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Biology > B4 > Flashcards

B4 Flashcards

1
Q

What is a population?

A

It is all the organisms of one species in a habitat

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2
Q

What do populations of different species in a habitat make up?

A

A community

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3
Q

What is a quadrat?

A

A square frame enclosing a known area.

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4
Q

How can you make estimates of a population in a large area (for plants)

A

Use a quadrat in a small area and scale it up to the size of the large area

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5
Q

How do you scale up an estimate for a population of plants using a quadrat?

A

Count all the organisms in a 1m squared quadrat

Multiply the number of organisms by the total area (1m squared) of the habitat

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6
Q

How can you estimate the population size using the capture-recapture method?

A

1) capture a sample of the population and mark the animals in a harmless way
2) release them back into the environment
3) recapture another sample of the population. Count how many of this sample are marked
4) estimate the population size using the ‘population size’ equation

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7
Q

What is the equation for estimating a population size?

A 
 number in second sample previously marked
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8
Q

What affects the accuracy of your estimate (when guessing a population)?

A

The sample size.

The bigger your sample, the more accurate your estimate will be.

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9
Q

What three things do you have to assume when using the capture-recapture method?

A

1 - there have been no deaths, and the animals haven’t moved anywhere else
2 - The sampling methods are identical
3 - The marking hasn’t affected the individuals chance of survival

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10
Q

What is an ecosystem?

A

All the organisms living in a particular area, as well as all the no-living (abiotic) conditions

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11
Q

What is a habitat?

A

The place where an organism lives

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12
Q

Is an eco system the same thing as a habitat?

A

NO!!!

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13
Q

How are ecosystems self supporting?

A 
They contain (almost) everything they need to maintain themselves.
e.g. water, nutrients and essential elements like carbon all get recycled within the ecosystem.
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14
Q

What is the only additional thing that an eco system needs?

A

An energy source. This is normally the sun.

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15
Q

What is distribution?

A

Where organisms are found within a particular area.

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16
Q

How can you investigate distribution?

A

Using lines called transects.

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17
Q

How can you do a transect?

A

You mark out a line using a tape measure and place quadrats next to each other all the way along the line. you then count and record the organisms you find in the quadrats.

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18
Q

What does it mean to do a percentage over?

A

This means estimating the percentage area of the quadrat covered by a particular organism.
e.g. by counting the number of little squares covered by the organisms. (if its grass for example)

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19
Q

How can you plot the results of a transect?

A

In a kite diagram

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20
Q

What do kite diagrams allow you to do?

A

Map the distribution of organisms in an area

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21
Q

What can kite diagrams show?

A

The distribution an abundance of organisms along as transect

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22
Q

What is the abundance of each organisms shown by in a kite diagram?

A

The thickness of the shape.

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23
Q

What does the shape look like in a kite diagram?

A

It should always be a symmetrical kite shape

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24
Q

What are abiotic factors?

A

All the non-living, physical factors in an environment - e.g. light, temperature, water, oxygen, salt level and soil quality.

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25
Q

Why is the distribution of organisms affected by abiotic factors?

A
  • organisms are adapted to live in certain physical conditions.
    This means they are more likely to survive and reproduce in areas with these conditions.
  • many organisms can only survive in the conditions they are adapted to.
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26
Q

Give an example of a plant which is adapted to its environment

A

Woodland ferns are adapted to live in shaded areas so you won’t find them in sunny open places.

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27
Q

What is zonation?

A

THE GRADUAL CHANGE IN THE DISTRIBUTION OF SPECIES ACROSS A HABITAT

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28
Q

Give an example of zonation

A

In a costal habitat, changes in salt levels and soil depth result in zones where different types of plants grow.

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29
Q

Why can only a few plants grow in a coastal environment very close to the sea?

A

Because the salt level is very high.

However, marram grass can grow because it is adapted to the salty conditions.

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30
Q

What is biodiversity a measure of?

A

The variety of life in an area

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31
Q

What does biodiversity include?

A

The amount of variation between individuals of the same species in an area
The number of different species in an area
The number of different habitats in an area

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32
Q

What ecosystems are healthier?

A

Those with more biodiversity

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33
Q

Why is it important to have lots of biodiversity?

A

Because more diverse ecosystems are better able to cope with changes in the environment.

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34
Q

Out of natural and artificial ecosystems, which one has a higher biodiversity?

A

A natural ecosystem.

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35
Q

What has a higher biodiversity, native woodland or forestry plantations?

A

Native woodlands

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36
Q

What do native woodlands contain?

A

Variety of species
Variety of trees
Variety of plants
Variety of habitats

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37
Q

What do forestry plantations contain?

A

One species of tree
Fewer plant species
Fewer habitats
Fewer animal species

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38
Q

What has a higher biodiversity, lakes or fish farms?

A

Lakes

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39
Q

What do lakes contain?

A

Many different fish species
Variety of plant species
Variety of animal species

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40
Q

What do fish farms contain?

A

One fish species
Fewer plant species
Fewer animal species

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41
Q

What does photosynthesis use?

A

Energy from the sun

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42
Q

What does photosynthesis do?

A

Uses energy from the sun to change CO2 and water into glucose and oxygen

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43
Q

Where does photosynthesis take place?

A

In the chloroplasts in plant cells

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44
Q

What do chloroplasts contain?

A

Pigments like chlorophyll that absorb light energy

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45
Q

What is the balanced symbol equation for photosynthesis?

A

6CO2 + 6H2O —> C6H12O6 + 6O2

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46
Q

What are the two main stages of photosynthesis?

A

1st - light energy is used to split water into oxygen gas and hydrogen ions
2nd - Carbon dioxide gas then combines with the hydrogen ions to make glucose and water

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47
Q

What is glucose used for?

A 
Respiration
Making cells walls
Making proteins
Storing in seeds
Stored as starch
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48
Q

After the glucose used for respiration to make energy, what is the rest of the glucose used for?

A

It is converted into various other useful substances

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49
Q

What is glucose converted into to make cell walls?

A

Cellulose

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50
Q

Why is glucose stored as starch?

A

So it is ready to use when photosynthesis isn’t happening

e.g. at night

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51
Q

Why is starch good for storing?

A

Because it can’t dissolve in water and it doesn’t affect the water concentration inside cells

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52
Q

What are lipids?

A

Fats and oils

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53
Q

Why is glucose turned into lipids?

A

For storing in seeds

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54
Q

What is glucose combined with the make amino acids?

A

Nitrates

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55
Q

What are plant proteins used for?

A

Growth and repair

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56
Q

In the 1600s what experiment did Jan van Helmont do?

A

He dried some soil, weighed it, and put it in a pot
He planted a willow tree weighing 2.2kg in the soil
He added rainwater to the pot whenever it was dry
5 years later he removed the tree from the pot
it had gained 74.5kg of mass
He dried to soil and weighed it and realised that it hadn’t lost much mass
He realised that the plant much get its nutrients from other sources

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57
Q

How do plants gain mass?

A

Water

CO2

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58
Q

In 1770 what experiment did Joseph Priestly do?

A

He placed a burning candle in a sealed container and observed that the flame went out after a short time.
He then placed a burning candle and a living plant in the container. The flame went out after a short time but after a few weeks the candle could be re-lit.

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59
Q

Where does the oxygen that is given out by a plant come from?

A

The oxygen in the water not the oxygen from the carbon dioxide that is taken in

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60
Q

What are the three limiting factors that control the rate of photosynthesis?

A

Not enough light slows down the rate of photosynthesis
Too little carbon dioxide also slows it down
The temperature has to be just right

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61
Q

What happens if the light level is raised in photosynthesis?

A

The rate of photosynthesis will increase, but only to a certain point

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62
Q

What happens when the light level produces the optimum photosynthesis?

A

It will be either the CO2 level or the temperature that is holding it back

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63
Q

What happens as the temperature increases, regarding photosynthesis?

