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AQA GCSE BIOLOGY PAPER 1 > B4- Organising animals and plants > Flashcards

B4- Organising animals and plants Flashcards

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1
Q

What do multicellular organisms with a small surface area to volume ratio often have?

A

often have trasnport systems

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2
Q

What 3 components is the circulatory system consist of?

A

blood
blood vessels
and the heart

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3
Q

What is the liquid your blood is pased on?

A

Plasma

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4
Q

What does plasma carry?

A

RBCS, WBCs and platelets suspended in it

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5
Q

What does Plasma also do

A

Carries many dissolved substances around your body

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6
Q

The average person has how many litres of blood?

A

4-5

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7
Q

What is a platelet

A

small fragments of cells

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8
Q

What does the plasma transport around your body

A

blood cells and some other substances around your body

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9
Q

Give three examples of what the plasma has to carry

A

Waste carbon dioxide
Urea formed in the liver
small, soluble products of digestion

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10
Q

Expand on how CO2 is carried in the blood

A

Waste CO2- produced by cells- carried to the lungs

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11
Q

Expand on how urea is carried in the blood

A

Urea- formed in liver from breakdown of EXCESS PROTEINS- carried to KIDNEY where it is removed from your blood to form urine

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12
Q

Expand on how small, soluble products of digestion is carried in the blood

A

small, soluble products of digestion pass into the plasma from small intestine and are transported to individual cells.

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13
Q

There are more __ ____ ___ than any other type of ___ cell in your body. About _ ____ in each cubic mm of blood

A

i) red blood cells
ii) blood
iii) 5 million

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14
Q

What do red blood cells do?

A

pick up oxygen from the air in your lungs and carry it to the cells where it is needed

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15
Q

What adaptations do red blood cells have?

A

Is a biconcave disc
Packed w haemoglobin
no nucleus

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16
Q

Why are they biconcave discs?

A

Being pushed in on both sides- increased sa to v ratio for DIFFUSION

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17
Q

Why are they packed with a red pigment called haemoglobin?

A

BINDS to oxygen

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18
Q

What;s the red pigment in the red blood cell?

A

haemoglobin

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19
Q

Why do they have no nucleus?

A

more space for haemoglobin

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20
Q

TRUE/FALSE WBCs are bigger than RBCs

A

True

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21
Q

TRUE/FALSE There are less WBCs than RBCs

A

true

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22
Q

What does a WBC have that a RBC doesnt?

A

A nucleus

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23
Q

What is the term given for the WBC that form antibodies against microorganisms?

A

lymphocytes

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24
Q

What do some white blood cells form? (lymphocytes)

A

antibodies

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25
Q

What do WBCs form?

A

part of the body’s defence sstem against harmful micro-organisms

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26
Q

What else do some WBC’s do?

A

form antitoxins against POISONS made by microogranisms

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27
Q

Yet others (phagocytes) what do these type of WBCs do?

A

engulf and digest invading bacteria and viruses

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28
Q

What can WBC’s do?

A

Some- form antibodies against microorganisms
Some- form antitoxins against poisons made by microogranisms
Some- engluf and digest invading bacteria and viruses

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29
Q

What do platelets not have?

A

A nucleus

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30
Q

Why are platelets very important?

A

helping the blood to clot at the site of a wound

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31
Q

What is blood clotting

A

a series of enzyme-controlled reactions that result in converting fibrinogen into fibrin. This produces a network of protein fibres that catches lots of red blood cells and more platelets to form a jelly-like clot that stops you bleeding to death. The clot dries and hardens to form a scab

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32
Q

After a series of enzyme-controlled reactions that result in converting fibrinogen into fibrin is produced (blood clotting) what happens?

A

This produces a network of protein fibres that catches lots of red blood cells and more platelets to form a jelly-like clot that stops you bleeding to death.

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33
Q

After the jelly-like clot is produced from the fibres catching it, what happens now?

A

The clot dries and hardens to form a scab

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34
Q

What does scabbing protect?

A

The new skin as it grows and stops bacteria entering the body through the wound

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35
Q

Red blood cells, white blood cells and platelets are suspended where?

A

In the blood plasma

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36
Q

Blood is carried around your body in three main types of blood vessels. What are they?

A

Arteries
Veins
Capillaries

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37
Q

What is a way to remember what a blood vessel is?

A

Vessel- container or think of it as the tube

Container carries blood

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38
Q

What does your artery do?

