Examples of surface area in the following topics:
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- Cell size is limited in accordance with the ratio of cell surface area to volume.
- Therefore, as a cell increases in size, its surface area-to-volume ratio decreases.
- However, increased surface area can cause problems as well.
- Notice that as a cell increases in size, its surface area-to-volume ratio decreases.
- The cell on the left has a volume of 1 mm3 and a surface area of 6 mm2, with a surface area-to-volume ratio of 6 to 1, whereas the cell on the right has a volume of 8 mm3 and a surface area of 24 mm2, with a surface area-to-volume ratio of 3 to 1.
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- Recall that any three-dimensional object has a surface area and volume; the ratio of these two quantities is the surface-to-volume ratio.
- Consider a cell shaped like a perfect sphere: it has a surface area of 4πr2, and a volume of (4/3)πr3.
- The larger the size of the sphere, or animal, the less surface area for diffusion it possesses.
- Surface-to-volume ratio also applies to other areas of animal development, such as the relationship between muscle mass and cross-sectional surface area in supporting skeletons or in the relationship between muscle mass and the generation of dissipation of heat.
- The surface area of a sphere is 4πr2 and it has a volume of (4/3)πr3 which makes the surface-to-volume ratio 3/r.
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- You may remember from your high school geometry course that the formula for the surface area of a sphere is 4πr2, while the formula for its volume is 4/3πr3.
- Thus, as the radius of a cell increases, its surface area increases as the square of its radius, but its volume increases as the cube of its radius (much more rapidly).
- Therefore, as a cell increases in size, its surface area-to-volume ratio decreases.
- If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume.
- Notice that as a cell increases in size, its surface area-to-volume ratio decreases.When there is insufficient surface area to support a cell's increasing volume, a cell will either divide or die.The cell on the left has a volume of 1 mm3 and a surface area of 6 mm2, with a surface area-to-volume ratio of 6 to 1, whereas the cell on the right has a volume of 8 mm3 and a surface area of 24 mm2, with a surface area-to-volume ratio of 3 to 1.
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- The structure and organization of the lung is meant to maximize its surface area to increase gas diffusion.
- Due to the enormous number of alveoli (approximately 300 million in each human lung), the surface area of the lung is very large (75 m2).
- Having such a large surface area increases the amount of gas that can diffuse into and out of the lungs.
- In disease situations, the amount of air delivered may be reduced, the alveolar wall may be thickened, or the alveolar surface area may be reduced with the result that less gas is able to diffuse out of the alveolus.
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- Mycorrhizae help increase the surface area of the plant root system because hyphae, which are narrow, can spread beyond the nutrient depletion zone.
- Hyphae from the fungi extend from the mantle into the soil, which increases the surface area for water and mineral absorption.
- These hyphae greatly increase the surface area of the plant root, allowing it to reach areas that are not depleted of nutrients.
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- As animal size increases, diffusion distances increase and the ratio of surface area to volume drops.
- Gas exchange by direct diffusion across surface membranes is efficient for organisms less than 1 mm in diameter.
- The flat shape of these organisms increases the surface area for diffusion, ensuring that each cell within the body is close to the outer membrane surface and has access to oxygen.
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- Diffusion is a process of passive transport in which molecules move from an area of higher concentration to one of lower concentration.
- This is due to the diffusion of odor molecules through the air, from an area of high concentration (the kitchen) to areas of low concentration (your upstairs bedroom).
- A single substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across a space .
- Surface area and thickness of the plasma membrane: Increased surface area increases the rate of diffusion, whereas a thicker membrane reduces it.
- Diffusion through a permeable membrane moves a substance from an area of high concentration (extracellular fluid, in this case) down its concentration gradient (into the cytoplasm).
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- Botanists call the upper side the adaxial surface (or adaxis) and the lower side the abaxial surface (or abaxis).
- The cuticle reduces the rate of water loss from the leaf surface.
- Other leaves may have small hairs (trichomes) on the leaf surface.
- These needle-like leaves have sunken stomata and a smaller surface area, two attributes that aid in reducing water loss.
- Many aquatic plants have leaves with wide lamina that can float on the surface of the water; a thick waxy cuticle on the leaf surface that repels water.
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- In addition to phosphate runoff as a result of human activity, natural surface runoff occurs when it is leached from phosphate-containing rock by weathering, thus sending phosphates into rivers, lakes, and the ocean.
- This sediment then is moved to land over geologic time by the uplifting of areas of the earth's surface .
- A dead zone is an area within a freshwater or marine ecosystem where large areas are depleted of their normal flora and fauna.
- Phosphate enters the oceans via surface runoff, groundwater flow, and river flow.
- Worldwide, large dead zones are found in coastal areas of high population density.
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- The hydrophilic or water-loving areas of these molecules are in contact with the aqueous fluid both inside and outside the cell.
- This arrangement gives the overall molecule an area described as its head (the phosphate-containing group), which has a polar character or negative charge, and an area called the tail (the fatty acids), which has no charge .
- Thus, the membrane surfaces that face the interior and exterior of the cell are hydrophilic.
- Along with peripheral proteins, carbohydrates form specialized sites on the cell surface that allow cells to recognize each other.
- The glycocalyx is highly hydrophilic and attracts large amounts of water to the surface of the cell.