1. Lesson 2.3: Materials Plants Are Made Of

2. Large Scale: Farm field
Benchmark Scale
Power of Ten
Decimal Style
Large scale
Larger
Larger 100,000 10,000 1,000
Macroscopic
meter
Microscopic
Atomic-molecular
Smaller
Smaller
Glucose
Starch
Show students Slides 2-6 to zoom from the large scale down to the microscopic scale in plants.
Slide 2: Large Scale
This slide uses the Powers of Ten poster to look at plants from a Farm perspective, or 103 meters.
Scale: 10-6 meters = meters
Scale: 10-7 meters = meters
Scale: 10-9 meters = meters
Scale: 10-5 meters = meters
Scale: 10-8 meters = meters
Scale: 10-3 meters = meters
Scale: 102 meters = 100 meters
Scale: 103 meters = 1000 meters
Scale: 101 meters = 10 meters
Scale: 100 meters = 1 meters
Scale: 10-2 meters = 0.01 meters
Scale: 10-1 meters = 0.1 meters
Scale: 10-4 meters = meters

3. What are plants made of?
We can find out what materials plants made of by reading nutrition labels for plant foods.
We will use labels with a serving size of 100 g.
This means that 1 g = 1% of the materials in the food
Slide 7 introduces nutrition labels as a way to learn about the molecules that plants are made of.
Notice that all the nutrition labels used in this lesson have the same serving size: 100 grams. This makes it easy to compare the composition of different plant foods.
The inedible parts of plants differ from plant foods mostly in that they have much more fiber (consisting of cellulose, hemicellulose, and lignin).

4. What are plants made of? CARBOHYDRATES
fiber
glucose
Slides 8 and 9 introduce carbohydrates as a key part of plants.
Carbohydrates are organic molecules with C-C and C-H bonds.
Starches and materials making up plant fiber such as cellulose are polymers made from many sugar molecules (monomers) bonded together.
Human digestive enzymes can break the bonds in starch molecules, but not in cellulose molecules.
(NOTE: Actual starch and cellulose molecules have hundreds or thousands of glucose molecules linked together.)
What atoms are carbohydrates made of?
starch

5. An Example of a Plant Root: Carrots
Total carbohydrate = starch + sugar + fiber (such as cellulose)
How much starch is in 100 grams of carrots?
Slides 8 and 9 introduce carbohydrates as a key part of plants.
Carbohydrates are organic molecules with C-C and C-H bonds.
Starches and materials making up plant fiber such as cellulose are polymers made from many sugar molecules (monomers) bonded together.
Human digestive enzymes can break the bonds in starch molecules, but not in cellulose molecules.
(NOTE: Actual starch and cellulose molecules have hundreds or thousands of glucose molecules linked together.)

6. What are plants made of? FATS
What atoms are fats made of?
Slides 10 and 11 introduce fats as a key part of plants.
Fats are organic molecules with C-C and C-H bonds.
Most fats have three fatty acids bonded to a three-carbon glycerol molecule.
(NOTE: The fatty acids in most plant fats have longer carbon chains—typically carbon atoms. Unsaturated fatty acids have a C=C double bond somewhere in the carbon chain.).
1 glycerol
3 fatty acids
Fat molecule

7. Fat in Peanuts (Plant Seeds)
How much fat is in 100 grams of peanuts?
Slides 10 and 11 introduce fats as a key part of plants.
Fats are organic molecules with C-C and C-H bonds.
Most fats have three fatty acids bonded to a three-carbon glycerol molecule.
(NOTE: The fatty acids in most plant fats have longer carbon chains—typically carbon atoms. Unsaturated fatty acids have a C=C double bond somewhere in the carbon chain.).

8. What are plants made of? PROTEIN
Two of the Amino Acids
What atoms are proteins made of?

9. Protein in Carrots
How much protein is in 100 grams of carrots?

10. Organic Molecules in Plants
CARBOHYDRATES:
GLUCOSE
FATS
STARCH
Slide 16 summarizes the main organic molecules in plants
All of these molecules have C-C and C-H bonds, which store chemical energy.
All of these molecules are made of just 4 kinds of atoms: C, H, O, and N.
(NOTE: Plants also have organic molecules with a few other kinds of atoms, such as sulfur and phosphorous.)
What atoms are organic molecules in plants made of?
PROTEINS

11. Minerals in Plants
Plants also contain minerals that are used for plant functions. These minerals have different kinds of atoms, including:
Nitrogen
Phosphorous
Calcium
Sodium
Slides 15 and 16 introduce minerals found in plants.
Minerals are inorganic molecules that do NOT have C-C or C-H bonds. Therefore they do not provide stored chemical energy.
Minerals and other organic molecules such as vitamins and cholesterol make up a small part of plants’ mass—less than 1%.

12. Other Molecules in Plants
Vitamins, minerals, and cholesterol make up less than 1% of plants (less than 1 gram out of 100 grams).
Slides 15 and 16 introduce minerals found in plants.
Minerals are inorganic molecules that do NOT have C-C or C-H bonds. Therefore they do not provide stored chemical energy.
Minerals and other organic molecules such as vitamins and cholesterol make up a small part of plants’ mass—less than 1%.

13. Water in Plants
Besides organic materials or biomass (fats, proteins, and carbohydrates) plants are made up mostly of water.
About how much water is in 100 grams of carrots?
Slides 17 and 18 introduce water in plants.
Water is not listed on nutrition labels, but it makes up more than 50% of the mass of most plant roots, stems, and leaves.
Students can find out how much water is in a plant food by subtracting the weight of the organic materials from the total weight (always 100 grams in these labels.)

14. How Much Water Is in Carrots?
Organic materials in carrots
Protein: 1% (1 g out of 100 g)
Carbohydrates: 10%
Fat: 0%
Cholesterol and vitamins: less than 1%
Inorganic materials in carrots
Minerals (sodium, iron): less than 1%
What’s left?
WATER: about 89%
Slides 17 and 18 introduce water in plants.
Water is not listed on nutrition labels, but it makes up more than 50% of the mass of most plant roots, stems, and leaves.
Students can find out how much water is in a plant food by subtracting the weight of the organic materials from the total weight (always 100 grams in these labels.)

15. Chemical Energy in a Plant Root: Carrots
Organic molecules in plants have chemical energy in their high-energy bonds (C-C and C-H).
Calories measure how much usable energy is stored in the organic molecules of a plant.
Slide 19 introduces stored chemical energy in plants.
The organic materials in plants have energy stored in their C-C and C-H bonds.
The amount of chemical energy is the number of calories on the nutrition labels.

16. Where are atoms moving from?
Plant Growth: The Movement Question
Where are atoms moving from?
Carbon dioxide in the air enters plants through their leaves
Water in the soil enters plants through their roots
Minerals enter plants dissolved in water through their roots
Slide 20 addresses the Movement Question.
It shows how the atoms that plants are made of enter the plants: Carbon dioxide enters plant leaves from the air and water and minerals enter plants through their roots.

17. Plant Growth: The Carbon and Energy Questions
Carbon: Where do the atoms that make up carbohydrates, fats, and proteins come from?
Carbon
Oxygen
Hydrogen
Nitrogen
Energy: Where does the chemical energy in the high-energy (C-C and C-H) bonds of carbohydrates, fats, and proteins come from?

18. Plant Growth: The Carbon and Energy Questions
Carbon: What materials do the atoms that make up carbohydrates, fats, and proteins come from?
Carbon: from CO2 to glucose made in photosynthesis
Oxygen: from CO2 to glucose made in photosynthesis
Hydrogen: from H2O to glucose made in photosynthesis
Nitrogen: from soil minerals
Energy: Where does the chemical energy in the high-energy (C-C and C-H) bonds of carbohydrates, fats, and proteins come from?
From light to C-C and C-H bonds in glucose made in photosynthesis