A

carries blood AWAY from the HEART to the organs of your body

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39
Q

What does your veion do?

A

carries blood AWAY from the ORGANS TOWARDS your heart

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40
Q

What do capillaries do?

A

Form a huge network of tiny vessels linking the ARTERIES and the VEINS

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41
Q

What sort of blood is the artery?

A

bright-red oxygenated blood

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42
Q

What sort of blood is the veins

A

Usually low in oxygen- purple-red colour

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43
Q

What do vein do not have?

A

A pulse

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44
Q

What sort of walls do veins have?

A

Thin walls

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45
Q

What do veins often have and why?

A

Valves to prevent backflow of blood

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46
Q

How is the blood squeezed back towards the heart in the veins?

A

by the action of the skeletal muscles

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47
Q

What do the arteries do as the blood is forced through them?

A

They stretch and then go back into shape afterwards (reference pulse)

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48
Q

Arteries have ____ walls containing ____ and _____ ____

A

i) thick
ii) muscle
iii) elastic fibres

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49
Q

Why is it very dangerous if an artery is cut?

A

Blood in arteries- under presssure

Blood will spurt out rapidly every time the heart beats

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50
Q

Capillaries are _____ with very ___ walls

A

narrow

thin

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51
Q

What does the thin walls allow capillaries to do?

A

enables sunstances such as oxygen and glucose to DIFFUSE easily out of the blood and into the cells

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52
Q

The substances produced by your cells such as CO2 can do what?

A

pass easily into the blood through the walls of the capillaries

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53
Q

How are the blood vessels arranged?

A

In a double circulatory system

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54
Q

Name the two transport systems

A
  1. carries blood from heart -> lungs and back again

2. carries blood from heart to all other organs of your body and back again

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55
Q

carrying blood from heart to lungs allows what?

A

oxygen and carbon dioxide to be exchanged with the air in the lungs

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56
Q

Where does the fully-oxygenated blood travel?

A

returns to the heart from the lungs

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57
Q

Where can fully oxygenated blood be sent off to?

A

Different parts of the body at high pressure

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58
Q

Why is fully oxygenated blood sent off to different parts of the body at high pressure?

A

More areas of your body can receive fully oxygenated blood quickly

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59
Q

What organ pumps blood around your body?

A

The heart

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60
Q

Why is the circulation around the body is made up of two pumps?

A

double circulation

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61
Q

The walls of your heart are almost entirely made of what?

A

Muscle

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62
Q

The muscles of the heart are supplied with _____ by the what?

A

oxygen

coronary arteries

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63
Q

What is the structure of the heart perfectly adapted for?

A

pumping blood TO your lungs and body

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64
Q

What do the two sides of the heart do?

A

fill and empty a the same time, giving a strong, coordinated heartbeat

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65
Q

Where does the blood enter?

A

the top chambers of the heart

ATRIA

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66
Q

The blood coming into the right atrium from the _____ ___ is deoxygenated blood from your body

A

vena cava

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67
Q

The blood coming into the left artrium in the ____ ___ is oygenated blood from you ____

A

pulmonary vein

lungs

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68
Q

What does the atria do?

A

contract together and force blood down into the ventricles

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69
Q

What do valves do?

A

stop the blood flowing backwards

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70
Q

What is the function of the ventricles?

A

contract and force blood out of the heart

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71
Q

What does the right ventricle do?

A

forces deoxygenated blood to the lungs in the pulmonary artery

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72
Q

What does the left ventricle do?

A

Pumps oxygenated blood around the body in a big artery called the aorta

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73
Q

What happens as blood is pumped into the pulmonary artery and the aorta?

A

valves close to make sure the blood flows in the right direction

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74
Q

The pulse is the…

A

sound of valves closing to prevent blood from flowing backwards

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75
Q

Why is the muscle wall of the left ventricle noticeably thicker?

A

Allows left ventricle to develop the pressure needed to force the blood through the arterial system all over the body

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76
Q

The blood leaving the right ventricle moves through the _____ ______ to your lungs where ____ ____ would _____ the delicate _____ network where __ ______ takes place

A

i) pulmonary arteries
ii) high pressure
iii) damage
iv) cappilary
v) gas exchange

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77
Q

Vena cava brings _______ blood INTO the HEART

A

deoxygenated

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78
Q

Pulmonary artery takes _______ blood TO the LUNGS

A

deoxygenated

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79
Q

Aorta carries _____ blood AROUND the BODY

A

oxygenated

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80
Q

Pulmonary veins bring ______ blood FROM the LUNGS

A

oxygenated

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81
Q

LEFT SIDE OF HEART= OXYGENATED BLOOD

A

RIGHT SIDE OF HEART=DEOXYGENATED BLOOD

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82
Q

What is on the right side of the heart?