A

The rate of photosynthesis will increase until it reaches an optimum then it will decrease rapidly as the enzymes in the plants are denatured.

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64
Q

What is diffusion?

A

THE NET MOVEMENT OF PARTICLES FROM AN AREA OF HIGHER CONCENTRATION TO AN AREA OF LOW CONCENTRATION

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65
Q

Where does diffusion happen?

A

In gas and water

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66
Q

Why are cell membranes clever?

A

Because they hold the cell together but they also let things in and out as well.

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67
Q

What is a partially permeable membrane?

A

It is like a cell membrane, where it only lets small things in and out of it because of tiny holes in the wall.

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68
Q

What things can pass through a cell membrane?

A

simple sugars, water or ions

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69
Q

What things can’t pass through a cell membrane?

A

Starch and proteins

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70
Q

What three things does the rate of diffusion depend on?

A

Distance
Concentration difference (gradient)
Surface area

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71
Q

How does distance affect the rate of diffusion?

A

Substances move more quickly when they haven’t got as far to move

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72
Q

How does the concentration gradient affect the rate of diffusion?

A

substances diffuse quicker if there’s a big difference in concentration. If there are lots more particles on one side, there are more there to move across.

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73
Q

How does surface area affect the rate of diffusion?

A

The more surface area there is available for molecules to move across, the faster they can get from one side to the other

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74
Q

Explain the structure of a leaf from the top, down.

A 
Waxy cuticle
Upper epidermis
Palisade mesophyll layer (this contains chloroplasts)
Vascular bundle and air spaces are all in the spongy mesophyll layer
Lower epidermis
Guard cells
Stomata 
Waxy cuticle
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75
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water —> glucose + oxygen

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76
Q

What is the word equation for respiration?

A

glucose + oxygen —> carbon dioxide + water

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77
Q

Does photosynthesis require energy?

A

Yes

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78
Q

Does respiration require energy?

A

No it releases energy

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79
Q

When does photosynthesis only happen?

A

During the day (i.e. when there is light available)

80
Q

When does respiration happen in a plant?

A

All the time

81
Q

What happens to plant during the day?

A

They make more oxygen by photosynthesis than they use in respiration. So in daylight, they release oxygen and take in carbon dioxide

82
Q

What happens to plants at night?

A

They only respire _ there’s no light for photosynthesis. This means they take in oxygen and release carbon dioxide - just like us.

83
Q

Explain how plants exchange gases during photosynthesis

A

1) When a plant is photosynthesising it uses but a lot of carbon dioxide, so there’s hardly any in the leaf
2) This makes more carbon dioxide move into the leaf by diffusion
3) At the same time lots of oxygen is being make as a waste products of photosynthesis
4) Some is used in respiration, and the rest diffuses out of the leaf

84
Q

Explain how plants exchanges bases during respiration

A

1) At night it’s a different story - there’s no photosynthesis going on because there’s no light. Lots of carbon dioxide is made in respiration and lots of oxygen is used up
2) There’s a lot of carbon dioxide in the leaf and not a lot of oxygen, so now it’s mainly carbon dioxide diffusing out and oxygen diffusing in.

85
Q

How are leaves adapted for diffusion?

A

They are broad and thin.
The lower surface of the leaf are full of holes called stomata
The leaves have guard cell
There are air spaces within the leaf

86
Q

Leaves are broad to help diffusion, why?

A

Because they have a large surface area which allows gases to diffuse better

87
Q

How does the thickness of a leaf have an effect on its diffusion?

A

Because leaves are thin, it means the carbon dioxide and water vapour only have to diffuse a short distance to reach the photosynthesising cells where they’re needed.

88
Q

How do the stomata help with diffusion?

A

They’re there to let out gases like CO2 and O2 in and out. They also allow water to escape - which is known as transpiration.

89
Q

What role do guard cells play in the diffusion of a leaf?

A

They control when the stomata opens and closes. This allows the guard cells to control gas exchange.

90
Q

Where are the air spaces in leaves and why are they there?

