B2- Organisation Flashcards
1
Q
Order these in size from smallest to biggest Tissue Cell Organ system Organ
A
Cell
Tissue
Organ
Organ system
2
Q
Define cell
A
Basic building blocks that make up all living organisms
3
Q
Define differentiation
A
The process by which cells become specialised for a particular job
4
Q
Define tissue
A
A group of similar cells that work together to form a particular function
5
Q
Define organ
A
A group of different tissues that work together to form a similar function
6
Q
Define organ system
A
A group of organs working together to perform a particular function
7
Q
Define enzyme
A
Catalyst produced by living things and a protien
8
Q
What does raising a temperature normally do to a chemical reaction
A
Speed it up
9
Q
What does the glands do
A
Produce digestive juices
10
Q
What function is the stomach and small intestines
A
Digest food
11
Q
What does the liver produce
A
Bile
12
Q
What does the small intestines absorb
A
Soluble food molecules
13
Q
What does the large intestines absorb
A
Water from undigested food leaving faeces
14
Q
Define catalyst
A
A substance which increases the speed of a reaction, without being changed or used up in the reaction
15
Q
Enzymes are all small proteins. True/false
A
False, large
16
Q
What are all enzymes made from
A
Chains of amino acids
17
Q
Why do enzymes have a special shape
A
So they can catalyse reactions
18
Q
What is the name of the diagram that shows an enzyme reaction
A
Lock and key
19
Q
What is the word to use instead of the enzyme died
A
Denatured
20
Q
What is the equation for the rate of the formula
A
1000/ time
21
Q
What do digestive enzymes do
A
Break down big molecules
22
Q
What do carbohydrases convert carbohydrates into
A
Simple sugars
23
Q
What do proteases convert proteins
A
Amino acids
24
Q
What do lipases convert lipids into
A
Glycerol and fatty acids
25
What neutralises the stomach acid and emulsifies fats
Bile
26
What does liver produce
Bile
27
Where is bile stored
Gall bladder
28
Where is bile released into after it's been stored
Small intestines
29
Is bile an acid or alkali
Alkali
30
Lungs are in the thorax. True/False
True
31
What protects the lungs
The rib cage
32
What in the lungs carries out gas exchange
Alveoli
33
What does the circulatory system do
Carries food and oxygen
34
What is the circulatory system made up of
Heart,blood vessels and blood
35
What does the right ventricle pump?
Deoxygenated blood to the lungs
36
What does the left ventricle pump
Oxygenated blood to the rest of the organs apart form the lungs
37
What are the walls on the heart mostly made up of?
Muscle tissue
38
What prevents back flow with the heart?
Heart vlalve
39
Name the 4 chambers of the heart
Left ventricle
Left atrium
Right ventricle
Right atrium
40
Blood flows to the aorta from the _ _
Vena Cava
41
What controls your resting heart rate?
Pace maker
42
What are the three types of blood vessels
- Arteries
- Capillaries
- Veins
43
Describe the walls of the arteries
Strong and elasticated because of the high pressure
44
Are capillaries big?
No they are very small
45
Arteries branch into_
Capillaries
46
How thick are capillaries walls
One cell
47
Where do veins take blood?
Back to the heart
48
What do red blood cells do?
Carry oxygen
49
What Is the term for the shape of the red blood cells
Biconcave disc
50
What is an advantage of the red blood cells shape
Larger surface area for absorbing oxygen
51
Do red blood cells have a nucleus
No
52
What is the red pigment in red blood cells called
Haemoglobin
53
What is the process called when a white blood cells gobbles a microbes
Phagocytosis
54
What helps blood clots
Platelets
55
No platelets have a nucleus
No
56
What does plasma do
The Liquid that carries everything in the blood
57
What do stents do?
Keep the arteries open
58
What is coronary heart disease?
Coronary artery gets blocked
59
What do statins reduce?
Reduce cholesterol
60
What is cholestrol?
An essential lipid
61
What are advantages of statins?
