Organisms Exchange Substances With Their Environment Flashcards
1
Q
What is the relationship between size and surface area to volume ratio?
A
The larger the organism, the smaller the surface area to volume ratio.
2
Q
What are some key terms associated with surface area to volume ratios?
A
- Surface area
- Volume
- Ratio
- Diffusion
- Exchange
- Radiation
3
Q
What factors affect the rate of diffusion?
A
- Higher temperature
- Shorter distance
- Larger concentration gradient
- Larger surface area
4
Q
What is the surface area formula for a cube?
A
Length x width = ? x the number of sides
5
Q
What is the volume formula for a cube?
A
Length x height x width
6
Q
Fill in the blank: The ______ the organism, the ______ the surface area to volume ratio.
A
[larger], [smaller]
7
Q
How do single-celled organisms exchange substances?
A
They have a large surface area to volume ratio and can easily exchange substances across their membrane.
8
Q
How does the size of an animal affect its surface area to volume ratio?
A
The larger the animal, the smaller the surface area to volume ratio, making it harder to exchange substances.
9
Q
What adaptations do larger animals have for exchange surfaces?
A
They have evolved specialized exchange surfaces.
10
Q
What is the impact of heat loss in newborns compared to adults?
A
A newborn baby loses heat ~4 times quicker than an adult.
11
Q
What percentage of their body weight do newborns eat daily to cope with heat loss?
A
80-90% of their body weight.
12
Q
Fill in the blank: Oxygen, carbon dioxide, ______, gases, lungs, membrane, diffusion, concentration gradient, ventilation, circulation.
A
[exchange]
13
Q
Fill in the blank: Oxygen, size, respiring, metabolic rate, ______, oxygen, surface area, efficiency.
A
[volume]
14
Q
What are spiracles in insects?
A
Small openings through which air enters and exits the insect
Spiracles are similar to guard cells that open and close stoma in plants.
15
Q
What is the tracheal system in insects?
A
A system of pipes that connects air outside to tissues that require oxygen
The tracheal system is held open by spiral bands of cuticle.
16
Q
What adaptations do insects have to minimize water loss?
A
- Exoskeletons that are hard and waxy
- Spiracle valves that can close
These adaptations help to minimize evaporation.
17
Q
How is the concentration gradient for oxygen created in insects?
A
Lower oxygen concentration in cells compared to the outside air allows oxygen to diffuse into cells
Oxygen is used in respiration.
18
Q
How is the concentration gradient for carbon dioxide created in insects?
A
Carbon dioxide produced by respiring cells at the end of tracheoles causes high concentration here
High levels of carbon dioxide lead to spiracles opening wider, increasing air movement.
19
Q
What is the role of muscle contraction in insect ventilation?
A
Muscle contraction changes volume and pressure, facilitating movement of air in and out of trachea
This process maintains concentration gradients and speeds up gas exchange.
20
Q
Describe the structure of gills in fish.
A
Gills consist of filaments and lamellae that increase surface area for gas exchange
Gills are supported by water flowing over them, which helps in gas extraction.
21
Q
What is countercurrent flow in fish?
A
Blood and water flow in opposite directions, maintaining a concentration gradient for oxygen diffusion
This allows more oxygen to diffuse from water to blood along the entire length of the lamellae.
22
Q
What are the key adaptations of gills for efficient gas exchange?
A
- Large surface area due to many filaments and lamellae
- Short diffusion distance as epithelial layers are only one cell thick
- Countercurrent flow maintains concentration gradient
These adaptations ensure efficient oxygen uptake and carbon dioxide removal.
23
Q
What is the difference between tidal and unidirectional ventilation?
A
- Tidal ventilation: air moves in and out in the same direction (e.g., mammals)
- Unidirectional ventilation: air flows in one direction (e.g., fish)
Fish have unidirectional ventilation to maximize oxygen extraction from water.
24
Q
Fill in the blank: Fish have a waterproof and ________ outer covering.
A
gas-tight
25
True or False: The concentration of oxygen in water is approximately 21%.
False
26
Why is it necessary for fish to have a specialized exchange surface?
Their surface area to volume ratio is too small to exchange gases effectively across their surface
## Footnote
Gills compensate for this limitation.
27
How does the movement of blood and water maintain the diffusion gradient in fish gills?
Movement ensures that blood continually meets water with higher oxygen concentration
## Footnote
This prevents equilibrium from being reached, allowing ongoing diffusion.
