organisms exchance substances with their environment Flashcards
1
Q
What is the primary function of exchange surfaces in organisms?
A
To facilitate the exchange of substances between the internal and external environments.
2
Q
What must most substances cross to enter or leave an organism?
A
Cell plasma membranes.
3
Q
What is the environment around the cells of multicellular organisms called?
A
Tissue fluid.
4
Q
What do cells need to take in for aerobic respiration?
A
Oxygen and nutrients.
5
Q
What waste products do cells need to excrete?
A
Carbon dioxide and urea.
6
Q
How does an organism’s surface area to volume ratio affect substance exchange?
A
A larger surface area to volume ratio facilitates more effective exchange.
7
Q
What is the surface area to volume ratio like in smaller organisms?
A
High surface area to volume ratio.
8
Q
What is the surface area to volume ratio like in larger organisms?
A
Low surface area to volume ratio.
9
Q
How do you calculate surface area to volume ratio?
A
SA ÷ V = surface area to volume ratio in the form X:1.
10
Q
How do substances exchange in single-celled organisms?
A
By diffusion directly across the cell-surface membrane.
11
Q
Why is diffusion across the outer membrane too slow in multicellular organisms?
A
Due to larger distances between some cells and the external environment and a low surface area to volume ratio.
12
Q
What do multicellular organisms require for effective substance exchange?
A
Specialised exchange organs.
13
Q
What is mass transport in mammals typically associated with?
A
The circulatory system.
14
Q
What substances does the circulatory system carry?
A
Glucose, oxygen, hormones, antibodies, and waste like CO2.
15
Q
What does mass transport in plants involve?
A
Transport of water and solutes in the xylem and phloem.
16
Q
What is metabolic rate?
A
The amount of energy expended by an animal over a specific period of time.
17
Q
How do organisms with a high metabolic rate impact their surface area to volume ratio?
A
They require a larger surface area to volume ratio.
18
Q
According to Fick’s Law of diffusion, which factors influence the rate of diffusion?
A
Surface area, concentration gradient, and length of diffusion path.
19
Q
What are key features of specialised exchange surfaces?
A
- Large surface area relative to volume
- Very thin
- Maintains a steep concentration gradient.
20
Q
How does body size affect heat exchange in organisms?
A
Larger volume means a relatively smaller surface area, making heat loss harder.
21
Q
What is the effect of body shape on heat loss?
A
Compact shapes minimize heat loss; less compact shapes increase heat loss.
22
Q
What adaptations do small multicellular animals have for heat exchange?
A
High metabolic rate and specialized organs.
23
Q
How do guard cells regulate stomata?
A
By changing their turgidity to open or close the stomatal pore.
24
Q
What is the main gas exchange surface in dicotyledonous plants?
A
The surface of the mesophyll cells in the leaf.
25
What happens to gas exchange during daytime in plants?
Photosynthesis occurs faster than respiration, consuming CO2 and releasing O2.
26
What adaptations do xerophytic plants have for water conservation?
* Thicker waxy cuticles
* Curled leaves
* Hairs on epidermis
* Reduced number of stomata.
27
What are the components of the tracheal system in insects?
* Spiracles
* Tracheae
* Tracheoles.
28
How do insects enhance gas exchange through ventilation?
By using rhythmic abdomen movements to pump air in and out.
29
True or False: Single-celled organisms require a specialized gas exchange system.
False.
30
What creates a concentration gradient for gas exchange in insects?
Diffusion of oxygen from tracheal tubes to cells and carbon dioxide from cells to tracheoles
## Footnote
This process is essential for efficient gas exchange in insects.
31
How do insects enhance gas exchange?
By using rhythmic abdomen movements to pump air in and out of spiracles
## Footnote
This increases CO2 release and raises pressure.
32
What happens to water in the ends of tracheoles during insect flight?
Water moves into muscle cells from tracheoles by osmosis, lowering pressure and volume in tracheoles
## Footnote
This forces air into the trachea.