A

They are in the spongy mesophyll layer. They are there to allow gases like CO2 and O2 to move between the stomata and the photosynthesising cells. This also means there’s a large surface area for gas exchange.
In other words, they have a very big internal surface area to volume ratio.

91
Q

How are leaves adapted to absorb light?

A

Large surface area, they contain lots of chloroplasts, they contain lots of different pigments, the upper epidermis is transparent.

92
Q

What do chloroplasts contain?

A

Chlorophyll and other photosynthetic pigments to absorb light energy.

93
Q

Why do leaves have lots of different pigments?

A

Because different pigments absorb different wavelengths of light, so plant cells make the most of the Sun’s energy by absorbing as much of it as possible.

94
Q

What are the four different pigments that are found in a plant cell and what are the wavelengths that they absorb?

A

Chlorophyll a - 400-450nm and 650-700 nm
Chlorophyll b - 450-500nm and 600-650nm
Carotene - 400-550nm
Xanthophyll - 400-530nm

95
Q

What does ‘nm’ stand for when talking about light wavelengths?

A

It stands for ‘nanometre’ - a really small unit of light.

96
Q

Why is the upper epidermis of a leaf transparent?

A

So that light can pass through it to the palisade layer

97
Q

What are vascular bundles?

A

They are the transport vessels, xylem and phloem. (in a leaf)

98
Q

What does the vascular bundle do?

A

It delivers water and other nutrients to every part of the leaf and take away the glucose produced by photosynthesis. They also help to support the leaf structure.

99
Q

What is osmosis?

A

The net movement of water molecules across a partially permeable membrane from a region of higher water concentration (i.e. a dilute solution) to a region of lower water concentration (i.e. a concentrated solution)

100
Q

How do water molecules move through a partially permeable membrane?

A

They pass through it both ways during osmosis. This happens because water molecules more about randomly all the time. However the net movement will be from a side of higher concentration of water molecules to a lower concentration of water molecules.

101
Q

What is osmosis a type of?

A

Diffusion

102
Q

What happens to a cell when it is turgid?

A

It becomes plump and swollen.

103
Q

When does cell turgidity happen?

A

When a plant has been watered and the cells try to even up the amount of water in the cell with the amount of water outside the cell through osmosis.

104
Q

What is turgor pressure?

A

When the contents of the cell push against the inelastic cell wall.

105
Q

What does turgor pressure help with?

A

It helps to support the plant tissues

106
Q

What happens if there is no water in the soil?

A

The plant will start to wilt (droop), this is because the plants will start to lose water and therefore lose their turgor pressure.
They’re then said to be flaccid.

107
Q

What happens to a cell when it is going flaccid?

A

The cell loses its turgor pressure and becomes slightly ‘looser’ than normal.

108
Q

What happens to a cell when it is plasmolysed?

A

If it is really short of water, the cytoplasm inside its cells starts to shrink and the membrane pulls away from the cell wall.

109
Q

Why does a plant not lose its shape when the cells become plasmolysed?

A

The inelastic cell wall keeps things in position. However the plant does tend to droop a bit.

110
Q

Do animals have an inelastic cell wall?

A

No

111
Q

What happens to an animal cell if it takes in too much water?

A

It bursts

112
Q

What is lysis?

A

Lysis is when an animal cell has too much water and bursts because of a lack of cell wall.

113
Q

What is crenation?

A

When an animal cell loses too much water and it shrivels up, crenation happens.

114
Q

Why are lysis and crenation both so bad? And what does this mean?

A

Because either way, it results in something bad happening to the body. This means that we have to keep our water levels more constant.

115
Q

Name the two transport systems that a plant has.

A

xylem and phloem

116
Q

What are the xylem and phloem both used for?

A

Transporting stuff around the plant.

117
Q

Give two properties of the xylem and phloem.

A

They are for transporting stuff around
They go to every part of the plant
They have continuous system
They are both totally seperate

118
Q

What is the main purpose of the phloem?

A

It transports food.

119
Q

Explain what happens in the phloem.

