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Biology gcse > ⭐️SB6- plant structures and their functions > Flashcards

⭐️SB6- plant structures and their functions Flashcards

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1
Q

What is the store of energy for plants?

A

Glucose and substances made from glucose

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2
Q

What is a biomass?

A

The materials in an organism

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3
Q

What are plants and algae in the food chain and why?

A

They are producers as they produce their own biomass and so produce the food for almost all life of earth

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4
Q

What is photosynthesis and what is the word equation?

A

A series of chemical reactions catalysed by enzymes

Carbon dioxide + water -> glucose + oxygen

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5
Q

Where does photosynthesis occur?

A

In chloroplasts which contain chlorophyll which traps energy transferred by lights

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6
Q

What kind of reaction is photosynthesis ?

A

Endothermic because energy enters from the surroundings and the products of photosynthesis have more energy than the reactants

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7
Q

What are the steps in photosynthesis?

A
  1. Chlorophyll traps energy transferred by light
  2. Glucose molecules are made and link together to make the polymer starch
  3. Starch stays in chloroplasts until broken down into simpler substances
  4. These are transported unto the cytoplasm and used to make sucrose
  5. the sucrose can be transported around the plant to make substances
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8
Q

What is sucrose used to make in a plant?

A
  • starch (in a storage organ like a potato)
  • other molecules for the plant like cellulose, lipids or proteins
  • glucose for respiration to release energy
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9
Q

How are leaves adapted to their function?

A
  • broad and flat giving them a large surface area
  • palisade cells are at the top of the leaf and are full of chloroplasts to allow the lead to absorb lots of light
  • they are thin so CO2 doesn’t have far to diffuse before reaching cells
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10
Q

Why is there air spaces in a cross section of a leaf?

A

They provide a large surface area for cells to exchange gases with the air

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11
Q

What are stomata?

A

Microscopic pores that allow carbon dioxide to diffuse into the leaf and oxygen and water vapour to escape into the air

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12
Q

What do guard cells do?

A

Open and close the stomata

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13
Q

How do the guard cells work?

A

In the light, water flows into pairs of guard cells making them rigid and opening the stomata and at night, water flows out of the guard cells, they loose rigidity and the stomata shuts

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14
Q

Describe the structures of a guard cell

A
  • Chloroplasts
  • cell membrane
  • vacuole
  • thin cell wall on the outside
  • thick cell wall on the inside by the stomata
  • mitochondrion
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15
Q

Give an example a way of gas exchange in a leaf

A

The stomata

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16
Q

What is a limiting factor?

A

A factor that prevents a rate increasing

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17
Q

Give three limiting factors of photosynthesis

A
  • CO2 concentration
  • temperature
  • light intensity
  • amount of chlorophyll
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18
Q

What controls the maximum rate of photosynthesis?

A

The limiting factor in shortest supply

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19
Q

Where can you properly learn limiting factors?

A

Go on YouTube or use mygcsescience

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20
Q

On a graph,
What does it mean if the line is straight?
What does it mean if the line goes through the origin?

A
  • There is a linear relationship between the two variables

- the two variables are in direct proportion

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21
Q

Inverse square law?

A

Watch a video / look through notes, Pearson active learn pg 127

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22
Q

Name what water absorbed by plant roots is used for

A
  • carrying dissolved mineral ions
  • keeping cells rigid
  • cooling the leaves when water evaporates
  • photosynthesis
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23
Q

What cells are roots covered with?

How are they adapted to their function?

A

Root hair cells
Adapted as:
-the ‘hairs’ are extensions of the cell that provide a large surface area so water and mineral ions can be quickly absorbed
-the ‘hairs’ also have thin cell walls so the flow of water into cells is not slowed down

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24
Q

What is diffusion?

A

Where particles in a fluid move from an area of high concentration to low conc

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25
Q

What is osmosis?

A

When solvent molecules diffuse through a semi permeable membrane from high to low concentrations

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26
Q

What is active transport?

A

Diffusion of particles agains the concentration gradient from low to high concentration and needs energy

27
Q

To learn more about limiting factors

A

Watch a video or look in old exercise book

28
Q

What is transpiration?

A

The flow of water into the root, up the stem and out of the leaves; it’s water in the xylem

29
Q

What’s glucose for in a plant?

A

The create anything in a plant that’s made of carbon

30
Q

Explain what’s happing inside xylem vessels

A

There is an unbroken chain of water when it’s flowing through due to weak forces of attraction between water molecules

31
Q

What do the xylem vessels do?

A

Transports water and solutes from the roots to the leaves

32
Q

How does water get transported out of the leaf via the xylem vessels

A

It gets pulled up the xylem vessels as water evaporates from the xylem in the leaves, as the water vapour diffuses out of the leaf, more water evaporates from the xylem inside the leaf

33
Q

How is water able to diffuse out of the leaf?

A

Because the concentration difference of water vapour in the air spaces of the leaf is greater than outside it is water molecules are able to diffuse down the concentration gradient and out of the leaf

34
Q

What process does the xylem help carry out

A

Transpiration

35
Q

What does the phloem do?

A

Transports food from the leaves to the rest of the plant

36
Q

What factors increase transpiration and why do they do this?

