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Cells and Systems 6-8 / Week 09 / Nature Day
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Week 09 · Food Becomes You

Nature Day

Nature Day: Every meal starts with a leaf
// Molecules broken apart and put back together
⏱ about 20 min

Nature Day: Every Meal Starts with a Leaf

Saturday morning the crew walks past a garden on the way to the park. Rocket is still thinking about calories.

"Where does the energy in a carrot come from?" he asks. "Carrots do not eat."

Raven points at the leafy tops. "Sunlight. The leaves made sugar in week 8. The root stores it."

"And an egg?" Rocket says. Nova hovers over a hedge where a bird is pecking at seeds. "What do you notice?"

"The bird eats seeds. Seeds come from plants. So the egg traces back to a leaf too." Rocket grins.

Raven nods. "Every meal starts with a leaf. Let us go find some."

  1. Food is made of large molecules: carbohydrates, proteins and fats.
  2. Digestion breaks them into small pieces, such as glucose and amino acids, by chewing and by chemical reactions.
  3. The body links amino acids into its own proteins to build and repair cells.
  4. Cells break glucose down with oxygen to release energy, giving off carbon dioxide and water.
  5. Atoms are conserved. Food molecules are rearranged, never lost.
◇ FAMILY FOOD TRAIL
Take a walk past a garden, a park or a farm stand. Each person names one food they ate this week.
Trace each food backward together. What plant or animal did it come from? What did that animal eat?
Keep going until you reach a green leaf that used sunlight. Count the steps for each food.
Talk it over. Which food had the shortest trail? Which had the longest?
For a grown-up
The textbook Concepts of Biology explains that every food traces back to organisms that carry out photosynthesis.
Even when the food is an animal, that animal was fed plant-based foods, so the trail always ends at a plant.
Nothing is picked or tasted on the walk. Hands are washed when you get home.
Safety first
Look at plants and animals from where you stand. Never touch an unknown plant or berry.
Nothing from the walk goes in your mouth.
Wash your hands when you get home.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
A plant makes its own sugar from sunlight, carbon dioxide and water. What is a plant called?
Humans must get energy and carbon from food. What are humans called?
Nature Day checkTrue or false?
Every food a person eats traces back to photosynthesis.?
Animals can make sugar from sunlight the way plants do.?
The energy in sugar was first captured from sunlight by a plant.?
WHY THIS EXERCISEThe energy you release from glucose today was sunlight on a leaf first.
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