33
What adaptation in insects allows for efficient gas exchange?
Large surface area to volume ratio due to highly branched tracheoles
## Footnote
This increases contact with air.
34
What is a key feature of tracheoles that aids in gas exchange?
Thin walls for a short diffusion pathway
## Footnote
This facilitates quicker gas exchange.
35
How do respiring cells in insects maintain a concentration gradient?
By using up oxygen and producing carbon dioxide
## Footnote
This creates a steep concentration gradient.
36
What adaptations do insects have to control water loss?
* Small surface area to volume ratio
* Lipid layer on exoskeleton
* Spiracles that open and close
* Tiny hairs around spiracles
## Footnote
These adaptations help balance gas exchange and water retention.
37
What is the primary gas exchange surface in fish?
The gills
## Footnote
Gills are specialized for extracting oxygen from water.
38
What is the role of the operculum in fish?
Protects the gills and regulates water flow over them
## Footnote
It opens and closes to allow water passage.
39
What is the structure of gill filaments?
Stacked in piles with lamellae at right angles
## Footnote
This increases the surface area for gas exchange.
40
How does the counter-current system in fish gills work?
Blood and water flow in opposite directions
## Footnote
This maintains a steep oxygen concentration gradient.
41
What happens to water flow over gill lamellae as temperature rises?
Water flow increases due to less dissolved oxygen and higher fish metabolism
## Footnote
More oxygen is required for respiration at higher temperatures.
42
What is the difference between a counter-current system and a concurrent system in gas exchange?
Counter-current maintains concentration gradient; concurrent reaches equilibrium
## Footnote
In concurrent systems, diffusion is not effective over the entire surface.
43
What are the key features of the human gas exchange system?
* Ribcage for protection and support
* Lungs for gas exchange
* Trachea for airway support
* Bronchi for mucus production and air passage
* Alveoli for gas exchange surface
## Footnote
Each part plays a crucial role in respiratory function.
44
What is tidal volume?
The volume of air inhaled or exhaled in each breath, typically 0.4 to 0.5 dm³ for adults
## Footnote
This measurement is important for assessing respiratory health.
45
How does asthma affect gas exchange?
Causes inflammation and constriction of airways, reducing airflow
## Footnote
This leads to decreased oxygen intake and gas exchange.
46
What is fibrosis and its effect on gas exchange?
Thickening of lung tissue, increasing diffusion distance and decreasing rate of diffusion
## Footnote
This results in reduced tidal volume and forced vital capacity.
47
What happens to alveoli in emphysema?
Walls are damaged, reducing surface area and trapping air
## Footnote
This significantly impairs ventilation and gas exchange.
48
What are the effects of tuberculosis on lung function?
Causes fibrosis and cavitation in lung tissue, impairing gas exchange
## Footnote
This can lead to severe respiratory issues.
49
What is the definition of correlation in a biological context?
A link between two variables where a change in one reflects a change in the other
## Footnote
Correlations can help identify relationships in biological studies.
50
What happens to lung tissue in the presence of fibrosis?
Lung tissue becomes thick and hard, cells may die, tissues tear, and cavitation occurs.
51
What is the effect of lung tissue damage on gas exchange?
Exchange of oxygen is impossible, cells in lung tissue die, and tearing and cavitation occur.
52
Define correlation in the context of two variables.
A link between two variables where a change in one reflects a change in the other.
53
True or False: A correlation implies causation.
False.
54
List the risk factors for COPD.
* Smoking
* Air pollution
* Genetic make-up
* Infections
* Occupation
55
What percentage of COPD patients are heavy smokers?
90%.
56
How do air pollutants contribute to COPD?
Pollutant particles and gases increase the likelihood of COPD, especially in industrial areas.
57
What is the role of the mesentery in the digestive system?
Supports and positions the digestive organs in the abdomen.
58
What is the first stage of digestion?
Physical breakdown of food into smaller pieces.
59
What is hydrolysis in the context of digestion?