- Reduce the risk of strokes, coronary heart disease, heart attacks
- Increase the amount of good cholesterol
- prevent other dieaseses
62
What are disadvantages of statins?
- Haveto take a drug regularly
- Negative side effects
- Effect isn't instant
63
What might a doctor do to somebody who has had heart failure
Perform a heart transplant or an artificial heart
64
What are advantages of an artificial heart
-Less likely to be rejected by the body's immune system
65
What are disadvantages to do with an artificial heart?
```
The surgery can lead to
-Bleeding
-Infections
An artificial heart also doesn't work as well as a natural one
-The patient also has to take drugs
```
66
What two things can faulty heart valves be replaced by
Biological and mechanical valves
67
What 3 things can weaken heart valves
- Heart attacks
- Old age
- Infection
68
How can severe heart valves be treated
Replacing the valve
69
What are the two types of valves?
Mechanical and biological
70
Is artificial blood a thing
Yes
71
Is artificial blood often used
Only in emergencies
72
Define health
The state of physical and mental wellbeing
73
What is a communicable disease
A disease that can be spread from person to person or between animals and people
74
What is an example of a non-communicable disease
- Cancer
- Asthma
- Coronary heart disease
75
Define non-communicable disease
A disease that cannot be spread from person to person or between animals and people
76
What are 3 things that impact your health
- Diet
- Stress
- Life situation
77
What is cancer caused by
Uncontrolled cell growth and division
78
Define benign tumor
A tumor grows in one place and doesn't spread to other parts of the body
79
Define malignant tumor
A tumor starts grows in one place and spreads to other parts of the body
80
What are 5 main risk factors for cancer
- Smoking
- Obesity
- UV exposure
- Viral infections
- Genetics
81
What are stems,roots and leaves categorised into
Organs
82
What is the function and structure of the epidermal
Coveredina waxy layer to prevent water loss
83
What is the function and structure of the upper epidermis
Transparent so light can get through
84
What is the function and structure of the palisade layer
Lots of chloroplast
85
What is the function and structure of the xylem and phloem
They form a network of vascular bundles which deliver water to the entire leaf and take away glucose
86
What is the function and structure of the tissue of the leaf
Adapted for gas exchange
87
What does the phloem tube do
Transports food
88
What is the name of the process the phloem tube does
Translocation
89
What does the xylem tube do
Transports water up. It carries water and mineral ions
90
What is the name of the process the xylem tube does
Transpiration stream
91
What is transpiration
The loss of water form the plant
92
What causes transpiration
Evaporation and diffusion
93
Where does most transpiration happen
The leaves
94
Transpiration is a _ _ of the way leaves are adapted for _
Side-effect
| Photosynthesis
95
What 4 main things impact transpiration rates
- Light intensity
- Temperature
- Air flow
- Humidity
96
What do guard cells do
Open and close the stomata
97
Why might somebody get an artificial pacemaker
An irregular heart beat
98
What does iodine test for
Starch
99
What does it mean if the iodine goes dark blue/ black
There is starch present
100
What does it mean if the iodine makes the object go orange/ brown
There is no starch present
101
What colour does iodine make go when the test is positive for starch
Dark blue/ black
102
What colour does iodine make go when the test is negative for starch
Orange / brown
103
What would you use to test for starch
Iodine
104
What would you use to test for protein
Burette
105
What does burette test for
Protein
106
What does it mean if after adding burette the food goes purple
There is protein present
107
What colour will burette go if there is protein present
Purple
108
What does it mean if after adding burette the food goes blue
There is no protein present
109
What colour will burette go if there is no protein present
Blue
110
What does the Benedict test do
It test for sugars
111
What is the test for sugars
The Benedict test
112
Explain how you would test for sugars
You would use the Benedict test and put it into a water bath of 60° +
113
What colours will the Benedict solution go if there is sugar present
Red or
Green or
Orange
114
When the Benedict test is positive it will go one of three colours order them from the strongest to least strong
Red
Orange
Green
115
What does is mean if the Benedict solution goes red
There is a lot of sugar
116
