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biology topic 3 Flashcards

1
Q

what type of animals have a larger surface area to volume ratio?

A

small animals

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2
Q

how does gas exchange occur in small organisms?

A

diffusion

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3
Q

how does a compact shape affect the surface area to volume ratio?

A

smaller surface area to volume ratio

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4
Q

how does water enter the mouth of a fish?

A

opens mouth, volume of buccal cavity increases, pressure decreases so water flows in

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5
Q

what happens to the water inside a fish’s mouth once it closes?

A

squeezes water out of the buccal cavity, over gills and out of the operculum

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6
Q

what do most gas exchange surfaces have in common?

A

thin, large surface area, steep concentration gradient

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7
Q

what is the structure of gills?

A

gills are made of thin plates=gill filaments, and these are covered in lamellae to further increase the surface area

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8
Q

how does the counter current system work?

A

concentration gradient maintained at all times, water and blood flow in opposite directions so blood meets water at a higher oxygen concentration

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9
Q

what is the site of gas exchange in fish?

A

lamellae

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10
Q

how do fish uptake oxygen efficiently?

A

large surface area from lamellae etc, large number of capillaries, thin epithelium, counter current flow

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11
Q

what do the guard cells do?

A

controls what enters the leaf, limits water loss

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12
Q

what does the waxy cuticle do?

A

stops water leaving the leaf

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13
Q

what does the palisade do?

A

contains chloroplasts for photosynthesis

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14
Q

what does the upper epidermis do?

A

transparent and protective

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15
Q

what does the spongy mesophyll do?

A

where gas diffusion occurs

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16
Q

where do xerophytes live?

A

hot, dry environments

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17
Q

what are the adaptations of xerophytes to improve water uptake?

A

deep root system, shallow roots to absorb dew, solutes in roots to lower the water potential

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18
Q

what are the adaptations of xerophytes to reduce water loss?

A

sunken stomata pits, thick waxy cuticle to reduce evaporation, reduced leaf area, curled leaves, hairy leaves trap saturated air

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19
Q

why can’t insects increase their surface area?

A

water would just evaporate

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20
Q

how does gas exchange occur in an insect?

A

valves in the spiracles open to allow air into the trachea, then air enters the tracheoles, and air directly goes to body cells

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21
Q

how is air moved in an insect?

A

rhythmic abdominal movements

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22
Q

what are the adaptations of the alveoli?

A

moist lining, 1 cell thick, surrounded by capillaries, constant blood flow, large surface area

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23
Q

what is the process for inspiration?

A

external intercostal and diaphragm muscles contract, ribs move up and out, diaphragm flattens, increased volume of thoracic cavity, air forced in down a pressure gradient

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24
Q

what is the process for expiration?

A

external intercostal and diaphragm muscles contract, ribcage moves down and in, diaphragm curves, volume of thoracic cavity decreases, pressure increases, air forced down a pressure gradient

