Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Section 3 - Organisms exchange substances with their environment: 7. Mass transport > Flashcards

Section 3 - Organisms exchange substances with their environment: 7. Mass transport Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a Haemoglobin molecule

A

A Globular protein within red blood cells, that transports oxygen within the bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the structure of Haemoglobin

A
  • 4 polypeptides linked together (quaternary structure)
  • Each polypeptide is associated with a haem group, containing an Fe^2+ ion.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many O2 molecules can bind to one Haemoglobin molecule

A

4
(each Fe^2+ binds to one O2 molecule)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is oxygen loading/association and where does it occur

A

Process where Haemoglobin binds with O2
(In humans, occurs in the lungs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is oxygen unloading/dissociation and where does it occur

A

Process where Haemoglobin releases O2
(In humans, occurs near the tissues/muscles cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is shown on an oxygen dissociation curve

A

Plot of Haemoglobin saturation (%) against partial pressure of oxygen (KPa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is meant by the Haemoglobin’s affinity for oxygen

A

Determines how easily it takes in/gives out O2
- Changes in different conditions within the body
- Different organisms are adapted to have different affinities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the shape of an oxygen dissociation curve.

A

Sigmoid shape (starts shallow, gets steeper, finishes shallow)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the position of the oxygen dissociation curve determine about the affinity

A
  • Line further to the left = Greater affinity (loads readily, harder to unload)
  • Line further to the right = Lower affinity (more difficult to load, but readily unloads)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the process of cooperative binding (of Haemoglobin and O2)

A

1) Due to the shape of the binding site of haemoglobin, it is difficult for the first O2 to attach, so the initial rate of association is low.
2) After the first has attached, it is easier for the second to bind as the shape has changed, so the rate of association increases.
3) Once 2 are attached, it is still easier for the third to bind as the shape has changed, but there is now only a 50% chance that the site an O2 collides with is empty, so the rate of association decreases.
4) Now there is only one empty binding site, so a 25% chance that the O2 collides with a site it can bind to, so the rate of association decreases further as the haemoglobin saturation approaches 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the effect of CO2 on affinity

A

Increased CO2 causes and increase in blood acidity, lowering the pH and effecting the ionic bonds in the haemoglobin’s tertiary structure, changing its shape, so decreasing its affinity for O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Bohr effect and how does it allow for different haemoglobin affinities within the body.

A
  • In areas of high O2 and low CO2 concentration (such as the lungs), the haemoglobin’s affinity increases to take in more O2
  • In areas of low O2 and high CO2 concentration (such as near the muscle tissue after respiration), the haemoglobin’s affinity decreases, unloading the O2, so it can be used by the cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What factors effect the affinity of haemoglobin at regular CO2 levels

A
  • Environment
  • Organism size
  • Activity level
    All impact metabolic rate (and respiratory rate), so alter the CO2 conc. near cells, changing the haemoglobin affinity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why do large organisms have specialised transport systems

A

Diffusion alone isn’t efficient enough to exchange materials of large distances (increased size = decrease SA:Vol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the main features of a mass transport system

A
  • Medium to carry materials (eg. blood, air, etc.)
  • A closed system of vessels to distribute the medium around the organism
  • A mechanism for moving the transport medium (pressure difference), such as muscle contractions, evaporation, etc
  • A mechanism to maintain unidirectional flow (eg. valves)
  • A way to control the flow for different needs in different areas (eg. Arteries –> Capillaries –> Veins)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a double circulatory system

A

Blood passes through the heart twice in each cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is a double circulatory system required in mammals

A

Travelling through the capillaries in the lungs reduces the blood pressure, so it must return the the heart before being circulated to the rest of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the structure of the human heart

A

2 pumps side by side, with the left (–>) containing oxygenated blood, and the right (<–) containing deoxygenated blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the structure and function of the atrium

A

Thin walled and elastic, collects blood into the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the structure and function of the ventricle

A

Thick, muscular wall that contracts to increase blood pressure, pumping blood out of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the values between the atria and ventricles

A
  • Right (<–) atrioventricular value = Tricuspid valve
  • Left (–>) atrioventricular valve = Bicuspid valve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of the Pulmonary artery

A

Carries deoxygenated blood from the heart to the lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of the Pulmonary vein

A

Carries oxygenated blood from the lungs to the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of the Aorta

A

Carries oxygenated blood out of the heart to the rest of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the function of the Vena Cava

A

Carries deoxygenated blood back to the heart from the rest of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the function of the coronary artery

A

Carries oxygenated blood to the muscle of the heart (branches off of the Aorta)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a Cardiovascular disease

