Unit B: Cells and Systems

Key Ideas     Unit Checklist 

Pre-assessment: What do you know?


Figure B.P.1 – All living things are made from tiny cells.
Figure B.P.2 – Cells work together in organ systems.


Figure B.P.3 – Scientists use a variety of technologies to study the human body.
Earth is filled with living organisms. All living things are made from tiny cells. Some living things have just one cell, while other organisms contain millions of cells.

In humans, cells work together in organ systems. Each organ system has a specific role in the body. When organ systems don’t operate correctly, people become sick. Some diseases are caused by people’s choices, but other diseases are caused by environmental factors. Millions of research scientists around the world work on discovering causes and cures for diseases.

Having a long and happy life requires taking precautions to stay healthy. What actions do you take every day to keep your body healthy?

How do cells in the human body work together to form organ systems? Why do people get sick? How do scientists cure diseases?

To learn more about how humans can heal diseases, we must first understand cells and body systems, and how their functions are affected by diseases.

Figure B.P.4 – Infectious diseases can quickly spread among people.
Figure B.P.5 – Health care professionals diagnose, treat, and cure diseases.

Pre-assessment Questions & Hints

Step 1: The Questions


This short pre-assessment is to find out what you might already know about the topic of cells and systems. Below are four questions. Think about them! If you need a hint, click on the question.

Optional: If you would like a place to write your answers, download this document.
Think about the characteristics that all living things have in common.
Think about substances that travel in both the respiratory and circulatory systems.
Think about a time when you or someone you know was vaccinated.

Step 2: The Answers

 Click each of the suggested answers below – how do they compare to your thoughts and answers?
Living organisms share the following characteristics:
  • They are made from cells.
  • They require nutrients and energy.
  • They respond to the environment.
  • They grow.
  • They reproduce.
  • They have adaptations that help them survive in their environment.
Cells contain many structures, which include:
  • A nucleus to control the cell.
  • A cell membrane to control substances travelling in and out of the cell.
  • Mitochondria to provide energy for the cell.
  • Ribosomes to make substances needed by the cell.
  • Vacuoles to store substances in the cell.
The respiratory system and the circulatory system work together to carry oxygen to all cells in the body, and to remove carbon dioxide from all cells in the body. Gases move into and out of the blood in the lungs through tiny blood vessels called capillaries.
Vaccinations are substances that prevent diseases. Vaccines are injected into an organism’s body. Vaccines contain a non-threatening form of a disease. The immune system uses the vaccine to build up resistance against the threatening form of the disease.

Step 3: Check In With Your Teacher

The start of a new unit is a great time to touch base with your teacher! Here are just a few reasons to consider contacting your teacher:

  1. Perhaps you found this pre-assessment quiz very easy because you have studied this material before, such as at another school. If so, it's important to tell your teacher.

  2. It's very good for your teacher to know you are starting a new unit; it will give them a good idea of your progress. It doesn't have to be a long message, just a "I'm starting Unit B; just thought you might want to know!"

  3. Your teacher may have special tips and suggestions for the unit you are starting.

  4. Just to say hi – your teacher always enjoys hearing from you!

To contact your teacher, post in the Course Questions Forum, send your teacher an email, or call on the phone if you like. Whatever way you choose, it's always a good idea to get in touch with your teacher – make sure you do it frequently.