A

It is made up of columns of living cells with perforated end-plates to allow stuff to flow through.
They transport food substances (mostly sugars) BOTH UP AND DOWN the stem to growing and storage tissues.

120
Q

What is translocation?

A

It is the movement of food substances around the plant.

121
Q

What is the main purpose of the xylem?

A

To take water UP the plant.

122
Q

Explain what happens inside the xylem.

A

They carry water and minerals from the roots up the shoot to the leaves in the transpiration stream.

123
Q

What are xylem vessels made from?

A

Dead cells joined end to end with no end walls between them and a hole (lumen) down the middle.
The thick side walls are made of cellulose. They’re strong and stiff, which gives the plant support.

124
Q

What is the hole in the xylem called?

A

A lumen

125
Q

What are the thick side walls of the xylem made up of?

A

Cellulose

126
Q

What supports the plant?

A

The xylem.

127
Q

Where are the xylem and phloem found in a plant?

A

They usually run alongside each other in vascular bundles (like veins)

128
Q

What does the location of the xylem and phloem depend on?

A

The xylem’s other function; support.

129
Q

Where are the three places that the xylem and phloem are found?

A

Root
Stem
Leaf

130
Q

How does the xylem help plant roots?

A

The roots have to resist crushing as they push through the soil. The xylem is in the centre to give it strength.

131
Q

Where are the xylem and phloem in a stem?

A

The xylem forms a sort of scaffolding and supports the stem from the inside.
The phloem is always around the outside of the stem.

132
Q

What is a ‘network of veins’?

A

They support the leaf and are made up of the xylem and the phloem.

133
Q

Why do roots have lots of tiny hairs?

A

To give the root a large surface area for absorbing water from the soil.

134
Q

Which has a higher water concentration, the soil or the plant?

A

The soil

135
Q

How is water drawn into a root cell?

A

By osomosis

136
Q

What is transpiration?

A

The loss of water from the plant.

137
Q

What is transpiration caused by?

A

Evaporation and diffusion of water vapour from inside the leaves.

138
Q

Explain the constant transpiration stream.

A

Water vapour is evaporated from the leaves, so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
This means more water ids drawn up from the roots. This just carries on.

139
Q

What is a side effect of the way leaves are adapted for photosynthesis?

A

Transpiration.

140
Q

What do the stomata in a plant do?

A

They exchange gas and water vapour.

141
Q

What benefits does the transpiration stream have for plants?

A

1 - The constant stream of water from the ground helps to keep the plant cool
2 - It provides the plant with a constant supply of water for photosynthesis
3 - The water creates turgor pressure in the plant cells, which helps support the plant and stops it wilting.
4 - Minerals needed by the plant can be brought in from the soil along with the water.

142
Q

What four things is transpiration rate increased by?

A

An increase in light intensity
An increase in temperature
An increase in air movement
A decrease in air humidity

143
Q

How does light intensity affect transpiration rate?

A

The brighter the light, the greater the transpiration rate. Stomata begin to close as it gets darker. Photosynthesis can’t happen in the dark, so they don’t need to be open to let CO2 in. When the stomata are closed, water can’t escape.

144
Q

How does temperature affect transpiration rate?

A

The warmer it is, the faster transpiration happens. When it’s warm the water particles have more energy to evaporate and diffuse out of the stomata.

145
Q

How does air movement affect transpiration rate?

A

If there’s loads of air movement around the leaf, transpiration happens faster.
Not windy : The water vapour just surrounds the leaf and doesn’t move away. This means there’s a high concentration of water particles outside the leaf as well as inside it, so diffusion doesn’t happen as quickly.
Windy : The water vapour is swept away, maintaining a low concentration of water in the air outside the leaf. Diffusion then happens quickly, from an area of high concentration to an area of low concentration.

146
Q

How does air humidity affect transpiration rate?

A

If the air around the leaf is very dry, transpiration happens more quickly. This is like what happens with air movement.
Humid : There’s a lot of water in the air so not much different between inside and outside the leaf
Diffusion happens fastest when there’s a really high concentration in one place and a really low concentration in the other.