What does is mean if the Benedict solution goes orange
There is sugar present
117
What does is mean if the Benedict solution goes green
There is a little bit of sugar present
118
What colour will the Benedict solution go if there is no sugar
Blue
119
What colour will the Benedict solution go if the test is negative
Blue
120
What does it mean if the Benedict solution goes blue
There is no sugar present
121
What are the two top halves of the heart called
○ Right atrium
| ○ Left atrium
122
What are the two bottom halves of the heart called
○ Right ventricle
| ○ Left ventricle
123
What does the pulmonary artery do
Brings blood to the lungs
124
What does the aorta do
Bring blood to the body
125
What does the pulmonary vein
Brings blood from the lungs to the heart
126
What do valves do
Stop back flow
127
Why is preventing back flow important
○ Stop blood mixing
| ○ Ensuring oxygenated blood is going to our body and deoxygenated to lungs
128
What are aphids and what do they do
○ Insect
| ○ Pierce the phloem and take glucose
129
What does magnesium deficiency called
Chlorosis
130
What is a consequence of a magnesium deficiency in a plant
Lack of chlorophyll
| Stunted growth
131
What is a consequence of a nitrate deficiency in a plant
Used to make proteins
| Stunted growth
132
What are ways to test if a plant is deficient in something
○ Look in a booklet
○ Look on the internet
○ Take it to a lab
133
What is fagasitosis
The white blood cell engulfs the pathogen
134
What is a cell?
The basic building block of a living
| organism.
135
What is a tissue
A group of cells with a similar structure and
function working together. For example,
muscular tissue contracts to bring about
movement.
136
What is an organ
A collection of tissues working together to
perform a specific function. For example,
the stomach contains glandular, muscular
and epithelial tissues
137
What is an organ system
A group of organs working together to perform
specific functions. For example, the digestive
system contains organs such as the stomach,
the small intestine and the large intestine.
138
What is the main function of the digestive
| system
To digest food and absorb the nutrients
| obtained from digestion
139
What is the role of the pancreas and the salivary
| gland in the digestive system
The pancreas and the salivary gland are glands
which produce digestive juices containing
enzymes.
140
What is the role of the stomach in the digestive
| system
Produces hydrochloric acid - which kills any
bacteria present and provides the optimum
acidic pH for the protease enzyme to
function
141
What is the role of the small intestine in the
| digestive system?
The small intestine is the site where soluble
food molecules are absorbed into the
bloodstream
142
What is the role of the liver in the digestive
| system?
Produces bile (stored in the gallbladder)
which emulsifies lipids and allows the lipase
enzyme to work more efficiently
143
What is the role of the large intestine in the
| digestive system
Absorbs water from undigested food,
| producing faeces
144
What is the role of enzymes in the digestive
| system
Enzymes act as biological catalysts which
speed up the rate of biological reactions (the
breakdown of food) without being used up.
145
How does the shape of an enzyme affect its
| function?
Enzymes have a specific active site which is
| complementary to their substrate
146
What is metabolism
The sum of all the reactions in an
| organism
147
What types of metabolic reactions do enzymes
| catalyse
● Building larger molecules from smaller molecules eg.
glucose to starch.
● Changing one molecule to another eg. glucose to
fructose.
● Breaking down larger molecules into smaller
molecules eg. carbohydrates to glucose.
148
What is the lock and key hypothesis of enzyme
| function?
The shape of the enzyme active site and the
substrate are complementary, so can bind
together to form an enzyme-substrate
complex
149
How does temperature affect enzyme action
Up to a certain point, increasing temperature increases
enzyme action, as molecules have a higher kinetic
energy. Above a certain temperature, the shape of the
active site is altered and the enzyme becomes
denatured, so it can no longer catalyse the reaction. The
optimum temperature is around 37°
150
How does pH affect enzyme function
The optimum pH for most enzymes is 7 (apart
from proteases in the stomach). If the pH is too
extreme, the shape of the active site may be
altered and the enzyme may no longer work
151
Where are carbohydrases, proteases and lipases
| produced in the body
```
● Carbohydrases: amylase - salivary gland and
pancreas; maltase - small intestine.