A

pulmonary artery
vena cava
right atrium
right ventricle

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83
Q

What is on the left side of the heart?

A

aorta
pulmonary vein
left atrium
left ventricle

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84
Q

REMEMBER THE TOP STRUCTURES OF THE HEART IS FOR DOUBLE CIRCULATION- TOWARDS IT

A

pulmonary artery- to the lungs

Aorta- around the body

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85
Q

What happens to the coronary arteries that supply blood to the heart muscles in coronary heart disease?

A

the coronary arteries become narrow

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86
Q

Common cause of coronory heart disease?

A

buildup of fatty material on the lining of the vessels

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87
Q

What happens if the blood flow through the coronary arteries is reduced?

A

supply of oxygen to the heart muscle is also reduced- causing pain, a heart attack or even death

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88
Q

How may doctors often solve the problem of coronary heart disease?

A

A stent

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89
Q

What is a stent

A

metal mesh that is placed in the artery

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90
Q

How is a stent injected?

A

A tiny ballon is inflated to open up the blood vessel and the stent at the same time.
Balloon- deflated + removed but stent reminds in place, holding the blood vessel opened. As soon as this is done. the blood in the coronary artery flows freely.

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91
Q

What is an adv. of a stent

A

Doctors can put a stent in place without a general anesthetic

92
Q

What happens after a tiny balloon is inflated to open up the blood vessel and the stent?

A

the balloon is deflated and removed but the stent remains in place. holding the blood vessel open

93
Q

Stents can be used how?

A

to open up a blocked artery almost naywhere in the body

94
Q

What do many stents release?

A

drugs to prevent the blood clotting

95
Q

Doctors can also carry out ___ surgery; what does this concern?

A

bypass surgery

replacing the narror or blocked coonary arteries w/ bits of veins from other parts of the body?

96
Q

what does bypass surgery work for?

A

badly blocked arteries where stents cannot help

97
Q

What is the disadv. of bypass surgery

A

expensive and involves a risk associated with a general anaesthetic

98
Q

What do statins do?

A

reduce blood cholersterol levels- slows don rate at hich fatty materials is desposited in the coronary arteries

99
Q

Heart valves have to withstand what

A

a lot of pressure

100
Q

Overt time, what might happen to the valves?

A

start to leak, or become stiff and not open fully; less efficient hearts

101
Q

true/false doctors cannot operate and replace fualty heart valves

A

false

102
Q

What are mechanical valves made of?

A

titanium and polymers

103
Q

What is a adv. of mechanical valves?

A

Last a v long time

104
Q

What is a disadv. of mechanical valves?

A

take medice for the rest of your life to prevent blood from clotting around it

105
Q

What are biological valves based on?

A

valves taken from animals such as pigs or cattle, or even juman donors

106
Q

What is an adv. and disadv. of biological valves?

A

no need for any medication

but only lasts 12-15 years

107
Q

What is the resting rhythm of a healthy heart?

A

Around 70 beats a minute

108
Q

What is the resting heart beat controlled by?

A

a group of cells found in the right atrium of your heart that acts as your natural pacemaker

109
Q

what happens when a persons heart rate is too slow

A

not get enough oxygen

110
Q

what happens when a persons heart rate is too high

A

cannot pump nlood properly

111
Q

how may problems with the rhythm og the heart can be solved

A

with an artificial pacemaker

112
Q

What is an artificial pacemaker?

A

an electrical device used to correct irregularities in the heart rate

113
Q

Where is an artificial pacemaker planted?

A

in the chese

114
Q

how much do artificial pacemakers weigh?

A

between 20 and 50g

115
Q

How are artificial pacemakers attached?

A

attached to the heart by two wires

116
Q

What do artificial pacemakers do?

A

send strong, regular electrical signals to your heart that stimulate it to beat properly

117
Q

Modern pacemakers are often sensitive to what?

A

to what your body needs and only work when the natural rhythm gies wrong

118
Q

If you have a pacemaker fitted, what is a consequence?

A

regular medical check-ups

119
Q

why may an artificial heart be used rather than a pacemaker?

A

is not enough to restore a person’s health

120
Q

When people need a heart transplant, what do they have to wait for?

