It has long been known that when exposed to light under
suitable conditions of temperature and moisture, the green parts use carbon
dioxide from the atmosphere and relecase oxygen to it. These exchanges are the opposite
o these that occur in respiration. The process is called photosynthesis. In photosynthesis,
carbohydrates are synthesized from carbon dioxide and water by the chloroplasts
of plant cells in the presence of light. In most plants, the water used in photosynthesis
is absorbed from the soil by the roots and translocated through the xylem of
the root and stem to the leaves. Except for the usually small percentage used
in respiration, the oxygen released in the process diffuses out of the leaf
into the atmosphere through the stomates. Oxygen is the product of the
reaction. For each molecule of carbon dioxide used, one molecule of oxygen is released.
A summary chemical equation for photosynthesis is:
6CO₂ +6H₂O - C₆H₁₂
O6 +₆O₂ →
As a result of this process, radiant energy from the sun is
stored as chemical energy. In turn, the chemical energy is used to decompose
carbon dioxide and water. The products of their decomposition are recombined into
a new compound, which is successively built up into more and more complex substances.
After many intermediate steps, sugar is produced. At the same time, a balance
of gases is preserved in the atmosphere.
7.
Which title best expresses the ideas in this passage?
a.
A chemical Equation
b.
The process of photosynthesis
c.
The parts of Vascular plants
d.
The production of sugar
8.
In photosynthesis water
a.
Must be present
b.
Is produced in carbohydrates
c.
Is stored as chemical energy
d.
Interrupts the chemical reaction
9.
Which process is the opposite of photosynthesis?
a.
Decomposition
b.
Synthesization
c.
Diffusion
d.
Respiration
10.
The combination of carbon dioxide and water to
form sugar results in an excess fo
a.
Water
b.
Oxygen
c.
Carbon
d.
chlorophyII
11.
the word “stored” in line 13 is closest in
meaning to
a.
retained
b.
converted
c.
discovered
d.
specified
12.
in photosynthesis, energy form the sun is
a.
changed to chemical energy
b.
conducted from the xylem to the leaves of green
plants
c.
not necessary to the process
d.
released one to one for each
molecule of carbon dioxide used
13.
the word “their “ in line 15 refers to
a.
radiant energy and chemical energy
b.
carbon dioxide and water
c.
products
d.
complex substances
14.
the word “
successively” in line 15 is closed in meaning to
a.
With effort
b.
In a sequence
c.
Slowly
d.
Carefully
15.
Besides the manufacture of food for plants, what
is another benefit of photosynthesis?
a.
It produces solar energy
b.
It diffuses additional carbon dioxide into the
air it maintains a balance of gases in the atmosphere
c.
It removes harmful gases from the air
16.
Which of the following is NOT true of the oxygen
used in photosynthesis?
a.
Oxygen is absorbed by the roots.
b.
Oxygen is the product of photosynthesis
c.
Oxygen is the used in respiration
d.
Oxygen is released into the atmosphere through
the leaves
Answer:
7.
A
8.
C
9.
B
10.
A
11.
A
12.
C
13.
A
14.
A
15.
D
16.
B
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