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Chapter 6- Gas Excha
A level Biology Chapter 6 - Gas Exchange
| Question | Answer |
|---|---|
| 3 ways in which insects do gas exchange? | Down a diffusion gradient, mass transport and water at ends of tracheoles |
| How does down a diffusion gradient work? | Insects respire = O2 is used up, conc of O2 at end of tracheoles falls. O2 diffuses from atmosphere along trachae and tracheoles. |
| How does Mass transport work? | Muscles contract which squeezes the trachae so theres mass movement of air in and out at a fast rate. CO2 pushed out by PRESSURE GRADIENT. |
| How does ends of tracheoles filled with water work? | Muscle cells respire anaerobically produces lactate which lowers water potential. water moves into cells from tracheoles by osmosis. Water in ends of tracheoles decrease in volume > draws air in. |
| Adaptations of insect gas exchange? | Many branched tracheoles = large surface area tracheoles = thin = short diffusion pathway |
| Gas exchange Fish structure? | Gill Lamellae at right angles to Gill filaments and therefore GL give larger SA Thin so short diffusion pathway |
| What is the counter Current exchange principle? | Blood and water which flow over gill lamellae do so in opposite directions. = Water with higher conc of O2 always meets blood with lower conc of O2; maintains steep diffusion gradient |
| Many large animals have blood systems. Explain why these animals need blood systems to supply their cells with oxygen | Gas exchange surface long distance from (some) respiring tissues; Blood system allows rapid transport/faster supply; Diffusion is slow |
| Describe the mechanism of breathing for inspiration | Internal intercostal muscles contract, external intercostal muscles relax; Ribs move upwards and outwards; Volume of thorax increases; lower pressure in thorax than atmospheric pressure; So air moves in down a pressure gradient |
| Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells inside the leaf. | (Carbon dioxide enters) via stomata; (Stomata opened by) guard cells; Diffuses through air spaces; Down diffusion gradient; |
| Describe and explain how fish maintain a flow of water over their gills. | mouth opens, operculum valve shuts; floor of mouth lowered; 3. water enters due to decreased pressure 4. mouth closes, operculum valve opens; 5. floor raised results in increased pressure increased pressure forces / pushes water over gills; |
| A large number of small alveoli is more efficient in gas exchange than a smaller number of larger alveoli. Explain why. | Larger SA for diffusion |
| Describe the gross structure of the human gas exchange system and how we breathe in and out. | Trachea,bronchi, bronchiole, alveoli Inspiration = external intercostal muscles contract, diaphragm contracts + flattens so volume of thorax increases, pressure decreases Expiration = internal intercostal muscles contract, diaphragm relaxes V = Decrease |
| How to measure Surface Area of a leaf? | Draw around leaf on graph paper Count squares Multiply by 2 |
| Explain how the ventilation mechanism of a fish and the structure of its gills result in the efficient uptake of oxygen from water. | Gill lamellae give larger SA Countercurrent principle = blood always meets with water with higher oxygen concentration thin epithelium = short diffusion pathway |
| Explain why ventilation of the lungs increases the efficiency of gas exchange. | Brings more oxygen/removes carbon dioxide; Maintains diffusion/concentration gradients; Between alveoli and blood/capillaries; |
| When first hatched, the young of some species of fish are less than 2 mm long. Explain how these young fish get enough oxygen to their cells without having gills. | diffusion across body surface = short diffusion pathway |
| Features of gills of fish which makes them more adapted. | large numbers of lamellae so large SA; lamellae thin so short (diffusion) pathway to blood / capillaries; high rate of oxygen uptake for respiration / energy release; |
| There is a one-way flow of water over the gills of a fish whereas there is a two-way flow of air in the lungs of a mammal. Suggest one advantage to a fish of this one-way flow of water over its gills. | less energy needed / continuous flow of water or O2; |
| After 4 minutes of exercise, the breathing rate was 20 breaths per minute. Explain how you could use this information and the graph to calculate tidal volume. | Find value of pulmonary ventilation from graph / 26-28; Divide by breathing rate / 20; |
| When a person starts to breathe out, the percentage of oxygen in the air first exhaled is the same as the percentage of oxygen in the atmospheric air. Explain why. | (c) Air is from nose / trachea / bronchi / not been in alveoli / dead space; Gas exchange / diffusion only in alveoli / not in these structures; |
| Describe how oxygen is loaded and unloaded? | Haemoglobin carries oxygen and loads at lungs at high partial pressure. Unloads at tissues at low partial pressure. unloading linked to carbon dioxide concentration. |
Created by:
ksatti12