147
Q

What do plants need to balance water loss with?

A

Water uptake

148
Q

How are leaves adapted to reduce water loss?

A

A waxy cuticles covering the upper epidermis.
Most stomata are found on the lower surface of a leaf, where its darker and cooler.
Fewer and smaller stomata on plants which are in hot climates.

149
Q

What adaptation on a leaf helps to slow down diffusion of water out of the leaf?

A

Most stomata are found on the lower surface of a leaf where it’s darker and cooler.

150
Q

In what situation will a plant lose more water? (refer to stomata)

A

The bigger the stomata and the more stomata a leaf has, the more water the plant will lose.

151
Q

Explain the properties of stomata and how they help to preserve the plant.

A

They close automatically when supplies of water from the roots start to dry up. This prevents too much water loss, and the plant stays alive.

The guard cells have a special kidney shape which opens and closes the stomata at the guard cells go turgid or flaccid.

Thin outer walls and thickened inner walls make this opening and closing function work properly.

Open stomata allow gases in and out for photosynthesis.

They’re sensitive to light, so they open during the day and close at night. This allows them to conserve water without losing out on photosynthesis.

152
Q

What happens when the guard cells are turgid?

A

The stomata opens

153
Q

What happens when the guard cells are flaccid?

A

The stomata closes

154
Q

What are the three main minerals that plants need?

A

Nitrates
Phosphates
Potassium

155
Q

What do nitrates contain and what happens to a plant when it doesn’t have enough nitrates?

A

They contain nitrogen for making amino acids and proteins.
These are needed for cell growth. If a plant can’t get enough nitrates, it’s growth will be poor and it’ll have yellow older leaves.

156
Q

Why does a plant need nitrates?

A

For cell growth

157
Q

What do phosphates contain and why does a plant need them?

A

They contain phosphorous for making DNA and cell membranes.
Plants need phosphates for respiration and growth, plants without enough phosphate have poor root growth and discoloured older leaves.

158
Q

Why do plants need phosphates?

A

For respiration and growth.

159
Q

Why do plants need potassium and what happens if they don’t have enough?

A

To help the enzymes needed for photosynthesis and respiration.
If there’s not enough potassium in the soil, plants have poor flower and fruit growth and discoloured leaves.

160
Q

Magnesium is also needed in small amounts, but is still very important, what is magnesium used for?

A

It is required for making chlorophyll

Plants without enough magnesium have yellow leaves.

161
Q

The concentration of minerals in the soil is usually pretty low, so diffusion doesn’t work to get minerals from the soil into plants. Instead, how is it done?

A

Using active transport

162
Q

How does active transport work?

A

It uses up energy from respiration to help the plant pull minerals into the root hair against the concentration gradient.

163
Q

What is nearly all decomposition done by?

A

Micro-organisms like soil bacteria and fungi

164
Q

What is fungi?

A

A decomposer

165
Q

What does the rate of decay depend on?

A

Temperature
Amount of water
Amount of oxygen

166
Q

Do things decay faster with a warmer temperature or a cooler temperature?

A

A warmer temperature.

This is because it speeds up respiration in micro-organisms.

167
Q

Why does water speed up decay?

A

Things decay faster when they’re moist because micro-organisms need water

168
Q

What are detritivores?

A

An organism that feeds on dead and decaying material.
As they do this they break it up into smaller bits, this gives a bigger surface area for smaller decomposers to work on and so speeds up decay.

169
Q

Give an example of a detritivore.

A

Earthworms
Maggots
Woodlice

170
Q

What are saprophytes?

A

They also feed on decaying material but they do so by extracellular digestion - i.e. they feed by secreting digestive enzymes on to the material outside of their cells. The enzymes break down the material into smaller bits, which can then be absorbed by the saprophyte.

171
Q

Give an example of a saprophyte.

A

Fungi

172
Q

What do food preservation methods do?

A

Reduce the rate of decay

173
Q

Name 6 ways that you can preserve food to stop decay.

