3) Organisims Exchange Substances With The Enviroment Flashcards
(50 cards)
1
Q
relationship between surface
area to volume ratio and metabolic
rate for a smaller organism.
A
- (Smaller so) larger surface area to volume ratio;
- More heat loss (per gram)
- Faster rate of respiration releases heat
2
Q
Exchange Surface adaptations - unicellular organisms
A
- thin so short diffusion pathway
- flat/long/small so large SA:V
3
Q
Fish – Ventilation Mechanism
A
- mouth opens, operculum / opercular valve shuts;
- floor of mouth lowered;
- water enters due to decreased pressure / increased volume;
- mouth closes, operculum / opercular valve opens;
- floor raised results in increased pressure / decreased volume;
- high / increased pressure forces / pushes water over gills;
4
Q
Fish Gill – Adaptations
A
- Many lamellae/filaments so large surface area;
- Thin (surface) so short diffusion pathway;
5
Q
Fish Gill – adaptations for efficient
gas exchange
A
- Large surface area provided by lamellae/filaments;
- Increases diffusion/makes diffusion efficient;
- Thin epithelium/distance between water and blood;
- Water and blood flow in opposite directions/counter current;
- maintains concentration gradient (along gill) /equilibrium not reached;
- As water always next to blood with lower concentration of oxygen;
- Circulation replaces blood saturated with oxygen;
- Ventilation replaces water (as oxygen removed)
6
Q
Fish Gill – counter-current
mechanism
A
- water and blood always flow in opposite directions
- blood always passing water with higher oxygen concentration
- diffusion gradient maintained throughout length of Gill.
7
Q
Insect Tracheole System –
adaptations for faster rate of
diffusion
A
- Tracheoles have thin walls so short diffusion distance to cells;
- Highly branched/large number of tracheoles so short diffusion distance to cells;
- Highly branched/large number of tracheoles so large surface area (for gas exchange);
- Tracheae provide tubes full of air so fast diffusion (into insect tissues);
- Fluid in the end of the tracheoles that moves out (into tissues) during exercise so faster diffusion through the air
to the gas exchange surface; - Body can be moved (by muscles) to move air so maintains diffusion/concentration gradient for oxygen/carbon
dioxide;
8
Q
Insect Tracheole System – structure
and function
A
- Spiracle;
- Tracheole/trachea;
- Oxygen used in (aerobic) respiration;
- Oxygen moves down a diffusion gradient
9
Q
Insect Tracheole System –
Abdominal Pumping - used in large insects
A
- Abdominal pumping/pressure in tubes linked to carbon dioxide release;
- (Abdominal) pumping raises pressure in body;
- Air/carbon dioxide pushed out of body /air/carbon dioxide moves down pressure gradient (to atmosphere
10
Q
Describe how carbon dioxide in the
air outside a leaf reaches
mesophyll cells inside the leaf
A
- (Carbon dioxide enters) via stomata; Reject stroma
- (Stomata opened by) guard cells;
- Diffuses through air spaces;
- Down diffusion gradient; Reject along
11
Q
Lungs – Adaptations for gas
exchange
A
- alveoli provide a large surface area;
- walls of alveoli thin to provide a short diffusion pathway / walls of capillary thin / close to alveoli provides
- a short diffusion pathway;
- walls (of capillaries / alveoli) have flattened cells
- cell membrane permeable to gases;
- many blood capillaries provide a large surface area;
- intercostal / chest muscles / diaphragm muscles / to ventilate lungs / maintain a diffusion / concentration gradient;
- wide trachea / branching of bronchi / bronchioles for efficient flow of air;
- cartilage rings keep airways open;
12
Q
Lungs – Pathway for oxygen
A
- Trachea and bronchi and bronchioles;
- Down pressure gradient;
- Down diffusion gradient;
- Across alveolar epithelium;
- Across capillary endothelium/epithelium;
13
Q
Explain how ventilation
maintains a concentration gradient
A
- Air high in oxygen is continuously entering the alveoli during inspiration
- Air low in oxygen is continuously being removed from the alveoli during expiration
14
Q
Describe Inspiration
A
external intercostal muscles contract
2. internal intercostal muscles relax
3. ribs move up and out
4. diaphragm muscle contracts and the diaphragm flattens / moves down
5. volume of thoracic cavity increases
6. pressure in thoracic cavity decreases
7. so air moves in down a pressure gradient
15
Q
Expiration
A
- internal intercostal muscles contract
- external intercostal muscles relax
