l'
A Hodel of the Process of Photosynthesis
Plants are called producers because they use sunlight energy to make food by
the process of photosynthesis.
.1
:!
Procedure
:1.. Hake a photosynthesis model using colored paper clips by following these
instructions:
Separate the paper clips by color. The bag contains:
• 6 large blue paper clips (carbon)
o 12 large yellow paper clips (hydrogen)
° 18 large green paper clips (oxygen)
2. Read the paragraphs below and follow the instructions to build a model of
photosynthesis. Answer the questions that follow each step.
Plants are called producers because they use sunlight energy to make food by
photosynthesis. Plant cells contain green chloroplasts that can be seen using a
microscope. Chloroplasts get their green color from chlorophyll, which is able to
absorb sunlight energy and use it to build chemical energy in a food called glucose,
The chemical equation for photosynthesis is:
6C02 + 6H20 -9 C6H1206 + 602
carbon dioxide + water
yields
glucose
+ oxygen
Describe how light is trapped for the process of photosynthesis,
Carbon dioxide is a gas in the air and mustbe present as a reactant or raw material for
photosynthesis to occur. It seems unusual that a gas from the air can change into food!
The chemical formula for carbon dioxide is CO2, which means it contains one carbon
atom and two oxygen atoms joined together.
TAKS Preparation Booklet
Grade 7 Science
© Permission granted to copy student pages for purchaser's class,
94
)
I
b
Make a model of CO2 molecules, using one blue and two green paper clips from the
bag. Look at the chemical equation for photosynthesis. The coefficient in front of
CO2 is six. This means there are six molecules of CO2. How many more COÿ
molecules should be made? How many of each colored paper clips will you need
.
from the bag?
Plants also need water as a reactant for photosynthesis. The chemical formula for
water is HÿO. There are two hydrogen atoms and one oxygen atom present in one
H20 molecule, lVlake a model of H20 using one green and two yellow paper clips
1
from the bag.
b
Look at the chemical equation for photosynthesis. The number coefficient
in front of H20 in the equation is six which means that there are six water molecules.
.
How many of each color of paper clips will you need from the bag?
b
b
.
Look at the right side"of the photosynthesis equation to see the products or the
result of the reaction. The chemical formula for glucose is C6HlzO0. Using the H20
and COÿ models, are there enough paper clips to build glucose?
b
b
1
Build a glucose molecule by taking apart the HÿO and COs models and combining
them in a new way to form glucose. How many glucose models are formed?
How many oxygen paper clips remain after the production of glucose? Oxygen does
not usually exist as a single atom, so each of the leftover green paper clips bonds
with another oxygen atom. How many 0z molecules remain?
b
Grade 7 Science
TAKS Preparation Booklet
b
@ Permission granted to copy student pages for purchaser's class,
95
• ,::::@
' i'i ÿJi
10, Use the photosynthesis equation to help you complete the T-chart to show the
number of atoms of each element on each side of the equation,
4
, 6C02 + 6H20 ÿ C6H120ÿ + 602
I
Reactants of raw materials
Products
Atoms of Each Element
Atoms of Each Element
q
C
C
H
H
0
0
11. Did you have any paper clips left over?
4
Were you lacldng any paper clips?
What does this tell you about a chemical reaction?
12. Summarize the photosynthesis equation by filling in the blanks in the paragraph
below.
4
Photosynthesis begins when
i< r:antured
by chloroplasts in plant cells. Other raw materials needed for
photosynthesis to begin are
from the air and
., which is transported from the roots to the
leaves by stems. As a result of photosynthesis,
formed and
is
is given off.
TAKS Preparation Booklet
Grade 7 Science
© Permission granted to copy student pages for purchaser's class,
96
13. Label the diagram by filling in the squares next to arrows. Use the word bank provided.
Word Bank
oxygen given off
carbon dioxide
water
light energy
glucose formed
Grade 7 Science
TAKS Preparation Booklet
© Permission granted to copy student pages for purchaser's class,
97