Science 8th grade
UNIT 1: Plants 1.1 Photosynthesis
Science 8th grade
UNIT 1: Plants 1.1 Photosynthesis
Where do you get your energy from?
Your energy comes from the food that you eat. Energy is passed from one organism to another along a food chain.
Every food chain begins with a plant. Plants capture energy from light, and transfer some of the energy into the food that they make. When we cat food, we get some of that energy.
In this unit, we will look at how plants use energy from light to make food.
Making with light
'Photo' means to do with light. 'Synthesis' means 'making'. So 'photosynthesis' means 'making with light'. Photosynthesis is the way that plants make food, using energy from light.
Questions
1) Think of two more words that begin with photoo. What does cach of your words mean?
2) In the food chain above, at which point does photosynthesis take place?
What else do plants need for photosynthesis?
• Plants use water in photosynthesis. They get the water from the soil.
• Plants use carbon dioxide in photosynthesis. They get the carbon dioxide from the air.
You already know that plants make food by photosynthesis. But they also make a very important gas-oxygen.
We can summarise photosynthesis like this:
Water and carbon dioxide are changed into food and oxygen, using energy from light.
Biomass
Plants use the food that they make in photosynthesis to make new cells and tissues. Material that is made of living cells and tissues is called biomass.
Activity 1.1 (Plants and light)
SE: You are going to find out what happens to plants that do not get light.
1) Sow some small seeds on damp filter paper, in two identical dishes.
Leave them in a warm place to germinate. Make sure that they do not dry out.
2) When the seeds have germinated, put one set into a dark cupboard, or into a closed cardboard box. Leave the other set in a light place, Keep giving them both a little water. Try to make sure that the temperature is the same for both sets of seedlings.
3) After two days, compare the appearance of the two sets of seedlings. You could also make labelled drawings of a seedling from each set.
Questions
${A_1}$: Explain why it was important to keep one set of seedlings in the light.
${A_2}$: Explain why it was important that the temperature was the same for both sets of seedlings.