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25
what route does air take in humans?
trachea, bronchi, bronchioles, alveoli
26
how does oxygen diffuse from the alveoli into the blood?
diffuses out of alveoli, across alveolar epithelium, and capillary endothelium, into haemoglobin into the blood
27
what is tidal volume?
volume of air in each breath
28
what is ventilation rate?
number of breaths per minute
29
what is forced expiratory volume?
max volume of air breathed out per second
30
what is forced vital capacity?
max volume of air to forcefully breathe out
31
what is minute ventilation?
tidal volume x breathing rate
32
what happens in pulmonary tuberculosis?
reduced tidal volume as immune system builds a wall around bacteria in the lungs, which damages the gas exchange system
33
what happens in fibrosis?
scar tissue forms, thicker and less elastic tissue so less able to expand
34
what happens in asthma?
mucus produced which constricts the airways, and reduces forced expiratory volume
35
what happens in emphysema?
alveoli destructed, foreign particles trapped in alveoli which attracts phagocytes
36
what is the role of the digestive system?
to break down food so that it is small and soluble
37
what is the role of amylase?
salivary amylase breaks down starch to maltose, this is then denatured in the stomach so pancreatic amylase hydrolyses starch to maltose in the small intestine, hydrolysis of glyosidic bonds breaks down maltase to glucose
38
how are the products of starch absorbed?
glucose moves in with sodium to the epithelial cell via a carrier protein, sodium is removed from the cell by the sodium potassium pump by active transport into the blood, this maintains a sodium concentration gradient between the lumen and the epithelial cell, so glucose can move into the blood by facilitated diffusion
39
what is maltose made of?
2 alpha glucose
40
what is sucrose made of?
glucose and fructose
41
what is lactose made of?
glucose and galactose
42
what is the ileum?
final section of the small intestine
43
what do lipases break down?
lipids into monoglycerides and fatty acids
44
what do endopeptidases break down?
hydrolyse peptide bonds within a protein
45
what do exopeptidases break down?
hydrolyse peptide bonds at the end of a protein
46
what do dipeptidases do?
hydrolyse the peptide bond in dipeptides
47
what do lipases do?
hydrolyse the ester bond
48
where do lipases work?
made in the pancreas and work in the small intestine
49
where are bile salts produced?
in the liver
50
what do bile salts do?
emulsify lipids to increase the surface area for lipase to work on
51
what are miscelles?
when monoglycerides and fatty acids stick together with the bile salts
52
what is haemoglobin?
a large protein which has a quaternary structure
53
how many molecules of haemoglobin can oxygen carry?
4
54
why is the graph for oxygen dissociation an s shape?
shallow at first as difficult to bind due to the change in shape, then steeper as first binding makes subsequent bindings easier, then shallower due to a lower probability of oxygen molecules successfully binding
55
why does the oxygen dissociation curve shift to the left?
greater affinity for oxygen, loads easier and dissociates less easily
56
why does the oxygen dissociation curve shift to the right?
lower affinity for oxygen, loads less easily and unloads easier
57
what is the bohr effect?
increase in carbon dioxide levels lower the pH of the blood, higher carbon dioxide levels mean that the graph shifts to the right- lower affinity for oxygen loads less easily unloads easier
58
how does oxygen dissociation change for animals with a high metabolic rate?
needs to release oxygen readily into tissues, shifts to the right
59
how does oxygen dissociation change for organisms living in an environment with little oxygen?
shifts to the left to have a greater affinity for oxygen
60
what is the function of the circulatory system?
transport gases, nutrients and waste, maintain pH levels and body temperature, contains cells to fight infection
61
what is a double circulatory system?
blood passes through the heart twice, pulmonary circulation= deoxygenated blood pumped from heart, and systematic circulation= oxygenated blood pumped from heart
62
what do arteries do?
carry blood from the heart to the rest of the body
63
what do veins do?
take blood back to the heart
64
how is the structure of artery adapted?
thick and muscular walls, elastic tissue to stretch and maintain a high pressure, folded endothelium to allow stretching, carry oxygenated blood
65
how is the structure of a vein adapted?
wide lumen, little elastic or muscle tissue, contain valves to prevent blood flowing backwards, carry deoxygenated blood
66
what is the role of a capillary?
to exchange substances, found near cells in exchange tissues so there is a short diffusion pathway, 1 cell thick to shorten the diffusion pathway, large number of capillaries
67
how is tissue fluid formed?
hydrostatic pressure is lower in the arteriole end of the capillary which forces small molecules out of the capillary, hydrostatic pressure lower at the venule end, water potential is lower at the venule end as there is a higher concentration of proteins which are too large to leave the capillary, this means some water re enters by osmosis, excess fluid is drained into the lymphatic system
