Similarities and Differences Among Organisms

1. Similarities and Differences Among Organisms Mrs. Faulkner

2. Millions of species live on Earth, and scientists have identified and described many, but not all of these. • All living things share features that are alike and there are also differences.

3. Structure • All Living things are composed of cells. • A cell is the basic unit of structure and function in an organism.

4. Growth and Development • All Living things grow and develop. • Some animals go through metamorphosis, while others show a very limited amount of growth. Some are so small, you can only see it with a microscope.

5. Reproduction • All Living things reproduce. Reproduction involves the processes of mitosis and meiosis. During the process of reproduction, living things pass on their heredity information to their offspring.

6. Response to Stimuli • All living things respond to stimuli. • A stimulus is anything that causes a response. Living things respond to various stimuli, including light, sound, touch, smell, and taste. • Some living things such as humans, have highly specialized structures to respond to stimuli.

7. Energy Use • All Living things use energy to carry out functions such as growth, development, reproduction, and responding to stimuli. • In addition, living things use energy to perform functions such as digestion, respiration, excretion, and circulation.

8. Adapt to change All species change themselves and adapt to change around them over time. Organisms develop adaptations and behavior that increase their survival. We know this because of the changes that we see in fossil records.

9. Different Structure • Although living things are made of cells, organisms can be composed of just a single cell or billions of cells.

10. Different Growth and Development Organisms display significant differences in the ways they grown and develop. For example, some organisms hatch from eggs, and other organisms are born alive.

11. Different Reproduction • Although all living things reproduce, you learned in Lesson 6 that organisms can reproduce sexually or asexually. There are many different types of sexual and asexual reproduction.

12. Different Responses to Stimuli • Organisms also respond to stimuli in many different ways. A plant’s response to stimuli such as light and gravity can be very slow. In contrast, if you step on a sharp object, your response is immediate.

13. Different Energy Use • Although all living things use energy, not all organisms depend on the same energy source. Plants, for example, can use light energy to carry out their life processes. In contrast, animals must take in nutrients to obtain energy.

14. Different Adaptations • Although all living things change, organisms do not all follow the same pattern of change. For example, changes in bacteria that are resistant to antibiotics have occurred over the last 50 years. In contrast, alligators have not changed significantly during the past 200 million years.