Download Grading the Explanations Tools for Plant Photosynthesis

Name: _________________________________ Class: _______________________________ Date: _______________
Grading the Explanations Tools for Plant Photosynthesis
This grading worksheet does not have an Activity number in the title because it can be used to grade all
Explanation Tools for photosynthesis in this unit.
This worksheet has “grading” in the title because at this point, students can be held accountable for correct
answers. Level 4 (correct) responses to the questions are in blue bold italics below. There are also
comments about common Level 2 and Level 3 responses to help you with grading and making decisions about
what to emphasize in future lessons.
Plants are made of cells that need small organic molecules to survive and grow. But unlike animals and
decomposers, they can make those organic molecules themselves. Answer the Three Questions to explain
how a plant makes small organic molecules for its cells.
The Movement Question: Zooming in to trace matter
1. Plant: Draw arrows that show how molecules with
carbon atoms move into and through the plant so that
a cell in the root gets the food it needs to grow larger
and divide. Label the arrows with the names of
molecules the carbon atoms are in.
Level 4: Students will draw arrows showing CO2
entering the plant through the leaves, then
glucose (or sucrose) molecules moving from
leaves to roots. Level 2 responses may draw carbon
entering the roots from the soil.
2. Cell: Draw arrows that show how carbon moves into,
and through a cell in the plant’s leaf that makes the
food. Label the arrows with the names of molecules
the carbon atoms are in.
Level 4: Students will draw arrows showing CO2
entering the cell, then glucose molecules moving
from the cell; they may also show carbon being
stored as starch.
3. What is the name of the process that makes organic
molecules in the leaf cells? Photosynthesis
The Carbon Question: How atoms are rearranged into new molecules
What molecules are carbon atoms in before the
What molecules are carbon atoms in after the
chemical change?
chemical change?
Carbon dioxide
Glucose
Chemical
Change
What other molecules are needed?
Water
What other molecules are produced?
Write the chemical equation for this change:
Oxygen
6CO2 + 6H2O -> C6H12O6 + 6O2
The Energy Question: How energy is transformed
What forms of energy are needed for this chemical
What forms of energy are produced by this chemical
change?
change?
Light energy
Chemical energy, heat energy
Energy
Transformation
Where does the energy come from?
Where does the energy go or stay after the
Plants Unit, Activity 3.2
Carbon: Transformations in Matter and Energy
Environmental Literacy Project
Michigan State University
The sun
change?
Chemical energy remains in the C-H and C-C
bonds of glucose; heat energy is released into the
environment.
Remember: Atoms last forever (so you can arrange atoms into new molecules, but can’t add or subtract atoms).
Energy lasts forever (so you can change forms of energy, but energy units can’t appear or go away).
Use the process tool to help guide your written explanation. Answer all Three Questions in your explanation.
Question: How does a plant get food to a cell in its roots? (Answer on the back)
Level 4 responses should contain answers to all Three Questions. Plant leaves conduct
photosynthesis, which uses energy from the sun to fix CO2 from the air into an organic molecule,
glucose. This process also requires H2O. Light energy from the sun is converted into chemical energy
that is stored in the C-C and C-H bonds of glucose. Glucose, a monomer, can be combined with other
monomers to make the polymer sucrose, which is transported through the phloem stream to the roots.
In the roots, the sucrose can be metabolized for biosynthesis, or converted into starch (a larger
polymer) and stored until it is needed.
Level 2 and 3 responses may describe the reactants and products of photosynthesis without understanding
how those molecules interact or are converted from one to the other. They may also explain that sunlight
energy is directly converted into food for the plant. Level 2 responses may suggest food for root cells comes
from materials in the soil.
Unit Title, Lesson X, Activity Y
Carbon: Transformations in Matter and Energy
Environmental Literacy Project
2
Michigan State University