7909676
Description
Flashcards by Joanne North, updated more than 1 year ago
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Created by Joanne North
about 7 years ago
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| Question | Answer |
| What are some examples of things that need to be interchanged between an organism and its environment? | - Respiratory gases (oxygen and carbon dioxide). - Nutrients (glucose, fatty acids, amino acids and vitamins and minerals). - Excretory products (urea and carbon dioxide). - Heat. |
| Except for heat, these exchanges can take place in two ways. What are the two ways? | 1. Passively by diffusion and osmosis. 2. Actively by active transport. |
| Organisms evolve multiple features to aid transport. What are they? | - A flattened shape so that no cell is ever far from the surface. - Specialised exchange surfaces with large areas to increase the surface area to volume ratio. |
| What are the features of a specialised exchange surface? | - A large surface area to volume ratio of the organism to increase the rate of exchange. - Very thin so that the diffusion distance is short and therefore materials cross the exchange surface rapidly. - Selectively permeable to allow selected materials to cross. - Movement of the environmental medium e.g., air to maintain a diffusion gradient. |
| How does gas-exchange take place in single-celled organisms? | Single celled organism are small and have a large surface area to volume ratio so oxygen can diffuse to the cell and carbon dioxide can diffuse out. |
| What is the structure of the gas exchange surface in insects? | Insects have evolved tubes called tracheae which are supported by rings to prevent them from collapsing. The tracheae divide into dead end tubes called tracheales which are fluid filled at the end. |
| What are the three main ways in which respiratory gases in insects move in and out of the tracheal system? | 1. Along a diffusion gradient. 2. Mass transport. 3. The ends of the tracheoles are filled with water. |
| How do respiratory gases move in and out of an insect by a diffusion gradient? | When cells are respiring, the concentration of oxygen in the ends of the tracheoles falls creating a diffusion gradient from the atmosphere to the tracheoles. Carbon dioxide is at a higher concentration at the ends of the tracheoles creating a diffusion gradient with the atmosphere. |
| How do respiratory gases move in and out of an insect by mass transport? | The contraction of muscles in insects can squeeze the trachea enabling mass movements of air in and out. This further speeds up the exchange of respiratory gases. |
| How do respiratory gases move in and out of an insect by the ends of the tracheoles being filled with water? | During periods of major activity muscle cells respire anaerobically producing lactate which lowers the water potential of the muscle cells. Water moves into the muscle cells by osmosis and draws air down the tracheoles with it. Final diffusion is more rapid and increases the rate to which air is moved into the tracheoles but leads to greater water evaporation. |
| How do respiratory gases leave an insects body? | By the spiracles. |
| What is the structure of the gas exchange system in fish (gills)? | They are made of gill filaments which are stacked up. At right angles to the filaments are gill lamellae which further increase the surface area of the gills. Water is taken in through the mouth and forced over the gills. Water and blood flow in opposite directions which is known as counter current flow. |
| Where are the gills found on a fish? | Behind the head of the fish. |
| What is the counter current exchange principle? | Blood and water flow over the gill lamellae in opposite directions. Blood that is well loaded with oxygen meet water which has the maximum concentration of oxygen allowing diffusion to take place. Blood with little oxygen meets water which has had most of the oxygen removed allowing diffusion to still take place. |
| Using the counter current exchange principle how much oxygen is taken up from water? | 80% |
| What is the structure of a leaf? | Waxy cuticle Upper epidermis Mesophyll cells (contain chloroplasts, valcuole and a nucleus) Lower epidermis Guard cell and stomata |
| What adaptation of leaves allow for rapid diffusion? | - Many small pores, called stomata, so no cell is far from a stoma and therefore the diffusion is short. - Numerous interconnecting air-spaces that occur throughout the mesophyll so that gases can readily come into contact with mesophyll cells. - Large surface area of mesophyll cells for rapid diffusion. |
| What is the function of the stomata? | Open and close the stomatal pore to control water loss and gas exchange. |
| Where is the stomata found? | Occur mainly on the underside of the leaf. |
| What cell controls the stomatal pore? | Guard cell. |
| How does insects reduce water loss? | a. Small surface area to volume ratio - minismies the area to lose water. b. Waterproofing covering c. Spiracles - can be closed to reduce water loss. |
| What are xerophytes? | Plants that are adapted to living in area where water is in short supply. |
| What adaptations do xerophytes have in order to conserve water? | a. A thick cuticle - less water can escape. b. Rolling up of leaves - regio becomes saturated with water vapour so has a high water potential. c. Stomata in pits or grooves - trap moist air to reduce the water potential gradient. d. A reduced surface area to volume ration of the leaves. |
| Why must the volume of oxygen absorbed and volume of carbon dioxide removed be high? | Because mammals are large organisms with a large volume of living cells. They also maintain a high body temperature which is associated with high metabolic and respiratory rates. |
| Why are the lungs located on the inside of the body? | Air is not dense enough to support and protect these delicate structures. The body as a whole would lose a great deal of water. |
| What are the lungs supported and protected by? | The ribcage |
| What are the main parts of the mammalian lungs? | Trachea Bronchi Bronchioles Alveoli |
| What are the lungs? | A pair of lobed structures made up of a series of highly branched tubules called bronchioles which end in tiny air sacs called alveoli. |
| What is the trachea? | A flexible airway that is supported by rings of cartilage to prevent it from collapsing as the air pressure falls. The trachea are lined with ciliated epithelium and goblet cells. |
| What is the bronchi? | Two divisions of the trachea. Also produce mucus to trap dirt particles and have cilia that move dirt towards the throat. Supported by cartilage to prevent them from collapsing. |
| What are the bronchioles? | A series of branching subdivision of the bronchi. Their walls are made of muscle and lined with epithelial cells. Muscle allows them to constrict so they can control air flow in the alveoli. |
| What are the alveoli? | Minute air-sacs, with a diameter between 100 um-300 um. Between the alveoli there are some collagen and elastic fibres allowing them to stretch when filling up and spring back. The alveoli are lined with epithelium, |
| Pressure changes within the lungs are brought about by the movement of? | The diaphragm - sheet like muscle that separates the thorax from the abdomen. The internal intercostal muscles - contraction leads to expiration. The external intercostal muscles - contraction leads to inspiration. |
| What are the stages of inspiration? | 1. The external intercostal muscles contract, while the internal intercostal muscles relax. 2. The ribs are pulled upwards and outwards, increasing the volume of the thorax. 3. The diaphragm muscles contract, causing it to flatten, which further increases the volume of the thorax. 4. The increased volume of the thorax results in a reduction of pressure in the lungs. 5. Atmospheric pressure is now greater than pulmonary pressure so air is forced into the lungs. |
| What are the stages of expiration? | 1. The internal intercostal muscles contract, while the external intercostal muscles relax. 2. The ribs move downwards and inwards, decreasing the volume of the thorax. 3. The diaphragm relaxes and becomes curved further decreasing the volume of the thorax. 4. The decreased volume of the thorax increases the pressure in the lungs. 5. The pulmonary pressure is now greater than that of the atmosphere so air is forced out of the lungs. |
| Is expiration passive or active? | Largely passive. |
| Is inhalation passive or active? | Active as it uses energy. |
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