1
Q
Whats the difference between glycoprotiens, integral protiens, and peripheral protiens?
A
Glyco: Conjugated protien with carbohydrate prosthetic group. Often acts as receptors for hormones and nuerotransmitters.
Integral: Carrier or channel protiens which make up part of the transport system.
Peripheral: Protiens that are situated either above or below the bilayer which maybe be enzymes or involved in regulating transport
2
Q
Diffusion definition
A
the net movement of particles from an area of high concentration to an area of low concentration (Down a concentration gradient)
3
Q
facilitated diffusion
A
process of diffusion in which molecules pass across the membrane through cell membrane carrier or channel protiens
4
Q
Osmosis definition
A
Diffusion of water through a selectively permeable membrane from an area of high water potential to a region of low water potential
5
Q
Endocytosis
A
The movement of large molecules into cells through vesicle formation. Requires ATP
6
Q
Exocytosis
A
The movement of large molecules out of cells through vesicle fusion. Requires ATP
7
Q
isotonic solution
A
A solution in which the concentration of solutes is essentially equal to that of the cell which resides in the solution
8
Q
hypotonic solution
A
A solution in which the concentration of solutes is less than that of the cell that resides in the solution
9
Q
hypertonic solution
A
A solution in which the concentration of solutes is greater than that of the cell that resides in the solution
10
Q
What is hydrostatic pressure
A
The pressure that the fluid exerts in all directions. In plant cells this comes from the push of the cell wall onto the protoplasm
11
Q
What is tugor pressure/Pressure potential/hydrostatic pressure
? (P)
A
Pressure inside a plant cell due to the cell wall when it accumulates water through osmosis. It is usally positive as the rigid cell wall shape exerts pressure onto the protoplasm of the cell, to counteract osmotic force. It is a form of hydrostatic pressure
12
Q
What is the state called when the plant cell is rigid as pressure potential balances osmotic force pushing water into the cell.
A
Turgor
13
Q
What is incipient plasmolysis?
A
The point at which so much water has moved out of the cell by osmosis that turgor is lost and the cell membrane begins to pull away from the cell wall as the protoplasm shrinks
14
Q
What is water potential? (Omega symbol)
A
Water potential is the measure for water molecules to diffuse out of a solution by osmosis. Usually negative and 0 in perfectly pure water
15
Q
How can turgor pressure be measured?
A
Pressure probe
16
Q
What is osmotic potential? (Pi sysmbol)
A
The tendency of water to move across a permeable membrane into a solution of high solute concentration. Usally negative
17
Q
Whats the formula of water potential?
Water potential of cell
A
Water potential of cell = Turgor pressure + Osmotic pressure
18
Q
What the difference between phagocytosis and pinocytosis?
A
Phago: The active process when a cell engulfs something relatively large such as a bacterium by endocytosis and encloses it in a vesicle
Pino: The active process when a cell takes in tiny amounts of extracellular fluid into vesicles
19
Q
Factors affecting rate of diffusion
A
- Steepness of concentration gradient
- Thickness of gas exchange surface
- Temperature
- Surface area
20
Q
How does cholesterol affect the cell membrane?
A
Increases the fluidity of membranes
21
Q
How does a carrier protien work?
A
- Carrier protiens are specific for a particular molecule according to their shape
- Once a molecules binds to the carrier protien, it changes shape, and releasing the molecule on the other side of the membrane
- Once released the carrier protien changes back to its orginal shape.
22
Q
Are carrier protiens uni or bi directional
A
Only one direction - Uni
23
Q
What is lung surfactant?
A
A special phospholipid that coats the alveoli and makes breathing easier, and prevents collapse of alveoli in low pressures
24
Q
Describe gas exchange in insects
A
- Air moves into trachae through spiracles, past an exoskeleton
- Oxygen travels down concentration gradient towards cells
- Trachae branch off into tracheoles with thin permeables that go into cells
- CO2 travels down concentration gradient towards spiracles to be released
- Rhythmic abdominal movements move air in and out of spiracles by creating low and high pressure through expansion of volumes
25
Which protien catalyses brake down of ATP to ADP and what provides energy from this reaction
ATPase
hydrolysis of ATP
26
What is the tracheae lined with in insects?
spirals of chitin
Chitin makes the tracheae relatively impermeable to gases so little gas exchange takes place here. In the tracheoles, there is no chitin and single elongated cells which allows for movement of gases.
