6 NUTRITION6 NUTRITION

What is Nutrition?What is Nutrition?

The entire process by which organism obtain energy from food for growth, maintenance and repair of damaged tissues

Nutrient – the substances that are required for the nourishment of an organism

6.1 Type of Nutrition6.1 Type of Nutrition

Two main types:1. Autotrophic2. Heterotrophic

1. Autotrophic 1. Autotrophic

A process in which organisms synthesise organic substances from inorganic substances

Autotroph = Auto – self, trophos – feed (organism which can make their own food)

The source of energy for synthesising food can be either light energy or chemical energy.

The synthesis of food using light energy – photosynthesis (photo – light)

Photoautotroph – organisms which produce organic molecules from carbon dioxide and water using sunlight as a source of energy

Example: green plants

The synthesis of food using chemical energy – chemosynthesis (chemo – chemical)

Chemoautotroph – organisms which synthesise organic compound by oxidising inorganic compound (hydrogen sulphide and ammonia)

Example: certain bacteria (Nitrosomonas sp. and Nitrobacter sp.)

2. Heterotrophic2. Heterotrophic

A type of nutrition in which organism obtain energy through the intake and digestion of organic substances.

Heterotroph =Hetero – other, trophos – feed (organism that cannot synthesis their own nutrients but obtain the nutrients from other organisms)

They may practice a) Holozioc nutrition, b) Saprophytism c) Parasitism

- holo –like, zoon – animal- The organism feeds by ingesting

solid organic matter which is subsequently digested and absorbed into their bodies

- Examples: humans, herbivores, carnivores and some carnivorous pitcher plants and Venus fly-traps

a) Holozoic nutritiona) Holozoic nutrition

- The organism called saprophytes- Feed on dead and decaying

organic matter- Digest their food externally

before absorbing the nutrients into their bodies

- Examples: bacteria, fungi

b) Saprophytismb) Saprophytism

- The organism called parasite- Obtain nutrient from living on

(ectoparasites) or in (endoparasites) the body of another living organism (host)

- They absorbs readily digested food from its host

- Examples: fleas (ectoparasites), lice, worms (endoparasites), Rafflesia plant

c) Parasitismc) Parasitism

Test YourselfTest Yourself

1. Differentiate between autotrophic and heterotrophic nutrition.

A: Autotrophic nutrition – A process in which organisms synthesise organic substances from inorganic substances Heterotrophic nutrition - A type of nutrition in which organism obtain energy through the intake and digestion of organic substances.

2. Name two types of autotrophic nutrition.

A: Photosynthesis and chemosynthesis

Test YourselfTest Yourself

3. Name three types of heterotrophic nutrition.

A: Holozoic nutrition, saprophytism and parasitism

Test YourselfTest Yourself

4. Name the nutritional habits of the following organisms;a) Pitcher plants

A: holozoic nutritionb) Green algae

A: photosynthesisd) Tapeworm

A: parasitism

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