A

-Wind - moves water away from the stomata

Low humidity - little water vapour in the air

They increase transpiration as concentration of water molecules outside is reduced so there’s a bigger difference between concentrations increasing the gradient making it steeped

37
Q

What other factors increase transpiration that don’t have anything to do with the concentration gradient?

A
  • Higher temps as particles move faster so diffuse faster

- greater light intensity as this makes the stomata wider

38
Q

What are the adaptations of a xylem cell?

A
  • Water can only move one way
  • there are no cell walls between cells making a lint tube
  • they have tiny pores allowing water and mineral ions to enter and exit the xylem vessels
  • the dead cells in the middle have no cytoplasm so it forms a hollow tube for water
  • have thick cell walls made of living to stand water pressure and can help support the plant
39
Q

What is translocation?

A

The movement of sucrose through the phloem of a plant

40
Q

What cells make up the phloem

A

The sieve tubes and companion cells

41
Q

What do sieve cells do

A

They form a large channel in the phloem tissue where each cell is connected to its neighbour by holes through which sucrose flows through

42
Q

What do companion cells do? How are they adapted?

A

They actively pump sucrose into or out of sieve cells that form the sieve tubes. They have a lot of mitochondria to produce the energy for active transport

43
Q

Where does the phloem take the sucrose?

A

An increase of pressure causes it to flow up to growing shoots or roots or down into storage organs

44
Q

What are the adaptations of the phloem?

A
  • It’s got holes in the ends of the cell walls to allow liquid to flow from one sieve cell to the next
  • there is only a small amount of cytoplasm and there’s no nucleus so more room for the central channel
  • the sucrose can flow two ways depending on where it needs to be transported
45
Q

Give the adaptations of leaves

A
  • have a large surface area to collect enough light
  • leaves are thin so CO2 doesn’t have far to diffuse before reaching photosynthesising cells
  • sponges cells in the leaf are irregular shapes so create air spaces for gas to easily diffuse in and out of the leaf
  • leaves have a waterproof waxy cuticle to help prevent water loss and to stop excess water and microorganisms getting in the leaf
  • chloroplasts can move towards light or away
46
Q

How do leaves trap energy?

A
  1. The energy transferred by light is trapped by chlorophyll packed into disks inside chloroplasts
  2. The energy is then transferred to glucose during photosynthesis
47
Q

What do the epidermis cells do?

A

They form the outer layer of a leaf holding the leaf together and protecting the cells inside

48
Q

what is a tropism? What does it mean if it’s positive or negative?

A

Responding to a stimulus by growing towards or away from it. Positive means it’s growing towards it and negative is growing away from it

49
Q

What is phototropism?

A

A tropism by light

50
Q

How are selective weed killers effective?

A

They contain artificial auxins to make plants grow uncontrollably so they die. This only effects plants with broad leaves so weeds and not those with narrow leaves like wheat and grass

51
Q

How are rooting powders effective?

A

The auxins cause plant cuttings to develop roots quickly so large numbers of identical plants can be produced quickly using cuttings instead of growing plants from seed

52
Q

What are gibberillins

A

They are plant hormones that are naturally released in a seed to start germination

53
Q

How can gibberellins be used?

A
  • to grow plants that usually need a period of cold and darkness before they germinate
  • to produce seedless fruits that would usually produce a seed
  • by spraying them on plants it can produce bigger fruits
54
Q

What is photoperiodism? What is it used for? How do farmers deal with it?

A

The response of an organism to the number of daylight hours in a day.
-Some plants use it to flower at a certain time like when it’s not too cold and so farmers can override it by using gibberellins

55
Q

How do fruit producers keep fruit unripened and for what reason?

A

By spraying the fruit with ethene ( a plant hormone gas) so that the fruit reaches the shop at just ripened condition. This is because fruits that aren’t ripe are easier to transport than ripe ones and ripe ones can be kept longer in storage without going off

56
Q

What is the mesophyll in leaves

A

The collection of cells with space between for gas exchange

57
Q

How are plants that live in cold and windy environments adapted?

A
  • they are deciduous to prevent soil and water loss when frozen
  • leaves are needle shaped so they collect less snow and so there’s less wind resistance
58
Q

How are plants that live in dry and hot environments adapted?

A
  • trap water vapour close to leaves to slow down rate of diffusion and reduce water loss
  • covered in tiny hairs to trap water vapour
  • stems store water
  • transpiration increases
  • guard cells become flaccid
59
Q

What kind of tropisms are plant roots?

A
  • negatively phototropic
  • positively geotropic
  • positively hydrotropic
60
Q

What’s positive phototropism caused by?

A

Auxins (type plant hormones)

61
Q

How do auxins control the growth of plant shoots towards the light?

A
  1. They are produced at the very tip of the shoot and move down it
  2. As auxins move down they move to the shaded part of the shoot when light is coming down on only one direction
  3. The auxins then cause cell elongation on the shaded side causing the plant to grow towards the light
62
Q

How do auxins effect plant roots?

A

They have the opposite effect to plant shoots:
Auxins are pulled downwards in the roots to prevent cell elongation to anchor the plant in place and reach moisture underground

63
Q

What equipment measures the rate of transpiration and how does it work?

A

A potometer

Works as air bubbles move along a tube as the plant loses water and the speed of bubbles gives the rate of transpiration

Biology gcse (32 decks)

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