Biology: Photosynthesis and Respiration
How plants make food and how living things release energy
Biology: Photosynthesis and Respiration
How plants make food and how living things release energy
Biology - Grade 4-5
- 1
Plants use sunlight, water, and carbon dioxide to make sugar and oxygen. What is this process called?
The word starts with photo, which means light.
This process is called photosynthesis. During photosynthesis, plants use sunlight to make their own food. - 2
Write the three main things a plant needs for photosynthesis.
A plant needs sunlight, water, and carbon dioxide for photosynthesis. These materials help the plant make sugar for food. - 3
What gas do plants release during photosynthesis that animals need to breathe?
This gas is the same gas people breathe in from the air.
Plants release oxygen during photosynthesis. Animals need oxygen to breathe and release energy from food. - 4
A student covers one leaf on a plant with dark paper and leaves another leaf uncovered. After a day in sunlight, which leaf will make more sugar? Explain why.
Photosynthesis needs light energy from the Sun.
The uncovered leaf will make more sugar because it can receive sunlight. The covered leaf gets little or no light, so it cannot do as much photosynthesis. - 5
Cellular respiration is how living things release energy from sugar. What two things are usually needed for cellular respiration?
Cellular respiration usually needs sugar and oxygen. Cells use them to release energy for the living thing. - 6
Circle the statement that is true: A) Only animals do respiration. B) Plants and animals both do respiration. Explain your choice.
Think about whether plant cells also need energy to grow and live.
Statement B is true because both plants and animals do cellular respiration. Plants make sugar during photosynthesis, but they also use sugar for energy through respiration. - 7
Complete this word equation for photosynthesis: carbon dioxide + water + light energy makes blank + oxygen.
Carbon dioxide + water + light energy makes sugar + oxygen. The sugar stores energy that the plant can use later. - 8
Complete this word equation for respiration: sugar + oxygen makes carbon dioxide + water + blank.
Cells use this to grow, move materials, and stay alive.
Sugar + oxygen makes carbon dioxide + water + energy. Respiration releases energy from sugar for cells to use. - 9
Look at a leaf. Tiny openings on leaves let gases move in and out. What are these openings called, and why are they important?
The tiny openings are called stomata. They are important because carbon dioxide enters the leaf and oxygen can leave through them. - 10
Chlorophyll is a green substance in leaves. What job does chlorophyll do during photosynthesis?
Chlorophyll is one reason many leaves look green.
Chlorophyll captures light energy from the Sun. This light energy helps the plant make sugar during photosynthesis. - 11
During the day, a healthy green plant is doing photosynthesis and respiration. Which process uses carbon dioxide, and which process releases carbon dioxide?
Photosynthesis uses carbon dioxide. Respiration releases carbon dioxide when cells break down sugar for energy. - 12
A plant is kept in a closet for one week and gets water but no light. Predict what may happen to the plant and explain why.
Water alone is not enough for photosynthesis.
The plant may become weak, pale, or stop growing well because it cannot do enough photosynthesis without light. It may use stored sugar but will not be able to make much new food. - 13
Match each process with its main purpose. Photosynthesis: makes sugar or releases energy. Respiration: makes sugar or releases energy.
Photosynthesis makes sugar. Respiration releases energy from sugar so cells can use it. - 14
The diagram shows a simple cycle between plants and animals. Plants give off oxygen. Animals give off carbon dioxide. Explain how this helps both living things.
Plants help animals by giving off oxygen that animals need for respiration. Animals help plants by giving off carbon dioxide that plants use for photosynthesis. - 15
Explain one way photosynthesis and respiration are connected.
Think about the materials made by plants and the materials used by cells.
Photosynthesis and respiration are connected because photosynthesis makes sugar and oxygen, and respiration uses sugar and oxygen to release energy. The products of one process can become materials for the other process.