3B - More Exchange and Transport Systems Flashcards
1
Q
What do amylase and membrane-bound disaccharidases break down in digestion?
A
- carbohydrates
2
Q
What is amylase and where is it produced?
A
- catalyses conversion of starch to maltose through hydrolysis
- salivary glands and pancreas
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
4
Q
What does lipase break down in digestion?
A
- lipids
5
Q
What is lipase and where is it produced?
A
- breakdown of lipids into monoglycerides and fatty acids by hydrolysis
- pancreas
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
7
Q
What do endopeptidases and exopeptidases break down in digestion?
A
- proteins
8
Q
What are endopeptidases?
A
- hydrolyse peptide bonds inside a protein
9
Q
What are exopeptidases?
A
- hydrolyse peptide bonds at the ends of protein molecules
- remove single amino acids from protein
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
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
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
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
14
Q
What is the rule of oxygen concentration to partial pressure?
A
- greater the concentration, the higher the partial pressure
15
Q
What is the partial pressure of oxygen when it’s loaded onto haemoglobin?
A
- high
16
Q
What is the partial pressure of oxygen when it’s unloaded off of haemoglobin?
A
- lower
17
Q
What happens to partial pressure of oxygen when cells respire?
A
- decreases
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
19
Q
Does haemoglobin of organisms living in environments with low oxygen concentration have high or low affinity?
A
- high
20
Q
Active organisms with high oxygen demands have high or low affinity?
A
- low
21
Q
What is the circulatory system made up of?
A
- heart and blood vessels
22
Q
What is the role of coronary arteries?
A
- hearts blood supply
- carries blood to heart muscles, tissues etc.
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
What is the veins function and how is it adapted?
- 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
How are capillaries adapted to their functions?
- found very near cells in exchange tissues, short diffusion pathway
- walls are one cell thick
- large number of capillaries, increases SA
27
How is tissue fluid formed?
- 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
What happens to the excess tissue fluid?
- drained into lymphatic system
| - lymphatic system transports fluid from tissues and dumps it back into circulatory system
29
Which side of the heart pumps deoxygenated blood to the lungs?
- Right
30
Where does the left side pump oxygenated blood?
- whole body
31
Why does the left ventricle have thicker, more muscular walls than the right ventricle?
- left ventricle needs powerful contraction to pump blood all around the body
32
What do the atrioventricular valves do?
- link atria to ventricles
| - stops blood flowing back into the atria
33
What do semi-lunar valves do?
- link ventricles to pulmonary artery and aorta
| - stops blood flowing back to heart
34
What is step 1 in the cardiac cycle?
- ventricles relax, atria contracts
- blood is pushed into ventricles
- semi-lunar valves close
- atrioventricular valves open
35
What happens in step 2 of the cardiac cycle?
- ventricles contract, atria relaxes
- atrioventricular valves forced shut
- semi-lunar valves open
- blood exits the heart
36
What happens in step 3 of the cardiac cycle?
- ventricles and atria relax
- semi-lunar valves forced shut
- atrioventricular valves forced open
- blood passively enters the heart
37
What is meant by atheroma formation?
- 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
What is meant by an aneurysm?
- 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
What happens if an aneurysm bursts?
- causes a haemorrhage
40
What is meant by thrombosis?
- 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
What is meant by a myocardial infarction?
- 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
What 3 factors are known for increasing the risk of cardiovascular disease and why do they increase risk?
- high blood cholesterol and poor diet; cholesterol is part of fatty deposits that form atheromas
- smoking; nicotine increases
43
What is transported up the xylem?
- water
| - mineral ions
44
What is transported up and down the phloem?
- organic substances e.g sugars
45
What is the structure of xylem tissues?
- long, tube-like
- formed from dead cells
- no end walls to pass up water through easily
46
What is meant by the cohesion-tension theory?
- 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
What is meant by transpiration?
- 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
How does light affect transpiration rate?
- the lighter it is, the higher the rate
| - stomata open when it gets light to let in CO2 for photosynthesis
49
How does temperature affect transpiration rate?
- 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
How does humidity affect transpiration rate?
- the lower it is, the faster the rate
| - if air around the plant is dry, the concentration gradient increases, increasing transpirations
51
How does wind affect transpiration rate?
- the windier it is, the faster the rate
- air movement blows away water molecules from around the stomata
- increases concentration gradient
52
What is meant by translocation?
- 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
What is stage 1 of the mass flow hypothesis?
- 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
What is stage 2 of mass flow hypothesis?
- 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
What is stage 3 of mass flow hypothesis?
- 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)