The splitting up of molecules by adding water to the chemical bonds.
60
What are the products of carbohydrate digestion?
* Disaccharides
* Monosaccharides.
61
What enzymes are involved in carbohydrate digestion?
* Amylase
* Maltase
* Sucrase
* Lactase.
62
Fill in the blank: The stomach produces _______ which helps to unravel proteins.
stomach acid.
63
What is the function of bile in digestion?
Emulsifies fats and neutralizes the acidity of chyme.
64
What is the function of amylase?
Hydrolyses starch into maltose.
65
Where is maltase found and what does it do?
In the small intestine; hydrolyses maltose to alpha glucose.
66
What type of transport is used for glucose absorption in the ileum?
Co-transport and facilitated diffusion.
67
What are endopeptidases responsible for?
Hydrolysing peptide bonds in the central region of protein molecules.
68
What is the role of exopeptidases?
Hydrolyse peptide bonds on the terminal amino acids of peptide molecules.
69
How are amino acids absorbed in the ileum?
Through co-transport with sodium ions.
70
What is the final product of protein digestion?
Amino acids.
71
What happens to the food bolus in the stomach?
It is churned and mixed with enzymes to form chyme.
72
What is the primary function of the small intestine?
Absorption of soluble products of digestion.
73
What is the primary function of epithelial cells in the ileum?
Absorption of glucose and other nutrients
## Footnote
Epithelial cells transport glucose against its concentration gradient.
74
How is glucose absorbed in the ileum?
By active transport and facilitated diffusion
## Footnote
Active transport involves Na+ concentration gradient.
75
What is the role of lipases in lipid digestion?
Hydrolyse triglycerides into monoglycerides and fatty acids
## Footnote
Lipases are produced in the pancreas.
76
Define emulsification in the context of lipid digestion.
The process of splitting fats and oils into tiny droplets
## Footnote
This increases the surface area for faster hydrolysis.
77
What structures are formed after lipids are digested by lipases?
Micelles
## Footnote
Micelles help transport fatty acids and monoglycerides to epithelial cells.
78
How do monoglycerides and fatty acids enter epithelial cells?
By diffusion across the cell-surface membrane
## Footnote
They are non-polar molecules.
79
What are chylomicrons?
Structures formed by triglycerides, cholesterol, and lipoproteins
## Footnote
They are adapted for lipid transport.
80
What is the structure of the ileum designed for?
Absorbing the products of digestion
## Footnote
The ileum is the third part of the small intestine.
81
What are villi?
Finger-like projections in the ileum that increase surface area
## Footnote
They are lined with epithelial cells and contain blood capillaries.
82
How do villi increase absorption efficiency?
By increasing surface area, reducing diffusion distance, and maintaining diffusion gradients
## Footnote
Villi are thin-walled and have a rich blood supply.
83
What is mass transport in multicellular organisms?
An efficient system to carry substances to and from cells
## Footnote
It involves specialized exchange organs.
84
What is the role of the circulatory system in mass transport?
Carries glucose, oxygen, hormones, antibodies, and waste products
## Footnote
In mammals, this system uses blood for transport.
85
What is hemoglobin?
A protein in red blood cells that binds to oxygen
## Footnote
It is crucial for oxygen transport in the body.
86
How does hemoglobin's structure facilitate its function?
It has a quaternary structure with four polypeptide chains and iron-containing heme groups
## Footnote
This allows it to bind oxygen efficiently.
87
What is the Bohr effect?
The reduced affinity of hemoglobin for oxygen in the presence of carbon dioxide
## Footnote
This effect enhances oxygen unloading at respiring tissues.
88
What happens to hemoglobin's affinity for oxygen as PO2 increases?
It increases, allowing for more oxygen to bind
## Footnote
Hemoglobin forms oxyhemoglobin at high PO2.
89
Describe the cooperative binding of oxygen to hemoglobin.
The binding of one oxygen molecule increases the likelihood of additional oxygen binding
## Footnote
This is reflected in the steep part of the dissociation curve.
