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A Level Biology Paper 1 > Section 3 - Mass Transport > Flashcards

Section 3 - Mass Transport Flashcards

1
Q

Why is mass transport systems required?

A
  • Most cells too far away from exchange surfaces for diffusion alone to maintain composition of tissue fluid
  • Mass transport maintains final diffusion gradients bringing substances to and from cells
  • Mass transport helps maintain relatively stable immediate environment of cells
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2
Q

What is the double circulatory system?

A
  • Pulmonary circulation: Deoxygenated blood in right side of heart pumped to lungs - oxygenated blood returns to side of heart - left side
  • Systemic circulation: Oxygenated blood in left side pumped to tissues/ deoxygenated blood returns on right side
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3
Q

Why is the double circulatory system important to animals?

A
  • Prevents mixing of oxygenated and deoxygenated blood - so blood is saturated with oxygen - efficient delivery of oxygen and glucose for respiration
  • Blood can be pumped at a higher pressure - substances taken to and removed from cells quicker and more efficient.
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4
Q

What are the coronary arteries?

A
  • Deliver oxygenated blood to cardiac muscle (heart)
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5
Q

What are the names if the blood vessels entering and leaving the heart?

A
  • Aorta - takes oxygenated blood from heart - respiring tissue
  • Vena cava - takes deoxygenated blood from respiring tissue to heart
  • Pulmonary artery - takes deoxygenated blood from heart to lungs
  • Pulmonary vein - takes oxygenated blood from lungs to heart
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6
Q

What are the names of the blood vessels entering and leaving the lungs?

A
  • Pulmonary artery
  • Pulmonary vein
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7
Q

What are the names of the blood vessels entering and leaving the kidney?

A
  • Renal artery - Takes oxygenated blood - kidneys
  • Renal veins - take deoxygenated blood to the vena cava from the kidneys
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8
Q

What are the different valves?

A
  • Atrioventricular valves - prevent backflow of blood to ventricles from atria
  • Semi-lunar valves - prevent backflow of blood from arteries to ventricles
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9
Q

What is the adaptation of the left ventricle

A
  • Has thicker muscular walls
  • Generates high blood pressure
  • For oxygenated blood has to travel greater distance around the body
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10
Q

What is the structure of arteries related to their function?

A
  1. Thick smooth muscle layer - Contract pushing blood along and control blood flow/pressure
  2. Elastic tissue layer - stretch as ventricles contract and recoil as ventricle relaxes. Even out blood pressure and maintain high pressure
  3. Thick wall - Withstands high pressure and prevents artery bursting
  4. Smooth endothelium - reduces friction
  5. Narrow lumen - Increases and maintains high blood pressure
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11
Q

What are arterioles and what is their structure related to their function?

A
  • Division of arteries to smaller vessels directing blood to capillaries. Structure similar to arteries BUT…
  • Thicker muscle layer - constricts to reduce blood flow and dilates to increase blood flow
  • Thinner elastic layer as lower pressure
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12
Q

What is the structure of veins related to its function?

A
  • Wider lumen than arteries
  • Very little elastic and muscle tissue
  • Valves - prevents the backflow of blood
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13
Q

Exam Question: The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why.(3)

A
  • Aorta is close/directly linked to the heart/ventricle/ pressure is higher
  • Aorta has elastic tissue
  • Aorta has stretch and recoil
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14
Q

Structure of capillaries related to its function

A
  • Capillary wall is a thin layer (1 cell thick) - short diffusion pathway - rapid diffusion
  • Capillary bed is made of a large network of capillaries - large SA - rapid diffusion
  • Narrow lumen - reduces flow rate so more time for diffusion
  • Capillaries permeate tissues - short diffusion pathway
  • Pores - allows substances to escape
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15
Q

What is tissue fluid?

A
  • The fluid surrounding cells/tissues
  • Provides respiring cells with water, oxygen, glucose, amino acids
  • Enables waste substances to move back into blood e.g urea, lactic acid
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16
Q

What is the formation of tissue fluid?

A
  • Higher blood/ hydrostatic pressure inside capillaries than tissue fluid
  • Forces fluid/ water out of capillaries
  • Large plasm proteins remain in capillary
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17
Q

What is the return of tissue fluid to the circulatory system?

A
  • Hydrostatic pressure reduces as fluid leaves
  • An increasing conc of proteins lowers the WP in the capillary below the tissue fluid
  • Water re-enters the capillaries from the tissue fluid by osmosis - down WP gradient
  • Excess water taken up by lymph system and returned to circulatory system
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18
Q

How does a low concentration of plasma proteins cause the accumulation of tissue fluid?

