作者:yoshe watson 17 年以前
541
YOSHE-Biology - Animal Survival-the need for food
Biology - Animal Survival(the need for food)
chemical structure of food types
proteins
basic units they are built from-amino acids
elements present-carbon, oxygen, hydrogen, nitrogen
fats
basic units they are built from-fatty acids and glycerol
carbohydrates
basic units they are built from-glucose molecules
elements present-carbon, oxygen, hydrogen
chemical tests
for starch
2/ solution will turn blue/black if starch is present
1/ add 2 drops of brown iodine solution to food solution
for glucose
3/ if glucose is present, an orange precipitate will form
2/ heat in a water bath until it boils
1/ add a few drops of blue benedicts solution to food solution
main chemicals in foods
fats-store energy, insulation, make cell membranes
proteins-growth and repair
carbohydrates eg sugar and starch-provide energy
how organisms obtain their food
animals-eat plants or other animals
plants-make their own food by photosynthesis
why we need food-a source of raw materials for growth and as a source of energy.