Topic 3 : Organisms and Exchange, Digestion and Absorption and Mass transport Flashcards
(267 cards)
1
Q
Why does having a high surface area to volume ratio advantage single-celled organisms ?
A
it means there is a short diffusion pathway to all parts of the cell, which satisfies gas exchange and ensures heat removals
2
Q
What happens to surface area to volume ratio as the size of the organism increases ?
A
it decreases
3
Q
Why do smaller animals have a higher metabolic rate ?
A
they have a large surface area to volume ratio so lose heat faster
therefore they need to respire more to maintain a constant body temperature
which means they have a high metabolic rate
4
Q
What is the trachea ?
A
the main tube supported by rings of cartilage which prevent it from collapsing during pressure changes
5
Q
What are the bronchi and bronchioles ?
A
tubes that the trachea splits into
6
Q
What are the alveoli ?
A
ends of the bronchioles that provide a large surface for gas exchange
7
Q
How are the alveoli adapted as a gas exchange surface ?
A
- shape and number provide large surface area
- fluid lining allows gases to dissolve and diffuse across
- only two cell layers separate blood and air, providing a short diffusion pathway
8
Q
How does a circulatory system maintain a high diffusion gradient in the lungs ?
A
it transports deoxygenated blood to the lungs and removes oxygenated blood from the lungs
9
Q
How does a ventilation mechanism maintain a high diffusion gradient in the lungs ?
A
it continually provides air with a high O2 concentration and removes air with a high CO2 concentration
10
Q
How does blood get from the alveoli to the blood ?
A
it diffuses across the epithelial wall of the alveoli and endothelial wall of the capillary into the blood
11
Q
How does carbon dioxide get from the blood to the alveoli ?
A
it diffuses through the endothelial wall of the capillary then through the epithelial alveoli wall
12
Q
What happens to oxygen when it enters the blood ?
A
it binds with haemoglobin to form oxyhaemoglobin
13
Q
What is ventilation ?
A
the method by which air or water is passed over the respiratory surface to maintain a high diffusion gradient
14
Q
Describe the process of inspiration.
A
- external intercostal muscles contract while internal intercostal muscles relax, pulling the ribs up and downwards
- diaphragm muscle contracts pulling the diaphragm down so it flattens
- both actions increase the volume of the thoracic cavity
- pressure in the lungs decreases below atmospheric and air enters along a pressure gradient
15
Q
What type of process is inspiration ?
A
active
16
Q
How do pairs of muscles work antagonistically ?
A
one contracts while the other relaxes
17
Q
Describe the process of expiration.
A
- external intercostal muscles relax while internal intercostal muscles contract pulling the ribs down and inwards
- diaphragm muscle relaxes and diaphragm moves up to dome shape
- both actions decrease the volume of the thoracic cavity
- pressure in the lungs increases above atmospheric and air is forced out of the lungs, aided by elastic recoil
18
Q
What type of process is expiration ?
A
passive
19
Q
What is pulmonary ventilation ?
A
the total volume of air that is normally moved into the lungs during one minute
20
Q
What is tidal volume ?
A
the volume of air normally taken in at each breath
21
Q
What is ventilation rate ?
A
the number of breath per minute
22
Q
How do you calculate pulmonary ventilation ?
A
pulmonary ventilation (dm^3min^-1) = tidal volume (dm^3) x ventilation rate (min^-1)
23
Q
What is forced expiratory volume (FEV) ?
A
max. air breathed out in 1 second
24
Q
What is forced vital capacity ?
A
the total volume of air breathed out after a deep breath in
25
What are the causes of emphysema ?
- mainly smoking
- could be air pollution
26
What happens to the lungs as a result of having emphysema ?
- surface area of alveoli reduced
- alveolar walls thicken
- loss of elasticity in the lungs
27
How does emphysema cause shortness of breath ?
- difficulty in exhaling due to loss of elasticity
- if lungs can't be emptied, it's harder to inhale fresh air, which causes breathlessness
28
How does emphysema cause rapid breathing ?
- smaller alveolar surface area leads ti reduced oxygen levels in the blood, so the patient breathes more rapidly to increase oxygen supply
29
How does emphysema cause a chronic cough ?
it is the body's effort to remove damaged tissue and mucus that can't be removed as the cilia on the bronchioles have been destroyed
30
What is a risk factor ?
anything that increases the chances of getting a disease
31
what are the risk factors associated with lung disease ?
- smoking
- air pollution
- infections
- genetic makeup
- occupation
32
What is a correlation ?
where a change in one of two variables is reflected by a change in the other variable
33
What is a cause ?
a factor which is directly a cause of a disease
34
What is relative risk ?
measured by comparing the likelihood of harm occurring in those exposed to a hazard with those who aren't exposed to it
35
What is the tracheal system ?
the system of pipes in insects that connects the air outside to the tissues in the body that require oxygen
36
What are spiracles ?
tiny holes on the surface of the insect that are the openings of the tracheae
37
What do the valves on spiracles do ?
they close the spiracles to reduce water loss
38
How does oxygen get from the air to the insect's cells ?
it diffuses from the air, through the spiracles along the tracheae and tracheoles into the cells
39
How are tracheoles adapted for gas exchange ?
- thin , so there is a short diffusion pathway
- numerous, so large surface area
40
How does CO2 get from the insect's cells to the air ?
it diffuse out of the cells along the tracheoles and tracheae out of the spiracles and into the air
41
Describe and explain the relationship between spiracles and CO2 levels in an insect.
CO2 levels rise due to respiration, causing spiracles to open wide, increasing rate of diffusion of gases
42
How do large or active insects use body muscles to increase gas exchange ?
- body muscles contract to compress the tracheae, forcing air out
- body muscles relax, tracheae spring back to shape and fresh air is drawn into them
43
What happens during anaerobic respiration in insects to increase rate of diffusion of oxygen ?
- anaerobic respiration produces lactic acid
- this lowers the water potential of cells, so some of the water in the ends of the tracheoles moves into the cells by osmosis
- this allows more air to move in along the tracheoles and into the cells, which speeds up the rate of diffusion of oxygen
44
How are the gills adapted for gas exchange ?
- large number of gill filaments, which all have thin plates called lamellae => large surface area
- two cell layers between blood and water (epithelial gill lamellae and endothelial capillaries) => short diffusion pathway
45
How does the circulatory system maintain a high diffusion gradient for gas exchange ?
ensures continual flow of blood through respiratory surface to absorb oxygen and remove carbon dioxide
46
How does the ventilation mechanism maintain a high diffusion gradient for gas exchange ?
provides continual flow of water over the gills bringing more O2 and removing CO2
47
What is the countercurrent system in fish ?
blood and water flow in opposite directions
48
How does a countercurrent system maintain a high diffusion gradient ?
ensures that blood continually meets water with a higher concentration of oxygen, so oxygen can always diffuse into the blood
49
What are the main structure involved in gas exchange in plants ?
stomata, mesophyll cells and air spaces
50
What are stomata ?
pores in the epidermis of leaves, surrounded by two guard cells
51
How does gas get into leaves ?
it diffuses in through the stomata
52
How are the leaves adapted for gas exchange ?
they are thin and flat, providing a short diffusion pathway
53
How do respiration and photosynthesis maintain diffusion gradients ?
by using and producing oxygen and carbon dioxide
54
How do mesophyll cells increase the rate of gas exchange ?
there are lots of them, which provides a large surface area
55
How does gas get into the mesophyll cells ?
- gases diffuse in through the stomata and rapidly through the intracellular air spaces
- gases dissolve in the moist cell walls of mesophyll cells
- gases diffuse across thin cell wall and cell membrane of mesophyll cells
56
What is digestion ?
the process in which large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed and assimilated
57
What stimulates the secretion of saliva ?
sight, smell and taste of food
58
What reaction does salivary amylase hydrolyse ?
starch into maltose
59
Why does only a small amount of starch get hydrolysed in the mouth ?
because food is only in the mouth for a short amount of time
60
How does chewing increase the rate of hydrolysis ?
chewing breaks food into smaller particle which increases the surface area
61
How does the pancreas aid the hydrolysis of starch into maltose ?
- the pancreas releases pancreatic amylase into the small intestine in pancreatic juice, which hydrolyses the rest of the starch into maltose
62
What is a disaccharide ?
an enzyme that hydrolyses disaccharides into monosaccharides
63
Where does starch get completely hydrolysed ?
in the ileum
64
Why do disaccharidases form part of the cell-surface membrane of epithelial cells ?
so they aren't lost to the contents of the guts
65
Why is the cell-surface membrane of the ileum folded ?
66
What does maltase hydrolyse ?
67
What does lactase hydrolyse ?
68
What does sucrose hydrolyse ?
69
What are lipids hydrolysed to ?
70
What secretes lipase ?
71
What bond does lipase specifically hydrolyse ?
72
What increases the rate of hydrolysis by lipase ?
73
What is bile ?
74
How does bile get into the small intestine ?
75
How do bile salts increase the rate of hydrolysis by lipids ?
76
What type of process is emulsification ?
77
What are the three types of enzymes that hydrolyse proteins ?
78
What is the first stage of protein hydrolysis ?
79
What do endopeptidases hydrolyse ?
80
Where does the first stage of hydrolysis occur ?
81
What is the endopeptidase in the stomach ?
82
How does the stomach accommodate pepsin ?
83
What is the second stage of hydrolysis of proteins ?