28
What happens to oxygen levels in water as fish extract oxygen?
About 80% of the oxygen in the water diffuses into the blood
## Footnote
This is more efficient than in parallel flow systems.
29
What is the significance of having lamellae on gill filaments?
They provide a large surface area for gas exchange
## Footnote
This adaptation allows for more oxygen to be supplied for respiration.
30
What is the role of the operculum in fish?
It covers the gills, aiding in the ventilation process
## Footnote
The operculum helps maintain water flow over the gills.
31
What is gas exchange in plants?
The process by which plants take in carbon dioxide and release oxygen during photosynthesis, and vice versa during respiration.
32
What adaptations do leaves have for gas exchange and water loss?
Adaptations include:
* Thin and flat shape
* Large surface area to volume ratio
* Stomata for gas exchange
* Guard cells to regulate stomata opening
* Waxy cuticle to reduce water loss.
33
How does gas exchange in plants compare to that in insects?
Plants use stomata for gas exchange, while insects have specialized structures called spiracles.
34
What are the equations for respiration and photosynthesis?
Photosynthesis: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP.
35
Do plants carry out respiration or photosynthesis?
Both.
36
What is chlorophyll's role in plants?
Chlorophyll is the pigment that absorbs light energy for photosynthesis.
37
When do plants photosynthesize and respire?
Plants photosynthesize during the day and respire both day and night.
38
What happens when respiration rate is higher than photosynthesis?
There is a net uptake of oxygen and loss of carbon dioxide from the cells.
39
What occurs when the rate of photosynthesis exceeds respiration?
There is a net uptake of carbon dioxide and loss of oxygen from the cells.
40
Describe the shape of a leaf.
Thin and flat.
41
What is the significance of a leaf's large surface area to volume ratio?
It maximizes light absorption and shortens the diffusion path for gases.
42
What structures in leaves facilitate gas exchange?
Stomata and guard cells.
43
When do stomata close and why?
Stomata close to prevent water loss, especially at night.
44
What is transpiration?
The evaporation of water from a plant’s surface, particularly through stomata.
45
Is transpiration a passive process?
Yes, it does not require metabolic energy (ATP).
46
What environmental factors affect the rate of transpiration?
* Temperature
* Humidity
* Air movement
* Light intensity.
47
How does high temperature affect transpiration rate?
It increases kinetic energy of water molecules, leading to increased transpiration.
48
How does humidity affect the water potential gradient?
High humidity decreases the water potential gradient, leading to decreased transpiration.
49
What effect does air movement have on transpiration?
It disperses the humid layer at the leaf surface, increasing the water potential gradient and thus increasing transpiration.
50
How does light intensity influence transpiration?
Higher light intensity increases the rate of transpiration due to more stomata being open for CO2 uptake.
51
What are xerophytes?
Plants adapted to living in dry environments.
52
Name one adaptation of xerophytes.
Adaptations include:
* Sunken stomata
* Rolled up leaves
* Thick waxy cuticle.
53
What are two reasons for decreased transpiration when a potted plant is placed inside a black bag?
1. Reduced light intensity hampers photosynthesis
2. Increased humidity inside the bag decreases the water potential gradient.
54
What is the structure of the mammalian respiratory system?
Includes trachea, bronchi, bronchioles, alveoli, intercostal muscles, and diaphragm.
## Footnote
Each component plays a specific role in the process of ventilation and gas exchange.
55
How is the structure of the mammalian respiratory system related to its function?
Facilitates gas exchange and ventilation through specialized structures like alveoli and intercostal muscles.
56
Define pulmonary ventilation.
Movement of air in and out of the lungs (breathing).
57
How do you calculate pulmonary ventilation?
Pulmonary ventilation = tidal volume x ventilation rate (dm³ min⁻¹).
58
What is tidal volume?
Amount of air taken in each breath.
59
What is ventilation rate?
Number of breaths taken in one minute.
60
What is the process of gas exchange in mammals?
Oxygen diffuses from alveoli to blood, carbon dioxide diffuses from blood to alveoli.
61
True or False: Respiration is the same as breathing.
False.
62
True or False: Alveoli provide a large surface area for gas exchange.
True.
63
What is the composition of inhaled air?
78% nitrogen, 21% oxygen, 0.04% carbon dioxide.
64
What is the composition of exhaled air?
