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1. What are cells�2. In and out of cells�3. Specialised cells�4. Metric prefixes�5. Using the microscope� - part 1� - part 2�6. How living things are organised

7B1 Cells and body systems

On your whiteboards – how do you know something is alive?

What are the characteristics of living things?

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7B1.1 What are Cells?

Keywords

Definition

Cell

Organelle

 

Microscopic

 

The smallest component of living things

Lit: ‘tiny organ’. Any structure found inside a cell that does a particular job

Too small to be seen with the naked eye.

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What are the 7 life processes?�Can you write all 7 on your whiteboards.

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MRS GREN

Remember organisms do these things, but so do the individual cells that they are made of.

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Movement

In animals muscles contract and parts of the body move.

Plants can grow towards or away from stimuli (gravity, water, light)

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Respiration

A chemical reaction in cells which uses oxygen to release energy from glucose.

Write the reaction for respiration in the space below the table.

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Sensitivity

The ability to sense and respond to stimuli.

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Growth

The increases in cell size and number that take place during the life of an organism.

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Reproduction

To produce offspring by sexual or asexual reproduction.

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Excretion

 To get rid of waste material from the blood, tissues and organs.

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Nutrition

Taking in food and converting it into energy and other vital nutrients.

Answer the 2 questions about nutrition in plants below.

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Alien invasion!

Imagine that an alien spaceship is firing its death rays at Earth!

  • The death rays will destroy everything that is made of cells.

  • Things that are not made of cells will not be affected.

12

Developed by the University of York Science Education Group and the Salters’ Institute.

This presentation may have been edited. Download the original from www.BestEvidenceScienceTeaching.org

© University of York Science Education Group

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Alien invasion!

Look at the statements in the table. Some are right and some are wrong.

Tick one box for each statement.

People will be destroyed.

Brick walls will be destroyed.

Plants will be destroyed.

Very small organisms will not be destroyed.

Dead bodies will be destroyed.

13

1

2

3

4

5

6

Bacteria will be destroyed.

I am sure this is right

I think this is right

I think this is wrong

I am sure this is wrong

A

B

C

D

E

Developed by the University of York Science Education Group and the Salters’ Institute.

This presentation may have been edited. Download the original from www.BestEvidenceScienceTeaching.org

© University of York Science Education Group

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  • All truly living things are made of cells
  • What is a cell? What does it look like?
  • Thumb up: it’s a cell
  • Thumb down: It’s not a cell

  • Write a tick of a cross under each of the tiny cell diagrams at the bottom of page 9

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Relative sizes

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The unit of life

The diagrams show an atom, a biological molecule and a cell.

They are not drawn to the same scale.

An atom

A biological molecule

A cell

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The unit of life

1 What is the smallest structure that can be alive?

A

An atom

B

Many atoms arranged to make a biological molecule

C

Many biological molecules arranged to make a single cell

D

Many cells arranged to make an organism

2 How would you explain your answer to question 1?

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A single cell can…

The drawing shows a single cell.

Parts of the cell have been cut away so that you can see inside the cell and its structures.

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A single cell can…

Look at the statements in the table.

How confident are you that each statement is right or wrong?

1

A single cell can take in food and other nutrients.

2

A single cell can get energy from food.

3

A single cell can get rid of waste.

4

A single cell can make new cells.

5

A single cell can respond to its surroundings.

I am sure this is right

I think this is right

I think this is wrong

I am sure this is wrong

6

A single cell is a living thing.

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Too small to see?

The picture shows cells from the root of an onion plant.

Which statement about cells is true?

A

All cells are too small to be seen without a microscope.

B

Most cells are too small to be seen without a microscope.

C

All cells can be seen with the naked eye.

D

Most cells can be seen with the naked eye.

B – except the human egg cells, unusually large bacteria, some amoebas and squid nerve cells can be seen by the naked eye 

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B – except the human egg cells, unusually large bacteria, some amoebas and squid nerve cells can be seen by the naked eye 

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Cell diagrams

  • You are going to label some diagrams of cells in your books.
  • I will talk through them and explain what all the organelles do.
  • Complete your table with the correct organelle names as we go.

Organelle

Description/function

The watery jelly inside a cell where the cell’s activities take place.

The membrane that controls what goes into and out of a cell.

The ‘control centre’ of a cell. It contains the genes that are the instructions for the cell.

Tiny structures in a cell that make proteins.

An organelle in the cytoplasm of cells, where aerobic respiration occurs. Plural is mitochondria.