● Proteases: pepsin - stomach; others -
pancreas and small intestine.
● Lipases: pancreas and small intestine
```
152
What is the role of carbohydrases in the digestive
| system?
Carbohydrases break down carbohydrates into
monosaccharides and disaccharides. Amylase
breaks down starch into maltose, and maltase
breaks down maltose into glucose.
153
What is the role of proteases in the digestive
| system
Proteases break down proteins into amino
| acids.
154
What is the role of lipases in the digestive
| system?
Lipases break down lipids into fatty acids
| and glycerol
155
How are the products of digestion used?
They are used to build bigger molecules
such as carbohydrates and proteins.
Glucose is used as a substrate in
respiration.
156
Where is bile made and stored in the body
Bile is made by the liver and stored in the
| gallbladder
157
What is the role of bile in the digestive system?
● Bile is an alkaline substance which neutralises
the hydrochloric acid secreted by the stomach.
● Bile emulsifies lipids to form droplets - this
increases the surface area for the lipase
enzyme to work on.
158
What is the heart?
An organ that pumps blood around the
| body
159
What is the purpose of the circulatory system
Carries oxygen and other useful
substances to bodily tissues, and
removes waste substances
160
How does the double circulatory system work
● One pathway carries blood from the heart to
the lungs - where the gaseous exchange of
oxygen and carbon dioxide takes place.
● One pathway carries blood from the heart to
the tissues.
161
Where does blood pumped by the right
| ventricle go?
The lungs
162
Where does blood pumped by the left
| ventricle go?
Body tissues
163
Why is the double circulatory system important
It makes the circulatory system more
efficient - for example, oxygenated blood
can be pumped around the body at a
higher pressure by the left ventricle
164
How many chambers does the heart have and
| what are they called?
4 - right atrium, right ventricle, left atrium,
| left ventricle
165
Why is the wall of the left ventricle thicker
The left ventricle has to pump blood at a
| higher pressure around the whole body
166
What are the four main blood vessels associated with
| the heart
● Aorta (left) - carries oxygenated blood from the heart to the
body.
● Pulmonary vein (left) - carries oxygenated blood from the lungs
to the heart.
● Vena cava (right) - carries deoxygenated blood from the body to
the heart.
● Pulmonary artery (right) - carries deoxygenated blood from the
heart to the lungs
167
What is the purpose of valves in the
| heart?
Prevent the backflow of blood
168
What is the purpose of coronary arteries
Coronary arteries supply the heart
| muscle with oxygenated blood.
169
Describe the process of blood flow through the heart
● Blood enters the right atrium via the vena cava, and the
left atrium via the pulmonary vein.
● The atria contract, forcing blood into the ventricles and
causing valves to shut.
● After the ventricles contract, blood in the right ventricle
enters the pulmonary artery (to the lungs) and blood in
the left ventricle enters the aorta (to the body).
170
What is the approximate value of the
| natural resting heart rate?
70 beats per minute
171
How is the heart rate controlled
Heart rate is controlled by a group of cells in
the right atrium which act as a pacemaker.
They release waves of electrical activity
which cause the heart muscle to contract
172
How can an abnormal heart rhythm be treated?
Irregular heart rhythms can be treated
using an artificial pacemaker, which
sends out electrical signals to correct the
heart’s rhythm
173
What are the three types of blood vessel in the
| body
● Arteries
● Veins
● Capillaries
174
How are arteries adapted for their function
● Function: carry blood away from the heart.
● Thick muscle layer - adds strength to resist high
pressure.
● Thick elastic layer - allows arteries to stretch
and recoil - in order to withstand high pressure
175
How are veins adapted for their function?
