Biology - Animal Survival(the need for food)

why we need food-a source of raw materials for growth and as a source of energy.

how organisms obtain their food

plants-make their own food by photosynthesis

animals-eat plants or other animals

main chemicals in foods

carbohydrates eg sugar and starch-provide energy

proteins-growth and repair

fats-store energy, insulation, make cell membranes

chemical tests

for glucose

1/ add a few drops of blue benedicts solution to food solution

2/ heat in a water bath until it boils

3/ if glucose is present, an orange precipitate will form

for starch

1/ add 2 drops of brown iodine solution to food solution

2/ solution will turn blue/black if starch is present

chemical structure of food types

carbohydrates

elements present-carbon, oxygen, hydrogen

basic units they are built from-glucose molecules

fats

elements present-carbon, oxygen, hydrogen

basic units they are built from-fatty acids and glycerol

proteins

elements present-carbon, oxygen, hydrogen, nitrogen

basic units they are built from-amino acids