ANTICIPATION GUIDE: PHOTOSYNTHESIS
Before each of the statements below, write agree / disagree in the blank space.
1. __________ Plants need water to make sugars.
2. __________ Plants do photosynthesis in order to feed us.
3. __________ The entire process of Photosynthesis occurs only in the light.
4. __________ Plants use more green light than any other wavelength of light.
5. __________ Most of the oxygen on Earth comes from the rain forests.
6. __________ The purpose of photosynthesis is to produce glucose.
7. __________ The purpose of photosynthesis is to produce Oxygen.
8. __________ Plants use the oxygen that they produce.
9. __________ At night plants respire (‘breath’) more rapidly.
10. _________ All organisms on earth depend on photosynthesis for energy.
11. _________ Carnivorous plants do not need to do photosynthesis.
12. _________ Plants get all their food from the soil.
Choose two statements you disagree with and explain your answer:
____________________________________________________________________________________
______________________________________________________
Count the atom totals on each side of the equation
C
C
O
O
H
H
Life’s greatest inventions
5. Photosynthesis
FEW innovations have had such profound consequences for life as the ability to capture energy from sunlight.
Photosynthesis has literally altered the planet’s face, transforming the atmosphere and cocooning Earth in a
protective shield against lethal radiation.
Without photosynthesis, there would be little oxygen in the atmosphere, and no plants or animals – just microbes
scratching a meagre existence from a primordial soup of minerals and carbon dioxide. It freed life from these
constraints and the oxygen it generated set the stage for the emergence of complex life.
Before photosynthesis, life consisted of single-celled microbes whose sources of energy were chemicals such as
sulphur, iron and methane. Then, around 3.5 billion years ago, or perhaps earlier, a group of microbes developed the
ability to capture energy from sunlight to help make the carbohydrates they needed for growth and fuel. It is unclear
how they achieved this feat, but genetic studies suggest that the light-harvesting apparatus evolved from a protein
with the job of transferring energy between molecules. Photosynthesis had arrived.
But this early version of the process didn’t make oxygen. It used hydrogen sulphide and carbon dioxide as its starting
ingredients, generating carbohydrates and sulphur as end products. Some time later – just when is uncertain – a new
type of photosynthesis evolved that used a different resource, water, generating oxygen as a by-product.
In those early days, oxygen was poisonous to life. But it built up in the atmosphere until some microbes evolved
mechanisms to tolerate it, and eventually hit on ways to use it as an energy source. That was a pretty important
discovery too: using oxygen to burn carbohydrates for energy is 18 times as efficient as doing it without oxygen.
Life on Earth became high-powered at this point, setting the scene for the development of complex, multicellular life
forms – including plants, which “borrowed” their photosynthetic apparatus from photosynthetic bacteria called
cyanobacteria. Today, directly or indirectly, photosynthesis produces virtually all of the energy used by life on Earth.
As well as providing an efficient means to burn fuel, oxygen made by photosynthesis helps protect life. Earth is
under constant bombardment from lethal UV radiation streaming out from the sun. A by-product of our oxygenated
atmosphere is a layer of ozone extending 20 to 60 kilometers above Earth’s surface, which filters out most of the
harmful UV. This protective umbrella allowed life to escape from the sanctuary of the ocean and colonize dry land.
“It has altered the atmosphere and cocooned Earth in a protective shield”
Now, virtually every biochemical process on the planet is ultimately dependent on an input of solar energy. Take a
deep breath and thank those primordial oxygen-hating microbes for their biochemical inventiveness.
Alison George.
1. What does the following quote mean? Explain.
“It has altered the atmosphere and cocooned Earth in a protective shield”
2. Why would using oxygen vs no oxygen be more beneficial to organisms that could tolerate it?
3. How might life be different if oxygen levels never increased in the atmosphere?(Think about how life
evolved when oxygen was present).
4. Research the following:
a. What variables affect the rate of photosynthesis?
b. Fill in the table for inputs of photosynthesis
Inputs of photosynthesis
How it enters the plant(include
plant part if possible)
Why the plant needs it
c. Fill in the table for outputs of photosynthesis
Outputs of photosynthesis
How it leaves the plant or where it
remains
Why the plant needs it
5. What happens during the light reactions?
6. What happens during the dark reaction (Calvin cycle).
7. What is ATP needed for in photosynthesis?
Research: You will interview a plant because they are considered one of life’s top inventions! Top 5 (read
this) You have to create questions and answers you would ask this plant. If only they could talk. Research
and find your answers online.
Must include the following: