Brainscape's Knowledge GenomeTM

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


See full index

Biology AS > Mass Transport > Flashcards

Mass Transport Flashcards

1
Q

Haemoglobin

A
  • Found in red blood cells
  • Large protein with a quaternary structure
  • Four polypeptide chains linking in a globular shape
  • Each chain has a haem group
  • Which contains an iron ion that can combine with a single oxygen molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Formation Of Oxyhaemoglobin

A
  • Haemoglobin has a high affinity (tendency to combine with) for oxygen
  • Each molecule can carry four oxygen molecules
  • In the lungs oxygen joins to haemoglobin in red blood cells to form oxyhemoglobin
  • Reversible reaction; oxygen can dissociate from oxyhemoglobin

Hb + 4O2 = HbO8

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

Partial Pressure Of Oxygen

A
  • Measure of oxygen concentration
  • The greater the concentration of dissolved oxygen, higher the partial pressure
  • There is high partial pressure in the lungs so haemoglobin has a high affinity for oxygen there
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Loading & Unloading Of Oxygen

A
  • Oxygen enters blood capillaries at the alveoli in the lungs
  • Alveoli have a high partial pressure of oxygen so oxygen loads onto haemoglobin to form oxyhemoglobin
  • Respiring cells use up oxygen, this lowers the partial pressure of oxygen
  • Red blood cells deliver oxyhemoglobin to respiring tissues where it unloads its oxygen
  • Haemoglobin returns to the lungs to pick up more oxygen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Haemoglobin In Different Organisms

A
  • Different structures because of different DNA
  • Form different primary structures and have different numbers of polypeptide chains in the tertiary structure
  • Organisms in environments with low concentration of oxygen (partial pressure) have haemoglobin with a higher affinity for oxygen than human haemoglobin
  • This dissociation curve is to the left of the human one
  • Organisms that are active with high oxygen demand have haemoglobin with a lower affinity for oxygen than human (so it can dissociate more easily for use in respiration)
  • This curve is to the right of the human one
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Dissociation Curves Show Affinity For Oxygen

A
  • Lungs: partial pressure is high so haemoglobin has a high affinity for oxygen; it readily combines to oxygen as there is a high saturation of it
  • Respiring Cells: partial pressure is low in respiring tissue so haemoglobin has a low affinity for oxygen; it releases oxygen as there is a low saturation of it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

S-shape Of Dissociation Curves

A
  • When haemoglobin combines with the first oxygen molecule it’s shape alters
  • It makes it easier for other oxygen molecules to then join too
  • As haemoglobin becomes more saturated it gets harder for more oxygen molecules to join
  • The curve has a steep middle where it’s easy for oxygen molecules to join and shallow ends parts where it’s harder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Haemoglobin & Carbon Dioxide

A
  • Respiring cells produce carbon dioxide
  • This decreases blood pH and makes it slightly acidic
  • Haemoglobin is a protein so its shape is changed as hydrogen bonds are broken
  • This decreases it’s affinity for oxygen and allows oxygen to unload more easily and be used up by respiring cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The Bohr Effect

A
  • Respiring cells produce carbon dioxide which increases the partial pressure of carbon dioxide
  • At higher partial pressures of carbon dioxide haemoglobin unloads it’s oxygen more easily
  • This increases the rate at which oxygen dissociates from oxyhemoglobin
  • The dissociation curve shifts to the right because the saturation of blood with oxygen is lower for a given partial pressure of oxygen as more is being released for use by respiring cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The Circulatory System

A
  • There are two circuits
  • One circuit takes blood from the heart to the lungs then back to the heart
  • The other takes blood around the rest of the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Coronary Arteries

A
  • Supply the heart with oxygenated blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Arteries

A
  • Carry blood from the heart to the rest of the body
  • All carry oxygenated except for pulmonary arteries (take deoxygenated blood to the lungs)
  • Have thick walls to maintain high pressure
  • Branch into arterioles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Arterioles

A
  • Form a network throughout the body
  • Muscles inside arterioles direct blood to areas of demand in the body
  • By contracting to restrict blood and relaxing to allow full blood flow
  • Branch into capillaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Capillaries

A
  • Smallest blood vessels
  • Found near exchange tissues e.g. alveoli
  • One cell thick walls for a short diffusion pathway
  • Large number of capillaries to increase surface area for exchange
  • Network of capillaries in a tissue are called capillary beds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Veins

A
  • Take blood back to the heart
  • Under low pressure so have a wider lumen than arteries and little muscle tissue
  • All carry deoxygenated blood except pulmonary veins (carry oxygenated blood to the heart from the lungs)
  • Have valves to prevent blood flowing backwards
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Tissue Fluid

A
  • Surrounds cells in tissues
  • Made from small molecules that leave the blood plasma e.g. water, oxygen and nutrients
  • Tissue fluid forms because of the high hydrostatic pressure of blood at the arteriole end of the capillary that pushes fluid out of the blood
  • Most fluid re-enters the capillaries e.g. the water by osmosis
  • Excessive tissue fluid is drained into the lymphatic system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The Heart

A
  • Consists of two muscular pumps
  • The right-side pumps deoxygenated blood to the lungs
  • The left-side pumps oxygenated blood to the whole body
  • Diastole is a period of relaxation
  • Systole is a period of contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The Heart [Process]

A
  • Right atrium contracts and opens AV valves
  • Deoxygenated blood flows into the right ventricle
  • Right ventricle contracts opening AL valves
  • Blood flows into the pulmonary artery then to the lungs
  • Oxygenated blood from the lungs enters the left atrium via the pulmonary vein
  • Left atrium contracts opening AV valves
  • Blood enter the left ventricles
  • These are thicker than the right; contract powerfully to pump blood around the body (all ventricles have thicker walls than atria; they push blood out of the heart)
  • Left ventricle contracts
  • Blood goes to the aorta via SL valve where it goes to the rest of the whole body at a high pressure
19
Q

The Cardiac Cycle

A
  • When the ventricles are relaxed the atria contract
  • This causes pressure in the atrium to increase so AV valves open
  • Pushing blood into ventricles
  • The ventricles contract once atria relax
  • This increases pressure in the ventricles so the SL valves open after the AV valves shut (prevent back flow)
  • Blood is forced into the arteries
  • The ventricles and atria relax
  • Pressure increases in the pulmonary artery and aorta so SL valves close to prevent back flow into ventricles
20
Q

Cardiovascular Disease

A
  • Most start with atheroma formation
  • When damage is caused to the arteries endothelium by high blood pressure
  • White blood cells, lipids and connective tissue build up overtime
  • They harden and form a fibrous plaque called an atheroma
21
Q

Coronary Disease

A
  • Type of cardiovascular disease
  • Caused when coronary arteries have lots of atheroma
  • Restricting blood flow
22
Q

Aneurysm

A
  • Atheroma cause capillaries to narrow
  • Blood travelling at a high pressure can push the inner layers through the outer layer
  • Forming a swelling which bursts and causes a haemorrhage
23
Q

Thrombosis

A
  • Atheroma plaques can rupture the endothelium of an artery
  • Causing platelets and fibrin to accumulate and form a blood clot
  • This blocks the artery
24
Q

Myocardial Infarction

A
  • When a coronary artery is blocked
  • The area is cut off from blood supply and oxygen
  • Causing a heart attack [myocardial infarction]
25
Q

High Blood Cholesterol & Poor Diet

A
  • Cholesterol is on the main constituents of the fatty deposits which form atheroma
  • A diet high in fat is linked to high blood cholesterol levels
  • A diet high in salt increases risk of cardiovascular disease due to increased risk of high blood pressure
26
Q

Cigarette Smoking

A
  • Nicotine increases risk of high blood pressure; it causes adrenaline
  • Carbon monoxide combines with haemoglobin reducing the amount of oxygen transported the blood and available to tissues
  • If the heart muscle doesn’t receive enough oxygen it can lead to heart attack
27
Q

High Blood Pressure

A
  • Increases risk of damage to artery walls; increases risk of atheroma formation
  • Atheroma lead to blood clots which block flow of blood to the heart muscle
  • May result in myocardial infarction
  • High blood pressure can be caused by being overweight, not exercising and excessive alcohol consumption
28
Q

Xylem

A
  • Tissue that transports water and mineral ions in solution

- These substances move up the plant from the roots to the leaves

29
Q

Structure Of Xylem

A
  • Hollow lumen (formed from dead cells with no cytoplasm): allows water to move in a continuous column using the cohesion-tension theory
  • Pits in their walls: allows lateral movement of water so it reaches other parts of the leaf
  • Lignified walls: kill the xylem and make it water proof
  • Thick walls: strengthens the xylem to prevent bursting under pressure
30
Q

Root Pressure

A
  • When an influx of water from soil creates a hydrostatic pressure
  • Water is forced into the roots
  • The pressure is enough to move water up the xylem by a small amount
31
Q

Root Pressure Evidence

A
  • If the leaves are removed
  • A monometer is added below
  • There is still water movement up the monometer which acts as the roots
32
Q

Capillary Action

A
  • Water adheres to the sides of the xylem and moves upwards

- Adhesive properties of water allow it to stick to the xylem and move upwards

33
Q

Capillary Action Evidence

A
  • The meniscus of water in glassware shows how it sticks to the sides of the tube
  • Creating a curve and in smaller test-tubes this curve is bigger
  • As the space is more confined there is more capillary action
34
Q

Cohesion Tension

A
  • Water is polar
  • Slightly negative oxygen attracts to slightly positive hydrogen of another water molecule
  • This forms hydrogen bonds
  • Within a xylem, the water is held together by hydrogen bonds so water moved upwards by tension created by evaporation from leaves
35
Q

Cohesion Tension Evidence

A
  • If the roots are taken off and a monometer is added
  • Water still moves up as there is still tension from the leafs
  • If the leaves are removed there is less water movement due to less tension
  • If the temperature is increased there is more water movement as the molecules have more kinetic energy to move up the stem
36
Q

Transpiration

A
  • When water evaporates from the plants surface
  • Stomata open and water moves out of the leaf down a concentration gradient
  • This is due to there being more water inside the leaf than in the air outside
37
Q

Transpiration Process

A
  • Water moves out of the soil into the roots by osmosis
  • Water moves from the roots into the xylem
  • This movement is all down a concentration gradient
  • Water molecules are cohesive so they form a continuous column of water up the xylem
  • It is also moved up by root pressure and capillary action
  • Water evaporates through stomata in the leafs
  • As each water molecule evaporates the column of water is pulled up the xylem by cohesion-tension
38
Q

Factors Affecting Transpiration Rate

A
  • Light: the lighter it is the faster the rate; stomata open when it gets light to release CO2 for photosynthesis
  • Temperature: the higher the temperature the faster the rate; water molecules have more energy to evaporate from cells in the leaf faster
  • Humidity: the lower the humidity the faster the rate; the concentration gradient between the leaf and air increases as the air around the plant is dry
39
Q

Phloem

A
  • Tissue that transports organic substances e.g. sugars up and down the plant
40
Q

Structure Of Phloem

A
  • Phloem tube is made from sieve tubes which are living cells
  • These sieve tubes have mitochondria; energy is needed
  • There’s a companion cell for each sieve tube element
  • Companion cells carry out living functions for sieve tubes e.g. providing energy needed for active transport of solutes
41
Q

Translocation

A
  • The movement of solutes to where they’re needed in a plant
  • Moves solutes from sources to sinks
  • Source is where the solute is made so it’s at a high concentration there
  • Sink is the area where its taken up so its at a lower concentration there
  • It’s an energy requiring process that happens in the phloem
42
Q

Mass Flow Hypothesis

A
  • Explains the movement of sap through the phloem
  • Solutes are loaded into sieve cells from companion cells at the phloem’s source
  • Through active transport
  • This lowers the water potential in the sieve tubes so water enters them from the xylem and companion cells by osmosis
  • Creates high pressure inside sieve tubes at the source
  • At the sink solutes are removed from the phloem to be used up
  • Increasing water potential inside the sieve tubes so water leaves them by osmosis
  • This lowers pressure inside the sieve tubes at the sink
  • There is a pressure gradient from the source end to the sin end
  • This pushed solutes towards the sink
  • Where they are used for respiration or stored as starch
  • The higher the concentration of sucrose at the source, the higher the rate of translocation
43
Q

Evidence For Mass Flow

A
  • Downward flow of sugars: when a ring of bark is removed from a woody stem a bulge forms above the ring and fluid inside the bulge has a higher concentration of sugars than food below the ring
  • A pressure gradient: when a phloem is pierced by aphids, the sap flows out quicker nearer the leaves than further down the stem
  • Active transport is involved: when a metabolic inhibitor which stops ATP production is put into the phloem, translocation stops
44
Q

Evidence Against Mass Flow

A
  • Sugar travels to many different sinks not just one with the highest water potential
  • The sieve plates would create a barrier to mass flow; a lot of pressure would be needed for solutes to get them through at a reasonable rate
  • Not all solutes move at the same speed and they should do if the mass flow theory is correct

Biology AS (7 decks)

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