78% nitrogen, 15% oxygen, 4% carbon dioxide.
65
What causes pressure changes in the lungs?
Particles colliding with an object.
66
What happens to pressure when the volume of a gas container is decreased?
Pressure increases.
67
What happens to pressure when the volume of a gas container is increased?
Pressure decreases.
68
What is the role of the diaphragm in ventilation?
Contracts to increase thoracic volume and decrease pressure for inhalation.
69
What happens during expiration?
Diaphragm relaxes, thoracic volume decreases, and pressure increases.
70
What is the function of external intercostal muscles?
Assist with inspiration by pulling the rib cage up and out.
71
What is the function of internal intercostal muscles?
Assist with forced expiration.
72
How many alveoli are there in a human lung?
Over 250 million alveoli.
73
What is the total surface area of alveoli in the lungs?
Approximately 80 m².
74
What is the thickness of the alveolar wall?
Only 0.05 µm thick.
75
What is the thickness of capillary walls in the lungs?
0.04-0.2 µm thick.
76
Fill in the blank: Gas exchange occurs in the _______.
[alveoli]
77
What is a risk factor?
A factor that increases the likelihood of disease.
78
True or False: Correlation implies causation.
False.
79
What is relative risk?
Comparison of likelihood of harm between exposed and non-exposed groups.
80
What happens to pulmonary ventilation during exercise?
It increases significantly.
81
Calculate the percentage increase in pulmonary ventilation if it goes from 6 dm³/min to 90 dm³/min.
1,400%.
82
Calculate the percentage decrease in pulmonary ventilation after exercise if it drops from 90 dm³/min to 6 dm³/min.
93.3%.
83
What monomer unit is starch made up of?
Alpha glucose
84
Is starch a mono, di or polysaccharide?
Polysaccharide
85
Which bonds hold the monomers in starch together?
Glycosidic Bonds
86
What is the name of the reaction which breaks down starch?
Hydrolysis
87
Which enzyme breaks down starch, and what product is formed?
Amylase breaks down starch into maltose
88
Where is starch digested?
Mouth and Small intestine
89
What do salivary glands release to aid in starch digestion?
Saliva containing salivary amylase
90
What is the role of pancreatic amylase in starch digestion?
Hydrolyses starch into maltose
91
What is digestion?
Hydrolysis (by enzymes) of large molecules into smaller molecules that can be absorbed and assimilated
92
What is the function of villi in the ileum?
Increase surface area for absorption
93
What type of molecules are maltose, lactose, and sucrose?
Disaccharides
94
What type of molecules are maltase, lactase, and sucrase?
Disaccharidases
95
Why will maltose bind to maltase but not to lactase?
Maltase is specific to maltose
96
What type of reaction does maltase catalyse?
Hydrolysis
97
What is the name of the bond that is broken during the reaction catalysed by maltase?
Glycosidic bond
98
What are the products formed when lactase breaks down lactose?
Glucose and galactose
99
What are the products of complete triglyceride hydrolysis?
Glycerol and fatty acids
100
What are the components of a triglyceride?
1 glycerol, 3 fatty acids
101
What’s the difference between saturated and unsaturated fatty acids?
Saturated fatty acids have no carbon-carbon double bonds (no C=C)
102
Describe the biochemical test for lipids.
Dissolve in ethanol, add water and mix → cloudy white emulsion
103
What enzyme hydrolyses triglycerides in the small intestine?
Lipase
104
What is the function of bile in lipid digestion?
Emulsifies lipids into small droplets to increase surface area
105
Where is bile produced and stored?
Produced in the liver, stored in the gall bladder
106
What is the optimum pH for pancreatic enzymes?
Alkaline pH to neutralise acidity from the stomach
107
What are micelles?
Complexes of monoglycerides and fatty acids with bile salts for absorption
108
How do fatty acids enter epithelial cells?
By simple diffusion
109
What happens to fatty acids once inside epithelial cells?
They are recombined into triglycerides
110
What are chylomicrons?
Lipids coated with proteins that leave epithelial cells and enter lacteals
111
What is co-transport in the context of glucose absorption?
Sodium ions create a gradient that allows glucose to be absorbed into epithelial cells
112
What is the role of sodium-potassium pump in glucose absorption?
Maintains sodium gradient for co-transport of glucose
113
What happens to glucose after it enters epithelial cells?
It travels into blood capillaries by facilitated diffusion
114
Cyanide is a respiratory inhibitor. How does this affect glucose uptake?
