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Chapter 5

Chapter 5. Obtaining energy & nutrients for life. Digestion. Obtaining energy & nutrients for life. What kind of foods are eaten by heterotrophs ?. All forms of life are eaten by heterotrophs (web of life).

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Chapter 5

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  1. Chapter 5 Obtaining energy & nutrients for life Digestion

  2. Obtaining energy & nutrients for life • What kind of foods are eaten by heterotrophs? • All forms of life are eaten by heterotrophs • (web of life) • Any source of organic matter will be a source of food for some form of heterotroph • Examples?

  3. Obtaining energy & nutrients for life • What kind of foods/meals does your family eat? • Has this changed over the years? • What events in human history have changed the human diet? • Fire (~400.000y.a) • Farming (~10,000y.a) • Sea trade & exploration (~500y.a) potato, capsicum, etc • Sugar & refined foods • Migration (changes in Australian diet) • Diets of humans (& animals) change over time

  4. Digestion Digestion makes the energy & organic matter in food available for the cells of your (or another animals) body

  5. Digestion & absorption • What are some of the foods that we eat? • What are the names of the macromolecules that we need from our food? • starch/sugars (polysaccharides) • fats • proteins • vitamins & minerals • Digestion is the process of breaking down our food into these macromolecules

  6. Digestion & absorption • What are the four steps to digestion? • Ingestion of food • Step 1 • Step 2 • Step 3 • Step 4 • Mechanical breakdown of food • Secretion of enzymes onto food • Absorption of food

  7. Step 2:Mechanical breakdown of food • What structures do vertebrate animals use to mechanically break down food? • What are the four types of teeth? • …and their purpose? • Incisors • Canines • Premolars • Molars • cutting • tearing • grinding/tearing • grinding • (modifies from Biology, 4th Ed. Campbell) • Teeth have evolved to suit the diets of different organisms

  8. Digestion & absorption • What were the names of the macromolecules that we get from digesting our food? • starch/sugars (polysaccharides) • fats • proteins • vitamins & minerals • (http://cae2k.com) • Which parts of the digestive system are responsible for digesting/absorbing these molecules?

  9. Digestion & absorption • mechanical breakdown of food • cellulose digestion (ruminants) • protein digestion begins • Stomach: • Small intestine: • fat & protein digestion begins • Large intestine: • cellulose digestion • water reabsorption • (http://cae2k.com) • Which parts of the digestive system are responsible for digesting/absorbing these molecules?

  10. Digestion & absorption • mechanical breakdown of food • cellulose digestion (ruminants) • protein digestion begins • Stomach: • Small intestine: • fat & protein digestion begins • Large intestine: • cellulose digestion • water reabsorption • (http://cae2k.com) • How might the digestive system have changed/evolved differently to sui different diets?

  11. Digestion in herbivores • There are two classifications of herbivores: • foregut fermenters & hindgut fermenters • What adaptations can you see here that each has acquired to their gastrintestinal (GI) tract? • (modifies from Nature Of Biology, Jacaranda)

  12. Carnivores & pollen feeders • What adaptations might their gastrointestinal tracts have? • (modifies from Nature Of Biology, Jacaranda)

  13. Digestion & absorption • Diets of animals have changed over time, this includes humans (The diet of Australians has changed over the last 60 years, and the diet of humans has changed through time). • Animals teeth have evolved to match their diet • Food must be broken down into its macromolecular components (sugar/fat/protein/vitamins & minerals) to be absorbed. This process is known as digestion. • Digestion of food involves mechanical breakdown of food into smaller pieces • Digestion also involves secretion of enzymes that break down food into small molecules for absorption

  14. (modifies from Nature Of Biology, Jacaranda) Cellular respiration What is this process/equation the opposite of? And why is this process necessary?

  15. Digestion systems Specialised parts of the digestive system vary in different animals What adaptations do foregutfermenters have? What adaptations do hindgutfermenters have? What adaptations do carnivores & nectar eaters have? What form of energy is absorbed from organic matter? What form is it converted to that can be utilised by cells? What form is it converted to for use within cells? What is the name of this process when cells make ATP from glucose?

  16. Specialised parts of the digestive system vary in different animals Foregut-fermenters (herbivores) have very large and complex stomachs Herbivores that are hindgut-fermenters have large caecums Nectar eaters have relatively short, simple digestive systems Carnivores have relatively short alimentary canals compared with those of herbivores Chemical energy stored in organic matter is converted to ATP by cellular respiration

  17. Digestion • Homework: • Quick-check questions from p106 & p123 “Nature of Biology 1, 3rd Ed. (Jacaranda). • Digestive system worksheets

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