A

a donor heart that is a tissue match

121
Q

What do artificial hearts need a lot of?

A

machinery to keep them working

122
Q

What risk is there of having an artifical heart?

A

risk of blood clotting

123
Q

what can artificial heats also be used for?

A

to givea diseased heart a rest so that it can recover

124
Q

why are artificial hearts not widely used?

A

very expensive

125
Q

What must you need for a gas exchange system to work efficiently?

A

a large difference in cncentrations of the gas on different sides of the exchange membrane

126
Q

a large difference in cncentrations of the gas on different sides of the exchange membrane. What does this mean?

A

a steep conc. gradient

127
Q

How may humans maintain a steep conc. gradient?

A

By changing the composition of the air in the lungs, they maintain a steep concentration gradient for both ocygen diffusing into the blood and co2 diffusing out of the blood

128
Q

Where are your lungs found and protected?

A

in the chest and protected by the ribcage

129
Q

Where are the lungs seperated?

A

from the digestive organs beneath (in your abdomen) bu the diaphragm

130
Q

What is the diaphragm?

A

strong sheet of muscle

131
Q

What is the job of the ventilation system?

A

to move air in and out of lungs- providing an efficient surface for gas exchange in the alveoli

132
Q

How is ventilating the lungs brought about by?

A

contraction and relaxation of the intercostal muscles between the ribs and the diaphragm

133
Q

What does the contraction and relaxation of intercostal muscles do?

A

changes pressure inside the chest cavity so air is forced in or out of the lungs as a result of differences in pressure

134
Q

What happens when you breathe?

A

oxygen rich air moves into your lungs

135
Q

What does ‘oxygen-rich air moving into your lungs’ maintain?

A

maintains a steep conc. gradient with the blood

136
Q

What is the result of a steep concentration gradient with the blood?

A

oxygen continually diffuses into your bloodstream through the gas exchange surfaces of your alveoli

137
Q

What does breathing out do?

A

removes carbon-rich air from the lungs

138
Q

What does ‘removes carbon-rich air from the lungs’ maintain?

A

maintains a concentration gradient so CO2 can continually diffuse out of the blood stream into the air in the lungs

139
Q

Why is a concentration gradient maintained when breathing out?

A

CO2 can continually diffuse out of the blood stream into the air in the lungs

140
Q

What is the percentage of air breathed in by nitrogen oxygen and co2 and air breathed out?

A

nitrogen- both 80%
oxygen- 20% breathed in 16% out
coz- 0.04% breathed in, 4% breathed out

141
Q

Your lungs are specially adapted to make what?

A

gas exchange more efficient

142
Q

What are the lungs made up of?

A

clusters of alveoli that provide a very large surface area

143
Q

Why is a large surface area important for the alveoli?

A

most effective diffusion of carbon dioxide and oxygen

144
Q

What does the alveoli have a rich supply of?

A

blood capillaries

145
Q

Having a rich blood supply of blood capillaries does what?

A

maintains a conc. gradient in BOTH directions

146
Q

The ___ coming to the lungs is always relatively __in ____ and high in ______ ____ compared to the ____ air

A

i) blood
ii) low
iii) oxygen
iv) carbon dioxide
v) inhaled

147
Q

As a result, where does gas exchange takes place down?

A

the steepest concentration gradients possible

148
Q

Why does gas exchange take place in the steepest conc. gradients possible?

A

Makes exchange rapid and effective

149
Q

Why might the layer of cells between the air in the lungs and the blood in the capillaries very thin and how thin?

A

one cell wide

Allows diffusion to take place over the shortest possible distance

150
Q

What happens if all of the alveoli in your lungs were spread flat?

A

they would have a surface area equivalent to 10-15 table tennis tablets

151
Q

What does a good blood supply maintain?

A

concentration gradient for DIFFUSION by removing oxygen and bringing lots of carbon dioxide

152
Q

What does ventilation do?

A

moves air in and out and helps maitain a steep diffusion gradient

153
Q

What do the very thin alveolus walls do?

A

short distance between air and blood- make diffusion east

154
Q

Why does the alveolus have a spherical shape??

A

gives relatively large SA for diffusion

155
Q

What do epidermal tissues do?

A

cover the surfaces and protect them

156
Q

What do epidermal cells often secrete?

A

a waxy substance that waterproofs the surface of the leaf

157
Q

What does palisade mesophyll tissue contain?

A

lots of chloroplasts to carry out photosynthesis

158
Q

Spongy mesophyll tissue contains what?