 

A green disc containing chlorophyll, found in plant cells. Where the plant makes glucose, using photosynthesis.

 

A tough layer of material around some cells, which is used for protection and support. It is stiff and made of cellulose in plant cells.

 

A storage space in cells. Plant cells have a large, permanent vacuole that helps to keep them rigid.

 

Liquid found in the vacuole in a plant cell.

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Animal Cell Plant Cell

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Animal Cell Plant Cell

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Animal cell and plant cells

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We’ll look at specialised cells in a future lesson.

Let's have a look at some real cells using the digital microscope.

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The diagram below shows a plant cell.

  1. (i) Give the function of the nucleus.

(ii) Give the function of the chloroplasts.

(iii) Give the function of the cell wall.

(b) Give the names of two labelled parts that are not present in animal cells.

Cell wall/vacuole/chloroplast

Answer: controls the cell functions/contains the DNA / genes / chromosomes

Answer: carry out photosynthesis/make food for the plant

Answer: gives cell shape/support

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1. What are cells�2. In and out of cells�3. Specialised cells�4. Metric prefixes�5. Using the microscope� - part 1� - part 2�6. How living things are organised

7B1 Cells and body systems

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7B1.2 In and Out of Cells

Keywords

Definition

Particle

 

Molecule

 

Diffusion

 

Cell membrane

A tiny piece of matter that everything is made out of.

 

A particle of a particular substance e.g. oxygen or water.

 

The random movement and spreading of particles. The overall movement of particles is from where there are many to where there are fewer.

 

A semi-permeable ‘bag’ that holds the cell contents and controls what goes in and out of the cell.

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7B1.2 In and Out of Cells

During this concept you will learn how cells absorb what they need to live and get rid of their waste

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What do living cells need?

  • Think back to MRS GREN and the characteristics of living things.
  • What things do cells need?

Animal Cells

Plant Cells

Air

Air

Water

Water

Food

Light

Nutrients from soil

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Why do living things need these things?

  • Discuss with your neighbour: how do living things use these things? What exactly do they do with them?
  • Work together to fill the spaces in the grids on pages 15 and 16.

Animal Cells

Plant Cells

Air

Air

Water

Water

Food

Light

Nutrients from soil

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What animals need

Why animals need it

What animal cells do with it

Air

 

Animal cells use oxygen for respiration to provide energy for life processes.

Water

To store and transport dissolved substances.

 

Food

 

 

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Fit these statements into your grid:��‘Whys’ are red ‘what fors’ are blue

As a source of oxygen.

For nutrition and respiration.

Animal cells use it to get energy, and to make new cells and materials.

Animal cells are filled up with it.

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What animals need

Why animals need it

What animal cells do with it

Air

 As a source of oxygen.

Animal cells use oxygen for respiration to provide energy for life processes.

Water

To store and transport dissolved substances.

Animal cells are filled up with it.

 

Food

 For nutrition and respiration.

Animal cells use it to get energy, and to make new cells and materials.  

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What plants need

Why plants need it

What plant cells do with it

Air

As a source of

carbon dioxide.

 

 

Plant cells use it for respiration to provide energy for life processes.

Water

 

 

Plant cells are filled up with it.

For nutrition.

 

Light

 

The energy is used for a chemical reaction in cells that makes food.

Nutrients from soil

For nutrition and growth.

 

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Plant cells use nutrients to make new cells and materials for growth.

Plants need to absorb energy.

Plant cells use it in a chemical reaction to make food.

To store and transport dissolved substances.

As a source of

oxygen.

Plant cells use it in a chemical reaction to make food.

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What plants need

Why plants need it

What plant cells do with it

Air

As a source of

carbon dioxide.

Plant cells use it in a chemical reaction to make food.

As a source of

oxygen.

Plant cells use it for respiration to provide energy for life processes.

Water

To store and transport dissolved substances.

Plant cells are filled up with it.

For nutrition.

Plant cells use it in a chemical reaction to make food.

Light

Plants need to absorb energy.

The energy is used for a chemical reaction in cells that makes food.

Nutrients from soil

For nutrition and growth.

Plant cells use nutrients to make new cells and materials for growth.

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So…

  • …we know what cells need to survive. What waste substances do animals and plants produce?

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Think back to the cells structure we learned about in the last concept. Refer to your notes if you like.

  • We need to think about how substances required for life get into the cells, and how the waste substances get out.