68
why is the left ventricle of the heart thicker?
needs to pump blood all around the body
69
what is systole?
period of ventricular contraction
70
what is diastole?
period of ventricular relaxation
71
what happens in diastole?
blood enters the atria via the vena cava and pulmonary vein, this increases the pressure in the atria
72
what happens in atrial systole?
atria contract which increases the pressure, valves open so blood flows into the ventricles
73
what happens in ventricular systole?
ventricle walls contract, atrioventricular valves close, semi lunar valves open, blood forced out into the aorta and pulmonary artery
74
what is cardiac output?
heart rate x stroke volume
75
what is heart rate?
number of beats per minute
76
what is stroke volume?
volume of blood leaving the heart each beat
77
where are the semi lunar valves located?
in the aorta and pulmonary artery
78
where are the atrioventricular valves located?
between the atria and ventricles
79
what are the atrioventricular valves also known as?
bicuspid and tricuspid valves
80
how does an atheroma form?
endothelium is damaged, white blood cells and lipids clump under the lining, these form a fibrous plaque
81
what is an aneurysm?
atheroma damages the artery, blood travels through at high pressure, balloon like swelling forms as walls pushed
82
what is thrombosis?
atheroma ruptures the endothelium, damages artery wall and leaves a rough surface, blood clot formed, blocks an artery
83
what is myocardial infarction?
coronary artery is blocked, heart receives no oxygen, causes a heart attack
84
what risk factors affect cardiovascular disease?
high blood cholesterol, poor diet, cigarette smoking, high blood pressure
85
what is the role of companion cells?
carry out living functions for sieve cells
86
what is the phloem tissue made of?
companion cells, sieve tubes, sap, sieve plate
87
what is translocation?
movement of solutes around a plant
88
how does translocation take place?
mass flow hypotheses
89
what is a source?
area where solutes are made (high concentration)
90
what is a sink?
area where solutes are used up (lower concentration)
91
how is a lower concentration maintained at the sink?
enzymes break down/remove solutes at the sink
92
how does the mass flow hypotheses work?
sucrose is made via photosynthesis, moves down a concentration gradient into companion cells hydrogen ions are actively transported out of the companion cells and diffuse into the sieve tube element, sucrose is co transported with this lower water potential in sieve tubes due to high water potential water moves from the xylem to the phloem down the water potential gradient which increases the hydrostatic pressure substances move from high to low pressure sucrose is used or stored at the sink sucrose is actively transported from sieve tubes to cells which lowers the water potential water moves into cells via osmosis which lowers the hydrostatic pressure further down, resulting in a pressure gradient for the substance to move down the phloem
93
how do ringing experiments provide evidence for mass flow hypotheses?
sugars accumulate above the ring as they cannot move down the stem, sugars don't pass below the ring so tissues die, phloem responsible for translocation in plants
94
how are ringing experiments formed?
outer layers of bark and phloem removed from the stem, stem above missing tissue fluid swells with sugar liquid, tissues below the ring wither and die
95
how are tracer experiments performed?
carbon isotope used to make 14CO2, incorporated into sugars produced in photosynthesis, autoradiography allows these sugars to be tracked
96
how do tracer experiments work?
radioactive areas correspond to phloem not xylem
97
what is evidence to support the mass flow hypotheses?
pressure in sieve tubes (sap released when cut), sucrose concentration higher in leaves (source) than roots (sink), downward flow stops in shade or night, companion cells contain many mitochondria, lack of oxygen inhibits sucrose transport
98
what evidence questions the mass flow hypotheses?
unclear function of sieve plates, not all solutes move at the same speed, sucrose doesn't go quickest to areas with the lowest concentration
99
how does cohesion tension occur?
water evaporates from mesophyll cells, lower water potential in leaf cells so water moves down the water potential gradient, lower pressure at the top of the xylem, water pulled up the xylem, water is cohesive so a continuous column is formed, adhesion between water and wall, water moves across root from soil down the water potential gradient
100
what does the xylem transport?
minerals in solution and water
101
how does light affect transpiration rate?
lighter= faster rate, stomata open for photosynthesis
102
how does temperature affect transpiration rate?
higher= faster rate, evaporate faster so larger concentration gradient
103
how does humidity affect transpiration rate?
lower= faster transpiration rate, as decreased concentration gradient
104
how does wind affect transpiration rate?
windier= faster transpiration rate, increased concentration gradient

biology (5 decks)

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