How do the physical features of the surroundings affect organisms? What are these physical factors?

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Okay, let's start with the a term called the abiotic environment. (The abiotic factors of the environment include light, temperature, and atmospheric gases.)



Abiotic factors

1. Climate

• Light intensity





• Temperature





• Amount of water available

2. Oxygen content

3. Salinity (salt concentration) of soil or water

4. pH of soil or water

How does all of the physical surroundings mentioned above affect the environment?

Firstly, the physical features of the surroundings and the nature of the soil determine the types of plants found in a region. (eg. plants that need more water, plants that need less water)

Since animals rely directly or indirectly on plants for food, the diversity of the animals in a region is thus first determined by the plant source. Organisms in a region are usually adapted to their environment.

How does light intensity affect organisms?

Light intensity affects the distribution and growth of both plants and animals. Plants that carry out photosynthesis naturally exist where there is an adequate amount of sunlight.

eg. Plants that photosynthesis only exist at areas where their is sufficient sunlight. However, too much sunlight will cause the plant to grow slowly, which shows why plants that grow under the sun end up much shorter than those which grow in the shade.

Temperature

Temperature affects the rate of enzymes, which control the metabolic or physiological activities of plants and animals. Since most organisms cannot tolerate extremes of temperatures, temperatures that are too high or too low would kill them.

eg. Migrating birds migrate twice a year. When winter arrives, they fly in a group to an area which has a warmer climate, and they return when winter has passed.

Amount of available water

Water is essential for living. Thus, the amount of available water greatly affects the number and location of various species in the region. The amount of available water also depends on the amount of precipitation throughout the year.

eg. Aquatic animals have gills for absorbing oxygen or special structures for swimming.

Oxygen content

Most organisms are aerobic, which means that they require oxygen for respiration, thus they are unable to survive in an environment with low oxygen content.

eg. Carp, an air-breathing fish, can gulp air at the surface of the water.

Salinity

Salinity (salt concentration) of water is an important factor affecting aquatic organisms, as animals that live in seawater tend to lose water by osmosis.

eg. The cytoplasm of the cells of freshwater organisms usually has a higher salt concentration than the surrounding water. The cell walls of freshwater plants have rigid cell walls that prevents the cell from bursting.

pH

pH refers to the acidity or alkalinity of a solution. Aquatic organisms are very sensitive to the pH of water that they live in.

eg. In strong daylight, photosynthesis in plants makes water more alkalie by using up the carbon dioxide. At night, photosynthesis stops, and thus the carbon dioxide produced in respiration makes the water more acidic.