90
What occurs at the gas exchange surface (lungs) regarding oxygen?
Oxygen associates with hemoglobin due to high PO2
## Footnote
This leads to the formation of oxyhemoglobin.
91
What is the outcome of high carbon dioxide concentration on hemoglobin?
It decreases hemoglobin's affinity for oxygen, leading to oxygen release
## Footnote
This is crucial during respiration in tissues.
92
What is the role of myoglobin?
It stores oxygen in muscle cells for cellular respiration
## Footnote
Myoglobin has a single polypeptide chain.
93
What effect does carbon dioxide have on hemoglobin in respiring tissues?
It lowers the pH, changing the conformation of hemoglobin to one with a lower affinity for oxygen, leading to oxygen release to respiring tissues.
94
What happens to hemoglobin's affinity for oxygen at the gas exchange surface?
The pH is raised due to low levels of carbon dioxide, which changes the shape of hemoglobin to one that enables it to load oxygen readily.
95
How does the activity level of a tissue affect oxygen unloading?
The more active a tissue, the more oxygen is unloaded due to higher rates of respiration and carbon dioxide production, which lowers pH and facilitates hemoglobin shape change.
96
What is the relationship between the type of hemoglobin and an organism's environment?
Different types of hemoglobin are adaptations that help organisms survive in specific environments.
97
What is sickle cell anemia?
A genetic disorder that causes abnormal hemoglobin, resulting in sickle-shaped red blood cells that cannot carry as much oxygen.
98
Describe the shape of the dissociation curve for hemoglobin.
It is sigmoidal, with a slow start for oxygen binding, increasing until a plateau region where hemoglobin is fully saturated with oxygen.
99
What happens to hemoglobin's affinity for oxygen at high altitudes?
It decreases due to lower air pressure and oxygen concentration, making it harder for hemoglobin to transport oxygen.
100
How does temperature affect hemoglobin's ability to transport oxygen?
Higher temperatures increase the solubility of oxygen in blood, facilitating oxygen transport by hemoglobin.
101
What does a leftward shift in the dissociation curve indicate?
It indicates a greater affinity of hemoglobin for oxygen, meaning it readily loads oxygen but unloads it less easily.
102
What is the significance of fetal hemoglobin's higher affinity for oxygen?
It allows the fetus to attract oxygen from the mother's blood at the placenta, as the fetus cannot inhale/exhale.
103
What happens to fetal hemoglobin after birth?
The baby begins to produce adult hemoglobin, which gradually replaces fetal hemoglobin for easier oxygen release in more metabolically active tissues.
104
How does the surface area to volume ratio affect small mammals' oxygen demand?
Small mammals have a higher surface area to volume ratio, leading to quicker heat loss and a higher metabolic rate, resulting in a high oxygen demand.
105
How does high activity level influence hemoglobin's affinity for oxygen?
Organisms with high activity levels have hemoglobin with a lower affinity for oxygen, allowing for easier unloading to meet high oxygen demands.
106
What is myoglobin and how does it differ from hemoglobin?
Myoglobin is a single polypeptide chain with one oxygen binding site, fully saturated after one oxygen molecule binds, and has a higher affinity for oxygen than hemoglobin.
107
What is the Bohr Effect?
The phenomenon where increased carbon dioxide concentration shifts the dissociation curve to the right, lowering hemoglobin's affinity for oxygen and promoting unloading.
108
What is the primary role of blood in the body?
Blood transports respiratory gases, products of digestion, metabolic wastes, and hormones throughout the body.
109
Describe the circulatory system in mammals.
Mammals have a closed, double circulatory system where blood passes twice through the heart for each complete circuit of the body.
110
What are the benefits of a systematic circulatory system?
Prevents mixing of oxygenated and deoxygenated blood, allows higher pressure for efficient substance transport, and improves circulation speed.
111
What is the structure of the heart in terms of chambers and walls?
