Rocket unpacks the groceries onto the kitchen table while Raven checks the turned seedling jar.
"It leaned back toward the window," she reports. "In four days. What do you notice, Rocket?"
"The stems follow the light," Rocket says, holding up a loaf of bread. "This does not."
"It did once," Nova says, hovering over the bag. "Bread is made from grain. What is grain?"
Rocket thinks. "Seeds. From a plant. That stood in a field in the sun."
Raven holds up a carrot and a bag of rice. "Light, light, light," she says, tapping each one.
"Every meal starts with light," Rocket says, and puts the apples in the bowl with new respect.
Each cell in your body runs on the chemical energy found mainly in carbohydrate molecules, that is, food.
The majority of these molecules are produced by one process: photosynthesis.
Bread, cereal and pasta come largely from grains, which are the seeds of photosynthetic plants.
Sweet foods and drinks contain sugar, the basic carbohydrate produced directly from photosynthesis.
Animal foods link to photosynthesis too, because the animals were fed plants. Every food traces back to an autotroph catching light.
All organisms that carry out photosynthesis require sunlight. A seedling that leans toward the window is reaching its energy source.
The energy harnessed from photosynthesis enters the living world continuously. It is transferred from one organism to another.
Directly or indirectly, photosynthesis provides most of the energy required by living things on Earth.
Oceanic algae are autotrophs too. They contribute enormous quantities of food and oxygen to the world's food chains.
| Food on the table | Plant it came from | How it links to photosynthesis |
|---|---|---|
| Bread, cereal, pasta | Grain plants | Grains are the seeds of photosynthetic plants |
| Carrot, apple, rice | The plant itself | Built from sugar the plant made |
| Sweet foods and drinks | Sugar-making plants | Sugar is the basic carbohydrate from photosynthesis |
| Animal foods | Plants the animal ate | The animal was fed plants |
| Week review | True or false? |
|---|---|
| Photosynthesis needs sunlight, carbon dioxide and water. | ? |
| Photosynthesis produces sugar and releases oxygen. | ? |
| The carbon in a plant's sugar came from the soil. | ? |
| Chlorophyll is responsible for the green color of plants. | ? |
| Humans are autotrophs. | ? |
A plant builds sugar and stores energy in it. When you eat the plant, your body takes that sugar apart.
Next week you will follow food into the body and find out how it is broken down and rebuilt into you.
Keep watering jars A and B. Keep the dark paper on the leaf until its seventh day.
Strong week, scientist. Tomorrow is Nature Day: a garden look at leaves in the sun and in the shade.