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Biology Paper 2 > Topic 6 Plants Structures and Functions > Flashcards

Topic 6 Plants Structures and Functions Flashcards

1
Q

What is the primary function of photosynthesis?

A

To make glucose using energy from the Sun

Photosynthesis is crucial for the food chains on Earth.

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2
Q

Which organisms are known for carrying out photosynthesis?

A

Green plants and algae

These organisms are essential producers of food for nearly all life on Earth.

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3
Q

What is biomass in the context of photosynthesis?

A

The mass of living material produced by plants or algae

Biomass is created from glucose and is transferred through the food chain.

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4
Q

Where does photosynthesis occur in plant cells?

A

Inside chloroplasts

Chloroplasts contain chlorophyll, which absorbs light.

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5
Q

What is the equation for photosynthesis?

A

Carbon dioxide + water → glucose + oxygen
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

This equation represents the reactants and products of photosynthesis.

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6
Q

Is photosynthesis an endothermic or exothermic reaction?

A

Endothermic

Energy is taken in during the process of photosynthesis.

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7
Q

What factors can limit the rate of photosynthesis?

A

Light intensity, concentration of CO₂, and temperature

Any of these factors can become limiting, preventing faster photosynthesis.

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8
Q

How does temperature affect the rate of photosynthesis?

A

It affects the enzymes involved

Low temperatures slow down enzyme activity, while high temperatures can denature enzymes.

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9
Q

At what temperature do enzymes involved in photosynthesis typically denature?

A

About 45 °C

Enzyme denaturation affects the plant’s ability to perform photosynthesis.

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10
Q

Fill in the blank: Photosynthesis happens inside _______.

A

chloroplasts

Chloroplasts are crucial for the photosynthesis process.

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11
Q

True or False: Photosynthetic organisms are the main producers of food for nearly all life on Earth.

A

True

They form the base of food chains.

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12
Q

What is the primary role of light in photosynthesis?

A

Light transfers the energy needed for photosynthesis.

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13
Q

How does the rate of photosynthesis change with increasing light intensity?

A

Increases steadily up to a certain point.

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14
Q

What happens to the rate of photosynthesis beyond a certain light intensity?

A

It levels off; temperature or CO2 becomes the limiting factor.

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15
Q

What is the relationship between light intensity and distance from the lamp?

A

Light intensity decreases in proportion to the square of the distance.

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16
Q

What is the inverse square law in the context of light intensity?

A

If you halve the distance, the light intensity will be four times greater.

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17
Q

Using the inverse square law, what happens to light intensity when the distance is doubled?

A

The light intensity will be four times smaller.

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18
Q

What is the formula for calculating light intensity based on distance?

A

Light intensity = 1/distance^2

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19
Q

What is one of the raw materials needed for photosynthesis?

A

Carbon dioxide (CO2).

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20
Q

How does increasing CO2 concentration affect the rate of photosynthesis?

A

Increases the rate up to a point.

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21
Q

What happens to the rate of photosynthesis when CO2 is in plentiful supply?

A

Light or temperature becomes the limiting factor.

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22
Q

Fill in the blank: The rate of photosynthesis is affected by light intensity, temperature, and _______.

A

carbon dioxide (CO2).

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23
Q

True or False: The rate of photosynthesis can increase indefinitely with more light.

A

False.

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24
Q

What does the graph of photosynthesis against light intensity look like beyond a certain point?

A

It flattens out.

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25
Q

What experimental method can be used to investigate light intensity’s effect on photosynthesis?

A

Move a lamp closer to or further away from the plant.

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26
Q

What are the two types of transport vessels in flowering plants?

A

Xylem and phloem

Both types of vessel go to every part of the plant, but they are totally separate.

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27
Q

What is the function of root hair cells?

A

To absorb water and mineral ions from the soil

They increase surface area for absorption.

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28
Q

How do mineral ions enter root hair cells?

A

By active transport

This occurs because the concentration of mineral ions is usually higher in the root hair cells than in the surrounding soil.

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29
Q

How is water absorbed by plant roots?

A

By osmosis

Water moves from areas of higher concentration to lower concentration.

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30
Q

What are phloem tubes primarily made of?

A

Columns of elongated living cells

They have small pores in the end walls to allow substances to flow through.

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31
Q

What is the main substance transported by phloem tubes?

A

Sucrose

Phloem transports food substances made in the leaves to the rest of the plant.

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32
Q

What is the process of transporting food substances in plants called?

A

Translocation

This process requires energy from respiration.

33
Q

What do xylem tubes carry from the roots to the stem and leaves?

A

Water and mineral ions

Xylem tubes are made of dead cells joined end to end.

34
Q

What is the transpiration stream?

A

The movement of water from the roots, through the xylem and out of the leaves

It describes how water is transported upward in plants.

35
Q

True or False: Phloem vessels transport substances only in one direction.

A

False

Phloem transports substances in both directions, while xylem only transports things upwards.

36
Q

Fill in the blank: Xylem vessels carry _______ and phloem vessels carry sucrose.

A

water

This is a key distinction to remember in plant transport.

37
Q

What is transpiration?

A

The loss of water from the plant through evaporation and diffusion

Most transpiration occurs at the leaves

38
Q

Where does most transpiration occur in plants?

A

At the leaves

Transpiration is essential for maintaining water balance in plants

39
Q

What happens when water is lost through transpiration?