27
What controls water loss in insects?
Spiracle sphincters allows the closing and opening of the spiracle, useful in drier climates. More are open when the oxygen demand is higher during activity
28
What are and explain the adaptions of tracheoles?
3
- Single elongated cells without chitin which makes it permeable to gases and short diffusion distance
- Huge network of tracheoles which provides are large surface area for diffusion to occur
- Some may contain water at the end of the tracheoles. This limits the penetration of gases for diffusion. When the insect in very active, needs more oxygen, lactic acid builds in cells, causing osmotic gradient so water moves into the cells by osmosis, more SA for gas exchange
29
How are very active insects adapted for gas exchange?
Mechanical ventilation: Rhythmic abdominal movements move air in and out of spiracles by creating low and high pressure through expansion and contraction of volumes
Collapsible tracheae or air sacs: These are air reservoirs which can increase the volume of air moved through the respiratory system.
30
Where does gas exchange occur in fish?
Gills
31
Explain gas exchange in fish
1) Gas exchange in fish is helped by the gills
2) Water, carrying oxygen, is moved across gill archs which is made up of gill filaments which have a large number of vertical lamellae
- Provides large SA
3) Lamellae consist of a single layer of flattened epithelial cells
- Reduces DD
4) Blood is carried to the gills in a large number of capillaries which carries oxygen away
- Increases CG
5) Gills are ventilated by moving water across them
- Oxygen concentrations are kept high in water surroudning the gill, but the vast network of filaments also means water moves slow around the llamella which results in greater gas exchange
6) Blood is carried in the opposite direction to water
- Counter-current principle (Maintains steep concentration gradient)
7) Increases gas exchange:
- Diffusion of oxygen and carbon dioxide can occure over the entire gill surface
- Oxygen concentration of water always exceeds that of the blood
- A CG always exists
- Equilibrium is never reached
32
How do bony fish ventilate their gills?
By opening and closing the mouth together with opening and closing the operculum. This bony flap is a protective sheets over the gills and maintains water flow even when the fish is stationary.
Water enters mouth opening as buccal chamber expands, whilst operculum is closed, water moves over the gills -> Mouth closes Buccal chamber contracts, operculum opens, water flows over the gills and water flows out through operculum opening
33
How do cartilaginous fish ventilate their gills
They have to keep swimming all the time (E.g sharks and rays)
34
What is the structure of leaf
Waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, stomata, the leaf includes the xylem & phloem (Vascular bundle), guard cells
35
What are the stomata found on leaf stems?
Lenticels
36
how do guard cells open stomata?
K+ ions move into guard cells by active transport, which causes water to follow by osmosis --> Turgor pressure increases -> the guard cell becomes turgid -> Stomata opens because of the uneven bending in arrangement of cellulose in the cell walls
37
circulatory system of fish
have a single circulatory system, one atrium one ventricle. The blood is delivered at high pressure to the gills after being pumped from the heart (Steep conc gradient) but is at low pressure by the time it reaches the body
38
Role of plasma
Transports carbon dioxide, digested food, urea, hormones and distributes heat energy
39
Role of platelets
blood clotting
40
Scientific name for red blood cells?
erythrocytes
41
Scientific name for white blood cells?
leucocytes
42
What are granulocytes? The name of them? And their function?
Leucocytes that have granules in the cytoplasm of cells and contain lobed nuclei
- Nuetrophils (Non specific, engulf and disgest pathogens by phagocytosis, multi lobed nuclei)
- Eosinophils (Non specific, Allergic reactions and inflammation by releasing hitamines, seen using eosin stain)
- Basophils (Non specific, Allergic reactions and inflammation by releasing hitamines, two lobed nuclei)
43
What are Angranulocytes? The name of them? And their function?
