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Transport in Cells - Coggle Diagram
Transport in Cells
Adaptations
The small intestine in mammals - The oxygen, nutrients and digested foods are absorbed into the surface lining cells which from there go into the bloodstream and carbon dioxide comes out. The large surface area is needed so that as many nutrients can get into the bloodstream as possible. The small tissue called villi increases the surface area and contains specialised cells that transport substances into the bloodstream.
The lungs in mammals - In the alveoli there is lots of oxygen. This can happen very quickly because of the surface area. In the lung, oxygen goes in and carbon dioxide goes out. The surface area of the alveoli is large and the membranes separating the lungs from the red blood cells are very thin. The rate of oxygen diffusion is dependent on the surface area so gas exchange can occur more quickly because of the larger surface area. Oxygen moves from the alveolar space into the red blood cell by diffusion
Gills in fish - There isn't much oxygen in the water compared to the air and fish need oxygen to be able to survive. Fish use gills for gas exchange taking in oxygen and giving out carbon dioxide. Gills have many folds providing a very large surface area. The fill filaments have many gill llamellae which are thin plates or layers
Roots in plants - The roots absorb water from the soil by dissolving the minerals from the soil by active transport. The water is transported to be used as a reactant in photosynthesis, as well as to cool the laves by evaporation and support the leaves and shoots by keeping cells rigid. The oxygen gets carried in through the water from the soil and carbon dioxide gets let out through the leaves. They need a large surface area so that water and mineral ions can be absorbed and exchanged. Lots of root hairs make up the large surface area
Leaves in plants - The structures of leaves are adapted for efficient photosynthesis. Most leaves are broad and so have a large surface area allowing them to absorb more light. A thin shape means a short distance for carbon dioxide to diffuse in and oxygen to diffuse out easily. Oxygen gets expelled through the stomata
A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.
Active Transport - Moves substances from a more dilute solution to a more concentrated solution against a concentrated gradient. This requires energy from repiration
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The carrier protein changes back to its original shape. Molecules can only be transported in one direction against their diffusion gradient
Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.
Active transport allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.
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Multicellular organisms
In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. The effectiveness of an exchange surface is increased by having:
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As the size of an organism increases, its surface area to volume ratio decreases. Large multicellular organisms therefore cannot rely on diffusion alone to supply their cells with substances such as food and oxygen and to remove waste products. Large multicellular organisms require specialised transport systems.
Osmosis - The movement of water molecules through a partially permeable membrane from a region of high water concentration to low water concentration
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