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A-Level Biology > 3B - More Exchange and Transport Systems > Flashcards

3B - More Exchange and Transport Systems Flashcards

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1
Q

What do amylase and membrane-bound disaccharidases break down in digestion?

A
  • carbohydrates
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2
Q

What is amylase and where is it produced?

A
  • catalyses conversion of starch to maltose through hydrolysis
  • salivary glands and pancreas
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3
Q

What are membrane-bound disaccharidases and where are they attached to?

A
  • help break down disaccharides into monosaccharides through hydrolysis
  • cell membranes of epithelial cells
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4
Q

What does lipase break down in digestion?

A
  • lipids
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5
Q

What is lipase and where is it produced?

A
  • breakdown of lipids into monoglycerides and fatty acids by hydrolysis
  • pancreas
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6
Q

What are bile salts and where are they produced?

A
  • emulsify lipids (form small droplets)
  • monoglycerides and fatty acids stick to it to from micelles
  • liver
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7
Q

What do endopeptidases and exopeptidases break down in digestion?

A
  • proteins
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8
Q

What are endopeptidases?

A
  • hydrolyse peptide bonds inside a protein
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9
Q

What are exopeptidases?

A
  • hydrolyse peptide bonds at the ends of protein molecules

- remove single amino acids from protein

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10
Q

How are the three main monosaccharides absorbed in digestion?

A
  • glucose and galactose: active transport w/ sodium ions via co-transporter proteins
  • fructose: facilitated diffusion through a different transporter protein
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11
Q

How are monoglycerides and fatty acids absorbed in digestion?

A
  • micelles help move them towards the epithelium

- they are lipid-soluble, diffuse directly across epithelial cell membrane

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12
Q

How are amino acids absorbed in digestion?

A
  • similar way to glucose and galactose
  • actively transported into the ileum
  • diffuse back to cells through sodium-dependent transporter proteins
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13
Q

What protein structure is haemoglobin?

A
  • quaternary (four polypeptide chains)
  • each chain has a haem group; contains iron ions
  • high affinity for oxygen
  • haemoglobin + oxygen <=> oxyhaemoglobin
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14
Q

What is the rule of oxygen concentration to partial pressure?

A
  • greater the concentration, the higher the partial pressure
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15
Q

What is the partial pressure of oxygen when it’s loaded onto haemoglobin?

A
  • high
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16
Q

What is the partial pressure of oxygen when it’s unloaded off of haemoglobin?

A
  • lower
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17
Q

What happens to partial pressure of oxygen when cells respire?

A
  • decreases
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18
Q

How does carbon concentration affect oxygen unloading?

A
  • cells produce CO2 when they respire
  • increases the rate of oxygen unloading
  • on a graph, a dissociation curve shifts right
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19
Q

Does haemoglobin of organisms living in environments with low oxygen concentration have high or low affinity?

A
  • high
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20
Q

Active organisms with high oxygen demands have high or low affinity?

A
  • low
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21
Q

What is the circulatory system made up of?

A
  • heart and blood vessels
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22
Q

What is the role of coronary arteries?

A
  • hearts blood supply

- carries blood to heart muscles, tissues etc.

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23
Q

What substances does blood transport around the body?

A
  • respiratory gases
  • digestion products
  • metabolic wastes
  • hormones
24
Q

What is the arteries function and how is it adapted?

A
  • carry blood away from the heart to he body
  • thick, muscular walls have elastic tissue to maintain high pressure
  • inner lining is folded
25
Q

What is the veins function and how is it adapted?

A
  • carry deoxygenated blood to the heart under low pressure
  • wider lumen than arteries
  • very little elastic or muscle tissue
  • valves stop blood flowing backwards
26
Q

How are capillaries adapted to their functions?

A
  • found very near cells in exchange tissues, short diffusion pathway
  • walls are one cell thick
  • large number of capillaries, increases SA
27
Q

How is tissue fluid formed?

A
  • hydrostatic pressure inside capillaries > pressure in tissue fluid
  • difference in pressure forces fluid out of capillaries and into spaces around cells
  • pressure reduces in capillaries
  • due to fluid loss, water potential at venule end < water potential in tissue fluid
  • some water re-enters capillaries by osmosis
28
Q

What happens to the excess tissue fluid?

A
  • drained into lymphatic system

- lymphatic system transports fluid from tissues and dumps it back into circulatory system

29
Q

Which side of the heart pumps deoxygenated blood to the lungs?

A
  • Right
30
Q

Where does the left side pump oxygenated blood?

A
  • whole body
31
Q

Why does the left ventricle have thicker, more muscular walls than the right ventricle?