A
  • Water potential in capillary not as low so WP potential gradient is reduced
  • More tissue fluid formed at arteriole end
  • Less/ no water absorbed into blood capillary by osmosis
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19
Q

How does high blood pressure lead to the accumulation of tissue fluid?

A
  • High blood pressure = high hydrostatic pressure
  • Increases outward pressure from arterial end
  • So more tissue fluid formed/ less reabsorbed
  • Lymph cant drain fast enough
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20
Q

What are the different stages of the cardiac cycle?

A
  • Atrial systole
  • Ventricular systole
  • Diastole
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21
Q

What is atrial systole?

A
  • Atria contract - decreasing volume and increasing pressure inside atria
  • AV forced open, semi lunar closed
  • Blood pushed into ventricles
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22
Q

What is ventricular systole?

A
  • Ventricles contract from the bottom up - decreasing the volume and increasing pressure in ventricles
  • Semi lunar valves are open
  • AV valves shut
  • Blood pushed out of heart through arteries
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23
Q

What is diastole?

A
  • Atria and ventricles relax - increasing volume and decreasing pressure inside chambers
  • Blood from veins fill atria (increasing pressure slightly) and flows passively into ventricles
  • AV valves open, SL valves closed
24
Q

How do you calculate cardiac output and what do the different parts of the equation mean?

A
  • Cardiac output = stroke volume x heart rate
  • Cardiac output = amount of blood pumped out of the heart per minute
  • Stroke volume = volume of blood pumped by the ventricles in each heart beat
  • Heart rate = number of beats per minute
25
Q

How do you calculate heart rate from cardiac cycle data?

A
  • 1 beat = 1 cardiac cycle
  • Find the length of 1 cardiac cycle
  • Heart rate in beats per minute = 60 seconds
26
Q

What is cardiovascular disease and name an example of one?

A
  • Conditions affecting structure or functions of the heart
  • Coronary heart disease
27
Q

How can an atheroma result in a heart attack

A
  • Atheroma causes narrowing of coronary arteries
  • Restricts blood flow to heart muscle supplying glucose or oxygen
  • Heart anaerobically respires - less ATP produced - not enough energy for heart to contract - lactate produced - damages heart tissue
28
Q

What are the common risk factors of cardiovascular disease (increase probability of getting disease)

A
  • Age
  • Diet - high in salt or saturated fat
  • High consumption of alcohol
  • Stress
  • Smoking
  • Genetic
29
Q

Exam Question: Studies of CVD patterns between different countries suggest there is a link between CBD and diet. Suggest why such studies may not prove the link between CVD and diet (2)

A
  • Other variables/ uncontrolled variables affect CVD
  • Genetic differences
  • Different countries have different lifestyles
  • Data does not provide a causal link
30
Q

What is haemoglobin?

A
  • Is a group of chemically similar molecules found in many different organisms
  • This structure may differ between organisms
31
Q

Where is Haemoglobin found?

A
  • In red blood cells
32
Q

What is the structure of haemoglobin?

A
  • No nucleus - contain more haemoglobin
  • Biconcave shape - increase surface area for rapid diffusion
  • Quaternary structure - 4 polypeptide chains
  • Each polypeptide chain contains a haem group of Fe2+ which combines with oxygen
33
Q

What is the structure of haemoglobin?

A
  • No nucleus - contain more haemoglobin
  • Biconcave shape - increase surface area for rapid diffusion
  • Quaternary structure - 4 polypeptide chains
  • Each polypeptide chain contains a haem group of Fe2+ which combines with oxygen
34
Q

Where in the body does haemoglobin have a high and low affinity to oxygen?

A
  • In lungs there is a high pO2, haemoglobin has a high affinity for oxygen - readily loads
  • At respiring tissues, a low pO2 oxygen readily unloads. CO2 conc high increasing unloading
35
Q

Explain the shape of the oxyhaemoglobin dissociation curve?

A
  • Haemoglobin has a low affinity for oxygen as first oxygen binds
  • After first binds the shape changes that makes 2nd and 3rd easier to bind
  • After 3rd, haemoglobin starts to become saturated, shape changes and it is hard to bind
36
Q

What is the effect of CO2 (bohr effect)

A
  • Lowers the pH and reduces haemoglobin’s affinity for oxygen as haemoglobin changes shape
  • Oxygen rapidly unloads
  • Advantageous - provides more oxygen for muscles for aerobic respiration. Curve shifts to the right
37
Q

What is the effect of the curve being shifted to the left?