84
What do exopeptidase hydrolyse ?
85
What secretes exopeptidases ?
85
What is the final stage of protein hydrolysis ?
86
What do dipeptidases hydrolyse ?
87
How does the combined action of exopeptidases and endopeptidases increase the efficiency f hydrolysis of proteins ?
88
What adaptations does the ileum have to improve absorption of digested products ?
89
How does a large surface area increase absorption of digested products in the ileum ?
90
How do the blood capillaries in the villi increase absorption of digested products in the ileum ?
91
How do lacteals in the villi increase absorption of digested products in the ileum ?
92
How does a single layer of epithelial cells in each villi wall increase absorption of digested products in the ileum ?
93
How does a large number of mitochondria increase absorption of digested products in the ileum ?
94
How do carrier and channel proteins in the cell-surface membrane increase absorption of digested products in the ileum ?
95
How are micelles formed ?
96
Why are micelles necessary ?
97
What happens when the micelles reach the epithelial cells ?
98
Why can the fatty acids and monoglycerides diffuse straight through the cell-surface membrane ?
99
How do short-chained fatty acids diffuse into the blood ?
100
What happens to long-chained fatty acids, monoglycerides and glycerol in the epithelial cells ?
101
How are chylomicrons formed ?
102
How do chylomicrons get into the blood ?
103
How do monosaccharides and amino acids initially diffuse into epithelial cells ?
104
When does co-transport of monosaccharides and amino acids occur ?
105
What is co-transport of amino acids and monosaccharides ?
106
How does co-transport occur ?
107
What are the atria ?
108
What are the ventricles ?
109
What is the purpose of the right atria ?
110
What is the purpose of the right ventricle ?
111
What is the purpose of the left atrium ?
112
What is the purpose of the left ventricle ?
113
Why is the left ventricle's muscular wall much thicker than the right ventricle's ?
114
When do the atrioventricular valves open ?
115
What happens when atrioventricular valves open ?
116
When do the atrioventricular valves close ?
117
Why do the atrioventricular valves close ?
118
What is the purpose of tendinous cords ?
119
When do the semilunar valves open ?
120
What happens when the semilunar valves open ?
121
When and why do the semilunar valves close ?
122
Where are the atrioventricular valves ?
123
Where are the semilunar valves ?
124
What is the cardiac cycle ?
125
Describe the process of the cardiac cycle.
126
How do you find the heart rate ?
127
How long does a typical cardiac cycle last ?
128
What is cardiac output ?
129
What is stroke volume ?
129
What is heart rate ?
130
What is the equation for cardiac output ?
131
What factors increase the risk of cardiovascular disease ?
132
What is a risk factor ?
133
What does the cardiovascular system consist of ?
134
What type of circulatory system do mammals have ?
135
What is the purpose of the double circulatory system ?
136
What is the name of the artery and vein that enter and leave the kidneys ?
137
How do blood vessels change as blood is pumped to the body and back to the heart ?
137
What is the purpose of the arteries ?
138
What happens in the aorta as the left ventricle contracts ?
139
What happens in the aorta as the left ventricle relaxes ?
140
What does elastic recoil of the arteries help with ?
141
Describe the structure of an artery.
142
143
What type of blood do arteries carry ?
144
Why do arteries near the heart have a higher ratio of elastic fibres to smooth muscle fibres ?
145
Why do arteries have more smooth muscle fibres than elastic fibres ?
146
How do arterioles control the flow of blood ?
147
What does contraction of smooth muscle do ?
148
What does relaxation of smooth muscle do ?
149
What type of blood do veins carry ?
150
What is the purpose of veins ?
151
Describe the structure of a vein.
152
Why do veins have a larger lumen ?
153
Why do valves contain semilunar valves ?
154
Why do muscles in the legs and body need to press on the veins ?
155
Why are capillary walls one cell thick ?
156
Why are there gaps between endothelial cells in capillaries ?
157
Why are capillaries highly branched ?
158
Why do capillaries have a high total cross-sectional area ?
159
What is the advantage of all cells being close to a capillary ?
160
Why do capillaries have a very small diameter ?
161
What does blood consist of ?
162
What do the blood capillaries supply cells with ?
163
What do blood capillaries remove ?
164
Where does the exchange of substances occur ?
165
What is hydrostatic pressure like at the arteriole end of a capillary ?
166
What causes filtration of blood plasma ?
167
How are smaller molecules exchanged into cells ?
168
What stays in the capillary during exchange of substances ?
169
What is tissue fluid ?
170
What causes a reduction in blood pressure ?
171
What causes the osmotic uptake of water into the capillaries ?
172
Why does some water from tissue fluid get reabsorbed by osmosis into the blood ?
173
What are lymph capillaries ?
