Gas Exchange
- Created by: beth-marie2511
- Created on: 09-03-16 16:17
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- Insects
- BY2 - Gas Exchange (2)
- Birds
- Gas exchange surface = lungs.
- Similar internal structure to mammals' lungs.
- Thin
- Moist
- Permeable
- Additional air sacks so more efficient.
- Store oxygen.
- Ribs moves up and down to allow them to breathe.
- Gas exchange surface = lungs.
- Amphibians
- Gas exchange surface = skin and within the lungs.
- Skin alone acts as the gas exchange surface with water or air when the creature is inactive.
- Well developed capillary network just beneath the surface.
- Tadpoles have gills as their gas exchange surface.
- Gas exchange surface = skin and within the lungs.
- Reptiles
- Pairs of ribs project from the backbone.
- Provide support and protection to inner organs.
- Gas exchange surface = lungs.
- Large surface area to volume ratio.
- Thin
- Pairs of ribs project from the backbone.
- Human Respiratory System
- Lungs
- Lungs are internal because we need to reduce water and heat loss.
- Inspiration
- Intercostal muscles contract.
- Ribs move up and out.
- Diaphragm contracts and flattens.
- Volume of the thorax increases.
- Pressure of the thorax decreases.
- Atmospheric pressure forces air into the lungs.
- Lungs
- Plants
- Leaf adaptations
- Flat - large surface area to absorb sunlight and carbon dioxide.
- Grow towards light source for maximum light.
- Thin to allow light to penetrate and this is also a short diffusion pathway.
- Cuticle and epidermis are transparent to allow light to penetrate into cells.
- Palisade cells are elongated to be more tightly packed together to absorb more light.
- Chloroplasts can move to get a better position for absorbing light.
- Spongy mesophyll cells are moist for gas exchange as gases dissolve in moisture.
- Xylem (vascular bundle) provides water for photosynthesis.
- Waxy cuticles reduce water loss by evaporation but reduce gas exchange.
- Guard cells can open and close to reduce water loss.
- Stomata allow entry and exit of gases.
- Air spaces allow circulation of gases and create a concentration gradient between inside the leaf and the atmosphere.
- Respire during night and day so oxygen is required.
- Carbon dioxide is required too )Photosynthesis).
- Diffuses into leaves from the atmosphere.
- Produced by photosynthesis - some is retained for respiration.
- Carbon dioxide is required too )Photosynthesis).
- O2 + GLUCOSE --> H20 + CO2 + ATP.
- H20 + CO2 --> O2 + GLUCOSE
- Stomata
- Pores found on the lower epidermis of the leaf.
- Allow gas exchange.
- Controls water loss.
- Opening of Stomata
- 1. K+ is actively pumped into guard cells and starch is converted into malate.
- This lowers water potential.
- 2. Water moves from a high water potential (epidermal cells) to a low water potential (guard cells) by osmosis.
- 3. Guard cells become TURGID.
- 4. Inner wall of the guard cell is thicker/inelastic than the outer wall and the guard cells bend away from each other.
- Cyanide stops active transport into the guard cells because it is a non-competitive respiratory inhibitor.
- 4. Inner wall of the guard cell is thicker/inelastic than the outer wall and the guard cells bend away from each other.
- Opposite steps occur for the closing of the stomata.
- 3. Guard cells become TURGID.
- 1. K+ is actively pumped into guard cells and starch is converted into malate.
- Leaf adaptations
- Birds
- Diffusion into the body is difficult because of their small surface area to volume ratio.
- Waterproof exoskeleton made of chitin.
- Prevents diffusion of gases through the skin so a different gas surface has evolved.
- Waterproof exoskeleton made of chitin.
- Air moves in and out through spiracles (holes along the abdomen).
- Paired spiracles transfer gas in branched, chitin-lined tubes called tracheae.
- Gas exchange takes place in trachioles (where oxygen passes into cells).
- Paired spiracles transfer gas in branched, chitin-lined tubes called tracheae.
- Functions of Spiracles
- Control gas exchange.
- Reduce water loss.
- Gas exchange occurs directly in the tissue as there is no blood.
- Thorax spiracles open first then the abdomen spiracles.
- Thorax spiracles act as a pump to pull air in.
- Flight - movement of the abdomen ventilates the tracheae.
- BY2 - Gas Exchange (2)
- Moist
- Permeable
- Gas exchange surface = skin and within the lungs.
- Skin alone acts as the gas exchange surface with water or air when the creature is inactive.
- Well developed capillary network just beneath the surface.
- Tadpoles have gills as their gas exchange surface.
- Features
- Large surface area to volume ratio
- Alveoli are large in numbers.
- Thin
- Alveoli have thin walls and therefore a short diffusion pathway.
- Moist
- Permeable.
- Gases dissolve.
- Lungs
- Lungs are internal because we need to reduce water and heat loss.
- Inspiration
- Intercostal muscles contract.
- Ribs move up and out.
- Diaphragm contracts and flattens.
- Volume of the thorax increases.
- Pressure of the thorax decreases.
- Atmospheric pressure forces air into the lungs.
- Large surface area to volume ratio
- Each pore is surrounded by 2 guard cells.
- Unevenly thickened walls.
- Outer wall is thin and inner wall is thick.
- Contain chloroplast.
- Stomata
- Pores found on the lower epidermis of the leaf.
- Allow gas exchange.
- Controls water loss.
- Opening of Stomata
- 1. K+ is actively pumped into guard cells and starch is converted into malate.
- This lowers water potential.
- 2. Water moves from a high water potential (epidermal cells) to a low water potential (guard cells) by osmosis.
- 3. Guard cells become TURGID.
- 4. Inner wall of the guard cell is thicker/inelastic than the outer wall and the guard cells bend away from each other.
- Cyanide stops active transport into the guard cells because it is a non-competitive respiratory inhibitor.
- 4. Inner wall of the guard cell is thicker/inelastic than the outer wall and the guard cells bend away from each other.
- Opposite steps occur for the closing of the stomata.
- 3. Guard cells become TURGID.
- 1. K+ is actively pumped into guard cells and starch is converted into malate.
- Unevenly thickened walls.
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