Chapter 6 of 8

All 8 chapters
  1. 1Signs of life, readunderstood
  2. 2Seeing small things, readunderstood
  3. 3Animal and plant cells, readunderstood
  4. 4What each part does, readunderstood
  5. 5Cells with special jobs, readunderstood
  6. 6Cells, tissues and organs, readunderstood
  7. 7Diffusion, readunderstood
  8. 8Living things with one cell, readunderstood

S3.1.6 Chapter 6

Cells, tissues and organs

How do tiny cells make a whole body, or a whole tree?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

  • Put cell, tissue, organ, organ system and organism in order of size
  • Give an example of each level in a plant and an animal

A dog is not one huge cell. It is made of an enormous number of tiny cells. They join together in steps, from small to large.

A tissue is a group of the same kind of cell, doing one job. Muscle cells together make muscle tissue.

An organ is made of different tissues that work together. The heart is an organ. It has muscle tissue to squeeze, and other tissues too.

An organ system is a group of organs that do one big job together. The heart and the blood tubes form the blood system.

An organism is a whole living thing, such as a dog or a tree. Draw the steps from cell to organism.

Draw it first

Draw the steps up from a cell

  1. A list of levels from the smallest at the top to the largest at the bottom. Each level has a bar that is longer than the one above it, and an arrow marked bigger points down. The strip adds one level at a time. Labels: cell, tissue, organ, organ system, organism, bigger.celltissuebigger

    1 Write cell, then tissue. Draw a bar for each, with the tissue bar longer.

  2. A list of levels from the smallest at the top to the largest at the bottom. Each level has a bar that is longer than the one above it, and an arrow marked bigger points down. The strip adds one level at a time. Labels: cell, tissue, organ, organ system, organism, bigger.celltissueorganbigger

    2 Add organ. Its bar is longer still.

  3. A list of levels from the smallest at the top to the largest at the bottom. Each level has a bar that is longer than the one above it, and an arrow marked bigger points down. The strip adds one level at a time. Labels: cell, tissue, organ, organ system, organism, bigger.celltissueorganorgan systembigger

    3 Add organ system, with a longer bar again.

  4. A list of levels from the smallest at the top to the largest at the bottom. Each level has a bar that is longer than the one above it, and an arrow marked bigger points down. The strip adds one level at a time. Labels: cell, tissue, organ, organ system, organism, bigger.celltissueorganorgan systemorganismbigger

    4 Add organism, the longest bar. Draw an arrow marked bigger beside them.

Here is a tissue. Every cell is the same kind and they fit together. Together they do one job.

A round view of plant cells that fit together like bricks. There are 18 cells, all the same kind, and each has a dark nucleus. The words below say that many cells make a tissue. Labels: cell, nucleus, many cells make a tissue.cellnucleusmany cells make a tissue
A tissue is many cells of one kind.

Plants have the same levels. A leaf cell is a cell. The skin of a leaf is a tissue. The whole leaf is an organ. The stem and leaves together form the shoot system, which is an organ system. The roots form the root system. The whole tree is the organism.

A table of the five levels for a plant. Cell: leaf cell. Tissue: leaf skin. Organ: leaf. Organ system: shoot system. Organism: a tree. Labels: level, plant, cell, tissue, organ, organ system, organism, leaf cell, leaf skin, leaf, shoot system, a tree.levelplantcellleaf celltissueleaf skinorganleaforgan systemshoot systemorganisma tree
The five levels in a plant.

An animal has them too. A muscle cell is a cell. Heart muscle is a tissue. The heart is an organ. The heart and blood tubes are the blood system. The whole dog is the organism.

A table of the five levels for an animal. Cell: muscle cell. Tissue: heart muscle. Organ: heart. Organ system: blood system. Organism: a dog. Labels: level, animal, cell, tissue, organ, organ system, organism, muscle cell, heart muscle, heart, blood system, a dog.levelanimalcellmuscle celltissueheart muscleorganheartorgan systemblood systemorganisma dog
The five levels in an animal.

See it three ways

With things

Tighten the muscle at the front of your upper arm and feel it go hard. That muscle is an organ.

As a picture

An arm bent at the elbow, seen from the side. The biceps muscle at the front and the triceps muscle at the back are labelled. Each muscle is an organ made of muscle tissue and other tissues. Labels: biceps, triceps.tricepsbiceps

In words

A muscle is an organ. It is made of muscle tissue, which is made of muscle cells. It also has tissue that carries blood and tissue that carries messages.

Your skin is an organ too. It is the biggest organ you have. Here are some organs and what they do.

A table of four organs and their jobs. The heart pumps blood. The lungs take in oxygen. The stomach digests food. The brain controls the body. Labels: organ, job, heart, lungs, stomach, brain, pumps blood, take in oxygen, digests food, controls the body.organjobheartpumps bloodlungstake in oxygenstomachdigests foodbraincontrols the body
Four organs and their jobs.

Try it

Find an organ on yourself

You need: your own body, a quiet place.

  1. Sit still for a minute. Put two fingers on the inside of your other wrist, below the thumb. Feel your pulse. It comes from your heart.
  2. Put a hand on your chest. Breathe in slowly. Feel your chest rise. Your lungs are filling with air.
  3. Run a fingertip along your arm. Your skin is an organ too.

What you will see: Each thing you felt came from an organ. Each organ is made of tissues, and each tissue is made of cells.

If you cannot try it, this is what happens.
A table of what you feel, the part of the body it comes from, and its level. A pulse comes from the heart, an organ. The skin touch comes from the skin, an organ. A chest that rises comes from the lungs, which are organs. Labels: you feel, part, level, pulse, heart, organ, skin touch, skin, chest rises, lungs, organs.you feelpartlevelpulseheartorganskin touchskinorganchest riseslungsorgans

A wrong idea many people have

An organ is just a very big cell.