174
Why does some tissue fluid move into the lymph capillaries ?
175
What is lymph ?
176
How does tissue fluid eventually get back to the blood ?
177
How is oxygen carried around the body ?
178
What is haemoglobin ?
179
What is haemoglobin made of ?
180
How many molecules of oxygen can one haemoglobin molecule transport ?
181
What is the equation for oxygen binding to haemoglobin ?
182
What type of blood enters lung capillaries ?
183
How does blood maintain a concentration gradient ?
184
How does oxygen get into respiring cells ?
185
How is haemoglobin ideally suited as a respiratory pigment for the transport of oxygen ?
186
What does the oxyhemoglobin dissociation curve show ?
187
What causes the characteristic shape of the oxyhaemoglobin dissociation curve ?
188
How does the uptake of one O2 molecule increase the affinity of the remaining ham units to take up oxygen ?
189
What happens in muscle cells during exercise ?
190
How does an increase in CO2 change the O2 dissociation curve ?
191
Why does the Bohr effect occur ?
192
Why is the Bohr effect a physiological advantage to the body ?
193
Why does the oxygen dissociation curve move to the left ?
194
What happens to haemoglobin when the oxygen dissociation curve moves to the left ?
195
When might the oxygen dissociation curve move to the left ?
196
Why does the oxygen dissociation curve move to the right ?
197
When might the oxygen dissociation curve move to the right ?
197
What factors might cause the oxygen dissociation curve to move to the right ?
198
What happens to the haemoglobin when the oxygen dissociation curve moves to the right ?
199
Where does uptake of water and mineral ions occur in plants ?
200
What is the advantage of root hairs ?
201
How are ions absorbed into the roots ?
202
How is water taken up into the roots ?
203
How does water move from the roots to the xylem ?
204
How is the water potential gradient maintained in plants ?
205
What are nitrates used for in plants ?
206
What are phosphates used for in plants ?
207
How does the structure of a shoot differ from that of a root ?
208
What is the purpose of the epidermis ?
209
What are cambium cells ?
210
What does the xylem consist of, and where is it ?
211
Why does the xylem contain lignin ?
212
What is the advantage of the cross walls in xylem vessels being broken down, and the end walls of tracheids being partially broken down ?
213
What is the advantage of xylem vessels and tracheas having bordered pits (holes) ?
214
What is transpiration ?
215
Why do the stomata open ?
216
How does transpiration occur ?
217
What are the environmental factors that affect the rate of transpiration ?
218
How does light affect the rate of transpiration ?
219
How does temperature affect the rate of transpiration ?
220
What is humidity ?
221
How does an increase in humidity affect the rate of transpiration ?
222
How does air movement affect the rate of transpiration ?
223
What are xerophytes ?
224
How does a thick cuticle reduce the rate of transpiration ?
225
How do hairs on the leaf surface reduce the rate of transpiration ?
226
How does a reduced surface area to value ratio reduce the rate of transpiration ?
227
How does the curling of leaves affect the rate of transpiration ?
228
How does the position of stomata reduce the rate of transpiration ?
229
Why do you cut the shoot and put it in the potometer under water ?
230
How does the reservoir of water allow repeat measurements to be made ?
231
Why should the tube be greased and wired when setting up the potometer ?
232
Why might the rate of water uptake not be the same as the rate of transpiration ?
233
What measurements need to be taken to calculate the rate of transpiration ?
234
How do you calculate the volume of water taken up by the plant ?
235
How do you determine the rate of water loss per mm^2 of surface area ?
236
What does cohesion-tension theory explain ?
237
Describe cohesion-tension theory.
238
What is meant by cohesion ?
239
What is meant by adhesion ?
239
What is the evidence for cohesion-tension theory ?
240
How does the change in diameter of a branch or tree trunk prove cohesion-tension theory ?
241
What evidence is there to prove movement of ions in the xylem ?
242
How do radioactive isotopes provide evidence for the movement of ions in the xylem ?
243
What is translocation ?
243
How are carbohydrates transported in plants ?
244
How are proteins transported in plants ?
245
How are lipids transported in plants ?
246
What are sources in a plant ?
247
What are the sinks in a plant ?
248
What does the phloem consist of ?
249
What type of cells is the phloem made of ?
250
Describe the structure of the phloem.
251
What are sieve plates ?
252
What is the mass flow hypothesis ?
253
How does mass flow occur ?
254
What evidence is there to support the mass flow hypothesis ?
255
What are the benefits of ringing ?
256
What is ringing ?
256
How does ringing provide evidence for mass flow ?
257
What is autoradiography, and how does it provide evidence for mass flow ?
258
How do radioactive tracers provide evidence for mass flow ?
259
How do respiratory inhibitors provide evidence for mass flow ?
259
How do aphids provide evidence for mass flow ?