A

some chloroplasts for photosynthesis but also has big air spaces and a large SA for diffusion of gases easier

159
Q

What are xylem and phloem ?

A

the transport tissue in plants

160
Q

What does xylem carry?

A

water and dissolved mineral ions from the ROOTS up to the LEAVES

161
Q

Phloem carries what?

A

dissolved food from the LEAVES around the PLANT

162
Q

Where is the meristem tissue located?

A

Growing tips of roots and shoots

163
Q

What is the meristem tissue made up of?

A

rapidly dividing plant cells that grow and differentiate into all the other cell types needed

164
Q

Leaves, stems and roots are all categorised into what?

A

plant organs

165
Q

What does the stomata do?

A

allow gases to move in and out of the leaf

166
Q

guard cells, what do they do?

A

control the opening and closing of the stomata

167
Q

Plants make ______ by photosynthesis in the ____ and other green parts

A

glucose

leaves

168
Q

Where is glucose needed in the plant?

A

all over

169
Q

Water and mineral ions move into the plant from the soil through the roots, but they are needed where?

A

by every cell of the plant

170
Q

What does the phloem do?

A

transport the sugars made by photosynthesis from the leaves to the rest of the plant?

171
Q

What does the transportation of sugars by the phloem also include?

A

transport to the growing areas of the stems and roots where the dissolved sugars are needed for making new plant cells.

172
Q

Where is food also transported to?

A

the storage organs where it provides an energy store for the winter

173
Q

Phloem is a _____ tissue- the phloem cells are ____

A

living

alive

174
Q

What is translocation?

A

the movement of dissolved sugars from the leaves to the rest of the plant

175
Q

Greenfly and other aphids are what?

A

plant pests

176
Q

What do plant pests do?

A

push their sharp mouthparts right into the phloem feed on the sugary fluid

177
Q

Mature xylem cells are _____

A

dead

178
Q

In woody plants like trees, what does the xylem make up?

A

the bulk of wood

179
Q

Where is the phloem found in the tree?

A

in a ring just underneath the bark

180
Q

How might young trees be particularly vulnerable to damage by animals?

A

If a complete ring of bark is eaten, transport in the phloem stops and the trees will die

181
Q

What are elephant yams?

A

plants that produce a large flower that releases a disgusting stench like rotten meat that attracts carrion beetles

182
Q

What happens to trapped insects in elephant yams?

A

trapped in flower
slippery, waxy walls stop them escaping
Day later- pollen coats beetles and they are able to escape for reproduction

183
Q

What sort of specialized cells are within the body of the plant and are arranged to form organs

A

palisade, spongy mesophyll, xylem, and phloem

184
Q

Give an example of a plant with a specialized defense tissue or organ

A

nettles have specialized hairs that act like hypodermic needles, injecting poison into any animal brushing past or attempting to eat them

185
Q

What does mesophyll tissue do?

A

carry out photosynthesis

186
Q

Why is it vital to move the food made by photosynthesis around the plant?

A

all the cells need sugars for respiration as well as for providing materials for growth

187
Q

Why is the movement of water and dissolved minerals from the roots really important?

A

the mineral ions are needed for the production of proteins and other molecules within the cells

188
Q

Why may a plant need water?

A

photosynthesis

hold itself upright

189
Q

Why may water hold the plant upright

A

plenty of water- vacuole presses the cytoplasm against cell walls, pressure of cytoplasm against cell walls gives support for young plants and for the structure of the leaves

190
Q

Explain why a plant needs a transport system

A

transport of food made in leaves and water and mineral ions taken from soil to rest of plant

191
Q

Describe the differences between xylem and phloem in a plant

A

Mature xylem- dead, found on inside of vascular bundles, water + mineral ions
Phloem-living, on the outside, glucose/ dissolved sugars

192
Q

How may protecting bark allows a forest to grow?

A

Phloem in trees found in a ring just underneath bark.
Soft bark of young trees vulnerable to damage by animals.
If complete ring of bark is eaten, transport of water from roots and
sugars from leaves stops and young tree will die.
Plastic covers protect young bark from animals.
Covers can be removed once trees are more mature and bark is harder.
If covers aren’t used, most of young trees are likely to be destroyed and
woodland will eventually die as old, mature trees are not replaced.

193
Q

What sort of system does plants have?

A

separate transport system

194
Q

All over the leaf surface, there are small openings known as what?

