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Nutrition
The way organisms obtain and use food
Autotroph
An organism that makes its own food, e.g. green plants.
Heterotroph
An organism that cannot make its own food, and must consume other organisms, e.g. animals and fungi.
Herbivores
Organisms that only eat plants, e.g. cattle, sheep, deer
Carnivores
Organisms that only eat other animals, e.g. dogs, cats, seals.
Omnivores
Organisms that eat both plants and animals, e.g. humans, badgers, bears.
Ingestion
(1) Food is taken in
Digestion
(2) Food is broken down into smaller pieces by mechanical and chemical means.
Absorption
(3) Food enters the blood stream
Assimilation
(4) Biomolecules are sent to carry out their functions in body parts.
Egestion
(5) Removal of unabsorbed matter excretion of faecal matter.
Physical/Mechanical digestion in the mouth
Teeth cut, slice and grind food into smaller pieces. This increases the surface area on which enzymes can work and also makes food easier to swallow.
Chemical digestion in the mouth
The mouth contains salivary amylase, found in saliva, secreted by glands under the tongue, in cheeks, and back of jaw. Saliva helps to soften the food, and amylase digests starch into maltose. Mouth pH is typically 7.
Canine teeth
Sharp pointed teeth for cutting and tearing. 4
Molars
Back teeth for grinding and mashing food. 12
Premolars
Teeth at the side for crushing and grinding food. 8
Incisors
Front teeth for cutting and chopping food. 8
Dental formula
I 2/2 C1/1 Pm 2/2 M3/3
