In this unit, you will explore photosynthesis and cellular respiration, learning how plants (producers) and animals (consumers) obtain and use energy, and you'll use models to understand the flow of matter and energy in these processes.
Photosynthesis and Cellular Respiration Introduction
It’s a beautiful, sunny day. You’re sitting on a grassy lawn, surrounded by trees and other plants, eating a sandwich. You see a hummingbird flitting about, feeding in the flowers. Hummingbirds have the fastest metabolism of any animal we know, which means they need to eat all the time. Hummingbirds drink their weight in nectar every day. They are constantly on the move, feeding every few minutes, in order to get enough food to stay alive. They perch on nearby branches for a few minutes in between eating to digest the nectar, before doing it all over again.
A photo shows a hummingbird sucking out the nectar from a flower.
Source: Matt Cuda/Shutterstock
What do you and that hummingbird have in common? Both you and the hummingbird need energy to live and grow. How does a hummingbird turn nectar into energy? How does your body turn your food into energy? And furthermore, where did the energy in food come from in the first place?
Consider what you already know about energy flow, food webs, and cell organelles. Recall that plants make their own food, and are called primary producers. Their basic needs are sunlight, water, carbon dioxide, nutrients, and space to grow. Plants make their own food through the process of photosynthesis, which uses sunlight, carbon dioxide and water to create sugars and oxygen.
Plants not only make the energy to support immediate needs, but they also store energy, which they can use in the future for growth, reproduction and other life processes. Photosynthesis occurs in the chloroplasts in plants.
Recall that animals, or consumers, do not make their own food, and must consume (eat) other organisms to get the energy they need to live and grow. Consumers, like the hummingbird and like you, convert the energy stored in food to usable energy through a process called cellular respiration. Cellular respiration occurs in the mitochondria of plants and animals.
Activity
Look at the following images and identify whether the organism shown is a consumer or a producer.
A photo shows a hummingbird.
consumer
Source: Holly Miller-Pollack/Shutterstock
A photo shows an animal.
consumer
Source: nattanan726/Shutterstock
A photo shows the succulent plant, houseleek.
producer
Source: Naruedom Yaempongsa/Shutterstock
A photo shows a roasted chicken on a plate.
consumer
Source: magone/123RF
A photo shows different kinds of fruits.
producer
Source: Olga Pink/Shutterstock
A photo shows a garden with different plants and flowers.
producer
Source: Elenathewise/123RF
In this unit, you will learn about the processes of photosynthesis and cellular respiration. You will use models to understand how matter and energy flow between the environment and an organism. You will use models to show how energy is transferred, stored, and accessed to sustain life’s processes. First, you will complete eight lessons. Then, you will apply what you learned to solve problems. Last, you will take a unit assessment.
You will have access to all the key words in the glossary, which will be linked throughout the text. The glossary contains key words and their definitions.
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