A

Disease that affects the heart or blood vessels (such as coronary heart disease)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the risk factors for cardiovascular diseases

A
  • Smoking
  • High blood pressure
  • Blood cholesterol
  • Diet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How will smoking increase the risk of cardiovascular diseases

A
  • Carbon monoxide binds with haemoglobin irreversibly, preventing O2 from binding, reducing blood oxygen saturation
  • Nicotine produces adrenaline, increasing heart rate, so increasing blood pressure.
  • Can cause platelets to become sticky
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How will high blood pressure increase the risk of cardiovascular diseases

A
  • The heart has to work harder to pump the blood, so is prone to failure
  • Can cause an aneurysm, resulting in blood vessels bursting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How will high cholesterol increase the risk of cardiovascular diseases

A

Cholesterol is a fatty substance, so can cause clots and blockages

32
Q

How will diet effect the risk of cardiovascular diseases

A
  • High levels of salt can increase blood pressure (increasing risk)
  • Saturated fats contain low-density lipoproteins which transport cholesterol to the tissue (increasing risk)
  • High-density lipoproteins remove cholesterol from tissue (reducing risk)
  • Antioxidant foods such as vitamins and dietary fibre will reduce the risk
33
Q

What are the stages of the cardiac cycle

A

Left and right occur simultaneously:
- Diastole (relaxation of the heart)
- Atrial Systole (contraction of the atria)
- Ventricular systole (contraction of the ventricles)

34
Q

What is the process of diastole (relaxation of the heart) in the cardiac cycle

A
  • Blood returns to the atria through the Pulmonary vein/Vena Cava
  • Pressure in the atria rises until it exceeds that of the ventricles
  • The atrioventricular valves open so blood flows into the ventricles (aided by gravity)
  • The relaxation of the ventricle walls that occurs at the same time as this causes the pressure within them to drop lower than the Pulmonary Artery/Aorta, so the semi-lunar valve closes
35
Q

What is the process of atrial systole (contraction of the atria)

A
  • The atrial wall contracts as the ventricle wall recoils, forcing the remaining blood through the atrioventricular valve to the ventricle.
36
Q

What is the process if ventricular systole (contraction of the ventricles)

A
  • After a short delay to allow the ventricles to fill with blood, the ventricle walls contract
  • This increases the pressure within them, closing the atrioventricular valves, preventing backflow
  • The pressure in the ventricles then continues to rise, until it exceeds that of the Pulmonary Artery/Aorta.
  • Blood is then forced out of the ventricles, through the semi-lunar valves, an is carried away from the heart.
    (the left ventricle is thicker to give a higher pressure for blood being pumper to the rest of the body.
37
Q

What are the 3 main types of valves in the circulatory system

A
  • Atrioventricular valves (between corresponding atria and ventricles): Prevents backflow when ventricle pressure is increased, ensuring blood only moves from here into the Pulmonary Artery/Aorta
    Semi-Lunar valves (in the aorta and pulmonary artery): Prevents backflow when the pressure in the vessels exceeds that of the ventricle
  • Pocket valves (within veins): Prevents backflow when the skeletal muscles contract and squeeze the veins, ensuring that the blood flows towards the heart.
38
Q

What is the structure of a valve

A

Made of flaps of tough, flexible, fibrous tissue in a cusp-shape:
- Greater pressure on the convex side allows blood to pass through
- Greater pressure on the concave side pushes the flaps together to stop the flow of blood

39
Q

How does the Ventricular pressure and volume change throughout the cardiac cycle

A
  • Pressure low at first, but increases as it fills with blood from the atria as they contract (Increase in vol.)
  • Pressure increases when the atrioventricular valve closes, until it is greater than that of the Pulmonary Artery/Aorta.
  • Pressure decreases as the semilunar value opens, emptying the blood, and the ventricle walls relax (decrease in vol.)
40
Q

How does the Atrial pressure and volume change throughout the cardiac cycle

A

Pressure always relatively low due to the thin walls:
- Pressure drops when atrioventricular valve closes, as muscle relaxes
- Pressure increases as it fills with blood from the Pulmonary Vein/Vena Cava (Increase in vol.)
Pressure drops again as the atrioventricular valve opens, and blood flows into the ventricles (decrease in vol.)