Leucocytes that do not have granules in the cytoplasm of cells and do not contain lobed nuclei
- Monocytes (Specific Immune system, differentiate into macrophages which are phagocytes, largest of the leucocytes)
- Lymphocytes (Specific immune system, smallest leucocytes but very large nuclei)
44
Scientific name for platelets and where are they produced
Thrombocytes
-Irregularly shaped cell fragments from megakaryocytes in the bone marrow
45
Structure of Haemoglobin (Hb)
● Protein with a quaternary structure
● Made of 4 polypeptide chains (2 alpha, 2 Beta pleated sheets)
● Each chain contains a Haem group containing an iron ion (Fe2+)
46
Explain cooperative binding
- The affinity haemoglobin has for oxygen changes depending on how many oxygen molecules are already associated with it.
- Haemoglobin can associate with four oxygen molecules and as each molecule binds, the shape of haemoglobin changes making the binding of further oxygen molecules easier.
- Therefore, in areas with high partial pressure of oxygen, meaning a high concentration, the affinity of haemoglobin for oxygen is high and it loads more oxygen. In humans, the alveoli have a high partial pressure of oxygen and therefore haemoglobin will readily load with oxygen here.
47
Explain the Bohr effect
As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape. The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin.
48
Explain the haemoglobin dissociation curve
-haemoglobin associates with oxygen in a way that produces an s-shaped curve (haemoglobin disassociation curve)
-at low oxygen(pp) the haemoglobin does not readily associate with oxygen molecules as the haem groups are in the centre of the molecule and it is difficult fr the oxygen molecule to reach them
-as the oxygen (pp) rises the diffusion gradient into the haemoglobin molecule increases and finally one oxygen molecule enters and associated with a haem group causing the conformational change
-this allows more oxygen molecules to enter the molecule and associate with other haem groups easily (as shown by steepness of graph)
-oxygen (pp) in respiring tissue is low so causes oxygen to dissociate readily from the oxyhaemoglobin
49
Fetal haemoglobin Vs Adult haemoglobin
Fetal haemoglobin has a higher affinity for oxygen than the adult so the graph shifts left
If the affinty for oxygen was the same, little oxygen would be transferred to the fetus. Maternal and fetal blood also run in opposite direction so there is a counter current system
50
Myoglobin
(Mb) only one heme group, small, bright red protien.
Higher affinity for oxygen which causes oxygen to dissociate from haemoglobin and onto myoglobin, a store of oxygen for respiration. Myoglobin not affected by ppO2 in the tissues
51
How is carbon dioxide transported around the body?
~5% dissolved in the plasma
~10-20% combines with haemoglobin to form carbaminohaemoglobin
- Most transported in cytoplasm of red blood cells as hydrogencarbonate ions
52
Describe the blood clotting process
1) idea that there is a cascade of events (leading to blood clotting).
Serotonin can be released which cuts off blood supply by restricting blood flow through vasoconstriction
2) ref. to thromboplastin (starting the cascade).
3) ref. to conversion of prothrombin into thrombin.
4) idea that {thromboplastin/thrombin} is {an
enzyme / a catalyst} ;
5) ref. to conversion of fibrinogen into fibrin.
6) ref. to formation of mesh of {fibres/fibrin}.
7) ref. to requirement of {calcium ions/ Ca2+ / vitamin K} ;
8) ref. to {platelets/blood cells} getting trapped (in the mesh) ;
53
Features of arteries
1. Arteries carry blood from the heart to the rest of the body.
2. Blood is carried under high pressure.
2. Thick, muscular walls (smooth muscle) with elastic tissue = expand and recoil
3. Narrow lumen - maintain high pressure
4. Folded endothelium allowing expansion to cope with high pressure.
5. All arteries carry oxygenated blood except for the pulmonary arteries, which take deoxygenated blood to the lungs.
54
Features of veins
1. Veins carry blood back to the heart.
2. Blood is carried under low pressure.
2. Walls have little elastic or muscle tissue.
3. Wider lumen = reduced friction which would otherwise slow down blood flow.
4. Have valves to stop back flow of blood.
5. Blood flow through the veins is helped by contraction of the body muscles surrounding them.
6. All veins carry deoxygenated (oxygen used up by cells), except the pulmonary veins, which carry oxygenated blood to the heart form the lungs.
55
Explain how the heart contracts.