A
  • Haemoglobin has a higher affinity for oxygen
  • More oxygen associates with haemoglobin more readily at low pO2 and dissociates less readily
  • Advantageous - for those living in high altitudes, underground
38
Q

What is the effect of the curve being shifted to the right?

A
  • Oxygen dissociates from haemoglobin more readily to respiring cells
  • Advantageous to organisms with a high rate of respiration
39
Q

What is the function of the xylem?

A
  • Is the tissue that transports water in the stem and leaves of plants
40
Q

What is the cohesion tension theory?

A
  • How water moves up the xylem against transpiration via transpiration stream
41
Q

What is the process of the cohesion tension theory?

A
  • Water evaporates from the leaves via the stomata due to transpiration
  • Reducing WP in the cell and increasing WP gradient
  • Water drawn out of xylem
  • Creating tension
  • Cohesive forces between water molecules pull water up as a column
42
Q

What are some adaptations of the xylem?

A
  • Elongated cells arranged end to end to form a continuous column
  • Hollow
  • End walls break down for flow
  • Thick cell walls
  • Rigid - less likely to collapse under low pressure
  • Waterproof
43
Q

What is the process of transloaction?

A
  • Movement of solutes from source to sink
44
Q

What is the mass flow hypothesis at the source?

A
  • High conc of solute
  • Active transport loads solutes from companion cells to sieve tubes of the phloem
  • Lowering WP inside sieve tubes
  • Water enters sieve tubes by osmosis from xylem and companion cells
  • Increasing pressure inside sieve tubes at the source end
45
Q

What is the mass flow hypothesis at the sink?

A
  • Low conc of solute
  • Solutes removed to be used up
  • Increasing WP inside sieve tubes
  • Water leaves by osmosis
  • Lowering pressure inside sieve tubes
46
Q

What is the mass flow in the mass flow hypothesis?

A
  • Pressure gradient from source to sink
  • Pushes solutes from source to sink
  • Solutes used/stored at sink
47
Q

What are the adaptations of the phloem?

A
  • Sieve tubes have no nucleus and few organelles
  • Companion cell for each sieve tube carry out important functions - provide ATP
48
Q

What are some of the ways to investigate transport in plants?

A
  • Use of tracers and ringing experiments
  • Aphid
  • Metabolic inhibitor
49
Q

How do you use tracers to investigate transport in plants?

A
  • Supply plant with C14
  • This is incorporated into organic substances produced by the leaf and undergo translocation
  • Plant killed and placed in autoradiography and turns black when radioactive substance is present
50
Q

How do you use aphids to investigate transport in plants?

A
  • Aphids pierce the phloem using mouthpiece
  • Releasing sap from plants
  • Flow of sap higher at leaves than at sink
  • Evidence of pressure gradient - higher near source
51
Q

How do you use of metabolic inhibitors to investigate transport in plants?

A
  • Add a metabolic inhibitor to phloem
  • Translocation stops
  • Proves active transport is involved - as it requires ATP against conc gradient
52
Q

What does a potometer do?

A
  • Estimates the transpiration rate by measuring water uptake
53
Q

What is the method of using a potometer?

A
  • Cut shoot underwater - prevent air entering
  • Assemble potometer and insert shoot underwater
  • Dry leaves and allow time to acclimatise
  • Shut off tap reservoir
  • Remove the end of the capillary tube from water beaker until 1 bubble has formed
  • Record position of air bubble and record time
  • Rate of air movement = estimate transpiration rate can change variables
54
Q

How does light affect the rate of transpiration?

A
  • Higher light intensity - faster transpiration
  • Because stomata open in light to let CO2 in for photosynthesis
  • Allowing more water to evaporate faster
  • Stomata close when it is dark - low transpiration rate
55
Q

How does temperature affect the rate of transpiration?

A
  • Higher temperature = faster transpiration rate
  • Water molecules gain K.E and move faster
  • Water evaporates faster
56
Q

How does humidity affect the rate of transpiration?

A
  • Lower humidity - faster transpiration rate
  • Because as humidity increases, more water is in the air so has a higher WP potential
  • Decreasing WP gradient - water evaporates more slower
57
Q

How does wind affect the rate of transpiration?

A
  • Windier = faster transpiration rate
  • Wind blows away water molecules from around stomata
  • Decreasing WP of air around stomata
  • Increasing WP gradient
  • Water evaporates faster

A Level Biology Paper 1 (15 decks)

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