What is Photosynthesis?
Directions: Setup your composition book for Cornell style notes. Record notes from the passage below, using
the question to help identify important details.
Etymology (or origin) of the Word
To understand photosynthesis, let us first explore the etymology (or origin) word by breaking it down
into three parts: photo-syn-thesis”. The prefix, “photo”, comes from the Greek word “photos”, meaning “light”.
The second part of the word, “syn”, means “together”, and the final part “thesis” is taken from the Greek word,
“tithena”, meaning “put”. So, photosynthesis actually translates to “light together put.” If we rearrange the
words, then we get a translation like “put together with light”. But what does that mean, and who or what is
using light to put things together?
Main
Idea/question
Notes: Use the questions to identify important details
1) What does each part of the word, Photo-syn-thesis, mean
Origin of the word,
Photosynthesis
Photo means ___________, syn means _________, and thesis means ________.
Photosynthesis translates to “________ _____________ _______ _________”.
Photosynthesis by Plants
Plants are a highly diverse group of organisms and include flowering plants, mosses, and trees. Plants
grow, reproduce, and respond to changes in the environment, and therefore are classified as living organisms.
Unlike many organisms, plants do not hunt or consume food. Instead, plants use light from the sun to put
together their food, and this process is called photosynthesis. Photosynthesis is performed by special organelles
inside the plant cell known as chloroplasts. Chloroplasts use the radiant energy (or light) from the sun and two
other ingredients, carbon dioxide gas (CO2) and water (H2O), to make their food. If just one of the three
ingredients– radiant energy, CO2, and H2O – is missing, then the plant will be unable to make food. Yes, there
are some rare and wonderful exceptions like the Venus fly trap or the pitcher plant that both consume insects,
but most plants are not like this.
Main
Idea/question
Notes: Use the questions to identify important details
2) What is the name of the process used by plants to generate their food?
Plants
The process used by plants to make food is ___________________________.
3) Which plant cell organelle inside the plant performs photosynthesis?
The organelle in a plant cell that performs photosynthesis a ________________.
Inputs of
Photosynthesis
4) What is photosynthesis?
Photosynthesis is ____________________________________________________________.
5) What three ingredients or inputs are needed in order for photosynthesis to happen? Write their
name and chemical formula
The three inputs for photosynthesis are ______________________, ___________(____), and
____________ (______)
Products of Photosynthesis
If plants are using radiant energy from the sun, carbon dioxide gas (CO2), and water (H2O) to make
food, then what kind of food are they making? Sugar! Yes, plants depend on carbohydrates (or sugars) for
energy just like you. There are many kinds of sugars, but photosynthesis is used to generate one, glucose.
Glucose is a ring-shaped, organic compound with the chemical formula C6H12O6. Remember that organic
compounds must contain carbon and hydrogen atoms. The carbon atoms used to construct glucose come from
the carbon atoms in carbon dioxide gas (CO2).
Why do plants need sunlight or radiant energy to make glucose? Like all living organisms, plants need
energy to survive. Radiant energy cannot be used by the plants to perform life sustaining functions. Therefore,
plants must transform or change the radiant energy into form of energy they can use. Photosynthesis transforms
the radiant energy from the sun into chemical energy. The plant collects the radiant energy and uses is to create
the chemical bonds that hold together the carbon (C), hydrogen (H), and oxygen (O) atoms in glucose (Figure
1). When the plant needs energy, it will break the bonds to release the energy.
Glucose (C6H12O6) is not the only product of photosynthesis, and that is a good thing for animals like us.
Photosynthesis also generates oxygen gas (O2), which almost all life needs to survive, even plants. Although
plants need oxygen like us, they produce more than what they need. So, we get the leftovers.
Figure 1: Transformation of Energy during Photosynthesis
Sun
1. Radiant Energy given
off by sun
Main
Idea/question
2. Plant transforms energy
during photosynthesis
3. Chemical energy stored
in glucose
Notes: Use the questions to identify important details
6) What are the two products or outputs of photosynthesis? Writ their name and chemical formula.
Products of
Photosynthesis
The two products of photosynthesis are __________(_____), and ____________(__________)
7) What does it mean to say that glucose is a carbohydrate and an organic compound?
Glucose is a carbohydrate, which means it is a ___________, and it is an organic compound
because it contains ______________ and ____________ atoms.
8) Describe the energy transformation performed during photosynthesis
Plants transform _____________________________________________________________
Summary: Explain why the translation of photosynthesis, “put together with light”, is a good name for the
process of plants making food.