1. SAN initiates/depolarises and spreads impulse across atria, so they contract. Due to non-conducting tissue called annulus fibrosus, the impulse does not move onto ventricles
2. AVN receives, delays, and then conveys impulse down the bundle of his.
3. impulse travels into purkinje fibres which branch across ventricles, so they contract from the bottom up (From Apex)
56
fast heart rate is called
tachycardia
57
Electrocardiogram (ECG) points
P wave - Depolarisation of atria
QRS wave - Ventricle depolarisation
T wave - Ventricle repolarisation which masks atrial repolarisation
58
formation of atherosclerosis
1. slight damage to endothelial cells lining the artery
2. leads to build up of LDLs - start of plaque deposit
3. platelets form a cap over the deposit
4. narrows the artery
59
aneurysm
ballooning of a weakened portion of an arterial wall
60
angina
a condition of episodes of severe chest pain due to inadequate blood flow to the myocardium (Heart)
61
myocardial infarction
heart attack
62
Formation of tissue fluid
1) high hydrostatic pressure in arterial end of capillary bed. Hydrostatic pressure higher than oncotic pressure so fluid is pushed out into surrounding tissues, forming tissue fluid. Most of plasma is pushed out except for RBC's and plasma proteins.
2) Diffusion takes place between blood and cells via tissue fluid.
3) High oncotic pressure in venous end of capillary bed due to plasma proteins generating low water potential in the blood. Hydrostatic pressure is low. 95% tissue fluid moves back into capillary via osmosis. remaining 10% move back into lymphatic tissue.
63
Role of lymph glands
Contain lymphocytes that make antibodies
64
Where are antibodies released into the blood stream from lymphatic system?
Sub clavian vien
65
Describe the structure of a vascular bundle
cambium (meristematic tissue) (Middle)
phloem tissue (Outside)
xylem tissue (Inside)
66
Formation of the xylem
. Starts of as living tissue called protoxylem
2. Cells grow and stretch
3. Cells die, then end walls removed and strengthened with lignin to become impermeable to water and other substances, but provides structural support. (Metaxylem is formed)
4. Pits are formed in xylem vessels to allow for lateral movement of water and substances
67
How is xylem adapted to its function?
- They are hollow which means there is little resistance to the flow of water (as there is more space).
- It is also made of spirals of (dead) lignin which prevents the collapsing and supports the xylem and stops it from bursting. - The spirals also allow flexibility and stretching
- It also waterproofs the wall, improving adhesion of water.
68
Structure of phloem tissue
Sieve tube elements (living cells) joined end to end to form sieve tubes. Sieve parts are the end walls which have lots of holes to allow solutes to pass through. There is a companion cell for every sieve tube element
69
How is the phloem adapted to its function?
It contains elongated cells with pores in the end cell walls to allow for the movement of dissolved sugars
70
Apoplast pathway
The route taken by water between the cells or through the cell walls in a plant. Water moves by osmosis into the cell wall and this happens until it reaches the casparian strip in which it needs active transport to move ions into the cytoplasm of the cells
71
Symplastic pathway
route through the cytoplasm and plasmodesmata of plant cells by which water and dissolved substances are transported. Dissolved substances must be actively pumped into the cyotplasm of the cell
72
cohesion-tension theory
the mechanism of water movement from roots to leaves due to water cohesion and water tension (Bipolar nature).
73
Explain translocation
It is the movement of sugars within a plant
1) At SOURCE: high conc of solute (e.g. sucrose)
2) active transport (ATP) used to load solutes from companion cells to ST cells (down conc grad)
3) this decreases the water potential
4) water moves IN by osmosis from CC and xylem
5) creates high hydrostatic pressure in phloem
6) this forces stuff down
- SINK uses/breaks down/converts solute
7) creates low conc of solute (e.g. sucrose - starch)
8) increases water potential so water moves OUT by osmosis
9) decreases pressure in phloem - pressure gradient from source to sink
- pushes solutes towards the sink
74
How heart is stimulated
SAN depolarises first
Atria pump
AVN is slight delay then wave goes through bundle of his before ventricles pump
75
What is Bohr effect
rise in CO2 levels reduce haemoglobin affinity to O2
76
How is tissue fluid formed
High hydrostatic pressure from heart and constant oncotic pressure squeezes fluid out of cell. Only plasma proteins and red blood cells continue. This creates fluid. Most of fluid is pushed back in by oncotic pressure but rest is drained by lymphatic system
77
Biology B
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