Reduces ATP production, halting active transport of Na+ and glucose co-transport
115
What is the primary function of oxyhaemoglobin in respiration?
Releases oxygen which diffuses into respiring cells
## Footnote
Oxyhaemoglobin is formed when oxygen combines with haemoglobin in red blood cells.
116
How does oxygen maintain a concentration gradient in the body?
Oxygen is carried away by the blood
## Footnote
This process helps facilitate the diffusion of oxygen from the alveoli to the blood.
117
What happens to blood entering lung capillaries?
It is deoxygenated
## Footnote
Deoxygenated blood will pick up oxygen in the lungs.
118
How many oxygen molecules can one haemoglobin molecule transport?
Four oxygen molecules
## Footnote
Each haem unit in haemoglobin can combine with one oxygen molecule.
119
What is the structure of haemoglobin?
Consists of four haem units and four polypeptide chains
## Footnote
This quaternary structure allows it to carry oxygen effectively.
120
Fill in the blank: Haemoglobin is an iron containing pigment that ______ with oxygen to form oxyhaemoglobin.
loosely and reversibly combines
## Footnote
This property allows for efficient oxygen loading and unloading.
121
What is the role of alveoli in the respiratory process?
Contain a high concentration of oxygen, facilitating diffusion
## Footnote
The high concentration gradient aids in the movement of oxygen into the blood.
122
What is meant by the term 'mass transport' in animals?
The loading, transport, and unloading of oxygen by haemoglobin
## Footnote
This is a crucial aspect of respiratory physiology.
123
124
What is the primary function of haemoglobin?
Transport of oxygen from the lungs to body tissues.
## Footnote
Haemoglobin combines with oxygen to form oxyhaemoglobin, allowing for efficient oxygen transport.
125
What is the saturation level of haemoglobin in the lungs?
96% saturated.
## Footnote
This occurs where the partial pressure of oxygen is high.
126
What happens to haemoglobin at low partial pressures of oxygen?
It unloads (dissociates) some of its oxygen to respiring cells.
## Footnote
This process is crucial for delivering oxygen where it is needed in the body.
127
What does the oxyhaemoglobin dissociation curve illustrate?
The relationship between the concentration of oxygen carried by haemoglobin and the partial pressure of oxygen.
## Footnote
This curve reflects conditions in both the lungs and body tissues.
128
Describe the shape of the oxyhaemoglobin dissociation curve.
Characteristic S (sigmoid) shape.
## Footnote
This shape indicates cooperative binding of oxygen to haemoglobin.
129
What is cooperative binding in the context of haemoglobin?
The increase in affinity for oxygen as more oxygen molecules bind to haemoglobin.
## Footnote
This allows subsequent oxygen molecules to bind more easily.
130
What occurs to the tertiary structure of haemoglobin when oxygen binds?
Slight change in the tertiary structures of the haem units.
## Footnote
This change facilitates increased binding of additional oxygen molecules.
131
Fill in the blank: The partial pressure of oxygen in the lungs is _______.
[high].
## Footnote
High partial pressures are crucial for the loading of oxygen onto haemoglobin.
132
True or False: Haemoglobin has a low affinity for oxygen in the lungs.
False.
## Footnote
Haemoglobin has a high affinity for oxygen in the lungs.
133
What is the approximate partial pressure of oxygen found in tissues?
Approx. 5-10 kPa.
## Footnote
The exact value can vary depending on the rate of respiration.
134
How does the binding of the first oxygen molecule affect haemoglobin?
It increases the affinity for subsequent oxygen molecules.
## Footnote
This is part of the cooperative binding mechanism.
135
What is the Bohr Effect?
The effect of CO2 on oxygen dissociation from hemoglobin, occurring in tissues during exercise
## Footnote
It does not occur in the lungs.
136
When does the Bohr Effect primarily occur?
During exercise
## Footnote
It is associated with increased CO2 production in muscle cells.
137
What happens to pH levels during the Bohr Effect?
pH decreases as CO2 dissolves in blood plasma to form an acid
## Footnote
This change in pH is critical for hemoglobin's oxygen release.
138
What is the result of the Bohr Effect on hemoglobin's affinity for oxygen?
Hemoglobin's affinity for oxygen decreases
## Footnote
This allows more oxygen to be released to tissues.
139
How does the O2 dissociation curve change during the Bohr Effect?