A

stomata

195
Q

When can the stomata be opened?

A

when the plant needs to allow air into the leaves

196
Q

What diffuses into the air spaces (stomata) and then into the cells down a concentration gradient?

A

Carbon dioxide

197
Q

What happens at the same time as CO2 diffuses into the stomata

A

oxygen produced by photosynthesis is removed from the leaf by diffusion into the surrounding air

198
Q

As CO2 is let in and O2 is diffused out, what does this maintain?

A

maintain a concentration gradient for oxygen to diffuse from the cells into the air spaces of the leaf

199
Q

What is the size of the stomata and their opening and closing controlled by?

A

the guard cells

200
Q

What also happens when the stomata is opened?

A

plants lose water vapor through them

201
Q

How does the plant lose vapour through the stomata?

A

water vapour evaporates from the cells lining the air spaces and them passes out of the leaf through the stomata by diffusion

202
Q

What is the loss of water vapour known as?

A

transpiration

203
Q

What happens as water evaporates from the surface of the leaves

A

More water is pulled up through the xylem to take up its place

204
Q

What is the constant movement of water molecules through the xylem from the roots to the leaves called?

A

transpiration system

205
Q

What is the transpiration system driven by?

A

the loss of water by evaporation of water from the leaves, out of the stomata
(anything that affects the rate of evaporation will also affect transpiration)

206
Q

Where is most of the water vapor lost in plants?

A

from the leaves

207
Q

Why is it important that plants can close the stomata?

A

to limit the loss of water vapour

208
Q

Explain how water moves up a plant in the transpiration stream

A

As water evaporates from leaf surface, more water is pulled up through
xylem to replace it.
Water moves into roots by osmosis to replace water moving up xylem.
Transpiration stream is constant movement of water molecules through
xylem from roots to leaves.

209
Q

Describe the process of transpiration

A

Water vapour evaporates from cells lining air spaces
and diffuses out of leaf through stomata
down a concentration gradient

210
Q

Why is it that anything that increases the rate of photosynthesis, will increase the rate of transpiration?

A

more stomata open up to let in carbon dioxide and when the stomatas are open, the rate at which water is lost by evaporation and diffusion increases

211
Q

Which conditions increase the rate of transpiration

A

hot, dry and windy conditions

212
Q

Why does hot,dry and windy conditions increase rate of transpiration?

A

more water evaporates from the cells and diffusion happens quicker

213
Q

How may wind increase the rate of evaporation and maintain a steep concentration gradient?

A

removing water vapour as it diffuses out

214
Q

How may temp. affect the rate of transpiration

A

increase in temp= diffusion occurs more rapidly (molecules move faster)
rate of photosynthesis also increases- more stomata will be open for gas exchance

215
Q

What 3 conditions affect the rate of transpiration

A

How windy it is
Temperature
How hot and dry it is

216
Q

What adaptation do most leaves have?

A

a waxy, waterproof layer (the cuticle) to prevent uncontrolled water loss

217
Q

Where are most of the stomata found in leaves and why?

A

underside of the leaves- protects them from the direct light and energy of the sun

218
Q

What happens if a plant begins to lose water faster than it is replaced by the roots?

A

The whole plant may wilt- protection mechanism against further water loss
(leaves collapse and hang down, greatly reduces the surface area available for water loss by evaporation)

219
Q

If a plant begins to lose water faster than it is replaced by the roots, the stomata…

A

closes- stops photosynthesis and risks overheating

This prevents most water loss and any further wilting

220
Q

What can a potometer be used for?

A

to show how the uptake of water by a plant changes in different conditions

221
Q

What does using a potometer give a good idea of?

A

the amount of water lost by the plant in transpiration

222
Q

Almost all of the water taken up by a plant is lost in transpiration, but a small amount is used in what?

A

metabolism, for example, photosynthesis

223
Q

Name the parts of the leaf that help the plant to reduce water loss under normal conditions

A

waxy cuticle

guard cells

224
Q

Describe the effect on plant transpiration of coating the top surface of the leaves in petroleum jelly

A

Petroleum jelly on top surface has little effect as few stomata covered.
Most stomata are found on underside of leaves and would be
unaffected.

225
Q

Why may water lillies have their stomata on the tops of their leaves

A

Stomata on underside would be under water and water could not be lost
through them.
Stomata on top surface enable effective gas exchange for
photosynthesis through direct exposure to sunlight.

AQA GCSE BIOLOGY PAPER 1 (8 decks)

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