A

More water is drawn up from the rest of the plant through the xylem vessels

This creates a constant transpiration stream of water through the plant

40
Q

What role do xylem vessels play in transpiration?

A

They transport water from the roots to the leaves

The transpiration stream carries dissolved mineral ions along with water

41
Q

What are stomata?

A

Tiny pores on the surface of a plant that allow gas exchange

Stomata are mostly found on the lower surface of leaves

42
Q

What gases can diffuse through stomata?

A

Carbon dioxide (CO2) and oxygen

Stomata also allow water vapor to escape during transpiration

43
Q

What is the function of guard cells?

A

To control the size of the stomatal pore

Guard cells change shape based on their water content

44
Q

What happens to stomata when guard cells are turgid?

A

The stomata are open

Turgid guard cells are swollen with water

45
Q

What happens to stomata when guard cells are flaccid?

A

The stomata are closed

Flaccid guard cells are low on water and limp

46
Q

Fill in the blank: Transpiration is a side-effect of the way leaves are adapted for _______.

A

photosynthesis

47
Q

True or False: Stomata only allow gas exchange and do not play a role in transpiration.

A

False

Stomata are essential for both gas exchange and transpiration

48
Q

What is transpiration rate?

A

The rate at which water evaporates from the leaves of a plant

Transpiration is a critical process for water and nutrient uptake in plants.

49
Q

How does light intensity affect transpiration rate?

A

The brighter the light, the greater the transpiration rate

Stomata close in the dark, reducing water loss.

50
Q

What happens to stomata in darkness?

A

They begin to close

This is because photosynthesis cannot occur without light, so CO₂ intake is not necessary.

51
Q

What is the relationship between temperature and transpiration?

A

The warmer it is, the faster transpiration happens

Higher temperatures provide water particles with more energy to evaporate.

52
Q

How does air flow around a leaf influence transpiration?

A

The better the air flow, the greater the transpiration rate

Stronger winds help remove water vapor, maintaining a concentration gradient for diffusion.

53
Q

What occurs when air flow around a leaf is poor?

A

Water vapor surrounds the leaf, slowing down diffusion

High concentrations of water particles outside and inside the leaf hinder the diffusion process.

54
Q

What is the effect of good air flow on transpiration?

A

Water vapor is swept away, maintaining a low concentration of water in the air outside the leaf

This enhances the diffusion of water vapor from the leaf.

55
Q

Fill in the blank: The faster the transpiration rate, the faster the water _______ by the plant.

A

uptake

56
Q

True or False: Stomata being open is crucial for plants to survive.

A

True

Open stomata allow for gas exchange, which is essential for photosynthesis.

57
Q

What are leaves adapted for?

A

Photosynthesis and gas exchange

58
Q

How are leaves adapted to get more light?
(3 ways)

A

Leaves are broad, large surface area
Palisade layer has lots of chloroplasts
The upper epidermis is transparent

59
Q

What does the xylem do in leaves?

A

Provide the leaf with water for photosynthesis

60
Q

What does the phloem do in the leaves?

A

Take away the glucose produced

61
Q

What do the xylem and phloem form in the leaves?

A

A network of vascular bundles to help support the structure

62
Q

What is covered in a waxy cuticle?

A

The epidermal tissue

63
Q

What the waxy cuticle help prevent?

A

Helps reduce the loss of water by evaporation

64
Q

How are tissues of leaves adapted for efficient gas exchange?
(2 ways)

A

Lower epidermis- lots of stomata (CO2 directly diffuse into the leaf)
Spongy mesophyll- air spaces ( increase the rate of diffusion in and out)

65
Q

What do plant hormones regulate?

A

The plants growth and development

66
Q

What are auxins?

A

Growth hormone at the tips of shoots and roots

67
Q

What do the auxins in the tips do?

A

Diffuse backwards stimulating cell elongation that occurs just behind the tips

68
Q

What do auxins promote and inhibit?

A

Promotes growth in the shoot
Inhibits growth in the root

69
Q

What is phototropism?

A

A growth response to light

70
Q

What is gravitropism?

A

A growth response to gravity

71
Q

How does positively phototropism work?

A

Shoot tip exposed to light
More auxins are on the shaded size
Promotes faster growth on the shaded side
Bends towards the light

72
Q

How does negatively gravitropism work?

A

Shoot growing sideways
Gravity produces and unequal distribution of auxins
More on the lower side
Faster growth on the lower side
Bending upwards

73
Q

How does positive gravitropism work?

A

Root growing sideways
More auxins on the lower side Bends towards
The extra auxins inhibit growth
Top cells elongate faster
Bending downwards

74
Q

What do auxins do?

A

Change the direction of root growth

75
Q

How does negatively phototropism work?

A

Root starts being exposed to some light
More auxins go to the shaded side
The auxin inhibits cell elongation on the shaded side
Root bends downward

76
Q

Name 6 commercial uses of plant hormones.

A

Selective weedkiller
Growing from cuttings with rooting powder
Controlling flower and fruit formation
Producing seedless fruit
Controlling the ripening of fruits
Controlling seed germination

77
Q

What hormone stimulates seed germination?

A

Gibberellins

78
Q

What hormone ripens fruits?

A

Ethene

Biology Paper 2 (4 decks)

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