The O2 dissociation curve shifts to the right
## Footnote
This indicates more oxygen is released at the same partial pressure.
140
What physiological advantage does the Bohr Effect provide?
It ensures hemoglobin releases more oxygen to the most active cells
## Footnote
This is crucial during increased respiration.
141
What effect does an increase in temperature have on oxygen release?
It causes the O2 dissociation curve to shift to the right
## Footnote
More oxygen is released to cells due to increased respiration heat.
142
In the context of the Bohr Effect, what is the relationship between CO2 partial pressure and oxygen release?
Higher CO2 partial pressure leads to more oxygen being released
## Footnote
This is important for active tissues.
143
Fill in the blank: The Bohr Effect occurs primarily in _____ during exercise.
tissues
144
True or False: The Bohr Effect occurs in the lungs.
False
145
What is the relationship between the type of haemoglobin and the environment of an organism?
The type of haemoglobin is related to the environment or way of life of the organism.
146
What type of haemoglobin do organisms in low oxygen environments possess?
Haemoglobin with a higher affinity for oxygen.
147
Where might organisms with high-affinity haemoglobin be found?
In environments with low concentrations of oxygen, such as:
* in the mud
* at the bottom of polluted rivers
* at high altitudes
148
How does the oxyhaemoglobin dissociation curve differ for organisms in low oxygen environments?
It is further to the left when compared to organisms living in areas of higher oxygen concentration.
149
Which organism has a higher affinity for oxygen, the lugworm or the earthworm?
The lugworm.
150
Fill in the blank: The haemoglobin of the lugworm will load more oxygen than the earthworm at low partial pressures of oxygen, which are present in its _______.
surrounding environment.
151
What happens to the concentration of oxygen at high altitudes?
The concentration of oxygen in the air is reduced
152
What adaptation do animals living at high altitudes have regarding haemoglobin?
They have a different form of haemoglobin with a higher affinity for oxygen
153
How does high altitude haemoglobin function compared to low altitude species?
It loads more oxygen in the lungs than the low altitude species at low partial pressures of oxygen
154
What is a key characteristic of fetal haemoglobin compared to maternal haemoglobin?
Fetal haemoglobin has a different structure and a higher affinity for oxygen
155
What advantage does fetal haemoglobin provide in terms of oxygen transfer?
It enables oxygen to be transferred from maternal haemoglobin to fetal haemoglobin at low partial pressures of oxygen
156
Fill in the blank: At high altitudes, species have haemoglobin that has a _______ for oxygen.
higher affinity
157
True or False: Fetal haemoglobin has a lower affinity for oxygen than maternal haemoglobin.
False
158
Where is myoglobin present?
Myoglobin is only present in muscles.
## Footnote
Myoglobin is a protein found in muscle tissues that binds oxygen.
159
How does the affinity for oxygen of myoglobin compare to that of haemoglobin?
Myoglobin has a much higher affinity for oxygen than haemoglobin.
## Footnote
This means myoglobin can hold onto oxygen more tightly than haemoglobin.
160
Under what conditions does myoglobin release its oxygen?
Myoglobin releases its oxygen only when the partial pressure of oxygen in the tissues is very low.
## Footnote
This typically occurs when tissues are in need of oxygen.
161
What role does haemoglobin play in the release of oxygen from myoglobin?
Myoglobin releases oxygen when haemoglobin has already released almost all of the oxygen it carries.
## Footnote
This indicates a sequential release mechanism based on oxygen demand.
162
What function does myoglobin serve in muscle cells?
Myoglobin acts as a store of oxygen in muscle cells.
## Footnote
This storage capability is crucial for muscle metabolism during intense activity.
163
Which vessels carry blood away from the heart?
Arteries
164
What do the muscle cells need oxygen and glucose for?
Aerobic respiration, to release ATP
165
Which side of the heart contains oxygenated blood?
Left
166
Why is the right side of the heart thinner than the left?
It is less muscular as it only pumps blood to the lungs under a lower pressure
167
When do the semilunar valves open?
When there is a higher pressure in the ventricles than the arteries
168
When do the atrioventricular valves close?
When pressure in the ventricles is higher than pressure in the atria
169
Why do the ventricles contract from the bottom upwards?
So the blood moves upwards and out of the arteries
170
Why is mammalian circulation referred to as a 'double circulatory system'?