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The right structure for the job

The drawing shows a single cell.

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The right structure for the job

A

B

E

D

Which drawing shows the structure that…

1 …controls what can enter and leave the cell?

2 …lets the cell take in oxygen for respiration?

3 …lets the cell take in substances from food for respiration?

nucleus

digestive system

C

F

cell cytoplasm

mitochondria

lungs

cell membrane

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The right structure for the job

A

B

E

D

Which drawing shows the structure that…

4 …lets the cell take in water?

5 …lets the cell get rid of waste carbon dioxide?

nucleus

digestive system

C

F

cell cytoplasm

mitochondria

lungs

cell membrane

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So…

  • …cells absolutely do NOT have tiny lungs or digestive systems inside them that provide them with food and oxygen!!!
  • The cell membrane allows small molecules that the cell needs to pass through it into the cell.
  • The cell membrane also allows small waste molecules to pass through it out of the cell.
  • The movement of molecules from where there are many to where there are fewer is called DIFFUSION.

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Across the membrane

The diagram shows the particles of two solutions.

There is a selectively permeable membrane between the two solutions.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. Which statement is true?

A

Protein particles can move through the membrane in both directions.

B

Protein particles can only move from solution A to solution B.

C

Protein particles can only move from solution B to solution A.

D

Protein particles cannot move through the membrane in either direction.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. How would you explain your answer to question 1?

A

The membrane is permeable.

B

Protein particles are only found in solution B.

C

There is a concentration gradient.

D

Protein particles are too big to move through the membrane.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. Which statement is true?

A

Water particles will move through the membrane in both directions.

B

Water particles will only move from solution A to solution B.

C

Water particles will only move from solution B to solution A.

D

Water particles will not move through the membrane in either direction.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. How would you explain your answer to question 3?

A

There number of water particles in each solution is the same.

B

Solution B is much more concentrated.

C

Particles only move from higher concentration to lower concentration.

D

Water particles are small enough to move through the membrane.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. Which statement is true?

A

Oxygen particles will move through the membrane in both directions.

B

Oxygen particles will only move from solution A to solution B.

C

Oxygen particles will only move from solution B to solution A.

D

Oxygen particles will not move through the membrane in either direction.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. How would you explain your answer to question 5?

A

There is a concentration gradient.

B

There are more oxygen particles in solution B than in solution A.

C

Oxygen particles are small enough to move through the membrane.

D

Particles only move from higher concentration to lower concentration.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. Which statement is true?

A

The net movement of oxygen particles will be from solution A to solution B.

B

The net movement of oxygen particles will be from solution B to solution A.

C

There will be no net movement of oxygen particles.

D

The net movement of oxygen particles will be in both directions.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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Across the membrane

  1. How would you explain your answer to question 7?

A

Oxygen particles will only move from solution A to solution B.

B

Oxygen particles will only move from solution B to solution A.

C

Oxygen particles will move through the membrane in both directions.

D

Oxygen particles will move through the membrane in both directions but more will move from solution B to solution A.

solution A

solution B

membrane

water particle

protein particle

oxygen particle

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1. What are cells�2. In and out of cells�3. Specialised cells�4. Metric prefixes�5. Using the microscope� - part 1� - part 2�6. How living things are organised

7B1 Cells and body systems

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7B1.3: Specialised cells and Unicellular organisms

We are learning to:

  1. Explain what a specialised cell is and give some examples
  2. Explain what a unicellular organism is, and give examples
  3. Describe some features of unicellular organisms

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Therse are examples of specialised cells.

Can you identify which are plant and which are animal cells.

Label N, C, CM, M (nucleus, cytoplasm, cell membrane and mitochondrion) in each

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7B1 Start here Tue 15

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Who gets the job?

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Who gets the job?

  1. This job requires a plant cell. The right cell for the job will have lots of chloroplasts (small round-ish structures) to absorb sunlight.
  2. The right cell for this role must be able to swim fast and far to locate an egg cell.
  3. Applicants for this job must be able to reach over a long distance, and connect with other cells.

A leaf cell (palisade)

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Who gets the job?

  1. This job requires a plant cell. The right cell for the job will have lots of chloroplasts (small round-ish structures) to absorb sunlight.
  2. The right cell for this role must be able to swim fast and far to locate an egg cell.
  3. Applicants for this job must be able to reach over a long distance, and connect with other cells.

A sperm cell

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Who gets the job?

