Surface area and volume of a cell relationship

Cell Surface Area vs Volume

surface area and volume of a cell relationship

Cells are so small that you need a microscope to examine them. Why Unfortunately, the volume increases more rapidly than does the surface area, and so the. Students should be able to appreciate the relationship between surface area to Folding in the surface of the cell membrane to increase the surface area. As cells increase in size, the surface area and volume do not usually increase proportionally to It is this relationship that restricts the size of a particular cell.

Although it might seem logical for an organism to be made of one giant cell, our cells are specialized: Furthermore, there are physiological limits to how big a cell can grow. The scale, or size of a cell compared to other objects, is incredibly small. Cells are microscopic mostly because of this constraint. In this lesson, our goal is to investigate why this property is true and how it works.

Cell Size & Scale: Surface Area, Volume Ratio & Organelles

There is a logical explanation for the structure and function of all living things, and cells are no different. The reason cells can grow only to a certain size has to do with their surface area to volume ratio. Here, surface area is the area of the outside of the cell, called the plasma membrane.

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The volume is how much space is inside the cell. The ratio is the surface area divided by the volume. This indicates how much surface area is available compared to how big the cell is.

If the surface area to volume ratio is small, the cell is very big. If the ratio is big, the surface area is greater than the volume and the cell is small. For example, picture a balloon.

surface area and volume of a cell relationship

The air inside is the volume, and the latex outside is the surface area. As a balloon gets bigger, the volume expands, but there is a limit to how big the surface area can get.

You might still be wondering why this matters. It matters because a cell's efficiency depends on its size. For example, let's consider diffusion, and note that the plasma membrane serves an important purpose here.


It's the barrier of the cell and where the cell interacts with its environment. Waste diffuses out of the cell here, and important nutrients and oxygen diffuse in. The cell also receives signals from other cells about what to do, when to reproduce and where to move. These signals must move through the interior of the cell as well.

surface area and volume of a cell relationship

However, this is going to take much longer if the cell is large, or has a small surface area to volume ratio. For homeotherms animals that try to maintain a constant body temperatureit is necessary to make heat as it is lost to the environment in order to maintain equilibrium. If heat loss occurs only at the exposed surfaces, what would you predict about the metabolic rate per unit of body tissue of a large animal compared to a small one? Take what you know about surface area to volume ratio and try to explain the following graph, which is known as the "mouse-to-elephant curve.

How does the surface area to volume ratio affect the rate of osmosis for a plant cell?

Note for example that an elephant has a mass and volume of more than times that of a mouse while its metabolic rate and heat production is only about times that of a mouse. Why can an elephant heat itself more efficiently per unit of mass than a mouse?

Surface Area, Volume, and Life

Explain with reference to surface area and volume. Think about heat retention in cold climates or heat shedding in hot climates and make a prediction about body types. Although there are exceptions, this is generally true. Why should it be so?

surface area and volume of a cell relationship

In one of my favorite old monster movies, Them, giant ants attack the city. Unfortunately, it could never happen.

BBC Bitesize - GCSE Biology (Single Science) - Transport in cells - AQA - Revision 3

The incredible strength of the ant is dependent upon its small size. Scale him up to even human size and he'd collapse under his own weight on those skinny little legs. Volume and therefore weight scales to the power of 3 while surface area and size scale to the power of 2. Create a graph that shows why the giant ant can't destroy the city, but instead would collapse under its own weight. As shown empirically in Brody's graph, power is proportional to mass to the power of 0.

Animals in the real world do better than expected, but animals in the real world don't rely entirely on surface area for heating, cooling, gas exchange, etc.