Blood goes through the heart TWICE
171
What is the function of arterioles?
Control blood flow from arteries to capillaries
172
What is the function of capillaries?
Link arterioles to veins where exchange takes place
173
What do veins carry?
Blood towards the heart
174
What is the general structure of blood vessels?
Layered: Tough outer layer, muscle layer, elastic layer, lining layer (endothelium), lumen
175
What is the pressure in arteries?
High pressure
176
What is the typical wall structure of an artery?
Thick wall, small lumen, no valves except arteries leaving the heart
177
What is the function of valves in veins?
Ensure blood flows in one direction towards the heart
178
What occurs during vasoconstriction?
Smooth muscle contracts, narrowing arteriole, decreasing blood flow to capillaries
179
What occurs during vasodilation?
Relaxation of smooth muscle, widening arteriole, increasing blood flow to capillaries
180
How does blood pressure change as blood travels from arteries to veins?
Blood pressure decreases as it moves away from the heart
181
What is tissue fluid?
Fluid formed from blood plasma that exchanges metabolic materials with body cells
182
What is the role of hydrostatic pressure in tissue fluid formation?
Causes filtration of blood plasma and small molecules out of capillaries
183
What is reabsorption in the context of tissue fluid?
Water moves back into capillaries by osmosis due to lower water potential in blood
184
What happens to excess tissue fluid?
Drained by the lymphatic system and returned to blood plasma
185
What causes oedema?
Accumulation of tissue fluid, often due to heart failure or inactivity
186
What is the composition of tissue fluid?
Rich in O2, glucose, amino acids, ions; cells and proteins remain in blood
187
What is the importance of a large number of capillaries?
Increases rate of gas exchange due to larger surface area
188
What is the effect of a small lumen in capillaries?
Red blood cells travel in single file, slowing blood flow for more time to exchange
189
What happens to blood flow velocity as it moves through capillaries?
Blood flow velocity decreases due to increased frictional resistance
190
Fill in the blank: Blood is under _______ pressure at the arterial end of capillaries.
High hydrostatic
191
Fill in the blank: Blood is under _______ pressure at the venous end of capillaries.
Low hydrostatic
192
True or False: Arteries carry deoxygenated blood.
False
193
True or False: The walls of capillaries are one endothelial cell thick.
True
194
What are the main structures of the heart?
Atrium, Atria, Ventricles, Artery, Vein, Pulmonary, Valve, Semilunar, Atrioventricular
195
Where is the heart located?
In the chest (thorax), above the diaphragm, between the lungs, behind the sternum
196
What is the average weight of the heart?
250-300g
197
What type of muscle makes up the heart?
Cardiac muscle
198
How does cardiac muscle function?
Contracts involuntarily, does not fatigue, has many mitochondria
199
What is double circulation?
1) Pulmonary - To lungs, from the right side; 2) Systemic - To rest of body, from the left side
200
What is the largest artery in the body?
Aorta
201
What is the function of heart valves?
Prevent backflow of blood by closing
202
What causes the heart sounds 'lub' and 'dub'?
'Lub' - Atrioventricular valves closing; 'Dub' - Semi-lunar valves closing
203
What prevents valves from turning inside out during ventricular pressure increase?
Tendinous cords
204
What happens during atrial systole?
Atria contract, pressure increases, blood flows from atria to ventricles
205
What occurs during ventricular systole?
Ventricles contract, pressure increases, blood flows from ventricles to arteries
206
What is diastole?
All chambers of the heart relax
207
What is the cardiac cycle?
The sequence of events that make up one heart beat, including systole and diastole
208
What is stroke volume?
Amount of blood pumped from left ventricle in one beat
209
How is cardiac output calculated?
Cardiac output = stroke volume × heart rate
210
What factors influence cardiac output?
Stroke volume and heart rate
211
What happens to heart rate during exercise?
Increases due to higher demand for oxygen and glucose
212
What is a risk factor for cardiovascular disease?
Anything that increases the chance of getting a disease, e.g., smoking, high blood pressure, high cholesterol
213
Fill in the blank: The heart contracts during _______.
systole
214
Fill in the blank: Blood always moves from a higher to a _______ pressure.
lower
215
True or False: The heart can tire easily.
False
216
What is the heart rate of a person with a 0.8 seconds cycle?
75 bpm
217
What does regular exercise do to heart muscle?
Produces stronger contractions and increases stroke volume
218
What is the effect of muscle contraction on venous return?