  1. This job requires a plant cell. The right cell for the job will have lots of chloroplasts (small round-ish structures) to absorb sunlight.
  2. The right cell for this role must be able to swim fast and far to locate an egg cell.
  3. Applicants for this job must be able to reach over a long distance, and connect with other cells.

A nerve cell

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Who gets the job?

  1. The job requires a cell that can be flexible, with a large surface area to absorb oxygen. A lack of a nucleus would be a distinct advantage, as this would allow more space to carry oxygen.
  2. The successful applicant will be a plant cell with a large surface area to absorb water and minerals from the soil. Chloroplasts are not necessary as the work will be underground.
  3. Cells considering applying for this job must be flexible and able to change shape so that they can engulf bacteria and viruses. They may have a multi-lobed nucleus.

A red blood cell

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Who gets the job?

  1. The job requires a cell that can be flexible, with a large surface area to absorb oxygen. A lack of a nucleus would be a distinct advantage, as this would allow more space to carry oxygen.
  2. The successful applicant will be a plant cell with a large surface area to absorb water and minerals from the soil. Chloroplasts are not necessary as the work will be underground.
  3. Cells considering applying for this job must be flexible and able to change shape so that they can engulf bacteria and viruses. They may have a multi-lobed nucleus.

A root hair cell

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Who gets the job?

  1. The job requires a cell that can be flexible, with a large surface area to absorb oxygen. A lack of a nucleus would be a distinct advantage, as this would allow more space to carry oxygen.
  2. The successful applicant will be a plant cell with a large surface area to absorb water and minerals from the soil. Chloroplasts are not necessary as the work will be underground.
  3. Cells considering applying for this job must be flexible and able to change shape so that they can engulf bacteria and viruses. They may have a multi-lobed nucleus.

A white blood cell

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7B1.3: Unicellular organisms

Keywords

Pronunciation

Definition

Unicellular organism

 

 

 

Bacterium

 

 

 

Protist

 

Flagellum (pl. flagella)

You – nee – sell – you – lar

or – gan – iz – um

 

 

bak – tier – ee – um

 

 

 

Pro – tist

 

Fla – jell - um

A microscopic living thing that has only one cell (uni means one). Sometimes also called single celled organisms

 

A unicellular organism that is much smaller that plant and animal cells. (Pl. bacteria)

 

A unicellular organism with a nucleus

 

A tail-like appendage that some unicellular organisms use to swim

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A single cell can…

The drawing shows a single cell.

Parts of the cell have been cut away so that you can see inside the cell and its structures.

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A single cell can…

Look at the statements in the table.

How confident are you that each statement is right or wrong?

1

A single cell can take in food and other nutrients.

2

A single cell can get energy from food.

3

A single cell can get rid of waste.

4

A single cell can make new cells.

5

A single cell can respond to its surroundings.

I am sure this is right

I think this is right

I think this is wrong

I am sure this is wrong

6

A single cell is a living thing.

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How many cells?

  1. What is the smallest number of cells that a living organism can be made up of?

A

One cell

B

Hundreds of cells

C

Thousands of cells

D

Millions of cells

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How many cells?

  1. What is the largest number of cells that a living organism can be made up of?

A

One cell

B

Hundreds of cells

C

Thousands of cells

D

Millions of cells

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The size and shape of cells

Some children are talking about cells.

A

All cells are the same size and shape.

B

All cells are the same size, but

not all cells are the same shape.

C

All cells are the same shape, but

not all cells are the same size.

D

Different cells can have both different sizes and different shapes.

To discuss

1 Which person is correct?

2 Can you give examples that prove the other people are wrong?

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Unicellular organism or not?

  • Thumbs up: yes, it’s unicellular
  • Thumbs down: no it isn’t.

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This is a typical animal cell

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This is single bacterium

(bacteria)

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This is a typical plant cell

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This is a Euglena

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These are:

This is an Amoeba

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These are:

These are individual yeast

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These are:

These are lots of cells in a piece of skin

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These are:

These are many plant cell

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Types of unicellular organism

  • Protists
  • Fungi
  • Bacteria

Write these names into the space on page 23 and note an example of each.

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Protists

  • They are very similar to animal and/or plant cells.
  • They have a nucleus.
  • Some have chloroplasts and do photosynthesis.
  • All respire.
  • Some have a flagellum (pl. flagella from latin ‘whip’) a long ‘tail’ to swim with
  • They may have one or more ‘food vacuoles’, a ‘pouch’ inside the cell that contains recently ‘engulfed’ food.

