Nutrition

Specific Objective 2.1 of Section B of the CSEC Biology Syllabus requires us to distinguish between heterotrophic, autotrophic and saprophytic nutrition.

Nutrition can simply be defined as the process by which organisms obtain and utilise food.

There are three types of nutrition, as per the CSEC Biology Syllabus:

1.      Autotrophic Nutrition

Autotrophic nutrition involves the use of simple inorganic substances (such as carbon dioxide and water) by plants to produce their own food.

As a practical activity, we could observe the example of a tree, and observe its sources of food as an autotroph:

a)      Sunlight- Used in photosynthesis (photosynthesis will be discussed later)

b)     Carbon Dioxide- Used in photosynthesis, absorbed from the air through the stomata of the leaves.

c)      Water- Used in photosynthesis, absorbed from the soil through the roots.

d)     Minerals- Taken in from the soil (more on soil minerals in another note).

2.      Heterotrophic Nutrition

Unlike autotrophic nutrition, heterotrophic involves the use of complex organic substances consumed by animals for food.(This involves the consumption of another organism).

As a practical activity, we can observe some of the diet of a lion as an example, and observe its sources of food as a heterotroph:

a)      Zebra- Lions hunt zebras, and gain nutrients and energy from eating their flesh.

b)     Buffalos- Buffalos, which are herbivores, are also eaten by lions, and similar to zebras, they provide the lion with nutrients and energy.

3.      Saprophytic Nutrition

Saprophytic nutrition occurs through the consumption of decaying organic matter.

A popular example which can be used to explain saprophytic nutrition is the example of the food sources of a mushroom:

a)      Decaying leaves and wood- these provide organic matter which can be utilised by the saprophyte for nutrition.

b)     Compost- Similar to decaying leaves and wood, compost can also provide mushrooms with the organic matter needed.