Increases rate of venous return to the heart
219
What measurements are required to calculate the rate of transpiration?
Distance (d) air bubble moves, time taken, radius (r) of lumen of capillary tube
## Footnote
Radius is calculated by measuring diameter and dividing by 2. Volume of water taken up is calculated using the formula πr²d.
220
What is the cohesion-tension hypothesis?
Water molecules form hydrogen bonds, creating cohesion and a continuous column of water that travels up the xylem
## Footnote
This theory explains how water is pulled up from roots to leaves through transpiration.
221
List key terms associated with transpiration.
* Transpiration
* Stomata
* Water potential
* Osmosis
* Xylem
* Hydrogen bonds
* Cohesion
* Tension
* Adhesion
* The transpiration stream
222
What does the transpiration stream do?
Transports water from root hairs to stomata, moving water and dissolved ions through xylem
## Footnote
The cohesion-tension theory explains the mechanics of this process.
223
What structural features of xylem vessels contribute to minimal resistance?
* Dead, ‘empty’ cells
* End walls broken down
* Continuous, unbroken tubes from root to leaves
* Strengthened with lignin for rigidity and waterproofing
224
How does the evaporation of water from leaves affect water potential?
It lowers the water potential in the leaf mesophyll cells, drawing water from the xylem by osmosis
## Footnote
This creates negative pressure or tension in the xylem.
225
True or False: The diameter of a tree trunk increases during the day.
False
## Footnote
The diameter decreases due to increased transpiration and tension in the xylem.
226
What evidence supports the cohesion-tension theory?
As the rate of transpiration increases, the diameter of a tree trunk decreases
## Footnote
This indicates that tension pulls in the xylem walls.
227
What are the two phases of water movement in the cohesion-tension theory?
* Water evaporates from leaves (transpiration)
* Water is pulled up from roots due to cohesion
228
Explain the role of radioactive isotopes in studying ion movement in xylem.
Radioactive isotopes are used as tracers to measure the concentration of ions in xylem and phloem
## Footnote
Higher radioactivity in xylem indicates transport of ions like K+.
229
What is translocation in the context of phloem?
The transport of organic molecules, primarily carbohydrates like sucrose, from sources to sinks
## Footnote
Sources are usually leaves, and sinks include growing areas and storage tissues.
230
Describe the structure of phloem.
Sieve elements form sieve tubes with sieve plates at joins, no nucleus, and few organelles
## Footnote
Companion cells have many mitochondria to support active transport.
231
Fill in the blank: Photosynthesis in leaves produces glucose, which is converted into _______.
sucrose
232
What happens to the water potential of the phloem when sucrose is actively transported into it?
The water potential decreases, causing water from xylem to move into phloem by osmosis
233
Using the mass flow hypothesis, explain why the solution moves from A to C.
Solution with a water potential higher than A and lower than C moves down a hydrostatic pressure gradient from A to C
234
What effect does a respiratory inhibitor like cyanide have on translocation?
No ATP is produced, preventing active transport of sucrose into the sieve element
## Footnote
This disrupts the hydrostatic pressure gradient and halts translocation.
235
What is the purpose of ringing experiments in studying phloem transport?
To show that removing a ring of phloem prevents transport of photosynthetic products, causing swelling above the ring
236
What is the significance of using C-14 as a tracer in plants?
It allows tracking of photosynthetic products like glucose through autoradiography
## Footnote
Radioactive sucrose can be detected to observe its movement in the plant.
237
Why are plants important?
* Produce oxygen
* Carbon sinks
* Produce food for the whole food chain
* Most medicines originate from plants
* Wildlife habitats
238
What is transpiration?
The evaporation of water from a plant’s surface, particularly through stomata
239
What are stomata?
Pores on the surface of leaves that allow gas exchange
240
What is a xerophyte?
Plants that are adapted to living in dry environments
241
What is a potometer?
An apparatus used to measure the rate of transpiration in plants
242
What environmental factors affect the rate of transpiration?
* Temperature
* Humidity
* Air movement
* Light intensity
243
What adaptations do xerophytes have?
* Rolled leaves
* Sunken stomata
* Leaf hairs
* Thick waxy cuticle
* Long roots
* Swollen stems
* Spines
244
How does high temperature affect transpiration?
Increases kinetic energy of water molecules, leading to increased transpiration
245
How does humidity affect transpiration?
