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transport in animals exam questions Flashcards

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1
Q

State the meaning of the following terms:
- single circulatory system
- double circulatory system
- open system
- closed system
[4 marks]

A

Single Circulatory System - blood passes through the heart once for each circulation/cycle of the body
Double Circulatory System - blood passes through the heart twice for one complete circuit
Open System - blood is not always contained in vessels e.g. a heart that pumps blood like fluid called haemolymph through short vessels and into a large cavity called the haemocoel
Closed System - the blood is maintained inside vessels

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2
Q

Explain three reasons why mammals need a circulatory system whilst unicellular organisms do not [4]

A

SIZE
* Mammals are larger
* Cells deep in body
* But you need to get materials to all parts
* And diffusion would be too slow
ACTIVITY
* Mammals more metabolically active
* Need a rapid supply and removal of waste
SA:V Ration
* Large animals have a smaller surface area:volume ratio
* Diffusion alone would not be effective/would be too slow

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3
Q

List three reasons why a large, multicellular animal, such as a mammal needs a transport system. [3]

A
  • Low/small surface area to volume ration
  • Diffusion too slow/distance to great
  • To supply enough oxygen/nutrients
  • To prevent CO2/waste product building up
  • Active
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4
Q

What is the function of the coronary artery [1 mark]

A
  • Supply oxygen/nutrients to the heart muscle for aerobic respiration
  • Remove carbon dioxide/waste
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5
Q

Explain why the wall of the left ventricle is thicker than the wall of the left atrium [4 marks]

A
  • Need more muscle - to create more force
  • To create higher pressure
  • As has to pump blood against greater resistance/friction
  • Also left ventricle pumps blood further - to all parts of the body (systemic circulation)
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6
Q

Explain why it is important that the two sides of the heart are completely separated [2 marks]

A
  • Stops oxygenated and deoxygenated blood mixing
  • Ensures oxygenated blood gets to the body while deoxygenated blood to lungs
  • It also allows different pressures to be maintained on each side
  • There would be a possible drop in blood pressure if there was a hole present
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7
Q

Explain the advantage of the ventricles contracting from the bottom upwards [1 mark]

A
  • Allows the ventricles to empty completely
  • This is because aorta and pulmonary artery are found at the top
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8
Q

Explain how pressure changes in the heart bring about the closure of the atrioventricular (bicuspid) valve [3]

A
  • Ventricular systole (contraction of ventricle wall)
  • Raises ventricular pressure
  • When the pressure in ventricle is higher than atrial pressure
  • It pushes valve shut
  • Chordae tendinae prevents inversion
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9
Q

Describe how the action of the heart is initiated and coordinated [5]

A
  • SAN initiates excitation
  • Wave of excitation spreads over atrial wall/muscle
  • This results in atrial systole (contraction of atria)
  • In synchronization
  • A short delay occurs at AVN
  • Band of non-conducting collagen prevents excitation carrying straight on
  • and then excitation spreads down septum
  • through bundle of His and Purkyne fibres
  • This results in the ventricles contracting from apex/bottom upwards
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10
Q

What is the advantage of the slow rate of conduction through the AVN [2 marks]

A
  • Delays contraction of ventricles
  • Until of the atria have contracted completely filling the ventricles
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11
Q

Suggest one advantage of the high rate of conduction in the Purkyne fibres which carries impulses through the walls of the ventricles [1 mark]

A

Causes the rapid contraction of ventricles together

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12
Q

How would cutting the nerve connections from the brain to the SAN affect the heart? [1 mark]

A
  • It wouldn’t as the Heart is myogenic
  • SAN initiates beat
  • SAN generates impulses that cause contraction.
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13
Q

Describe how an artificial pacemaker regulated heart activity [2 marks]

A
  • Supplies electrical impulses to the heart
  • Replaces action of damages conducting tissue
  • Provides regular electrical impulses
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14
Q

Describe the role of the Atrioventricular node in the production of the heart beat [1 mark]

A
  • Produces electrical impulses in response to electrical activity from the SAN
  • Causes a time-delay
  • Passes on electrical activity from the SAN to the bundle of His
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15
Q

Describe the role of the Bundle of His [1 mark]

A

Carries electrical impulses from AVN to purkyne fibres extremely quickly

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16
Q

Describe the role of the purkyne fibres [1 mark]

A

This cause contraction of ventricles from the base simultaneously

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17
Q

The beating of the heart is myogenic
Explain what this means [2 marks]

A
  • SAN/sinoatrial node (starts each beat)
  • Beats initiated by the heart
  • Doesn’t need stimulation by nerve/nerve impulses to contract/beat
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18
Q

During the electrical stimulation of the heart, there is a short delay between the excitation of the atria and excitation of the ventricles. Explain why the delay is essential. [2]

A
  • To allow time for the atria to fully contract
  • To allow time for atria to empty/ventricles to fill
  • So that ventricles do not contact too early
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19
Q

The Purkyne tissue carries the excitation wave down the excitation wave down the septum to the apex of the heart. Explain why the excitation wave is carried to the apex. [2

A
  • So that ventricular contraction starts at apex/base
  • To push blood upwards - towards arteries
  • Complete/efficient emptying of ventricles.
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20
Q

Describe how the structure of an artery is related to its function [6]

A

1) The artery has a narrow lumen
- to help maintain pressure

2) The artery has a generally thick wall
- to prevent bursting and withstand pressure

3) The wall is made up of three layers tunica intima, tunica media and tunica externa

Tunica Intima
* This is a smooth endothelium
* Made up of squamous epithelium
* Smoothness helps reduce friction

Tunica Media
* Elastic fibres- allows stretching to help prevent bursting and withstand and maintain pressure
* Collagen fibres - provide strength
* Smooth muscle - help maintain pressure (vasoconstriction)

Tunica Externa
* Mainly collagen fibres
* Some elastic fibres

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21
Q

Describe how the structure of a vein is related to its function [6 marks]

A

1) The artery has a relatively large lumen - helps accommodate large volumes of blood

2) Veins have valves - help prevent back flow and allow blood to move towards heart

3) The wall is made up of three layers tunica intima, tunica media and tunica externa

Tunica Intima
* This is a smooth endothelium
* Made up of squamous epithelium
* Smoothness helps reduce friction

Tunica Media
* Thin but does have muscle and elastic tissue (less than artery)
* As only needs to withstand low pressure
* Also allows skeletal muscle to squeeze veins

Tunica Externa
* Mainly collagen fibres (less than artery) - provides strength

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22
Q

State ways in which the wall of an artery is different from the wall of a vein [2 marks]

A
  • Arteries have no valves
  • Arteries have thick layer of smooth muscle and elastic tissue (tunica media)
  • Arteries have more collagen (tunica externa)
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23
Q

Blood in arteries has a high hydrostatic pressure. State how this hydrostatic pressure in the heart is generated [1 mark]

A

Contraction of ventricle wall (ventricular systole)

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24
Q

Explain why the hydrostatic pressure of the blood drops as blood moves away from the heart [2 marks]

A

1) Arteries stretch and expand
2) There is more vessels
3) There is loss of fluid/plasma from capillaries

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25
Explain how the structure of capillaries enables them to carry out metabolic exchange efficiently [5 marks]
* Thin wall (one cell thick) - creates a short pathway for easy diffusion * Smooth endothelium - creates reduced friction/resistance and smooth flow * Small gaps - allows nutrients out * Narrow diameter - only one red blood cell can flow at a time (reduced rate of flow). This slows blood flow so substances can diffuse in and out
26
Describe and explain how the wall of an artery is adapted to both withstand and maintain high hydrostatic pressure [5 marks]
To withstand pressure: * Wall is thick * Thicker layer of collagen * This provides strength * Elastic fibers - allow it stretch to accommodate pressure To maintain pressure: * Elastic tissue * To cause recoil and return to original size * Thick layer of smooth muscle * This constricts lumen/artery
27
Explain why it is important that the pressure changes as blood flows from the aorta to the capillaries [2 marks]
- Capillary is thin/only one cell thick - High pressure would burst damage capillary - This could result in odema
28
Describe how red blood cells are adapted to their function [8 marks]
* Contains Haemoglobin - to carry oxygen * Flexible/elastic/stretchy/change shape - this allows red blood cells to fit/squeeze into capillaries * Biconcave - gives increased surface are relative to its volume (for diffusion). Also means haemoglobin never far from cell surface * No nucleus - to maximise room hemoglobin * Lack of organelles (e.g. endoplasmic reticulum) increased room for Hb * Small (about 7µm in diameter) - about the same size as a capillary
29
Explain two advantages of keeping blood inside vessels [2 marks]
- Maintain higher blood pressure - Increase rate of flow - Flow can be diverted (e.g vasoconstriction)
30
Describe and explain how substances that are dissolved in the blood plasma, such as oxygen or glucose enter the tissue fluid from the capillaries [3 marks]
- Diffusion - From high concentration to a low concentration - Pressure in the capillary high - Capillary wall leaky - Fluid forced out of capillary - down a pressure gradient - As the fluid moves out glucose and oxygen leave with the plasma
31
How does the composition of tissue fluid differ to blood plasma? [4 marks]
- Does not contain red blood cells (erythrocytes) - they are too large - Does not contain plasma proteins - they are too large - Does contain white-blood cells - Does contain oxygen, glucose and mineral ions
32
What is oedema? [1 mark]
build up of tissue fluid causing a swelling in the tissues
33
Suggest what could happen in tissues if a persons drainage of tissue fluid was inefficient [2 marks]
- Fluid collects in tissues - This will result in tissue swelling - This is called oedema - Especially dangerous in lungs (pulmonary oedema)
34
Explain why tissue fluid does not contain erythrocytes [2 marks]
- Gaps between endothelial cells are too small - Erythrocytes too large/cannot change shape - to fit through gaps/fenestrations
35
Describe the role of haemoglobin in transporting oxygen around the body [3 marks]
- has a high affinity for oxygen - oxygen binds to haemoglobin in lungs - forms oxyhaemoglobin - oxygen released in tissues where needed (where respiration is occurring)
36
Describe how the production of carbon dioxide during respiration leads to a higher concentration of hydrogen ions in the blood. [3 marks]
- Carbon dioxide reacts with water - To give carbonic acid - Carbonic acid acts as a catalyst - Carbonic acid then dissociates releasing H+ and HCO3- ions
37
Describe how haemoglobin acts to reduce the concentration of hydrogen ions in the blood [4 marks]
Hydrogen ions combine with haemoglobin Forms haemoglobinic acid
38
The blood contains hydrogen carbonate ion (HCO3 - ) Describe how these ions are formed in the blood [3 marks]
- Carbon dioxide diffuses into red blood cells - Carbon dioxide reacts with water - To form carbonic acid - Catalysed by Carbonic anhydrase - Carbon acid then dissociates to give H+ and HCO3
39
Outline the benefits of the Bohr shift to actively respiring tissue [3 marks]
- Actively respiring tissue needs/requires more oxygen - For aerobic respiration - to release more energy - More CO2 - Causes more oxygen to be released - As less haemoglobin available to combine with oxygen
40
Explain why the curve for fetal oxyhaemoglobin is to the left of the curve for adult oxyhaemoglobin [3 marks]
- Placenta has low pO2 - Adult haemoglobin will release O2/dissociate in placenta - Fetal haemoglobin has higher affinity for oxygen - Fetal haemoglobin is still able to take up some oxygen in the placenta
41
Explain why it is essential that the fetus has a different type of haemoglobin from the adult [4 marks]
* To allow fetus to gain oxygen from maternal blood * Across placenta * Partial pressure of oxygen is similar in the fetal and maternal parts of the placenta * Fetal haemoglobin has a higher affinity for oxygen * Oxygen is required for aerobic respiration
42
Explain why the change from fetal to adult hameoglobin seen in the diagram above is essential after birth [2 marks]
- Affinity of fetal haemoglobin would be too high - Would not release oxygen readily enough - Adult females will need difference with their fetuses in due course.
43
Describe what would be likely to happen to people who move to a high altitude if their red blood cells did not increase [4 marks]
* Haemoglobin becomes less saturated with oxygen * Altitude sickness * Results in hypoxia (shortage of oxygen to tissues) * Dizzinenss/weakness * Eventually result in death/coma
44
Explain why a large multicellular organism like a tree needs a water transport system whilst Chlamydomonas does not.
distance in tree is greater; not all tissues / cells in contact with water diffusion too slow Chlamydomonas has large surface area:volume
45
Why is the left ventricle thicker than right ventricle and atria?
provides more pressure/force to pump blood around body; Overcome the resistance of systemic circulation longer distance compared with distance right ventricle/atrium
46
Why do larger organisms require transport system?
larger organism= smaller SA:V distance is too great diffusion is too slow Insufficient rate of exchange of oxygen/co2 more metabolically active
47
What causes the rise and fall in pressure in the arteries?
cardiac muscle cause ventricles to contract/relax peaks coincides, with, systole (contraction) troughs coincide, with, diastole (relaxation) stretch-recoil effect
48
Why is the pressure much lower by the time it enters capillaries?
Capillaries are further away from the heart Less stretch and recoil effect There is more resistance to flow Total volume of capillaries is much greater
49
Why is it important to have low pressure by the time it reaches capillaries?
only one cell thick lack of elasticity high pressure damages its walls slower flow rate gives sufficient time for exchange to occur
50
Explain how the blood in veins is returned to the heart
valves prevent backflow Contraction of surrounding muscles helps transport blood *large lumen = little resistance gravity effect *negative pressure in chest
51
Purkyne tissue function
They branch down and across the walls of ventricles conduct waves of excitation so contracts from apex upwards *Both ventricles contract together
52
What happens when there’s lack of oxygen to the brain?
Less oxygen reach brain Reduced aerobic respiration Undergoes anaerobic respiration lactic acid builds up -> migraines
53
Why must the fetal Hb be different from adult Hb?
Fetal Hb has higher affinity for oxygen Able to obtain some oxygen from placenta where the partial pressure is lower Maternal Hb releases oxygen in placenta maintain diffusion gradient
54
Why must the fetal Hb change to adult Hb when born?
oxygen would not be released readily enough affinity of fetal haemoglobin would be too high; adult (females) will need difference with their fetuses in due course;
55
Impact of fibrillation
contractions are not coordinated less blood, leaves heart / goes to lungs / goes to body; cells / heart muscle deprived of oxygen; Chambers not full so blood pumped at low pressure
56
Why is it important that the steepest part of oxygen dissociation curve is between 2-5kpa?
2-5 kpa at muscle tissues which require lots of oxygen *a drop in Po2 gives large drop in saturation So release lots of oxygen for respiration
57
How does exercising muscle tissue bring changes in the dissociation curve?
More respiration = more energy released as heat Body temperature rises (Curve shifts to right) More o2 released from Hb
58
Describe how the structure of an artery relates to its function
Narrow lumen = maintains high pressure Thick wall= stop bursting/ withstand Collagen layer = provides strength and prevents it from bursting elastic tissue= stretch and recoil to even the surges of pressure smooth endothelium = reduce friction
59
Suggest why the system shown for the frog ( partial circulation) may be less effective at supplying the body tissues with oxygen
Mix of deoxygenated and oxygenated blood not fully oxygenated still carrying carbon dioxide lower pressure
60
Features of capillaries and its role in exchange
Thin wall= short diffusion pathway Smooth endothelium=reduced friction Pores=Allows nutrients to pass through Narrow diameter= RBCs squeeze through so short diffusion distance Total SA is large= more exchange
61
Differences between tissue fluid and blood
TISSUE FLUID no RBCs (don’t say Hb) no plasma proteins no platelets fewer WBCs not in vessels
62
What happens if the drainage into lymphatic system was insufficient?
Tissue fluid builds up in tissues -> swells Oedema
63
What is partial pressure?
Concentration of oxygen in atmosphere (Proportion of atmospheric pressure produced by oxygen)
64
Describe what would be likely to happen to people who move to high altitude if their red blood cell counts did not increase.
haemoglobin is less saturated with oxygen altitude sickness; hypoxia dizziness / headaches brain damage / lung damage / oedema in these organs
65
What is a vascular system
system of transport vessels in animals and plants
66
Why is the delay at AVN important?
-allow time for atria to fully contract -allow time for atria to empty/ ventricles to fill -so that ventricles dont contract too early
67
How is the wall of artery adapted to MAINTAIN pressure?
-Elastic fibre -stretch and recoil -thick smooth muscle cause narrow lumen
68
How is the wall of artery adapted to WITHSTAND pressure?
-thick layer of collagen -provides strength -folded endothelium -no damage to endothelium as wall can stretch
69
Advantages of keeping blood in vessels
-maintains high pressure -increases flow rate -blood can be diverted
70
Describe how the action of the heart is initiated and coordinated
-SAN initiates a wave of excitation -which spreads over the atrial walls -atrial systole -contraction is synchronised -delay at AVN -excitation spreads down the septum -purkyne fibres -ventricles contract from apex
71
Why does the hydrostatic pressure of blood drop further away from heart?
More vessels larger total cross sectional area reduced resistance to flow loss of fluid from capillaries
72
Double circulation advantages
1) more efficient supply of oxygen to tissues 2) helps to sustain high pressure 3) less resistance to flow 4) easier to return to heart 5) more rapid circulation

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