- ribs move down and in
- diaphragm muscles relax and diaphragm returns to dome-shape
- volume of thoracic cavity decreases
- pressure in thoracic cavity increases
- air moves out down a pressure gradient
16
Q
Lungs – Asthma and bronchi
A
- Muscle walls of bronchi/bronchioles contract;
- Walls of bronchi/bronchioles secrete more mucus;
- Diameter of airways reduced;
- (Therefore) flow of air reduced;
17
Q
Pulmonary ventilation equation
A
Pulmonary Ventilation = Tidal Volume x Breathing Rate
18
Q
Xerophytes – Adaptations to
desert plants
A
- Hairs so ‘trap’ water vapour and water potential gradient decreased;
- Stomata in pits/grooves so ‘trap’ water vapour and water potential gradient decreased;
- Thick (cuticle/waxy) layer so increases diffusion distance;
- Waxy layer/cuticle so reduces evaporation/transpiration;
- Rolled/folded/curled leaves so ‘trap’ water vapour and water potential gradient decreased;
- Spines/needles so reduces surface area to volume ratio;
19
Q
Digestion of proteins
A
- Hydrolysis of peptide bonds
- Endopeptidases break polypeptides into smaller peptide chains;
- Exopeptidases remove terminal amino acids;
- Dipeptidases hydrolyse/break down dipeptides into amino acids;
20
Q
Compare
endopeptidase and exopeptidase
A
- Endopeptidases hydrolyse internal (peptide bonds);
- Exopeptidases remove amino acids/hydrolyse (bonds) at end(s);
- More ends or increase in surface area (for exopeptidases)
21
Q
Digestion of starch
A
- Amylase;
- (Starch) to maltose;
- Maltase;
- Maltose to glucose;
- Hydrolysis;
- (Of) glycosidic bond;
22
Q
Function of bile salts and micelles
A
- (Bile salts emulsify lipids forming) droplets which increase surface areas (for lipase / enzyme action);
- (So) faster hydrolysis / digestion (of triglycerides / lipids);
- Micelles carry fatty acids and glycerol / monoglycerides to / through membrane / to (intestinal epithelial) cell;
23
Q
Artery – Structure and Function
A
- Elastic tissue to allow stretching/recoil/ smooths out flow of blood/maintains pressure;
- (Elastic tissue) stretches when ventricles contract OR Recoils when ventricle relaxes;
- Muscle for contraction/vasoconstriction;
- Thick wall withstands pressure OR stop bursting;
- Smooth endothelium reduces friction;
24
Q
Haemoglobin – loading and
unloading of oxygen
A
- Oxygen combines (reversibly) to produce oxyhaemoglobin;
- each haemoglobin molecule/ one haemoglobin may transport 4 molecules of
- high partial pressure of oxygen / oxygen tension / concentration in lungs;
- haemoglobin (almost) 95% / 100% saturated;
- unloads at low oxygen tension(in tissues);
- presence of carbon dioxide displaces curve further to right / increases oxygen dissociation;
- allows more O2 to be unloaded;
- increase temp/ acidity allows more O2 to be unloaded;
- low pO2 / increase CO2 / increase term / increase acid occur in vicinity of respiring tissue
25
How does exercise
enable release of oxygen at the
tissues/muscles?
1. CO2 (increased) from respiration;
2. (increased) dissociation oxygen from haemoglobin;
3. Low partial pressure in tissues/plasma;
4. Oxygen diffuses from red blood cells to tissues;
26
Animals living at
high altitudes shift to left - why?
1. high altitudes have a low partial pressure of O2;
2. high saturation/affinity of Hb with O2 (at low partial pressure O2);
3. sufficient/enough O2 supplied to cells / tissues;
27
Animals with high
metabolic rate shift to right - why?
1. (at the tissues at low conc./ pp oxygen) the haemoglobin is less saturated with oxygen / has reduced affinity;
2. oxyhaemoglobin dissociates more readily / haemoglobin releases oxygen more readily / more oxygen
released;
3. allowing greater demand / respiration rate;
28
Haemoglobin - How does binding
of oxygen cause more oxygen to
bind?
1. First oxygen binds (to Hb) causing change in shape;
2. (Shape change of Hb) allows more O2 to bind (easily) / greater saturation with O2 OR
3. Cooperative binding;
29
Hb Oxygen Dissociation Curve –
shift to the right (4) (oxygen releases)
1. Curve to the right so lower affinity/% saturation (of haemoglobin);
2. Haemoglobin unloads/dissociates more readily;
3. More oxygen to cells/tissues/muscles;
4. For greater/more/faster respiration;
30
Hb Oxygen Dissociation Curve –
shift to the left
1. Hb has greater affinity for O2;
2. becomes saturated at low(er) ppO2 / more saturated at same ppO2 / unsaturated at very low ppO2;
3. able to supply enough O2 to its tissues
31
Events of the cardiac cycle.
