell if they were photosynthesizing.

47
Q

What is the easiest way to destarch a plant?

A

Leave it in a dark cupboard for 24 hours so it cannot photosynthesize and uses up all its starch stores.

48
Q

How can we test if light is needed for photosynthesis?

A
  1. Take a healthy bean or pelargonium plant growing in a plant, leaving it in a cupboard to destarch it.
  2. Test a leaf for starch to make sure it does not contain any.
  3. Use a folded piece of black paper of aluminum foil, a little larger than a leaf, cutting a shape out. Fasten the paper or foil over both sides of the leaf on the plant, making sure the edges are held firmly together. don’t take the leaf off the plant.
  4. Leave the plant near a warm, sunny window for a few days
  5. Remove the cover from the leaf and test it for starch. Compare the covered part and the control.
49
Q

How do you test if chlorophyll is needed for photosynthesis?

A
  1. Destarch a plant with variegated (green and white) leaves, then leave the plant in a warm sunny spot for a few days.
  2. Test a leaf for starch.
50
Q

How do you test if oxygen is produced in photosynthesis?

A
  1. Set up an upside down test tube on top a inverted funnel with a water plant inside. Put these in a beaker full of water.
  2. Leave the apparatus near a warm, sunny window for a few days.
  3. Remove test tube from the top of the funnel, allowing the water to run out but not the gas to escape.
  4. Light a wooden splint and then blow it out so that it is glowing. Carefully put it into the gas in the test tube. If it bursts into flame, the gas is oxygen.
51
Q

What is sucrose used for in a plant?

A

For transport around the plant by phloem tubes, for root growth, fruit growth, or leaf growth.

52
Q

How can sucrose be released as energy?

A

Sucrose is unreactive so it is converted to glucose when it has to be used for respiration at certain parts of the plant.

53
Q

What is cellulose used for in a plant?

A

Building cell walls.

54
Q

What is nectar used for in a plant?

A

To attract insects for pollination.

55
Q

How do we test that carbon dioxide is used for photosynthesis?

A
  1. Pour equal volume of hydrogencarbonate indicator into two test tubes.
  2. Place plant leaf above one of them.
  3. Observe colour change

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