Download Photosynthesis

Photosynthesis
Photosynthesis is a process unique to the plant world. Photo means “light” and synthesis means
“putting together.” Photosynthesis, therefore, means “putting together with light.” Through this
process, plants are able to make their own food. Use the terms in the word list to complete each
sentence.
photosynthesis
consumers
chloroplasts
producers
oxygen
carbon dioxide
glucose
carbohydrates
sunlight
cellulose
water
chlorophyll
leaves
1. Water, carbon dioxide, and ___________________ are the three ingredients needed for
photosynthesis to occur.
2. Through photosynthesis, plants convert these ingredients into ___________, a food used
by the plant.
3. __________________ is the material in green plant cells that traps energy from the sun.
4. The plant takes in a gas called ______________ from the air.
5. Chlorophyll is found in the ___________________, structures within the cell where
photosynthesis will take place.
6. _________________ is a material the plant takes up through its roots and stems.
7. During photosynthesis, ________________ is a waste product released by the plant into
the air.
8. Plants produce more glucose than they need. The excess glucose is stored by the plant
as ______________ or starches.
9. Plants also change glucose into ______________, the structural material used in their cell
walls.
10. While chlorophyll is found in most aboveground parts of green plants, most
photosynthesis
takes place in a plant’s _________.
11. In many regions, there is not enough sunlight or water during winter for ______________
to occur.
12. Most plants are also called ______________ because they are able to produce their own
food.
13. Most animals are called ______________ because they obtain energy from other plants
or animals.
Green Plants Make Food
All animals must eat plants, or other animals that eat plants, to live. Green plants combine
energy from light with water and carbon dioxide to make food by the process of
photosynthesis. Carbohydrates, fats, proteins, minerals, vitamins, and water are produced by
green plants. To make carbohydrates, plants need materials that contain carbon, hydrogen,
and oxygen. Water, a compound of hydrogen and oxygen, comes from the soil and flows into
the roots. Carbon dioxide is found in the air and enters the plant through its leaves. Green
plants can change carbohydrates into fats. Proteins contain the elements that are in
carbohydrates and fats; but they also contain nitrogen, usually sulfur, and sometimes
phosphorus. Green plants get these and other elements from the soil.
True or False
1. Photosynthesis is the process by which green plants make food.
2. Carbohydrates, fats, and proteins are elements.
3. Most of our food comes from green plants or from animals that eat these plants.
4. Sugar and starch are carbohydrates.
5. The energy needed for photosynthesis comes from water.
6. All green plants make food in about the same way.
7. All green plants used for food contain the exact same nutrients.
8. Plants need carbon dioxide to make food.
9. Green plants can change carbohydrates into fats.
10. One of the gases in air is carbon dioxide.
11. Water is a compound of hydrogen and oxygen.
12. Carbon dioxide enters a plant through its roots.
13. Plants take in all the water they need through their leaves.
14. All proteins contain the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and
phosphorus.
15. Carbohydrates are not made by green plants.
16. Plants get nitrogen, sulfur, phosphorus, and other elements from the soil.
17. Oxygen is another product of photosynthesis.
18. Photosynthesis is a simple process.
Chlorophyll and the color of light
A pigment is a colored chemical compound that absorbs light. You can think of a pigment as a
kind of sponge that absorbs light of all colors except the ones that it transmits and reflects.
The colors that you see are the colors of light that the pigment reflects. The bar graph below
shows the percentages of light of different colors that are reflected by the plant pigment
chlorophyll.
1. Which color of light does chlorophyll reflect most (will this be the highest or the lowest bar)?
About what percent of light of this color does chlorophyll reflect?
2. Which color of light does chlorophyll
absorb the most (will this be the highest or
the lowest bar)? About what percent of light
does the chlorophyll absorb?
3. The colors that are reflected less than
50% contribute very little to what the eye
sees. Which colors does your eye respond to
when you look at a “green” leaf?
4. Which colors of light do you not see when
you look at a “green” leaf?
5. Explain in your own words how chlorophyll
makes a leaf look green.