● Function: carry blood towards the heart
● Wide lumen - enables low pressure
● Valves - prevent backflow of blood
176
How are capillaries adapted for their function
● Function: enable transfer of substances between
the blood and tissues.
● Walls are one cell thick - short diffusion path.
● Permeable walls - substances can diffuse across.
● Narrow lumen - blood moves slowly - more time
for diffusion.
177
How would you calculate the rate of blood flow
Volume of blood / number of minutes
178
Where are the lungs found in the body?
The lungs are located in the thorax (within the
chest). They are protected by the ribcage and
separated from the rest of the abdomen by
the diaphragm
179
What tissues and organs make up the
| gas exchange system
```
● Trachea
● Intercostal muscles
● Bronchi
● Bronchioles
● Alveoli
● Diaphragm
```
180
Explain how the lungs are ventilated by
| the action of intercostal muscles
● Intercostal muscles contract
● Ribcage moves upwards and outwards
● Diaphragm flattens and volume of the chest increases
● Increased volume results in decreased pressure
● Air is drawn into lungs down pressure gradient
The inverse occurs when air moves out of the lungs.
181
Describe how gas exchange occurs at the alveoli
● Oxygen diffuses from the alveoli into the
capillary bloodstream down its concentration
gradient.
● Carbon dioxide diffuses from the capillary into
the alveoli down its concentration gradient.
182
Describe how alveoli are adapted for gas
| exchange
● Small and arranged in clusters - larger surface
area.
● Rich blood supply - maintains concentration
gradient.
● Thin alveolar wall - short diffusion pathway.
183
How would you calculate the breathing rate
Number of breaths / number of minutes
184
What substance carries the different components of
| blood around the body
Plasma
185
What substances are transported by plasma
```
● Red blood cells
● White blood cells
● Platelets
● Carbon dioxide
● Urea
● Products of digestion
```
186
What is plasma
A yellow liquid within blood that
| transports substances around the body
187
What is the purpose of red blood cells in blood
Transport of oxygen around the body
188
How are red blood cells adapted for their
| function?
● Biconcave shape - increased surface area to
volume ratio.
● No nucleus - more room for haemoglobin to
bind to oxygen.
● Contain haemoglobin - binds to oxygen.
189
What is the purpose of white blood cells in
| blood?
They form part of the immune system,
which protects the body from invading
pathogens
190
How are white blood cells adapted for
| their function?
● Have a nucleus - contains DNA which codes for
proteins
● Can produce antibodies
● Can produce antitoxins
● Can engulf and digest pathogens (phagocytosis)
191
What is the purpose of platelets in blood?
Platelets are small cell fragments which aid
| the clotting of blood at the site of a wound
192
Why is the function of platelets important
● Platelets aid in the process of blood clotting
(conversion of fibrinogen to fibrin). As a result, red
blood cells are trapped in the fibrin network,
forming a clot which prevents excessive bleeding.
Scab formation (after the clot has dried) prevents
bacteria from entering the wound.
193
What is coronary heart disease
Coronary heart disease occurs when the
coronary arteries that supply the heart muscle
become blocked with a buildup of fatty material.
This restricts the supply of oxygen to the heart,
possibly leading to a heart attack or death.
194
What is a stent and how does it work
A stent is a metal mesh tube that is inserted
into a blocked artery so that it remains open.
The stent is inflated using a balloon, which is
later removed to allow blood to flow freely.
195
What are the advantages and disadvantages of
| stents
```
Advantages
● Insertion can be carried out without general anaesthetic
● Quick recovery time
● Lower the risk of a heart attack
Disadvantages
● Risk of postoperative infection
● Risk of blood clots at site of stent
```
196
What are statins
Statins are drugs which reduce the level of
LDL (bad) cholesterol which contributes to
the development of coronary heart disease.
