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All Topics GCSE Biology Triple > Topic 6 - Plant Structures And Functions > Flashcards

Topic 6 - Plant Structures And Functions Flashcards

1
Q

Where does photosynthesis take place ?

A

Photosynthesis takes place inside chloroplasts found in plants and algae

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2
Q

What type of reaction is photosynthesis?

A

The reaction is endothermic (needs energy)

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3
Q

What is the source of energy in photosynthesis ?

A

The source of this energy is sunlight

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4
Q

In photosynthesis How is sunlight trapped ?

A

sunlight is trapped by a chemical called chlorophyll inside chloroplasts

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5
Q

What is sunlight from photosynthesis used to make ?

A

It’s used to make carbohydrates

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6
Q

What are plants and algae know as and what stage of the food chain are they ?

A

Plants and algae are known as producers and form the first level of all food chains.

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7
Q

What is the word and symbol equation for photosynthesis ?

A

carbon dioxide + water → glucose + oxygen

6 CO2 + 6 H2O → C6H12O6 + 6 O2

(Over the arrow you can put light)

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8
Q

How does temperature effect the rate of photosynthesis?

A

Increasing the temperature increases the rate of photosynthesis because more energy is provided.

However, if the temperature is increased to above about 45°C (optimal temperature) , the enzymes that catalyse (speed-up) the reaction begin to denature (not work anymore).

This causes the rate of the reaction to drop sharply until it stops altogether.

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9
Q

How does light intensity effect the rate of photosynthesis ?

A

Increasing light intensity increases the rate of photosynthesis because more energy is provided.

However, if the light intensity is increased above a certain threshold, the rate of photosynthesis will not increase because another factor (such as temperature) is limiting the rate of the reaction.

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10
Q

How do carbon dioxide concentrations effect the rate of photosynthesis ?

A

Increasing the carbon dioxide concentration increases the rate of photosynthesis.

However, above a certain threshold, further increases in the carbon dioxide concentration do not increase the rate of photosynthesis because another factor (such as light intensity) is limiting the rate of reaction.

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11
Q

How does chlorophyll concentration effect the rate of photosynthesis ?

A

High chlorophyll concentration gives a high rate of photosynthesis

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12
Q

What are the limiting factors of photosynthesis ?

A 
A limiting factor restricts the rate of a reaction. The identity of the limiting factor in photosynthesis depends on the conditions faced by the plant.
(Winter)
(Night)
(Warm and bright)
(Mineral deficient soli)
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13
Q

How is the winter a limiting factor for photosynthesis?

A

In winter, temperature is usually the limiting factor.

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14
Q

How is the night a limiting factor of photosynthesis ?

A

At night, light intensity is usually the limiting factor.

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15
Q

How is mineral-deficient soil a limiting factor of photosynthesis?

A

If plants are grown in mineral-deficient (lacking minerals) soil, they may not absorb enough minerals to produce lots of chlorophyll.
In this case, chlorophyll concentration can be the limiting factor

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16
Q

In warm and bright conditions what is the limiting factor of photosynthesis?

A

In warm and bright conditions, carbon dioxide concentration is usually the limiting factor.

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17
Q

How do you test for the rate of photosynthesis?

A

You can easily investigate the effect of light intensity on the rate of photosynthesis by using an aquatic (lives in water) plant like pondweed.

To do this, change the distance between the lamp and the pondweed and count the number of bubbles produced.

In this experiment, light intensity is the independent variable and the number of bubbles is the dependent variable.

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18
Q

What is the inverse square law ?

A

Light intensity = 1/distance ^2

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19
Q

What is the difference between accuracy, reliability, and validity?

A

Accuracy: Accuracy is how close a measured value is to its true value. For example, let’s say we have a 1 kg (1,000 g) bag of sugar. We then take this bag and place it on some scales. The scales say the bag of sugar weighs 1 kg, so we would say the scales are accurate.
If the scales said the bag of sugar weighed 750 g, the scales would be inaccurate.

Reliability: Reliability refers to the ability of an experiment to produce consistent results. For example, let’s say we weigh the same 1 kg bag of sugar on a different set of scales. On the first weigh, the scales say the sugar weighs 750.5 g. On the second weigh, the scales say the bag of sugar weighs 750.5 g.
These scales are reliable as they produce the same result each time.
However, they are not accurate as the bag of sugar actually weighs 1 kg (the scales are reliable but inaccurate).

Validity: Validity is how appropriate an experimental method is at achieving the aim of an experiment. For example, a valid method for measuring the weight of a bag of sugar is using a set of scales.
Using a thermometer to measure the weight of the bag of sugar would not be a valid experimental method (…surprisingly).

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20
Q

How are root hair cells specialised?

A

Root hair cells are specialised (to perform a specific function). Their structure allows the plant to absorb more water. They also allow a plant to take in the minerals it needs to survive

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21
Q

How is the root hair cell adapted to its function?

A

No chloroplasts - These cells are located underground. This means that they do not contain chloroplasts (there is no light for photosynthesis).

Long projections - Root hair cells have long projections that increase the surface area that the plant can use to absorb water and minerals.

