6. Plants Flashcards
(113 cards)
1
Q
What is the word equation for photosynthesis?
A
Carbon Dioxide + Water -> Glucose + Oxygen
2
Q
What is the symbol equation for photosynthesis?
A
6CO2 + 6H2O -> C6H12O6 + 6O2
3
Q
What does photosynthesis produce?
A
Glucose (and oxygen) for respiration
4
Q
Where in the cell does photosynthesis happen?
A
Inside the chloroplasts.
5
Q
In what organisms are chloroplasts found?
A
In some plant cells and in algae.
6
Q
What substance do chloroplasts contain?
A
Chlorophyll, which is green.
7
Q
What is chlorophyll used for?
A
It absorbs light energy from sunlight and uses it to convert CO2 and H2O into glucose and oxygen.
8
Q
What is needed for photosynthesis to happen?
A
- Carbon dioxide
- Water
- Light energy
- Chlorophyll
9
Q
In which part of the plant does photosynthesis happen?
A
In the leaves.
10
Q
How is sunlight obtained for photosynthesis?
A
Light energy is absorbed by chlorophyll in chloroplasts.
11
Q
How is water obtained for photosynthesis?
A
It is taken from the soil and reaches cells via the xylem.
12
Q
How is carbon dioxide obtained for photosynthesis?
A
It diffuses into the leaf through stomata.
13
Q
What is the structure of the leaf from top to bottom?
A
Cuticle, Upper Epidermis, Mesophyll = (Palisade, Spongy Layer), Lower Epidermis (+ Guard Cells), Cuticle (+ Stomata)
(Diagram Pg 58)
14
Q
What factors affect the rate of photosynthesis?
A
• Light intensity • Carbon dioxide • Temperature (• Water) (• Chlorophyll)
15
Q
Why is water usually not considered a rate limiting factor in photosynthesis?
A
By the time water becomes the rate limiting factor for photosynthesis, the plant is already mostly likely dying or in big trouble.
16
Q
What does “rate limiting factor” mean in terms of photosynthesis?
A
The factor which is stopping photosynthesis from happening any faster.
17
Q
How can the rate of photosynthesis be investigated?
A
- Get a water plant like Canadian Pondweed
- Measure the gas produced in a certain amount of time (e.g. number of bubbles, volume of gas, etc.)
- Repeat -> Each time change a factor, like light
- Plot a graph of results
18
Q
How can light intensity be changed in an investigation on photosynthesis?
A
- Light intensity can be changed by moving a lamp closer or further from a plant
- Plot a graph of gas produced against light intensity (NOT distance from lamp)
19
Q
How can CO2 be changed in an investigation on photosynthesis?
A
• Dissolve different amounts of sodium hydrogencarbonate, which gives off CO2.
20
Q
How can temperature be changed in an investigation on photosynthesis?
A
• Put the flask with the plant in a water bath
21
Q
What does a graph of rate of photosynthesis against light intensity look?
A
The rate increases until a certain point, after which it remains constant.
22
Q
What does a graph of rate of photosynthesis against CO2 % look?
A
The rate increases until a certain point, after which it remains constant.
23
Q
What does a graph of rate of photosynthesis against temperature look?
A
The rate slowly increases up to a point, after which it quickly decreases.
24
Q
How does light affect the rate of photosynthesis and why?
A
As light intensity increases, so does the rate of photosynthesis at a constant rate. After a point, the rate of photosynthesis levels out because another factor becomes rate limiting.
25
How does CO2 concentration affect the rate of photosynthesis and why?
As CO2 concentration increases, so does the rate of photosynthesis at a constant rate. After a point, the rate of photosynthesis levels out because another factor becomes rate limiting.
26
How does temperature affect the rate of photosynthesis and why?
As temperature increases, so does the rate of photosynthesis because enzymes which catalyse photosynthesis work more efficiently. After a point, the rate decreases because the enzymes are denatured.
27
At which temperature are plant enzymes responsible for photosynthesis denatured?
About 45*C.
28
How can light, temperature and CO2 concentration be controlled in investigations into photosynthesis?
Light - Use a bench lamp
Temperature - Keep the flask in a water bath
CO2 - Not much can be done -> Just use a large flask to ensure there is more than enough CO2
29
What is the most common way to artificially create the ideal environment for plants to grow?
Grow them in a greenhouse.
30
How do greenhouses work?
* Trap sun's heat, ensuring temperature doesn't become rate limiting
* Ensure lots of light reaches plants
* Prevents pests and disease reaching plants
31
How do farmers help greenhouses maximise growth?
* In summer, use blinds to lower temperature -> In winter, use heaters to increase temperature
* Artificial light after dusk -> More photosynthesis time
* Paraffin heaters -> Increase heat and release CO2
* Fertiliser
32
Why is it important for farmers to provide just the right amount of heat, light, CO2, etc. for their plants?
They need to provide enough so that the plants grow well, but not too much so that money is wasted.
33
What are the ways in which plants use glucose?
1) Respiration
2) Making cell walls
3) Making proteins
4) Stored as fats or oils
5) Stored as starch
34
How is glucose used for respiration?
Respiration releases energy -> Energy allows plant to convert glucose into other useful substances-> Which can be used for building new cells and growth
35
How is glucose used for making cell walls?
Glucose is converted into cellulose for making cell walls.
36
How is glucose used for making proteins?
Glucose is combined with nitrate ions (from soil) to make amino acids, which then join to make proteins.
37
What are carnivorous plants adapted for?
Living in nutrient poor soil -> They get most of the nutrients they need (e.g. nitrates) from the animals they catch.
38
How is glucose used for storage as fats or oils and where is it stored?
Glucose is turned into lipids (fats and oils) for storing in seeds.
39
How is glucose used for storage as starch and where is it stored?
Glucose is turned into starch and stored in roots, stems and leaves.
40
Give an example of glucose being stored as fats or oils.
Sunflower seeds contain a lot of oil - we get cooking oil and margarine from them.
41
Give an example of glucose being stored as starch.
Potato and parsnip plants store starch underground over the winter so a new plant can grow form it the next spring.
42
Why is glucose stored as starch in plants?
So that it is ready for use when photosynthesis isn't happening (e.g. winter).
43
Why is starch a suitable form of storing glucose?
It is insoluble, so water is not drawn into cells.
44
How does CO2 reach plant cells?
It diffuses into the leaf through stomata, then it diffuses into cells.
45
How are leaves adapted to take in CO2?
• Many stomata
• Flattened shape -> Increases SA:V ratio
• Air spaces inside leaf -> Increase SA:V ratio
•
46
What substances diffuse in and out through the stomata?
In: Carbon dioxide
Out: Water vapour + Oxygen
47
What controls the size of stomata?
Guard cells
48
How do stomata control water loss?
When too much water is lost from the plant, the guard cells either side of the stomata close, stopping moe water being lost.
49
How is water lost from the leaves?
Water evaporates from cells inside the leaf and then diffuses out of the leaf.
50
When does water loss by transpiration happen most quickly?
In hot, dry and windy conditions.
51
What do plant roots absorb?
Water and mineral ions
52
What increases the surface area of roots?
Root hairs
53
Why can't you see through a leaf under a microscope?
It's too thick.
54
Which part of the leaf can be observed under a microscope and why?
The epidermis - It is transparent.
55
How can the epidermis be observed under a microscope?
1) Put the epidermis on a slide
2) Use a pipette to put a drop of water on the epidermis (this keeps it in place)
3) Use a mounted needle to lower the coverslip onto the water
4) Put the slide under a microscope
56
What are the two tubes which transport substances in the plant called?
Xylem and phloem
57
Which parts of the plant do the xylem and phloem reach?
Every part of the plant
58
Are the xylem and phloem interconnected?
No, they are completely separate.
59
What is the phloem made of?
Column of living cells with small holes in the walls between them.
60
What does the phloem transport and where?
* Food substances (mainly dissolved sugars)
| * From the leaves to growing regions (e.g. new shoots) and storage organs (e.g. root tubers)
61
In which direction does the phloem transport substances?
In both directions.
62
What is the process of transport in the phloem called?
Translocation
63
What is translocation?
The process by which food substances are transported in the phloem.
64
What is the xylem made of?
Dead cells joined end to end with no cell walls between them.
65
What does the xylem transport and where?
* Water and minerals
| * From the roots to the stem and leaves
66
In which direction does the xylem transport substances?
Upwards.
67
What is the movement of water from the roots, through the xylem and out of the leaves called?
The transpiration stream
68
What is the transpiration stream?
The movement of water from the roots, through the xylem and out of the leaves
69
What is transpiration?
The loss of water from a plant.
70
What causes transpiration?
Evaporation and diffusion of water from inside the leaves.
71
How does the transpiration stream work?
* Water evaporates and diffuses out of a plant
* This creates a shortage of water, so more is drawn up through the xylem
* This means more water is drawn up through the roots
72
What is auxin?
* A plant growth hormone
| * Controls growth near the tips of shoots and roots
73
What does auxin control plant growth in response to?
* Light
* Gravity
* Moisture
74
What is plant growth in response to light called?
Phototropism
75
What is plant growth in response to gravity called?
Geotropism / Gravitropism
76
What is plant growth in response to moisture called?
Hydrotropism
77
How does auxin work?