Each pump has two chambers: the atrium (thin-walled) and the ventricle (thicker muscular wall), with the left ventricle being thicker to pump blood further.
112
What is the function of valves in the heart?
Valves prevent backflow of blood, ensuring unidirectional flow as pressure changes.
113
What happens during diastole in the cardiac cycle?
The heart relaxes, allowing blood to fill the atria and ventricles as pressure decreases.
114
What occurs during atrial systole?
Atria contract, forcing blood into the ventricles while the ventricles remain relaxed.
115
What is the process during ventricular systole?
Ventricles contract, increasing pressure and forcing blood into the aorta and pulmonary artery while preventing backflow into the atria.
116
What is systole?
Contraction of ventricles
## Footnote
Ventricle walls contract from the bottom up, atria walls relax.
117
What happens to the volume of ventricles during systole?
Volume decreases.
118
What sound is produced when the atrioventricular valves shut?
‘Lub’ sound.
119
What forces the semilunar valves open during systole?
Pressure in ventricles exceeds that in aorta and pulmonary artery.
120
What is cardiac output?
Volume of blood pumped by one ventricle of the heart in one minute.
121
What is the formula for calculating cardiac output?
Cardiac output (cm³/min) = Stroke volume (cm³) X Heart rate (bpm).
122
What is stroke volume?
Volume of blood pumped by one ventricle of the heart in one contraction.
123
What is the function of arteries?
Transport oxygenated blood rapidly under high pressure from the heart to the tissues.
124
What is the structure of arteries?
Thick muscle layer, thick elastic layer, tough fibrous outer layer, thin inner endothelium lining.
125
What is the function of arterioles?
Carry blood from arteries to capillaries and control blood flow.
126
What is the function of veins?
Transport deoxygenated blood slowly, under low pressure, to the heart.
127
What is the structure of veins?
Thin muscle layer, thin elastic layer, small overall thickness, valves to prevent backflow.
128
What is the function of capillaries?
Exchange metabolic materials such as oxygen, carbon dioxide, and glucose between blood and cells.
129
What is the structure of capillaries?
Walls consist mostly of endothelium lining, very thin (1 cell thick), numerous and highly branched.
130
What is tissue fluid?
Watery liquid surrounding all cells, containing glucose, amino acids, fatty acids, ions, and oxygen.
131
What causes the formation of tissue fluid?
High hydrostatic pressure at the arterial end of capillaries causes ultrafiltration.
132
What happens at the venous end of capillaries regarding tissue fluid?
Tissue fluid is reabsorbed into capillaries due to higher hydrostatic pressure outside.
133
What absorbs excess tissue fluid?
Lymphatic system.
134
What is cardiovascular disease?
General term for diseases associated with the heart and blood vessels.
135
What is coronary heart disease (CHD)?
Type of cardiovascular disease caused by atheromas in the coronary arteries.
136
What is atheroma formation?
Fatty acid deposits in the endothelium of an artery.
137
What is thrombosis?
Formation of a blood clot.
138
What is an aneurysm?
Balloon-like swelling of the artery.
139
What causes myocardial infarction?
Complete blockage of a coronary artery cutting off blood supply to the heart muscle.
140
What are the risk factors for cardiovascular disease?
High blood pressure, high blood cholesterol, smoking, being overweight, lack of exercise, excessive alcohol consumption.
141
True or False: High blood pressure can lead to atheroma formation.
True.
142
Fill in the blank: A diet high in _______ is associated with high blood cholesterol levels.
[saturated fat]
143
How does carbon monoxide from smoking affect the heart?
Reduces the amount of oxygen transported in the blood.
144
What are atheromas?
Atheromas are fatty deposits that can lead to cardiovascular diseases.
145
What can atheromas lead to?
Increased blood pressure and blood clots, which could cause a myocardial infarction.
146
How does carbon monoxide from smoking affect the blood?
It combines with haemoglobin and reduces the amount of oxygen transported in the blood.
147
What is the effect of smoking on antioxidants?
