Heterotrophic Nutrition Year 11 Biology

Summary:

Heterotrophic nutrition is a type of nutrition where an organism cannot produce its own food and must rely on other organisms to obtain the nutrients it needs to survive. This is in contrast to autotrophic nutrition, where an organism is able to produce its own food through photosynthesis or chemosynthesis.

Heterotrophic organisms obtain their nutrients by consuming other living or dead organisms or absorbing nutrients from the environment. Examples of heterotrophic organisms include animals, fungi, and many types of bacteria.

Heterotrophic nutrition is a fundamental aspect of the food chain and plays a vital role in the cycling of nutrients in ecosystems.

Excerpt:

HETEROTROPHIC NUTRITION

= Mode of nutrition in which organisms obtain ready-made organic food from outside.

= Since heterotrophs consume the food they are called consumers

= Depending on whether the food is stationary (plants) or mobile(animals), consumers show different nutritive apparatus.

TYPES OF HETEROTROPHIC NUTRITION

= Depending on how an organism obtains food from outside heterotrophic nutrition can be of three types:

1. Saprophytic—- The organisms feed on dead & decaying organisms and perform external digestion(break down the food outside the body with the help of an enzyme and then absorb it).

e.g., fungi like bread molds, yeast, and mushrooms

2. Parasitic — The organisms derive nutrition from other living organisms(called the host) causing harm to them but without killing them.

e.g., Cuscuta (Amar-bel), ticks, lice leeches, and tapeworms.

3. Holozoic — The organisms take in solid pieces of food and break them down inside their bodies. It is found in animals and protozoan protists.

e.g., cow, lion, humans, amoeba, and paramoecium.

= Depending on the source of food, holozoic organisms are of three types:

• Herbivores — Organisms feed on plants. e.g. Cow, goat
• Carnivores — Organisms feed on animals. e.g. Lion, tiger
• Omnivores — Organisms feed on both plants and animals. e.g. Dogs, bears, crows, and humans

Scavengers are another category of holozoic organisms that feed on the dead bodies of other animals