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22
Q

How is the xylem cell specialised ?

A

The xylem is specialised to transport water up the stem of a plant and into the leaves.

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23
Q

How have xylem cells adapted to their function ?

A

Open ended cells - Xylem vessels are made up of a series of connected dead xylem cells.
The end walls of the dead cells are broken to allow water to move through.

Lignin - Lignin (a substance) strengthens the cell walls of xylem cells.

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24
Q

Why are xylem cells’ end walls broken ?

A

The end walls of the dead xylem cells are broken to allow water and dissolved minerals to move through.

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25
Q

What are stomata and what is their function ?

A

Stomata are gaps in the lower epidermis of leaves that facilitate (make easier) the diffusion of gases, including evaporated water, in and out of the leaf

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26
Q

What are guard cells and what are their functions ?

A

Cells that can open and close the stomata

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27
Q

What happens in the opening of stomata ?

A

The guard cells can open the stomata by taking up lots of water, causing them to swell.

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28
Q

What happens in the closing of the stomata ?

A

To close the stomata, the guard cells lose water and return to a limp state.

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29
Q

What does the state of stomata achieve ?

A

The state of stomata (open or closed) achieves a balance between allowing gases for photosynthesis into the leaves and conserving water in the plant.

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30
Q

When there is an abundance of water what is the state of stomata and why ?

A

OPEN:
When water is abundant (lots available) the plant can afford to lose water.
So it opens the stomata to allow gases for photosynthesis to move freely in and out of the leaf.

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31
Q

When there is scares water what is the state of stomata and why ?

A

CLOSED:
When water is scarce (rare), stomata close in order to prevent further water loss.
This is achieved by guard cells returning to a limp state after they lose water.

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32
Q

What is the state of stomata at night and why ?

A

CLOSED:
At night, stomata close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to prevent water loss.

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33
Q

Why do stomata close at night ?

A

Time of day affects the state of stomata.
At night, they close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to prevent water loss.

34
Q

What is transpiration ?

A

Transpiration transports water and the minerals dissolved in it through the plant. Water moves in one direction only: from the roots to the leaves

35
Q

In transpiration what is the purpose for root hair cells ?

A

Root hair cells absorb water from the soil via osmosis (movement of water from a dilute solution to a concentrated solution).

Mineral ions are taken up by active transport (movement of ions and molecules across a cell membrane to an area of higher concentration).

36
Q

In transpiration what is the purpose of root hair cells ?

A

After being absorbed by the root hair cells, the water and minerals are transported in xylem vessels up the stem and into the leaves.

To transport water and minerals into the leaves

37
Q

In transpiration what happens to leaves ?

A

Once it reaches the leaves, the majority of water evaporates and the water vapour diffuses out (is lost) through open stomata.

This loss of water from the leaves is known as transpiration and helps to pull water up from the roots.

38
Q

What does transpiration transport ?

A

Water and minerals

39
Q

What factors affect the rate of transpiration?

A

Humidity
Airflow
Light intensity
Temperature

40
Q

How does light intensity affect the rate of transpiration ?

A

Increased light intensity makes water evaporate faster, which increases the rate of transpiration.

41
Q

How does temperature affect the rate of transpiration?

A

Increased temperature makes water evaporate faster, which increases the rate of transpiration.

42
Q

How does humidity affect the rate of transpiration?

A

Increased humidity increases the amount of water in the air. This makes it more difficult for more water to evaporate.

Increasing humidity decreases the rate of transpiration.

43
Q

How does air flow affect the rate of transpiration ?

A

Increased air flow carries water away from the plant’s leaves, encouraging more water to evaporate.
Increased air flow increases the rate of transpiration.

44
Q

How do you measure the rate of transpiration ?

Practical

A

a potometer

As water is lost through the plant’s leaves, the air bubble moves.

The speed of the bubble’s movement shows the rate of water uptake.

This is only an estimation (guess) as a small amount of the water taken up by the shoot is used in the leaves.

45
Q

When measuring the rate of transpiration with a potometer, why is the calculation only an estimate?

A

A small amount of the water taken up by the shoot is used in the leaves and is not transpired.

46
Q

What apparatus is used to calculate the rate of transpiration?

A

Potometer

47
Q

What are phloem specialised for ?

A

The phloem is specialised to transport food products to parts of the plant where they are needed.

48
Q

What are phloem vessels made up of ?

A

Phloem vessels are made up of columns of living cells

49
Q

Why do phloem cells contain small holes ?

A

The end walls of phloem cells contain small holes to allow food products to move up and down the phloem vessels throughout the plant.

50
Q

What are the two types of cell that transport food and water ?

A

Xylem cells

Phloem cells

51
Q

What is translocation?

A

Translocation is the process by which food produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs

52
Q

What are the features of translocation ?

A

Phloem tubes

Bidirectional

53
Q

What does it mean by bidirectional ?

A

Unlike water transport (transpiration), translocation is bidirectional (movement is both up and down the plant).

54
Q

What are phloem cells ?

A

Translocation happens through phloem tubes.