Why it feels right: An organ is a bigger thing than a cell, and the word sounds like one object.

The test that breaks it: Look at the heart in the table of levels. It is made of many tissues. Each tissue is made of millions of cells. One cell cannot be a heart.

What is true: An organ is made of tissues, and tissues are made of cells.

Key words

tissue
a group of the same kind of cell, doing one job.
organ
different tissues that work together, such as the heart.
organ system
a group of organs that do one big job together.
organism
a whole living thing.

Back to your guess

The answer is A: Cells join in groups, and the groups join to make the parts of the body.

Cells join into tissues. Tissues join into organs. Organs work together in systems. Together the systems make the whole living thing.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Which list goes from the smallest to the largest?

    Tap your answer.

    1. Not this one. You have swapped tissue and organ. Tissues join to make an organ, so the tissue is smaller. Go to S3.1.6. Try another.

    2. Not this one. That list goes from the largest to the smallest. The question asks for smallest first. Go to S3.1.6. Try another.

    3. Yes, that is right. Cells make tissues, tissues make organs, organs make organ systems, and the systems make an organism.

    See the answer

    Cell, tissue, organ, organ system, organism

    Cells make tissues, tissues make organs, organs make organ systems, and the systems make an organism.

    • If you chose A: You have swapped tissue and organ. Tissues join to make an organ, so the tissue is smaller. Go to S3.1.6.
    • If you chose B: That list goes from the largest to the smallest. The question asks for smallest first. Go to S3.1.6.

  2. What is a tissue?

    Tap your answer.

    1. Not this one. A tissue is made of many cells, not one. A cell is smaller than a tissue. Go to S3.1.6. Try another.

    2. Not this one. That sounds like an organ system. A tissue is made of cells, and it is smaller than an organ. Go to S3.1.6. Try another.

    3. Yes, that is right. Muscle cells together make muscle tissue, for example.

    See the answer

    A group of the same kind of cell, doing one job.

    Muscle cells together make muscle tissue, for example.

    • If you chose A: A tissue is made of many cells, not one. A cell is smaller than a tissue. Go to S3.1.6.
    • If you chose B: That sounds like an organ system. A tissue is made of cells, and it is smaller than an organ. Go to S3.1.6.

  3. Which is an example of an organ system in an animal?

    Tap your answer.

    1. Not this one. The heart alone is one organ. A system is a group of organs. Go to S3.1.6. Try another.

    2. Yes, that is right. Organs that work together on one big job form an organ system. The heart and blood tubes move blood round the body.

    3. Not this one. A muscle cell is the smallest level, a cell. A system is much bigger. Go to S3.1.6. Try another.

    See the answer

    The heart and blood tubes together

    Organs that work together on one big job form an organ system. The heart and blood tubes move blood round the body.

    • If you chose A: The heart alone is one organ. A system is a group of organs. Go to S3.1.6.
    • If you chose C: A muscle cell is the smallest level, a cell. A system is much bigger. Go to S3.1.6.

  4. Which is an example of a tissue in an animal?

    Tap your answer.

    1. Not this one. The heart is an organ. It is made of several tissues, and heart muscle is one of them. Go to S3.1.6. Try another.

    2. Not this one. A whole dog is an organism, the largest level. Go to S3.1.6. Try another.

    3. Yes, that is right. Heart muscle is a group of the same kind of cell doing one job. That is a tissue.

    See the answer

    Heart muscle

    Heart muscle is a group of the same kind of cell doing one job. That is a tissue.

    • If you chose A: The heart is an organ. It is made of several tissues, and heart muscle is one of them. Go to S3.1.6.
    • If you chose B: A whole dog is an organism, the largest level. Go to S3.1.6.

  5. In a tree, which is an organ?

    Tap your answer.

    1. Yes, that is right. A leaf is made of several tissues working together, so it is an organ.

    2. Not this one. The skin of a leaf is a tissue, a group of the same cells. The leaf has other tissues too. Go to S3.1.6. Try another.

    3. Not this one. The whole tree is the organism, the largest level. Go to S3.1.6. Try another.

    See the answer

    A leaf

    A leaf is made of several tissues working together, so it is an organ.

    • If you chose B: The skin of a leaf is a tissue, a group of the same cells. The leaf has other tissues too. Go to S3.1.6.
    • If you chose C: The whole tree is the organism, the largest level. Go to S3.1.6.

  6. From an earlier chapter

    Which special cell carries messages?

    Tap your answer.

    1. Not this one. A red blood cell carries oxygen. A nerve cell carries messages. Go to S3.1.5. Try another.

    2. Yes, that is right. A nerve cell is long and thin. It carries messages from one part of the body to another.

    3. Not this one. A root hair cell takes in water for a plant. Go to S3.1.5. Try another.

    See the answer

    A nerve cell

    A nerve cell is long and thin. It carries messages from one part of the body to another.

    • If you chose A: A red blood cell carries oxygen. A nerve cell carries messages. Go to S3.1.5.
    • If you chose C: A root hair cell takes in water for a plant. Go to S3.1.5.

  7. How many cells are drawn in the picture of the tissue?

    A round field of plant cells fitting together like bricks, each with a dark nucleus. The picture shows 18 cells. Labels: cell, nucleus.cellnucleus
    See the answer

    18 cells

    Count every box in the picture, row by row. There are 18.

Keep it

Copy this into your exercise book.

Cells make tissues. Tissues make organs. Organs form organ systems. Systems together make an organism. The order is cell, tissue, organ, organ system, organism.

Draw: Draw five bars, each longer than the last. Write the five levels beside them, smallest first.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

No internet tomorrow? Save the whole book as one file (754 KB). It opens on any phone.