1. Atria contract (atrial systole);
2. Increased pressure in atria;
3. AV valves open (when pressure in atria is higher than in ventricles);
4. Blood flows into ventricles;
5. AV valves shut (when pressure in ventricles is higher than pressure in atria);
6. Ventricles contract (ventricular systole);
7. Increased pressure in ventricles (biggest difference);
8. Semi-lunar valves open (when pressure in ventricles is higher than pressure in arteries);
9. Blood moves into arteries fast at first (rapid ejection) and then more slowly;
10. Semi-lunar valves close (when pressure in ventricles low and pressure in arteries is high);
11. Diastole (heart relaxes and atria accept more blood from the veins
32
Cardiac output calculations
Cardiac Output = Stroke Volume x Heart Rate
33
Tissue Fluid – Formation and
reabsorption
1. At arteriole end high hydrostatic pressure/blood pressure;
2. Hydrostatic pressure higher than effect of osmosis;
3. Small molecules/named example eg glucose; water
4. Forces out;
5. Proteins remain in blood/ not removed as they are too large to leave capillary;
6. Increasing/giving higher concentration of blood proteins so proteins lower water potential of blood;
7. Water/fluid moves back into blood;
8. Water moves by osmosis
34
Why does a high
blood pressure cause more fluid
retained in tissues?
1. High blood pressure = high hydrostatic pressure;
2. Increases outward pressure from (arterial) end of capillary OR reduces inward pressure at (venule) end of capillary;
3. (So) more tissue fluid formed /less tissue fluid is reabsorbed
35
Transpiration – Describe the
cohesion-tension theory
1. Evaporation/transpiration from leaves;
2. Through stomata;
3. Cohesion of water molecules;
4. Leaf cells have more negative water potential, so water enters from xylem;
5. Water drawn up as column/continuous stream;
6. Adhesion of water to walls;
7. Capillarity due to narrow lumen of xylem;
8. Lignified walls keep xylem open;
9. Root pressure forces (some) water up;
36
Translocation - Mass transport of
sugars in phloem
1. In source/leaf sugars (sucrose) actively transported into phloem;
2. By companion cells;
3. Lowers water potential of sieve cell/tube and water enters by osmosis;
4. Increased volume (of water) causes increased pressure;
5. Increase in pressure causes mass movement (towards sink/root);
6. At sink/roots sugars (sucrose) are removed/unloaded;
7. Sugars used (glucose)/converted in root for respiration for storage (as starch);
37
Evidence of
Translocation in the Phloem
1. 14C used to label organic compounds – subsequent autoradiography shows labelled compounds are in the
phloem
2. The bark of a tree contains the active phloem – remove a ring of bark and downward movement of organic
compounds stops where bark removed
3. Sap-sucking insect – piercing mouthpart found to be in phloem and sap removed via piercing mouthpart found
to contain organic compounds
38
As pCO, increases what happens to the oxygen affinity of haemoglobin?
As carbon dioxide concentration increases affinity for oxygen in haemoglobin decreases.
39
How does increased respiration affect blood pH?
Increased respiration increases pCO, Carbon dioxide combines with water to form carbonic acid which lowers the pH of blood
40
Explain how saturation of haemoglobin affects it's affinity for oxygen.
The saturation of haemoglobin can also affect its affinity for oxygen. This is because as each oxygen molecule binds it changes the shape of the haemoglobin in a way that makes it easier for further oxygen molecules to bind. However, as the saturation of haemoglobin increases it becomes harder for the final oxygen molecules to bind.
41
With reference to protein structure, explain how lowering blood pH levels affects haemoglobin.
Lower blood pH means tertiary structure of Hb altered which reduces its affinity for oxygen. More oxygen dissociates.
42
What is the net result of the Bohr effect?
What is the net result of the Bohr effect?
More oxygen is released where more carbon dioxide is produced in respiration to help maintain metabolic rate
43
What direction will the dissociation curve shift during the Bohr effect?
To the right
44
What is the main difference between foetal haemoglobin and adult haemoglobin?
It has a higher affinity for oxygen than adult haemoglobin
45
Describe the simple structure of haemoglobin
Quaternary structure, each of the four polypeptide chains contains a haem group); haem groups each contain an Fe2+ ion.
46
Why can haemoglobin be described as having quaternary structure?
Made up of more than one polypeptide chain
47
What is the name for oxyhemoglobin releasing its oxygen to respiring cells?
Dissociation/ unloading
48
What is partial pressure
The partial pressure of a gas is a measure of concentration of that gas in a mixture of gases or in a liquid
49
What effect does p02 have on haemoglobins affinity for oxygen
as pO, increases haemoglobins affinity increases.
50
Where in the body has highest p02 and hameoglobin has high affinity for oxygen
Both in the lungs