41
Q

What is the Cardiac Output

A

Vol. of blood pumped by one ventricle in 1 minute
Cardiac output (dm^3 min^-1) = Heart rate x Stroke volume

42
Q

What is the Heart rate

A

No. of cardiac cycles in 1 minute

43
Q

What is the Stroke volume

A

Vol. of blood pumped out each beat

44
Q

What is the function of the Arteries

A

Carries blood away from the heart to the arterioles

45
Q

What is the function of the Arterioles

A

Smaller arteries that control blood flow to the capillaries

46
Q

What is the function of the Capillaries

A

Tiny vessels that link arterioles to veins

47
Q

What is the function of the Veins

A

Carries blood back towards the heart

48
Q

What are the main layers in the structure of blood vessles

A
  • Fibrous outer layer: resists pressure changes
  • Muscle layer: contracts to control the flow of blood
  • Elastic layer: helps to maintain blood pressure by stretching and recoiling
  • Thin inner layer (endothelium): smooth to reduce friction and thin to allow diffusion
  • Lumen: central cavity blood flows through
49
Q

What is the structure of an Artery and how is it related to its function

A
  • Thick muscle layer compared to veins, to constrict and dilate the lumen, controlling the flow of high pressure blood
  • Thick elastic layer compared to veins, maintaining high pressure to transport blood throughout the whole body
  • Overall thick wall, to prevent vessels bursting under pressure
  • No valves (except semi-lunar, leaving the heart), as there is no back flow due to high pressure
50
Q

What is the structure of an Arteriole and how is it related to its function

A
  • Muscle layer thicker than arteries, to contract and restrict blood flow into the capillaries
  • Elastic layer thinner than arteries, as blood is at lower pressure
  • Overall thick wall, to prevent vessels bursting under pressure
  • No valves, as there is no back flow due to high pressure
51
Q

What is the structure of a Capillary and how is it related to its function

A
  • Walls consist of mainly the lining layer, so it is thin for rapid diffusion
  • Numerous and highly branches, providing larger SA for diffusion
  • Narrow to permeate tissues and reach all cells
  • Spaces between the endothelial cells, allowing white blood cells to escape and deal with infections.
52
Q

What is the structure of a Vein and how is it related to its function

A
  • Muscle layer is relatively thin, as they carry blood away from tissue, so don’t contract to control flow
  • Elastic layer is relatively thin, as the blood is at low pressure
  • Overall thinner wall, allowing the skeletal muscles to compress the vessels and aid flow.
  • Valves at intervals throughout, to prevent back flow in low pressure
53
Q

What is tissue fluid

A

Watery solution that bathes all cells and is the means by which materials are exchanged between blood and tissue

54
Q

How is tissue fluid formed

A

High hydrostatic pressure at the arterial end of the capillaries, due to blood pumping from the heart, causes liquid to move out into the tissue.

55
Q

What 2 (weak) forces oppose the movement of liquid out of the capillaries during the formation of tissue fluid

A
  • Hydrostatic pressure due to tissue fluid surrounding the capillaries
  • Low water potential of the blood due to plasma proteins causes water to move in by osmosis

(Despite these, the overall movement of plasma out of the capillaries still occurs, forming the tissue fluid.

56
Q

How does the tissue fluid return to the circulatory system

A
  • The loss of plasma from the capillaries during the formation of the tissue fluid causes a low hydrostatic pressure at the venous end, causing the liquid to move back into the capillaries
  • The even lower water potential at the venous end causes water to move into the capillaries by osmosis
  • Some fluid returns to the blood through the lymphic system
57
Q

What is the lymphic system

A
  • A system of vessels beginning in the tissues that gradually merges into larger vessels, forming a network within the body.
  • Contents drains back into bloodstream as two ducts join into the veins before the heart
  • Movement occurs due to hydrostatic pressure differences caused by the tissue fluid, as when as contractions of body muscles squeezing the vessels
58
Q

What is transpiration

A

The process by which water is transported through the plant, fuelled by evaporation out of the leaves

59
Q

Describe movement of water out of the stomata during transpiration

A
  • Humidity of the atmosphere is usually less than that of the air spaces within the leaf, so water vapour will diffuse out of the stomata
  • Water lost by diffusion is replaced from the surrounding mesophyll
  • Regulation of the size of the guard cells, and the size of the stomata allows of the rate of transpiration to be controlled
60
Q

Describe the movement of water across the cells of the leaf during transpiration

A
  • Water evaporates form the mesophyll cell walls into the air spaces for diffusion out of the leaf.
  • This creates a lower water potential in these cells, so water enters by osmosis from neighbouring cells, lowering their water potential
  • This repeats as water is moved across the leaf by the water potential gradient, from the xylem
61
Q

Describe the movement of water through the xylem during transpiration

A
  • The polar water molecules form hydrogen bonds between them, causing them to stick together (cohesion)
  • This means that water forms a continuous chain across the mesophyll cells and down the xylem
  • The lower water potential in the mesophyll cells draws a column of water up the xylem (transpiration pull)
62
Q

What is the cohesion-tension theory

A

Transpiration pull due to the low water potential in the leaves puts the xylem under tension, due to the adhesion of the water molecules. This causes the diameter of the stem/trunk to reduce as water flows through, due to the contraction caused by the negative pressure.