A
  • left ventricle needs powerful contraction to pump blood all around the body
32
Q

What do the atrioventricular valves do?

A
  • link atria to ventricles

- stops blood flowing back into the atria

33
Q

What do semi-lunar valves do?

A
  • link ventricles to pulmonary artery and aorta

- stops blood flowing back to heart

34
Q

What is step 1 in the cardiac cycle?

A
  • ventricles relax, atria contracts
  • blood is pushed into ventricles
  • semi-lunar valves close
  • atrioventricular valves open
35
Q

What happens in step 2 of the cardiac cycle?

A
  • ventricles contract, atria relaxes
  • atrioventricular valves forced shut
  • semi-lunar valves open
  • blood exits the heart
36
Q

What happens in step 3 of the cardiac cycle?

A
  • ventricles and atria relax
  • semi-lunar valves forced shut
  • atrioventricular valves forced open
  • blood passively enters the heart
37
Q

What is meant by atheroma formation?

A
  • white blood cells and lipids clump together to form fatty streaks
  • more white blood cells, lipids and connective tissue build up fibrous plaque (atheroma)
  • plaque partially blocks lumen of artery and restricts blood flow
38
Q

What is meant by an aneurysm?

A
  • balloon like swelling of artery
  • atheromas damage and weaken arteries
  • blood travelling through weakened artery at high pressure pushes inner layers through the outer elastic layer, forming an aneurysm
39
Q

What happens if an aneurysm bursts?

A
  • causes a haemorrhage
40
Q

What is meant by thrombosis?

A
  • blood clot formation
  • plaque can rupture the endothelium, damaging artery wall and leaving a rough surface
  • platelets and fibrin form a clot at damage site
  • clot could cause complete blockage of artery
41
Q

What is meant by a myocardial infarction?

A
  • more commonly known as a heart attack

- if coronary artery becomes completely blocked, an area of heart muscle will be cut off from blood supply

42
Q

What 3 factors are known for increasing the risk of cardiovascular disease and why do they increase risk?

A
  • high blood cholesterol and poor diet; cholesterol is part of fatty deposits that form atheromas
  • smoking; nicotine increases
43
Q

What is transported up the xylem?

A
  • water

- mineral ions

44
Q

What is transported up and down the phloem?

A
  • organic substances e.g sugars
45
Q

What is the structure of xylem tissues?

A
  • long, tube-like
  • formed from dead cells
  • no end walls to pass up water through easily
46
Q

What is meant by the cohesion-tension theory?

A
  • water evaporates from top of xylem creates tension
  • tension pulls more water into the leaf
  • water molecules are cohesive, when some are pulled into the leaf others follow
47
Q

What is meant by transpiration?

A
  • water evaporates from moist cell walls and accumulates in spaces between cells in the leaf
  • when stomata open, it moves out of leaf down concentration gradient
48
Q

How does light affect transpiration rate?

A
  • the lighter it is, the higher the rate

- stomata open when it gets light to let in CO2 for photosynthesis

49
Q

How does temperature affect transpiration rate?

A
  • the higher it is, the faster the rate
  • warmer water molecules have more energy, evaporate from cells faster
  • increases concentration gradient between inside and outside of leaf, making diffusion water
50
Q

How does humidity affect transpiration rate?

A
  • the lower it is, the faster the rate

- if air around the plant is dry, the concentration gradient increases, increasing transpirations

51
Q

How does wind affect transpiration rate?

A
  • the windier it is, the faster the rate
  • air movement blows away water molecules from around the stomata
  • increases concentration gradient
52
Q

What is meant by translocation?

A
  • movement of solutes (assimilates) to where they’re needed in a plant
  • energy requiring process
  • enzymes maintain concentration gradient from source to sink by changing solutes at sink e.g breaking them down
53
Q

What is stage 1 of the mass flow hypothesis?

A
  • active transport actively loads solutes from companion cells into sieve tubes of phloem at the source
  • lowers water potential inside sieve tubes, water enters tubes by osmosis from xylem to companion cells
  • creates a high pressure inside sieve tubes at source end
54
Q

What is stage 2 of mass flow hypothesis?

A
  • at sink end, solutes are removed from phloem to be used up
  • increases water potential inside sieve tubes, so water leaves tubes by osmosis
  • lowers pressure inside sieve tubes
55
Q

What is stage 3 of mass flow hypothesis?

A
  • results in pressure gradient from source to sink
  • gradient pushes solutes along sieve tubes towards the sink
  • when they reach the sink the solutes will be used (respiration) or stored (e.g starch)

A-Level Biology (19 decks)

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