2.2 Nutrition in animals

• Modes of nutrition in animals: parasitic, saprophytic, symbiosis and holozoic
• Dentition in animals: homodont and heterodont; carnivorous, herbivorous and omnivorous
• Types of teeth: incisors, canines, premolars and molars, and their structure and functions
• The process of digestion in human beings: ingestion, digestion, absorption, assimilation and egestion

• outline the modes of nutrition in animals
• describe the structure and functions of different types of teeth
• classify animals based on their dentition
• describe the process of digestion in human beings
• appreciate that animals have varied modes of nutrition

“How do different animals feed?”

“How is food digested in the human body?”

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1. Four modes of nutrition
   40 min · 1 practice tasks · quiz
   Holozoic, parasitic, saprophytic and symbiotic: four ways of getting food.
2. Holozoic nutrition
   40 min · 1 practice tasks · quiz
   Take solid food in, break it down inside, use what you can and pass out the rest.
3. Parasitic nutrition
   40 min · 1 practice tasks · quiz
   Living at the expense of a host: the parasite gains and the host loses.
4. Saprophytic nutrition
   40 min · 1 practice tasks · quiz
   Feeding on what is already dead, and returning its nutrients to the soil.
5. Symbiosis
   40 min · 1 practice tasks · quiz
   Two organisms living together with both of them better off.
6. Incisors and canines
   40 min · 1 practice tasks · quiz
   The teeth at the front: chisels for cutting and points for gripping.
7. Premolars and molars
   40 min · 1 practice tasks · quiz
   The teeth at the back: broad ridged surfaces for crushing and grinding.
8. The structure of a tooth
   40 min · 1 practice tasks · quiz
   Crown, neck and root; enamel, dentine, pulp and cement.
9. Homodont and heterodont dentition
   40 min · 1 practice tasks · quiz
   All teeth alike, or four kinds doing four jobs.
10. Carnivore dentition
    40 min · 1 practice tasks · quiz
    Long canines, shearing carnassials and a jaw that only opens and shuts.
11. Herbivore dentition
    40 min · 1 practice tasks · quiz
    A horny pad, a gap where the canines should be, and ridged grinders.
12. Omnivore dentition
    40 min · 1 practice tasks · quiz
    Teeth of every kind, and none of them specialised.
13. Ingestion and the mouth
    40 min · 1 practice tasks · quiz
    Chewing, saliva and the first enzyme: digestion starts before you swallow.
14. Digestion in the stomach and small intestine
    40 min · 1 practice tasks · quiz
    Acid and pepsin, then bile and the pancreatic enzymes finish the job.
15. Absorption and assimilation
    40 min · 1 practice tasks · quiz
    Villi, a huge surface, and what the cells finally do with the food.
16. Egestion, and the whole journey
    40 min · 2 practice tasks · quiz
    The last stage, why it is not excretion, and the sub-strand in one picture.