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Photosynthesis

Last updated about 5 years ago
10 questions

Why do plants need sunlight?

Plants are an essential part of most ecosystems on Earth. As producers, they are the base of most food chains. Countless insects, animals, and people rely on green plants as a food source. When we consume green plants, or animals that have eaten green plants, we take in the energy stored in those plants so that we can use it ourselves.
2

Who relies on green plants for their food?

So the question is, where do green plants get the energy they store in their tissues—the same energy that is passed on to other organisms that eat the plants? Plants don’t have mouths to eat food. They can’t chase prey like a wolf or a lion can. They are literally rooted to the ground.

The solution is simple. Plants get their energy from the Sun. Like so many simple solutions, however, this one involves a more complex explanation. In this case, the process begins inside a tiny plant cell and grows from there.
1

Where do plants get their energy?

Inside many plant cells, especially those in a plant’s leaves, is a substance known as chlorophyll. Chlorophyll is green, and it is responsible for giving plants their color. Chlorophyll is stored inside organelles called chloroplasts. When radiant energy from the Sun hits the surface of a plant’s leaves, the chlorophyll absorbs some of the energy and converts it into a type of chemical energy in the form of sugar. This process is called photosynthesis.
1

Why are plants green?

1

Chrlorophyll is stored in the Cytoplasm

Through chemical reactions, photosynthesis uses the Sun’s radiant energy to convert water and carbon dioxide into oxygen and glucose. Glucose is a type of simple sugar that living things use as food. Plants take in water and carbon dioxide from their environments. For example, a plant growing in a prairie will obtain carbon dioxide from the air around it. The plant will then obtain water from rainfall, whether the rain water soaks into the soil and is absorbed by roots or is caught on the plant’s leaves.
2

What two things does a plant need in order to make glucose?

The chemical reactions that make up photosynthesis are divided into two phases. Light is necessary for the first phase of photosynthesis, which is simply referred to as the "light reaction". This is when sunlight is absorbed and used to make adenosine triphosphate (ATP), a chemical compound that stores energy. This reaction releases oxygen into the air that people and animals need to live.
1

What's the name of the chemical compound plants use to store energy?

1

What important gas is released during the "light reaction" of photosynthesis?

The next part of photosynthesis does not need light, and takes place in a part of the chloroplast called the stroma. The "dark reaction" is when the chloroplast uses carbon dioxide and the ATP that was made during the light reaction to produce glucose.
1

What is produced during the "dark reaction" phase of photosynthesis?

Plants need very basic things to perform photosynthesis—light, water, carbon dioxide, and small amounts of other substances, such as phosphorus. What happens to a plant if one of these is not available? You might have noticed that when it doesn’t rain for a long time, the grass and other plants in people’s yards become yellow. That is because, without water, photosynthesis cannot take place.

The same thing is true of light. Without light, plants cannot perform photosynthesis, and their green color fades. If you have ever put a plant into a dark place, you might have observed this effect.
5

If there's a plant that you REALLY don't like, what is one thing you could do to get ride of the plant? Use the passage above to explain your answer. (Write at least three complete sentences!)

BONUS: 2 points possible!
0

Why do leaves change color in the fall?