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) Any source of organic matter will be a source of food for some form of heterotroph Examples?

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 (~ y.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

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

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

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

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

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

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

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

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)

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

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

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

Digestion systems Specialised parts of the digestive system vary in different animals What adaptations do foregut fermenters have? What adaptations do hindgut fermenters 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?

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

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