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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
What experimental method can be used to investigate light intensity's effect on photosynthesis?
Move a lamp closer to or further away from the plant.
26
What are the two types of transport vessels in flowering plants?
Xylem and phloem ## Footnote Both types of vessel go to every part of the plant, but they are totally separate.
27
What is the function of root hair cells?
To absorb water and mineral ions from the soil ## Footnote They increase surface area for absorption.
28
How do mineral ions enter root hair cells?
By active transport ## Footnote This occurs because the concentration of mineral ions is usually higher in the root hair cells than in the surrounding soil.
29
How is water absorbed by plant roots?
By osmosis ## Footnote Water moves from areas of higher concentration to lower concentration.
30
What are phloem tubes primarily made of?
Columns of elongated living cells ## Footnote They have small pores in the end walls to allow substances to flow through.
31
What is the main substance transported by phloem tubes?
Sucrose ## Footnote Phloem transports food substances made in the leaves to the rest of the plant.
32
What is the process of transporting food substances in plants called?
Translocation ## Footnote This process requires energy from respiration.
33
What do xylem tubes carry from the roots to the stem and leaves?
Water and mineral ions ## Footnote Xylem tubes are made of dead cells joined end to end.
34
What is the transpiration stream?
The movement of water from the roots, through the xylem and out of the leaves ## Footnote It describes how water is transported upward in plants.
35
True or False: Phloem vessels transport substances only in one direction.
False ## Footnote Phloem transports substances in both directions, while xylem only transports things upwards.
36
Fill in the blank: Xylem vessels carry _______ and phloem vessels carry sucrose.
water ## Footnote This is a key distinction to remember in plant transport.
37
What is transpiration?
The loss of water from the plant through evaporation and diffusion ## Footnote Most transpiration occurs at the leaves
38
Where does most transpiration occur in plants?
At the leaves ## Footnote Transpiration is essential for maintaining water balance in plants
39
What happens when water is lost through transpiration?
More water is drawn up from the rest of the plant through the xylem vessels ## Footnote This creates a constant transpiration stream of water through the plant
40
What role do xylem vessels play in transpiration?
They transport water from the roots to the leaves ## Footnote The transpiration stream carries dissolved mineral ions along with water
41
What are stomata?
Tiny pores on the surface of a plant that allow gas exchange ## Footnote Stomata are mostly found on the lower surface of leaves
42
What gases can diffuse through stomata?
Carbon dioxide (CO2) and oxygen ## Footnote Stomata also allow water vapor to escape during transpiration
43
What is the function of guard cells?
To control the size of the stomatal pore ## Footnote Guard cells change shape based on their water content
44
What happens to stomata when guard cells are turgid?
The stomata are open ## Footnote Turgid guard cells are swollen with water
45
What happens to stomata when guard cells are flaccid?
The stomata are closed ## Footnote Flaccid guard cells are low on water and limp
46
Fill in the blank: Transpiration is a side-effect of the way leaves are adapted for _______.
photosynthesis
47
True or False: Stomata only allow gas exchange and do not play a role in transpiration.
False ## Footnote Stomata are essential for both gas exchange and transpiration
48
What is transpiration rate?
The rate at which water evaporates from the leaves of a plant ## Footnote Transpiration is a critical process for water and nutrient uptake in plants.
49
How does light intensity affect transpiration rate?
The brighter the light, the greater the transpiration rate ## Footnote Stomata close in the dark, reducing water loss.
50
What happens to stomata in darkness?
They begin to close ## Footnote This is because photosynthesis cannot occur without light, so CO₂ intake is not necessary.
51
What is the relationship between temperature and transpiration?
The warmer it is, the faster transpiration happens ## Footnote Higher temperatures provide water particles with more energy to evaporate.
52
How does air flow around a leaf influence transpiration?
The better the air flow, the greater the transpiration rate ## Footnote Stronger winds help remove water vapor, maintaining a concentration gradient for diffusion.
53
What occurs when air flow around a leaf is poor?
Water vapor surrounds the leaf, slowing down diffusion ## Footnote High concentrations of water particles outside and inside the leaf hinder the diffusion process.
54
What is the effect of good air flow on transpiration?
Water vapor is swept away, maintaining a low concentration of water in the air outside the leaf ## Footnote This enhances the diffusion of water vapor from the leaf.
55
Fill in the blank: The faster the transpiration rate, the faster the water _______ by the plant.
uptake
56
True or False: Stomata being open is crucial for plants to survive.
True ## Footnote Open stomata allow for gas exchange, which is essential for photosynthesis.
57
What are leaves adapted for?
Photosynthesis and gas exchange
58
How are leaves adapted to get more light? (3 ways)
Leaves are broad, large surface area Palisade layer has lots of chloroplasts The upper epidermis is transparent
59
What does the xylem do in leaves?
Provide the leaf with water for photosynthesis
60
What does the phloem do in the leaves?
Take away the glucose produced
61
What do the xylem and phloem form in the leaves?
A network of vascular bundles to help support the structure
62
What is covered in a waxy cuticle?
The epidermal tissue
63
What the waxy cuticle help prevent?
Helps reduce the loss of water by evaporation
64
How are tissues of leaves adapted for efficient gas exchange? (2 ways)
Lower epidermis- lots of stomata (CO2 directly diffuse into the leaf) Spongy mesophyll- air spaces ( increase the rate of diffusion in and out)
65
What do plant hormones regulate?
The plants growth and development
66
What are auxins?
Growth hormone at the tips of shoots and roots
67
What do the auxins in the tips do?
Diffuse backwards stimulating cell elongation that occurs just behind the tips
68
What do auxins promote and inhibit?
Promotes growth in the shoot Inhibits growth in the root
69
What is phototropism?
A growth response to light
70
What is gravitropism?
A growth response to gravity
71
How does positively phototropism work?
Shoot tip exposed to light More auxins are on the shaded size Promotes faster growth on the shaded side Bends towards the light
72
How does negatively gravitropism work?
Shoot growing sideways Gravity produces and unequal distribution of auxins More on the lower side Faster growth on the lower side Bending upwards
73
How does positive gravitropism work?
Root growing sideways More auxins on the lower side Bends towards The extra auxins inhibit growth Top cells elongate faster Bending downwards
74
What do auxins do?
Change the direction of root growth
75
How does negatively phototropism work?
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
Name 6 commercial uses of plant hormones.
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
What hormone stimulates seed germination?
Gibberellins
78
What hormone ripens fruits?
Ethene

Biology Paper 2 (4 decks)

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