63
Q

What is the evidence for the cohesion-tension theory

A
  • Tree trunk diameter decreases during the day, as transpiration rate is highest during high light levels.
  • If the xylem is broken, water doesn’t leak out, but air is drawn in due to the negative pressure (transpiration stops if the xylem (water column) is broken.
64
Q

How do you measure the transpiration rate

A
  • ~99% of water taken in through the roots is lost during transpiration, so rate of uptake ≈ rate of transpiration
  • The rate of uptake can be measured under different conditions (eg. light intensity, wind speed, etc.) using a potometer
65
Q

How do you use a potometer

A
  • Cut the shoots underwater to avoid air blocking the xylem (dry leaves as to not block stomata)
  • Completely fill the capillary tube with water
  • Fit the shoot in the potometer under water
  • Seal the potometer with waterproof jelly (leave the end open)
  • Introduce an air bubble
  • Measure the distance moved by the bubble in a given time (repeat and calculate a mean)
  • Calculate the volume of water using the mean length
  • Plot the water uptake against time, and use grad. to see the rate
66
Q

What is translocation

A

The process by which organic molecules and some mineral ions are transported from one part of a plant to another

67
Q

Describe the transfer of sucrose into the sieve elements, as part of the Mass Flow theory

A
  • Sucrose is manufactured from the products of photosynthesis
  • Sucrose moves by facilitated diffusion into the companion cells
  • H+ ions are actively transported from companion cells into spaces within the cell walls
  • H+ ions the diffuse down the conc. gradient through carrier proteins into sieve tube cells, moving the sucrose with them
    (Co transport)
68
Q

Describe the movement of sucrose through the sieve tube elements, as part of the Mass Flow theory

A
  • Sucrose in the sieve tube cells near the source cause a low water potential
  • Water therefore moves from the xylem into the sieve tube cells near the sources, by osmosis, increasing the hydrostatic pressure
  • Near the sink, sucrose in the sieve tube cells is used up, by respiration/storage
  • This movement of sucrose into respiring cells, reduces the water potential of these cells, while also increasing the water potential in the sieve tube cells
  • This causes water to move out of the sieve tube cells, into the xylem and the companion cells
    This low hydrostatic pressure near the sink causes the sucrose to flow through the sieve elements from the source
69
Q

Describe the transfer of sucrose from the sieve tube cells to the storage/sink , as part of the Mass Flow theory

A
  • Sucrose in the sieve tube cells is moved against it’s concentration gradient, into the companion cells and respiring tissue
    (Active transport)
70
Q

What is the evidence for the mass flow theory

A
  • Pressure within the phloem, as sap is released when they are cut
  • Sucrose conc. is higher in the leaves (source) than the roots (sink)
  • Downward flow in the phloem occurs in the day, but stops when leaves are shaded (photosynthesis produces glucose)
  • Increase in sucrose in the leaves causes a later increase in sucrose in the phloem
  • Metabolic poisons / lack of oxygen, inhibit translocation (they stop active transport, which stops mass flow)
  • Companion cells contain many mitochondria to readily produce ATP
71
Q

What evidence is there that may question the mass flow theory

A
  • The function of the sieve plates is unclear, as they seem to inhibit the flow (may be for structural purposes)
  • Not all solutes move at the same speed, which they should with the mass flow theory
  • Sucrose is delivered at roughly the same rate to all regions, rather than going faster to areas with lower conc., which the mass flow theory would suggest
72
Q

What is the ringing experiment for investigating transport in plants

A
  • A section of the outer layers (bark and phloem) is removed around the complete circumference
  • After some time, the stem swells just above the missing ring, containing a liquid rich in sugars and other dissolved substances
  • Some non-photosynthetic tissue below the ring (ie. roots) withers and dies
73
Q

What conclusions can be made from the ringing experiment, investigating transport in plants

A

The phloem, rather than the xylem, is responsible for the translocation of sugars in plants

74
Q

What is the tracer experiment for investigating transport in plants

A
  • Radioactive isotopes can be used for tracing the movement of substances within plants
    eg. use CO2 containing a C-14 isotope
  • This means that radioactive isotopes are incorporated into the sugars produced by photosynthesis, and therefore can be traced moving through the plant using autoradiography
75
Q

What conclusions can be made from the tracer experiment, investigating transport in plants

A

Only the phloem shows radioactive content, so only the phloem carries the sugar

Biology (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions