biology module 1 exchange Flashcards
1
Q
What substances do living cells need to keep them alive and why?
A
Oxygen for aerobic respiration Glucose for energy Proteins for growth and repair Fats for membranes and energy Water Minerals to maintain water potential and help aspects of metabolism
2
Q
What substances need to be removed and why?
A
Co2 from animals and micro organisms and plant cells that are actively doing photosynthesis
Oxygen (plants, protoctists)
Urea and ammonia and other wastes which contain excess nitrogen
3
Q
Explain why large, active organisms need special surfaces for exchange
A
- small surface area to volume ratio
- cant supply cells with gases and nutrients quick enough to keep them alive
- greater diffusion distance
4
Q
Describe and explain features that make an exchange surface sufficient
A
- large surface area: more space for molecules to pass through often by folding walls and membranes
- thin barrier: shorter diffusion distance
- fresh supply of molecule on one side: concentration +
- removal of required molecule: concentration low
5
Q
Describe inhalation
A
- diaphragm contracts to be flatter
- intercostal muscles contract to raise ribs
- volume of chest increase
- pressure In chest drop
- air in lungs
6
Q
Describe exhalation
A
- diaphragm relaxes
- intercostal muscles relax lower ribs
- volume decreased
- pressure increases above atmospheric pressure
- air out
7
Q
The role of the cartilage?
A
- structure
- prevents collapse when air pressure inside is low due to inhalation
- not closed so flexible and oesophagus to expand when eating
8
Q
The role of smooth muscle?
A
- contract to constrict the airway which makes the lumen narrower
- most obvious in bronchioles
- controls flow of Air to alveoli if harmful substances present
9
Q
What is one of the causes of asthma ?
A
Smooth muscle contracts and airways constrict because of involuntary reaction to allergic reaction
10
Q
Role of elastic fibres?
A
When smooth muscle contracts it deforms elastic fibres in loose tissue
- elastic fibres recoil into normal shape
- helps to widen the airway
11
Q
Role of goblet cells and glandular tissue?
A
Secrete mucus
Trap tiny particles from the air which may include pollen or harmful bacteria
Reduces risk of infection
12
Q
Role of ciliated epithelium?
A
Cilia move in pattern to waft mucus up the airway
Once there it is swallowed
Acidity in stomach kills any bacteria
13
Q
Tidal volume?
A
Volume of air moved in and out of lungs with each breath when at rest
Approx 0.5dm3
14
Q
Vital capacity?
A
Maximum volume of air that can be moved in and out of the lungs in one breath
Approximately 5dm3
15
Q
Residual volume?
A
Volume of air that remains in the lungs after maximum exhalation
Approx 1.5dm3
16
Q
Dead space?
A
Air in bronchioles, bronchi and trachea
No gas exchange takes place between this air and the blood
17
Q
Inspiratory reserve volume?
A
Amount of air that can be taken in above the normal tidal volume when you take in a big breath
18
Q
Exploratory reserve volume?
A
How much more site can be breathed out over and above normal tidal volume breathed in
19
Q
How does a spirometer work?
A
- chamber filled with oxygen that floats on a tank of water
- breathing in takes oxygen from chamber so it sinks down
- exhaling puts air in chamber so it floats up
- data logger records data and person can do different breathing to record different things
20
Q
Name two specialised exchange surfaces one in Animals one in plants and say which substances are transported in or out of that cell
A
Root hair cells: water and minerals absorbed
Small intestine: nutrients absorbed
Hyphae of fungi: nutrients absorbed
Liver:blood sugar levels adjusted
21
Q
Describe the journey of air from the outside of our bodies to our lung alveoli
A
- through the nose
- down trachea
- bronchi and bronchioles
- reaches alveoli where gas exchange takes place
22
Q
What is the role of surfactant in the alveoli of the lungs
A
Reduce cohesive forces between water molecules
Alveoli would collapse due to these cohesive forces between water molecules lining the air sac
23
Q
How Is surfactant produced
A
Passes through cell membrane of the cytoplasm of the alveolus cells
24
Q
Explain the action of the transport system maintains a diffusion gradient in the lungs
A
- blood brings co2 from tissues to lungs
- ensure concentration of co2 in the blood is higher than the air in alveoli
- blood carries oxygen away from lungs
- ensures concentration of blood kept lower than the air of the alveoli
25
How does ventilation of the lungs maintain diffusion gradient
- brings fresh oxygen in the lungs
- concentration of O2 in the air of the alveolus remains higher than in blood
- removes co2 from alveoli
- ensures co2 in blood kept higher than alveoli
26
Where are the goblet cells found q
Under the epithelium
27
Name the three main factors that affect the need for a transport system
Size
Surface area to volume ratio
Level do activity
28
How does size affect the need for a transport system
If an animal has several layers of cells the nutrients or oxygen needed would be taken up the outer cells
Would not reach the cells deeper within the body
29
How does surface are to volume ratio affect the need for a transport system?
Small a animals have a large surface area to volume ratio whereas a bigger animal with multiple structures and tissues have a relatively small surface area to volume ratio
-surface area is not large enough for the animal to supply all the oxygen and nutrients needed by internal cells
30
How does level of activity affect the need for a transport system?
Very active animals need a good supply of nutrients and oxygen to supply energy for movement
Animals such as mammals that keep the,selves warm need even more energy
31
Features of an effective transport system?
Fluid or medium to flow nutrients and oxygen around body (blood)
Pump to get pressure to push fluid around body (heart)
Exchange surfaces that enable O2 and nutrients to enter and leave blood when needed
32
Efficient transport system?
Tubes or vessels to carry blood around
| Two circuits one to pick up oxygen and one to remove it
33
What is pulmonary circulation
Blood flowing from the heart to the lungs to collect 02
34
What is systematic circulation?
Blood flowing from heart to the body to deliver oxygen and nutrients to the tissues
35
What is the cardiac cycle?
Sequence of events involved in one heartbeat
36
What is diastole?
When both the atria and ventricles are relaxing
Internal volume increases and blood flows into heart
Blood flows into atria then through atria ventricular valves to ventricles
37
What is atrial systole?
Atria contract to push blood into ventricles
This stretches the walls of the ventricles and they are full of blood
Contraction of the atria is ATRIAL SYSTOLE.
38
What is ventricular systole and explain it
Ventricles contract
Raises pressure in ventricles very quickly
Contraction starts at apex of heart so pushes blood in arteries
Semin lunar valves open and blood is pushed out of heart
39
What causes the atrioventricular valves to open?
When the ventricle walls relax and recoil and the pressure drops to below that in the atria
40
What causes the av valves to close
When the ventricles contract the pressure in them rises and blood starts to move upwards when the pressure is higher than that in the atria. This fills the valve pockets and keeps them closed which prevents blood back flow
41
How do the semi lunar valves open?
When the pressure inside the ventricles rises above pressure in aorta and pulmonary arteries semilunar valves are pushed open
42
How do semi lunar valves close?
Ventricles relax and pressure drops quickly
When dropped below pressure in major arteries semi lunar valves are pushed close by blood starting to flow backwards towards ventricles and collected in valve pockets
43
What is myogenic in the cardiac cycle?
Can contact and relax rhythmically even if not connected to the body
Initiate own contraction
44
Why is co ordination of contraction of the chambers of the heart important
Atria and ventricles each have own contraction frequency
Atria contract higher frequency than ventricles
Property could cause fibrillation
45
What is an open circulatory system?
Blood flows throughout the body cavity not contained
| Tissues and cells bathed in blood
46
What helps circulate blood in insects?
Muscular pumping organ
Underneath upper surface of insect
Blood enters through pores called Ostia
Pumped toward head by peristalsis
47
What directs blood in active insects
Open ended tubes teaches to heart
| Spread to active part of body where needed eg leg and wing
48
Why don't all animals have an open circulatory system?
Insects are small and blood does not transport oxygen or co2
Larger organisms rely on blood to carry co2 and 02
Open c system flow is slow, not fast enough to supply a larger active organism
49
What fluid bathes cells and tissues?
Tissue fluid
50
What is the inner layer or lining of all blood vessels called?
Endothelium
51
What do arteries do and it's features?
- carries blood away from the heart
- lumen wall small to maintain high pressure
- thick and contains collagen
- elastic tissue to recoil when stretched
- smooth muscle to contact and constrict the artery
- endothelium can unfold
52
What do veins do and features?
- carry blood away from heart at low pressure
- thin walls, thinner collagen etc
- lumen large to allow easy blood flow
- contain valves
53
Capillaries duty and features
- allow exchange of materials between blood and cells of tissues
- lumen narrow -ensures red blood cells are squeezed and give up oxygen reducing diffusion path to tissues
54
What are the fancy names for RBC and WBC
Erythrocytes
| Leucocytes
55
What does the term affinity mean and how does a haemoglobin molecule carry four oxygen molecules ?
Affinity means attraction
Haemoglobin is complex protein with 4 sub units
Each unit consists of polypeptide chain and haem group
Haem group contains single iron atom fe2+ which attracts and hold oxygen molecules
56
What is partial pressure ?
The amount of oxygen measured by the relative pressure that it contributes to a mixture of gases
57
What is the name given to the slight change of a haemoglobin molecule that allows more oxygen to dissolve into the haemoglobin molecule?
Conformational change
58
How does the s shape oxyhemoglobin disassociation curve occur.
Low oxygen tension means haemoglobin does not readily take up o2 molecules
This is because haem group at centre of cell so diff for O2 to reach
As O2 tension rises diffusion grad increases and an 02 molecule associates with haem group which causes slight change
Makes it easy for other 02 molecule so steep gradient as 02 tension rises
59
Why does the s shaped disassociation curve level off?
As 3 O2 molecules diffused increasingly hard for 4th
Hard to get 100% saturation level even if 02 tension very high
So curve levels off
60
Compare O2 tension in the lungs with 02 tension in the body tissues?
02 tension in lungs sufficient to produce almost 100% saturation
02 tension in respiring body tissues is sufficiently low or cause 02 to readily disassociate with oxyhemoglobin
61
Explain the curve for fetal haemoglobin ?
Fetal haemoglobin has higher affinity for oxygen than adult
Must be able to pick up 02 from enviroment that releases adult haemoglobin
Fetal haem absorbs O2 mothes blood fluid
Less 02 tension
Left of adult curve
62
Why do plants need a transport system?
Needs regular supply of water
Many cells inside the plant further from supply
Roots can obtain water but not sugars
Leaves can produce sugars but not water from the air
63
What substances need to be move in xylem tissue?
Water and soluble minerals travelling upwards
64
What substances need to be moved in phloem
Sugars up or down
65
WHere are the xylem and phloem found
In vascular bundles
66
What is transolocation ?
The movement of assimilates
67
What are assimilates
Sugars and other chemicals made by plant cells
68
What is a source
A part of the plant that releases sucrose into the phloem
69
What is a sink
A part of the plant that removes sucrose from the phloem
70
What is an exams of the source
A leaf
71
What's an example of a sink
A leaf
72
Describe and explain one other way in which a steep diffusion gradient is maintained in the lungs
continuous blood flow in the capillaries
bring in more carbon dioxide / take away more oxygen ;
oxygen combines with haemoglobin
to keep concentration in, blood / plasma, low
73
Suggest two advantages of keeping the blood inside vessels
maintain / high(er), (blood) pressure
increase rate of, flow / delivery ;
flow can be, diverted / directed
74
State the resolution that can be achieved by transmission electron microscope
0.05
75
How do sucrose enter the phloem?
- Companion cells use ATP to actively transport hydrogen ions out of the cytoplasm and into the tissue
- This sets up diffusion gradient which allows hydrogen ions to diffuse back into the companion cells
76
Where does this diffusion occur?
Through special co transporter Proteins
77
What do special cotransport proteins allow?
They allow hydrogen irons to bring sucrose molecules into the companion cells
78
What happens as the concentration of glucose molecules build up inside companion cells?
Diffuse into sieve tube elements through numerous plasmodesmata
79
How do many plants reduce water loss by transpiration?
- They have a waxy cuticle Which reduces water loss by evaporation through epidermidis
- stomata are on the underside of leaf Which reduces evaporation caused by direct heating of the sun
- 'stomata are closed at night
80
What is a property of deciduous plants?
They lose their leaves in the winter when the ground Maybe frozen and when temperatures may be too low for photosynthesis
81
What are xerophytes?
Plants that are particularly well adapted to living in very dry or arid conditions
82
What are their adaptations to reduce water loss from their leaves?
- They have smaller leaves which reduces the total surface area which reduces water lost by transpiration
- They have a densely packed spongy mesophyll
- They roll their leaves so that the lower epidermis is not exposed to the atmosphere Which reduces or eliminates the water potential gradient
- Some plants have a low water potential inside cell which reduces evaporation of water loss.
83
How do pits contains stomata stop water loss?
Trap Air saturated water vapour.
This reduces the gradient in the water vapour potential between inside and outside the leaf so reduces loss by diffusion
84
What route can water take between cells?
Apoplast pathway, symplast pathway, vacuolar pathway
85
How does apoplast pathway work?
- Water leaves through the water filled spaces between the cellulose molecules
- water does not pass through any plasma membranes so minerals ions and salts can be carried in this way
86
How does the symplast pathway work?
- What enters cell through cytoplasm and then passes through the plasmodesmata through one cell to the next
- Cytoplasm of adjacent cells is linked. Once inside the cytoplasm water can move through the continuous cytoplasm from cell to cell
87
What is plasmodesma?
Fine strand of cytoplasm that links the contents of adjacent cells
88
What is the vacuolar pathway?
Same as the symplast pathway but it does not restrict water to the cytoplasm
89
How can we measure oxygen uptake
when breathing into a spirometer the volume of oxygen breathed in is the same as the carbon dioxide breathed out so the CO2 removed is is equal to the volume of oxygen used up
90
Define heart
a muscular pump that creates pressure to propel blood through th =e arteries and around the body
91
What does the right side of the heart do
| What does the left side of the heart do
- Right side pumps deoxygenated blood to lungs to be oxygenated
- Left side pumps oxygenated blood to the rest of the body
92
Where are the atria found
Above the ventricle
93
Where do the coronary arteries lie and what do they do
Over the heart
| carry blood to the body LOOK OVER A PICTURE OF THE HEART
94
What do tendinous cords do
stops flimsy valves from turning inside out and allowing blood to flow back into atria
95
What does the septum do
separates the two ventricles to stop oxgenated and deoxygenated blood from mixing
96
Why are the atria thin
do not need to be under much pressure as they only push blood into ventricles
97
Why is the right atria thinner than the left
The right atria doesnt need to pump blood very far as the lungs are close to the heart and also the pressure must be kept low to stop the capillaries bursting
-left ventricle pumps blood to the rest of the body and the pressure needs to be high to overcome resistance of systemic circulation
98
State how this hydrostatic pressure is generated in the heart.
contraction of ventricle wall
99
what happens to the blood plasma at point A along the capillary in the figure above.
- moves out of the capillary
- forms tissue fluid
- tissue fluid moves down pressure gradient
100
what are the 3 ways CO2 is transported
-5% in plasma
-10% in haemoglobin forming carbaminoheamoglobin
-85% hydrogencarbonate ions (HCO3-)
`
101
how are hydrogencarbonate ions formed
as co2 in blood some enter RBC where it combines with water to form carbonic acid which then dissasociates to release H+ ions and HCO3- ions