* Produced in the tips of shoots and roots
* Moves backwards to stimulate cell elongation just behind the tip
* In shoots, auxin encourages growth
* In roots, auxin inhibits growth
78
What happens if the tip of a shoot is removed?
No auxin is available and the shoot may stop growing.
79
How does extra auxin affect the SHOOT of a plant?
Promotes growth
80
How does extra auxin affect the ROOT of a plant?
Inhibits growth
81
How do plant shoots respond to light in terms of auxin?
* More auxin accumulates on side away from the light
| * This causes more growth on the shaded side, so the shoot bend towards the light
82
How do plant shoots respond to gravity in terms of auxin?
* More auxin accumulates on lower side of shoot
| * This causes the lower side to grow faster, bending the shoot upwards
83
How do plant roots respond to gravity in terms of auxin?
* More auxin accumulates on the lower side
| * This causes the lower side to grow slower, bending the root downwards
84
How do plant roots respond to moisture in terms of auxins?
* More auxin accumulates on side closer to moisture
| * This causes that side to grow slower, bending the root towards the moisture
85
How can hormones be obtained for use in agriculture and horticulture?
They can be extracted or artificial versions can be made.
86
What is horticulture?
Growing things in gardens or orchards.
87
What are two uses of plant hormones in agriculture and horticulture?
1) Weed killers
| 2) Rooting powder
88
How can plant hormones be used as weed killers?
* Selective weed killers are made of plant growth hormones
* They disrupt growth patterns of broad-leaved plants (like weeds)
* But they don't affect narrow-leaved plants (like grasses and cereals)
89
How can plant hormones be used in rooting powder?
* Rooting powder contains auxin
* Auxin encourages plant cuttings to grow roots rapidly
* This allows clones of good plants to be produced
90
Are flowers male or female?
They have both male and female parts.
91
What are the 3 steps a flowering plant must take to reproduce sexually?
1) Produce male and female gametes
2) Transfer the male gametes to the female ovules - pollination
3) Undergo fertilisation
92
What is pollination?
The transfer of male gametes to female ovules (where the female gametes are).
93
What happens after fertilisation?
The ovules grow into seeds inside a fruit.
94
What is cross pollination?
When pollen is transferred from the anther of one plant to the stigma of a different plant.
95
What is the male reproductive part of the flower called and what does it consist of?
Stamen -> Anther and filament
96
What is the female reproductive part of the flower called and what does it consist of?
Carpel -> Stigma, style and ovary
97
Where is the anther on the flower?
It is the small bulb on the end of the filament. (On the stamen)
98
Where is the filament on the flower?
It is the stalk that supports the anther. (On the stamen)
99
Where is the stigma on the flower?
It is the large bulb on top of the central style. (On the carpel)
100
Where is the style on the flower?
It is the long rod-like section in the centre which supports the stigma. (On the carpel)
101
Where is the ovary on the flower?
It is the central bulge at the bottom of the style. (On the carpel)
102
Describe the structure of a flower.
* In the middle, there is a large bulb called a STIGMA, which is on the end of a long rod called the STYLE. At the bottom of the style is a large bulge called the OVARY, which contains the ovules. Inside these are the female gametes.
* Around this are several long stalks called FILAMENTS. On the ends of these are small bulbs called ANTHERS, which contain the pollen grains.
103
What does the anther do?
It contains pollen grains (which produce the male gametes).
104
What does the filament do?
It supports the anther.
105
What does the stigma do?
It is the part that the pollen grains attach to.
106
What does the style do?
It supports the stigma.
107
What does the ovary do?
It contains the ovules, which contain female gametes.
108
What are pollen?
Small grains which each contain male gametes.
109
Are pollen the male gametes?
No, they contain the gametes inside them.
110
Remember to learn how to label diagram of a plant.
Pg 65 of revision guide.
111
Describe the process of fertilisation in plants.
1) Anther produces male gametes in pollen grains.
2) Pollen grain lands on the stigma.
3) Pollen tube grows out of the pollen grain, down through the style, to the ovary and into the ovule.
4) A nucleus from the male gamete moves down the tube into the ovary -> Fertilises the egg cell nucleus
5) The two nuclei fuse (fertilisation) to make a zygote -> Divides by mitosis to form an embryo
6) Other nuclei from the male gametes fertilise endosperm nuclei in the ovule -> This produces endosperm (a food sac) that stores starch to feed the growing embryo
7) Endosperm and female tissues of the ovule make up a seed -> Ovary develops into a fruit around the seed.
112
What is fertilisation in plants?
When the male gamete and female gamete fuse together to make a zygote.
113
What is the endosperm and how is it formed?
* It is a food sac that stores starch for the growing embryo.
* Formed when additional nuclei from the male gametes fertilise endosperm nuclei in the ovule.