High humidity decreases the water potential gradient, leading to decreased transpiration
246
How does air movement affect transpiration?
Increases transpiration by dispersing the humid layer at the leaf surface and increasing the water potential gradient
247
How does light intensity affect transpiration?
Higher light intensity increases the need for CO2, leading to more stomata opening and increased transpiration
248
What is the cohesion-tension hypothesis?
Explains how water is transported from roots to leaves through the xylem due to cohesion between water molecules and tension created by transpiration
249
What is the role of xylem in plants?
Transports water and dissolved ions from roots to leaves
250
What is the function of the stomata?
Allow carbon dioxide to diffuse into the leaf for photosynthesis
251
Fill in the blank: Transpiration is a _______ process.
passive
252
True or False: A potometer can be used to measure transpiration rate.
True
253
What happens to the diameter of a tree trunk during high transpiration?
Decreases due to increased tension in the xylem
254
What is cohesion in the context of water transport?
The attraction of water molecules to each other by hydrogen bonding
255
What is adhesion in the context of water transport?
The attraction of water molecules to the xylem walls
256
What is the effect of rolling leaves in xerophytes?
Creates a humid microclimate, lowering the water potential gradient
257
What does a potometer measure?
The distance moved by an air bubble, indicating the rate of transpiration
258
How does osmosis relate to transpiration?
Water moves from the xylem into mesophyll cells by osmosis, creating a water potential gradient
259
What is the significance of the waxy cuticle in xerophytes?
Prevents water loss through evaporation
260
What energy drives the process of transpiration?
Solar energy, which causes evaporation of water
261
How can the rate of transpiration be experimentally manipulated?
* Varying temperature
* Creating humidity with a transparent bag
* Using a fan for air movement
* Adjusting light intensity with a lamp or dark cupboard
262
What happens to the water potential of mesophyll cells during transpiration?
It decreases, leading to water being drawn from the xylem
263
What is the relationship between transpiration and water uptake?
Higher transpiration rates lead to higher rates of water uptake from the soil
264
What are the main components of a potometer?
* End of stem cut in water
* Leafy shoot
* Reservoir
* Capillary tube with mm scale
* Air bubble
265
What type of pressure is created in the xylem due to transpiration?
Negative pressure, referred to as tension
266
How does a decrease in humidity affect transpiration?
Increases the water potential gradient, leading to increased transpiration
267
What is the transpiration stream?
Transports water from root hairs to stomata through the xylem
268
Describe the role of hydrogen bonds in the cohesion-tension theory.
Hydrogen bonds allow water molecules to stick together, forming a continuous column in the xylem
269
What is the effect of decreased light intensity on transpiration?
Decreases the rate of transpiration due to fewer stomata being open
270
What is the significance of the air bubble in a potometer?
Indicates the rate of transpiration by measuring the distance it travels
271
What happens to the diameter of a tree trunk during high light intensity?
Decreases
## Footnote
This change is related to the process of transpiration and water movement within the plant.
272
What is the term for the attraction between water molecules?
Cohesion
## Footnote
Cohesion helps maintain the water column in the xylem, allowing water to be pulled from roots to leaves.
273
What is the term for the attraction between water molecules and the wall of the xylem?
Adhesion
## Footnote
Adhesion assists in the movement of water through the plant's vascular system.
274
What is the effect that causes the inward pulling of the xylem wall?
Tension
## Footnote
Tension is created by the process of transpiration as water evaporates from the stomata.
275
Fill in the blank: The route water takes from root to leaf is called _______.
Transpiration stream
## Footnote
This route is critical for nutrient and water transport in plants.
276
Fill in the blank: The route water can take from xylem to stomata across the leaf is called _______.
Leaf intercellular spaces
## Footnote
This pathway is essential for gas exchange in photosynthesis.
277
What process pulls water upwards in the xylem?
Osmosis
## Footnote
Osmosis is the movement of water from areas of higher concentration to lower concentration, facilitating water transport.
278
What happens to the stomata during high light intensity?
Open
## Footnote
The opening of stomata allows for gas exchange and transpiration to occur.
279
What type of bonds are responsible for cohesion in water?
Hydrogen bonds
## Footnote
Hydrogen bonds contribute to the unique properties of water, including its cohesion.
280
True or False: The diameter of a tree trunk increases during high light intensity.
False
## Footnote
The diameter actually decreases due to the effects of transpiration.
