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GCSE Biology > Chapter 6 - Plants - Random Questions > Flashcards

Chapter 6 - Plants - Random Questions Flashcards

1
Q

What is a limiting factor?

A

A factor which inhibits growth/ anything in short supply that prevents photosynthesis occurring at its maximum rate

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2
Q

What is the role of the green pigment ‘chlorophyll‘?

A

To transfer energy from the environment and use it to synthesise glucose from carbon dioxide and water

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3
Q

List ways in which glucose (produced by photosynthesis) is used in plants

A
  • used for respiration
  • used to produce cellulose to strengthen cell walls
  • converted into insoluble starch for storage
  • used to produce fats or oils for storage
  • used to produce amino acids for protein synthesis
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4
Q

What are palisade cells?

A

Regular-shaped cells that have lots of chloroplasts. Most photosynthesis talks place in this layer

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5
Q

What do guard cells do?

A

They control the stomata - close when there is no water available

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6
Q

Where does water evaporate from and through what process?

A

From the leaves through the stomata - transpiration

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7
Q

Where does a plant get the reactants it needs for photosynthesis from?

A

Carbon dioxide - through stomata
Water - through roots
Light - from sun

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8
Q

How do plants conserve water?

A
  • have wide shallow roots to collect as much water as possible
  • have smaller leaf surface area so less water is lost through transpiration
  • thick cuticles prevent water loss between cells
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9
Q

What do root hairs do?

A

Enlarge the surface area of the root meaning that more water (and minerals) can be absorbed into the plant by osmosis. The cellulose in the cell wall helps absorb the water

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10
Q

How does water get from the soil to the roots?

A

Osmosis

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11
Q

Where does water go when it is in the roots?

A

Travels up the plant, through the xylem, to all the cells that require water

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12
Q

What is lignin?

A

The special chemical that water-proofs xylem vessels. It stops water leaving the vessels by osmosis (impermeable) as it passes up the plant (so that not all the water gets used up straight away by cells at the bottom and therefore let some get to the top)

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13
Q

How are sugar and other nutrients from the leaves transported, and what is this process called?

A

Through the phloem - transported from leaves (where they are produced in the form of sap) to places in the plant where they are needed - translocation

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14
Q

List properties of a xylem vessel:

A
  • only up
  • transports water and minerals
  • no end walls between cells
  • thick walls stiffened with lignin
  • dead tissue - empty tube
    TRANSPIRATION
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15
Q

List some properties of a phloem vessel:

A
  • transports water and food (sap)
  • cells have end walls with perforations - sieve tube elements (porous cell walls, nutrients can flow between)
  • companion cells
  • two way flow
  • living tissue/ cells
    TRANSLOCATION
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16
Q

What is the transpiration rate?

A

The rate at which water escapes out of a plant

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17
Q

Name some factors that effect the transpiration rate and explain how:

A

~ temperature - the warmer it is, the more kinetic energy in the water particles and the faster the water evaporates
~ humidity - if high humidity, rate is low as the air is already full of water
~ wind speed - the windier it is, the faster moist air is taken away from the leaf surface (dryer air) so the concentration gradient is bigger and the transpiration rate increases
~ light intensity - transpiration is faster when the stomata are open in the light
~ surface area of leaf - large surface area, more stomata, more water loss (higher rate of transpiration)

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18
Q

Why do all plant tissues require water to survive?

A

For support and photosynthesis

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19
Q

What is osmosis?

A

The movement of water from an area of high concentration to an area of low concentration through a partially permeable membrane

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20
Q

What are stomata?

A

Holes on the underside of the leaf, through which gases move in and out

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21
Q

What are plasmodesmata?

A

Small holes that make up the sieve

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22
Q

What are sieve tube elements?

A

Porous cell walls in phloem vessels that nutrients can flow between - freely permeable membranes (anything can pass through)

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23
Q

What is translocation?

A

The movement of assimilates (sugars and other chemicals), made by plant cells , along the phloem

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24
Q

How does the time of year effect the movement in the phloem (translocation)?

A
  • in summer - movement down to roots

- in spring - movement up to shoots and leaves

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25
Q

What is the main assimilate?

A

Sucrose - plants makes glucose in photosynthesis, but turns it into sucrose

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26
Q

Where do sugars move to and from?

A

They move from a source to a sink

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27
Q

What is the source?

A

Anywhere sucrose is released into the phloem (where it is made)

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28
Q

What is the sink?

A

Anywhere sucrose is removed from the phloem (where it is used)

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29
Q

How are companion cells adapted to their function?

A

They have lots of mitochondria

30
Q

What is ATP?

A

A very unstable molecule released by mitochondria (energy)

31
Q

Describe how sugar gets into the phloem

A
  1. Companion cells use ATP to actively transport hydrogen ions into the surrounding tissue
  2. This creates a diffusion gradient with a high concentration of hydrogen ions outside the companion cells
  3. Hydrogen ions move back into companion cells using co-transporter proteins
  4. This causes concentration of sucrose in the companion cells to increase
  5. Sucrose moves from companion cells to the sieve tube elements using plasmodesmata
32
Q

Why are co-transporter proteins needed, and what is this called??

A

The molecules are too big to move by theirselves - facilitated diffusion

33
Q

What can be used to measure transpiration?

A

Potometer

34
Q

How can the rate of transpiration be observed when using a Potometer?

A

The rate is the speed (d/t) that the bubble moves across the tube

35
Q

What is active transport and give an example?

A

Low concentration to high concentration

Eg. Minerals from soil into plant

36
Q

What is a disadvantage to a plant closing its stomata?

A

Gas exchange cannot happen meaning that carbon dioxide can’t get it. This results in photosynthesis not being able to take place, meaning no oxygen or glucose is created. These are needed for respirating to take place, so the plant will suffocate

37
Q

What are hormones?

A

Chemical messengers

38
Q

Where do hormones travel?

A

Through the phloem (sap)

39
Q

Where are hormones produced?

A

In the meristem (tip of plant)

40
Q

What is controlled by hormones?

A

~ growth - roots and shoots, seed germination, leaf fall, disease resistance, fruit formation and ripening, flowering time, bud formation
~ sensitivity - responding to the environment - can make adjustments to survive

41
Q

What is a tropism?

A

A growth response because of a stimulus

42
Q

What is phototropism?

A

A growth response to light

43
Q

What is geotropism/ gravitropism?

A

Growth response to ground

44
Q

What is special about the hormone ‘auxin‘?

A

The sunlight breaks them down, so the shoot tip (which has direct sunlight) will have the least amount of auxins

45
Q

Describe the relationship between the concentration of auxins and growth in the shoots

A

Any concentration promotes growth (auxins promote elongation of cells)

46
Q

Describe the relationship between the concentration of auxins and growth in the roots

A

High concentration inhibits growth (auxins prevent elongation of cells), small concentration promotes growth

47
Q

What are gibberellins?

A

Hormones that are important in starting off the seed germination (sprouting) process

48
Q

What is ethene?

A

A hormone that is a gas and controls cell division, leaf fall and the ripening of fruits

49
Q

What do auxins cause when they gather on the shaded side?

A

Increased cell elongation on the shaded side (grows longer)

50
Q

What are 5 limiting factors of photosynthesis?

A
  • light intensity
  • water
  • carbon dioxide
  • temperature
  • chlorophyll
51
Q

What is the optimum temperature for plant growth?

A

21˚C

52
Q

What is light intensity measured in?

A

Lux

53
Q

What is the inverse square rule?

A

Light intensity = 1/distance^2

54
Q

What do the graphs look like for the different factors?

A

Light intensity —> curved (inverse square rule)
Water, carbon dioxide + chlorophyll —> go up, then flatten when another factor becomes limiting
Temperature —> up and then down when enzymes denture

55
Q

What do chlorophyll and light act as?

A

Catalysts

56
Q

What do plants need minerals for?

A

To build complex molecules they need to survive and grow

57
Q

What can be done to establish which mineral a plant is deficient in?

A

Tests or a general purpose NPK (nitrogen, phosphorus, potassium) fertiliser added

58
Q

What are nitrate ions used for?

A

Building proteins and growth

59
Q

What are phosphate ions used for?

A

Respiration and growth

60
Q

What are potassium ions used for?

A

Respiration and photosynthesis

61
Q

What are magnesium ions used for?

A

Photosynthesis

62
Q

What are nitrate deficiency symptoms?

A

Poor growth and yellow leaves

63
Q

What are phosphate deficiency symptoms?

A

Poor root growth and discoloured leaves

64
Q

What are potassium deficiency symptoms?

A

Poor flower and fruit growth, discoloured leaves

65
Q

What are magnesium deficiency symptoms?

A

Yellow leaves

66
Q

Why is nitrate needed in plants?

A

All amino acids contain nitrogen. Amino acids are the building blocks of protein

67
Q

Why is phosphate needed in plants?

A

A component of DNA molecules and cell membranes

68
Q

Why must potassium be present in plants?

A

For photosynthesis and respiration enzymes to work

69
Q

Why is magnesium needed in plants?

A

Chlorophyll molecules contain magnesium ions. It’s the magnesium that makes chlorophyll green

70
Q

What are xerophytes?

A

Plants with adaptations to live in the dry (eg. Succulents, cactus)
- have thick leaves, grow slowly etc.

71
Q

What is transpiration?

A

The movement of water through and out of a plant (through xylem)

GCSE Biology (52 decks)

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