A 
Canning
Cooling
Freezing
Drying
Adding salt/sugar
Adding vinegar
174
Q

What is food preservation based on?

A

Reducing the amount of oxygen, moisture and heat that food can get.

175
Q

What is intensive farming used for?

A

Trying to produce as much food as possible with your land.

176
Q

What do farmers do to make the transfer of energy between organisms in a food chain more efficient, and therefore having a higher yield of crop?

A

Using herbicides to kill weeds
Using pesticides to kill insects
Battery farming animals

177
Q

What is battery farming?

A

Where animals are kept close together in small indoor pens, so that they’re warms and can’t move about. This saves them wasting energy as they move around, and stops them using too much energy to keep warm.

178
Q

What is hydroponics?

A

Where plants are grown without soil

179
Q

What are hydroponics used for?

A

They are often used for growing glass house tomatoes.

They can also be used to grow plants in areas with barren soil.

180
Q

How do plants grow using hydroponics if there’s no soil?

A

They are grown in nutrient solutions.

181
Q

What are the advantages of growing plants using hydroponics instead of soil?

A

Mineral levels can be controlled more accurately

Diseases can be controlled more effectively

182
Q

What are the disadvantages of growing plants using hydroponics instead of soil?

A

Lots of fertilisers need to be added

There’s no soil to anchor the roots and support the plants.

183
Q

Give three disadvantages of using intensive farming.

A

It is making the world we live in polluted
It is unattractive
It is a devoid of wildlife.

184
Q

What are the main effects of intensive farming?

A

Removal of hedges destroys the natural habitat of wild creatures, and causes soil erosion.
Careless use of fertilisers can pollute rivers and lakes.
Pesticides disturb food chains
Battery farming animals is cruel as they have very little space or freedom to move around.

185
Q

Why are pesticides bad?

A

They kill the animals that are pests but they also kill animals that aren’t pests such as bees and ladybirds.
Some tend to stick around ecosystems and are hard to get rid of
They travel along the food chain and kill the animals further up
They accumulate across the food chain.

186
Q

Explain what happened to our ecosystem because of a pesticide called DDT.

A

It seeps into the river
Small water plants take up a bit of it
Each tiny animal eats lots of small plants
Each small fish eats lots of tiny animals
Each eel eats a lot of small fish
Each otter eats lots of eels and ends up with a lot of pesticide
This resulted in otters almost being wiped out in England

187
Q

What is biological control?

A

Using living things to kill pests instead of chemicals.

188
Q

Aphids destroy roses and vegetables by eating them. How can you use biological control to get rid of aphids?

A

Ladybirds are aphid predators, so people release them into their fields and gardens to keep aphid numbers down.

189
Q

What are the advantages of biological control?

A

No chemicals are used, so there’s less pollution, disruption of food chains and risk to people eating the food that’s been sprayed.
There’s no need to keep repeating the treatment - like you would with chemical pesticides.

190
Q

What are the disadvantages of biological control?

A

The predator that you introduce might not eat the pest - making it useless
The predator could eat useful species
The predator’s population might increase and get out of control
The predator might not stay in the area where it’s needed.

191
Q

What is wrong with both pesticides and biological control?

A

It involves removing an organism from a food web which can affect organisms higher up in the food chain.

192
Q

What is the alternative to using intensive farming methods?

A

Organic farming

193
Q

What techniques are used in organic farming?

A 
Organic fertilisers
Crop rotation
Weeding by hand
Varying seed planting times
Biological control
194
Q

What is crop rotation?

A

Growing a cycle of different crops in a field each year. This stops nutrients from running out.

195
Q

Why does varying the seed planting times help with organic farming?

A

Sowing the seeds later or earlier in the season will avoid the major pests for that crop. This means the farmer wont need to use pesticides.

196
Q

What are the advantages of organic farming?

A

Uses fewer chemicals
Better for the environment
No battery farming

197
Q

What are the disadvantages of organic farming?

A

Takes up more space
More labour intensive
You can’t grow as much food

Biology (2 decks)

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