197
What are the advantages and disadvantages of statins
```
Advantages
● Reduce risk of strokes, coronary heart disease and heart
attacks
● Increase level of HDL (good) cholesterol
Disadvantages
● Have to be taken continuously
● May have side effects
● Effect may not be immediate
```
198
What is a heart bypass surgery?
A surgery where blocked coronary
arteries are replaced with sections of
veins taken from other parts of the body
199
What are the consequences of leaky heart
| valves
Blood flows in the wrong direction, causing
the heart to become less efficient. Patients
may become breathless and die as a result.
200
What types of valves can replace leaky valves
● Mechanical - made of metal or polymers
● Biological - taken from animals (pigs,
sometimes humans)
201
What are the advantages and disadvantages of
| mechanical valves
```
Advantages
● Last for a very long time
Disadvantages
● Need to take medication to prevent blood
clotting around valve
```
202
What are the advantages and disadvantages of
| biological valves?
Advantages
● Work very well - no medication required
Disadvantages
● Only lasts 12-15 years
203
What is the purpose of an artificial heart
Artificial hearts are intended to support a
patient’s heart while they wait for a suitable
donor heart
204
What are the advantages and disadvantages of
| artificial hearts
Advantages
● Less likely to be rejected by immune system
● Allows damaged heart to rest to help recovery
Disadvantages
● Risk of infection due to surgery
● Risk of blood clots
● Have to take blood-thinning drugs
205
What is health
Health is the state of physical and mental
| wellbeing
206
What is a communicable disease
A disease caused by a pathogen which can
be transmitted from one person to another
eg. the flu.
207
What is a non-communicable disease?
A disease which can not be transmitted
| from person to person eg. cancer
208
How can diet affect health
● Too little food / lack of nutrition - anaemia,
vitamin deficiencies.
● Too much food / too much unhealthy food -
obesity, type 2 diabetes
209
How can stress affect health
Prolonged stress is linked to a wide range
of health problems including heart
diseases, cancers and mental health
issues
210
How can life situations affect health
Many life factors such as location, gender,
financial status, ethnic group and
healthcare provision can impact a person’s
mental and physical health.
211
Give examples of how health problems can interact
● Infection with certain viruses can lead to cancer eg. hepatitis
infections can lead to liver cancer.
● A compromised immune system (eg. due to cancer) can lead to
a higher risk of infection with communicable diseases.
● Immune reactions caused by a pathogen can trigger allergic
reactions.
● Problems with physical health can lead to mental health issues.
212
What is a risk factor
A risk factor is an aspect of a person’s lifestyle
or a substance found in the body or the
environment which can increase the risk of a
disease
213
What is a causal mechanism
A mechanism which demonstrates how one
| factor biologically influences another
214
How do diet, smoking and exercise affect the
| development of cardiovascular disease
● Diet: high levels of LDL cholesterol causes arteries to
become blocked, increasing blood pressure and the risk of
a heart attack.
● Smoking: nicotine increases heart rate; other chemicals
damage the artery lining and increase blood pressure.
● Exercise: lowers blood pressure, reducing strain on the heart.
215
How does obesity affect the development of type 2
| diabetes?
● Obesity is strongly linked with the onset of
type 2 diabetes - a disease in which the body
stops responding to insulin.
216
How does alcohol affect liver and brain
| function
● Excessive long-term alcohol use may lead
to liver cirrhosis (scarring of the liver).
● Increases risk of liver cancer.
● Damages brain tissue and nerve cells.
217
How does smoking affect the development of
| lung disease and lung cancer
● Tar in tobacco can damage the alveoli of the
lungs, leading to chronic obstructive
pulmonary disease (COPD).
● Tar also damages the cells which line the
lungs, leading to lung cancer
218
How do smoking and alcohol affect unborn babies
● Carbon monoxide from tobacco smoke reduces the
amount of oxygen the foetus receives, which can lead
to premature birth or stillbirth.
● Alcohol passes across the placenta and damages the
developing foetus. Once born, the baby may have a
number of deformities and health problems as part of
foetal alcohol syndrome.