Phloem tubes are made up of columns of elongated cells that have holes in the end walls.

These holes allow cell sap (a liquid in plants that stores sugars, salts and amino acids) to pass between the cells

55
Q

How do transpiration and translocation differ?

A

Unlike water transport (transpiration), translocation is bidirectional (movement is both up and down the plant).

56
Q

What are the main components in plant leaves ?

A

Epidermal tissues
Palisade mesophyll
Stomata
Spongy mesophyll

57
Q

In a leaf what does the epidermal tissue ?

A

Epidermal tissue covers the outer surface of leaves (as well as the rest of the plant).

58
Q

In a leaf what does the palisade mesophyll do ?

A

Palisade mesophyll is a row of cells located below the upper epidermis.

The cells are exposed to a lot of sunlight.

The cells have lots of chloroplasts (where photosynthesis takes place) to maximise the energy created by photosynthesis.

59
Q

In leaves what do stomata do ?

A

Found in the lower epidermis, these gaps facilitate (make easier) the diffusion of gases in and out of the leaf, if they are open.
When necessary, specialised (perform a specific function) guard cells are capable of closing these gaps.
e.g. in hot weather to reduce water loss.

60
Q

In leaves what do spongy mesophyll do ?

A

Spongy mesophyll contains many air spaces, which help with gas exchange throughout the leaf.

61
Q

What is the purpose for plants having hormones ?

A

Plants produce hormones that let them respond to changes in the external environment

62
Q

What are the three key plant hormones?

A

Ethene
Gibberellins
Auxins

63
Q

What is the purpose of the plant hormone ethene ?

A

Ethene is a gas that controls cell division, leaf fall and the ripening of fruits.

64
Q

What is the purpose of the plant hormone gibberellins ?

A

Gibberellins are important in starting off the seed germination (sprouting) process.

65
Q

What is the purpose of the plant hormone auxins ?

A

Auxins change growth patterns to allow roots and shoots to move either towards or away from a stimulus (change in conditions).

66
Q

What is the Responses to stimuli that involve directional growth called ?

A

tropisms

67
Q

What are tropisms controlled by ?

A

Auxins

68
Q

What are the responses that tropisms can be split into ?

A

Gravitotropisms (or geotropisms)

Phototropisms

69
Q

What is gravitotropisms ?

A

Growth either towards (positively gravitropic) or away from (negatively geotropic) the direction of gravity.

70
Q

What are phototropisms ?

A

These involve growth either towards (positively phototropic) or away from (negatively phototropic) a light source.

71
Q

What is the Distribution of Auxin and Phototropism ?

A

One side of the shoot is exposed to more light.
Auxin is redistributed within the shoot so that the concentration is greater on the shaded side.
This unequal auxin distribution will result in increased cell elongation (grows longer) on the shaded side.
In shoots, auxins promote the elongation of cells.
However, in roots, auxins prevent the elongation of cells.

72
Q

What happens to a plant shoot when auxin concentration is greater on its right side?

A

Increased elongation on the right side

73
Q

In shoots and roots what do auxins promote and prevent ?

A

In shoots, auxins promote elongation of cells, whereas in roots, auxins prevent elongation of cells.

74
Q

What do people use plant hormones to control ?

A

People use plant hormones to control the growth of plants for agricultural (farming) and horticultural (gardening) purposes

75
Q

How are the plant hormones auxins used in gardening ?

A

Auxins are used as weed killers as they can start rapid enough growth for the weeds to use up all of their resources and die.

As weed killers, they selectively kill weeds (and not grasses like wheat).

They are also used as rooting powders (growth supplement) and to promote root growth in tissue culture.

76
Q

How is the plant hormone gibberellins used in gardening ?

A

Gibberellins are used to promote flowering, increase fruit size, and start seed germination.

They can also be used to trigger the production of seedless fruit (such as grapes and bananas). The fruit is produced without fertilisation of the plant’s ovules (gametes).

77
Q

How is the plant hormone ethene used in gardening?

A

Ethene is used in the food industry to speed up the ripening of fruit (such as bananas) during transport.
Other hormones can delay ripening, which can be useful when storing fruit.

78
Q

Plants are found all over the world and have evolved to survive in the harshest conditions. For a plant, the most challenging environment has high heat and low water availability

What is the type of plant that has adapted to this environment called ?

A

A xerophyte

79
Q

How are sunken stomata an adaptation for Xerophyte ?

A

Stomata are often sunken in pits.
This reduces the amount of water vapour that can diffuse out of the stomata.
Stomata also close during the day (as well as at night) when the plant is too low on water and the temperature is too high.

80
Q

How are small leaves , or spines or needles an adaptation for a Xerophyte ?

A

Xerophytes often have small leaves, or spines or needles instead (like cacti for example).

Smaller leaves have a reduced surface area, and so fewer stomata, and therefore less water is lost through transpiration.

81
Q

How is a waxy cuticle an adaptation for Xerophytes ?

A

A thick waxy cuticle covers the epidermis.

This is waterproof, so reduces water evaporation through it.

All Topics GCSE Biology Triple (9 decks)

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