Energy in food
Why do living things need food
They need to use the energy stored in food for all their activities to carry out life processes
To provide energy
It is released during respiration
How food is digested
Mouth
Stomach
Small intestine
Cells
Food is chewed into small pieces and digested slightly by saliva
Food is further broken down by digestive juices
Food is completely digested to become glucose (a type of sugar)
Glucose+oxygen (respiration)➡️ Energy+carbon dioxide+water
How plants make their own food
The sun gives off light and heat energy
Light energy allows green plants to make food during photosynthesis
Heat energy helps to keep earth and living things warm
Photosynthesis
Plants obtain energy from the sun, however , they cannot make use of the energy from the sun directly. Plants (only with chlorophyll a green pigment in the chloroplast of some plant cells)capture light energy from the sun to make food (in the form of sugar)using carbon dioxide and water, through a process called photosynthesis
Water is absorbed by the roots and transported to the leaves . Carbon dioxide enters the leaves through small openings called stomata
The food (in the form of sugar) can be broken down through a process called respiration, to provide energy that plants can use for their life processes
The oxygen produced during photosynthesis is given out to the surroundings
Excess sugar made during photosynthesis is usually stored in the form of starch in various plant parts
Storage parts
Root
Stem
Flower
Fruit
Carrot
tapioca
sweet potato
Ginger
potato
Broccoli
cauliflower
Mango
apple
orange
papaya
guava
When a part of the plant is growing, it will need more energy. The starch in the storage parts will be converted back into sugar and transported to the part if the plant.
How do animals obtain energy
Animals cannot make their own food. Animals eat plants or other animals to get the energy stored inside these organism for survival
animals satisfy their energy need by eating other living things
Some animals eat only plants.these animals are called plant-eaters. Examples:goats,cows,deer,caterpillars,grasshoppers and rabbits
Animals that eat only other animals are called animal-eaters. Examples:tigers,lions,foxes,snake,Hawks and spiders
Animals that eat both plants and animals are called plant-and-animal eaters. Examples:humans,chicken,monkeys and bear
The energy that plant-eaters obtain from eating plants is passed on to the animal-eaters or plant-and-animal eaters that eat these plant-eaters
Respiration
Respiration is the breakdown of sugar (glucose)with the release of energy in living cells
Why the sun is important to living things on earth
The sun is our primary source of energy. It provides us with heat and light
We need light to see and we need heat for our bodies to function.
Energy from the sun is passed on to plants, and from plants and animals to us when we eat them. All the energy in our food can be traced back to the sun
Without the sun,plants would not be able to photosynthesise and would die. Without photosynthesis, there would be no oxygen to support life on earth, as a result, all animals would die too.