219
How do carcinogens affect the development of
| cancer?
Ionising radiation is a type of carcinogen
which can cause mutations in DNA, potentially
leading to cancer
220
What is cancer
Cancer is the development of a tumour
| as a result of uncontrolled cell division
221
What is a benign tumour
● A tumour that is contained in one location,
usually within a membrane.
● They are not cancerous and do not invade other
parts of the body.
● Can grow large very quickly - may cause
damage to another organ
222
What is a malignant tumour?
● A tumour that can spread around the body via
the blood and lymphatic system.
● Can invade other tissues (metastasis).
● Cells divide more rapidly and have a longer
lifespan.
● Disrupts healthy tissues and may lead to death
223
How is epidermal tissue adapted for its function?
Epidermal tissue covers the entire plant. It
has a waxy cuticle which helps reduce water
loss from the leaf surface
224
How is palisade mesophyll tissue adapted for
| its function
Palisade mesophyll tissue contains lots of
chloroplasts which allows photosynthesis to
progress at a rapid rate
225
How is spongy mesophyll tissue adapted for its
| function
Spongy mesophyll tissue has lots of air
spaces which allow gases (including
oxygen and carbon dioxide) to diffuse in
and out
226
How is the xylem adapted for its function
● Made up of dead cells which form a continuous
hollow tube - allows the movement of water and
mineral ions from the roots to the leaves.
● Strengthened by lignin - makes the vessel strong and
waterproof.
● Has bordered pits - allow minerals to be transported
to specific places
227
How is the phloem adapted for its function
● Made up of elongated living cells.
● Cells have sieve plates that connect them
together - cell sap can move through plates
into other cells.
● Sieve tube cells have few organelles to allow
the efficient transport of substances
228
How is meristem tissue adapted for its function
Made up of stem cells which can
differentiate into many different cell types,
allowing the plant to grow
229
What tissues does the leaf organ contain
```
● Epidermis
● Palisade mesophyll
● Spongy mesophyll
● Xylem
● Phloem
● Guard cells
```
230
What is the function of guard cells
Guard cells control the opening and closing
of the stomata, according to the water
content of the plant
231
How are stomata adapted for their function
Stomata allow the control of gaseous exchange and
water loss from the leaf.
● More stomata on the base of the leaf - minimises
water loss as this side is cooler and shaded.
● Have guard cells which control their opening and
closing
232
How are root hair cells adapted for their function
Root hair cells allow the uptake of water and
mineral ions from the soil.
● Large surface area - maximises rate of
absorption.
● Contain lots of mitochondria -- release energy
for active transport of mineral ions
233
What is translocation
Translocation is the movement of
dissolved sugars from the leaves to other
parts of the plant
234
What is transpiration
Transpiration is the evaporation of water
| vapour from the surface of a plant
235
How does transpiration work
● Water evaporates from the leaf surface via the
stomata.
● Water molecules cohere together - more water is
pulled up the xylem in an unbroken column.
● More water is taken up from the soil - creating a
continuous transpiration stream
236
How does temperature affect the rate of transpiration
Increasing the temperature increases the rate
of transpiration.
● Higher rate of evaporation and diffusion of
water - therefore rate of transpiration is
increased
237
How does humidity affect the rate of transpiration
Increasing relative humidity decreases the rate of
transpiration.
● High relative humidity will reduce the water
vapour concentration gradient. The rate of
evaporation will decrease, and so will the rate of
transpiration
238
How does wind speed affect the rate of transpiration
Increasing wind speed/air movement increases the
rate of transpiration.
● Increased air movement lowers water vapour
concentration outside of the leaf. This increases the
water vapour concentration gradient, thereby
increasing the rate of evaporation and transpiration
239
How does light intensity affect the rate of
| transpiration
Increasing the light intensity increases the rate of
transpiration.
● The rate of photosynthesis increases, so more
stomata open. This allows the rate of evaporation
to increase, increasing the rate of transpiration