Smoking decreases the amount of antioxidants in the blood, leading to increased cell damage.
148
What is the relationship between smoking and myocardial infarction?
Smoking contributes to atheroma formation, which can result in myocardial infarction.
149
What types of trends can be described in data about cardiovascular diseases?
Positive/negative correlation, linear/non-linear, and anomalies.
150
What is correlation?
The relationship between two variables.
151
What is causation?
A change in one variable directly causes a change in another variable.
152
What is the xylem's function in plants?
To transport water and mineral ions from roots to leaves by transpiration.
153
What is the phloem's function in plants?
To transport organic substances, such as sugars, up and down the plant by translocation.
154
Where is the xylem located in the roots?
In the center of the vascular bundle.
155
What is the structure of xylem vessels?
Long, tube-like structures formed from dead cells lined with lignin.
156
What adaptations do xylem vessels have?
* Elongated cells arranged end to end
* Lignified cell walls
* Rigid structure
* Hollow interior
* Waterproof
* Pits for lateral water movement
* Narrow lumen
157
What is root pressure?
Water in roots pushes water up the xylem, but it is limited to small plants.
158
What is capillary action?
Water's tendency to move up into small tubes, although it is too slow for plant needs.
159
What does osmosis refer to in the context of water flow from soil to roots?
Water moves from an area of higher water potential in the soil to an area of lower water potential in the root hair cell.
160
What is apoplastic flow?
Water and dissolved minerals move through cell walls and intercellular spaces directly to the xylem.
161
What is symplastic flow?
Water moves from cell to cell through the cytoplasm and plasmodesmata.
162
What is transpiration?
The evaporation of water from a plant's surface, especially the leaves.
163
How does humidity affect the transpiration rate?
Lower humidity increases the transpiration rate, while higher humidity decreases it.
164
What is the potometer used for?
To estimate transpiration rates by measuring water uptake by a plant.
165
What are the components of phloem?
* Sieve tube elements (living cells)
* Companion cells
166
What is translocation?
The movement of solutes/organic substances through the plant from the source to the sink.
167
What happens during ringing experiments?
A section of phloem is removed, preventing the downward movement of sugars, leading to swelling above the ringed area.
168
What is the mass flow hypothesis in translocation?
The mechanism by which sucrose moves into phloem by active transport, leading to increased hydrostatic pressure.
169
What happens when the phloem is removed in plants?
It interrupts the continuity of the phloem tubes, preventing the downward movement of sugars and other organic compounds.
## Footnote
The upward flow of sap in the xylem vessels remains unaffected.
170
What is the result of the accumulation of sugars above the ringed area?
It leads to the swelling of the region known as the ring of callus, a bulge.
## Footnote
The fluid from the bulge has a higher concentration of sugars than the fluid from below the ring.
171
What occurs to the tissues below the ring after phloem removal?
The tissues below the ring die because sugars are not provided.
## Footnote
This is a direct consequence of the interruption in sugar translocation.
172
What conclusion can be drawn from ringing experiments?
Phloem is the tissue responsible for translocating sugars in plants.
## Footnote
The continuity of xylem was not broken, confirming phloem's role.
173
What are tracer experiments used for?
To track the movement of materials within plants using radioactive isotope substances.
## Footnote
For example, C-14 is introduced into a leaf to create radioactively labelled carbon dioxide.
174
What happens to the plant during tracer experiments?
The tracer is detected in other parts of the plant over time, indicating movement through the phloem.
## Footnote
This is tracked using autoradiography.
175
How is autoradiography used in tracer experiments?
The plant is killed and placed onto photographic film; wherever the film turns black, the radioactive substance is present.
## Footnote
This reveals the spread of the radioactive tracer in the plant.
176
What conclusion can be drawn from tracer experiments?
Organic compounds, such as sugars, move bidirectionally in the phloem and can be transported from source to sink tissues.
## Footnote
The lack of blackening in other tissues indicates that phloem alone is responsible for sugar translocation.