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Fungi

  • They have a nucleus
  • They have a cell wall (but not made of the same substance as a plant cell wall)
  • They respire
  • Many species can live together to form multicellular fungi that we can see, like mushrooms etc.

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Bacteria

  • a diverse and amazing group of organisms.
  • They have no nucleus, and their genetic material is stored in a single chromosome in the cytoplasm.
  • They respire.
  • Some do photosynthesis
  • They have a cell wall (but not made of the same substance as a plant cell wall, or the fungal cell wall)
  • Some have a flagellum a long ‘tail’ to swim with
  • They are smaller than plant and animal cells

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The hungry alien

Imagine there’s an alien visiting Earth.

The alien is very hungry.

The alien can only eat organisms made from

a single cell.

1 Which of these organisms can the alien eat?

2 Can you think of one word to describe all of the organisms the alien cannot eat?

humans cows sheep trees

ants head lice slugs grass mushrooms

tadpoles moss bacteria amoeba

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The hungry alien

  1. The alien can eat

2 One word to describe all of the organisms the alien cannot eat –

humans cows sheep trees

ants head lice slugs grass

mushrooms tadpoles moss

bacteria amoeba

multicellular.

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Euglena

This is an example of a protist. A protist is a living thing that is made of a single cell. The things that you can see inside the euglena are called organelles (lit. ‘little organ’) and they do jobs that make the cell work.

This is a scale bar. It shows us how much the image is magnified. 25μm is 25 micrometres. One micrometre is one millionth of 1 metre.

Euglena has an ‘eyespot’, an organelle that senses light. Why?

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Euglena

Nucleus: the control centre of the cell which contains important genetic information.

Chloroplasts: contain green chlorophyll, which absorbs light energy and carries out photosynthesis

Flagellum: long, whip-like structure that Euglena uses to swim.

Cell membrane: surrounds the cell, and controls what substances pass in and out of the cell

Cytoplasm: jelly-like substance that provides support for everything in the cell. Chemical reactions happen here

Contractile vacuole: pumps excess water out of the cell

Copy the names of the parts onto your diagram on page 25

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Paramecium

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Rocket man: Listeria monocytogenes

The bacteria can be found in soil and water or on plants, but it really shows its stuff when it lands in an animal or person.

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Paramecium

Cytoplasm: jelly-like substance that provides support for everything in the cell. Chemical reactions happen here

Cell membrane: surrounds the cell, controls what substances pass in and out of the cell

Nucleus: the control centre of the cell which contains important genetic information.

Cilia: tiny ‘hairs’ that beat back and forth to allow the paramecium to move through the water

Copy the names of the parts and any definitions you don’t already know onto your diagram on page 25

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Euglena

Nucleus: the control centre of the cell which contains important genetic information.

Chloroplasts: contain green chlorophyll, which absorbs light energy and carries out photosynthesis

Flagellum: long, whip-like structure that Euglena uses to swim.

Cell membrane: surrounds the cell, and controls what substances pass in and out of the cell

Cytoplasm: jelly-like substance that provides support for everything in the cell. Chemical reactions happen here

Contractile vacuole: pumps excess water out of the cell

Answer the exam question on page 26

Copy the names of the parts and any definitions you don’t already know onto your diagram on page 25

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Answer to the exam question on page 26

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1. What are cells�2. In and out of cells�3. Specialised cells�4. Metric prefixes�5. Using the microscope� - part 1� - part 2�6. How living things are organised

ARRIVAL TASK:

Draw and label a plant cell and an animal cell in the space on page 30 – do what you can from memory and then fill in the gaps using the diagrams on page 13

7B1 Cells and body systems

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Microscopes

Eyepiece lens

Objective lens

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You are going to see 10 photographs taken with a microscope.

Shout out what you think each picture is of.

Can you guess what it is?

Clue:

It plays music.

1/20

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Loves Cats.

Can you guess what it is?

2/20

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Can you guess what it is?

  • Inside your mouth

3/20

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Can you guess what it is?

Saline solution

4/20

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Can you guess what it is?

Loves heads

5/20

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Can you guess what it is?

Creepy crawly

6/20

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Can you guess what it is?

Light the way.

7/20

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Can you guess what it is?

Reads data

8/20

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Can you guess what it is?

Eyes on you.

9/20

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Can you guess what it is?

Leg ware

10/20

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How to calculate the magnification of microscope

Total magnification

magnification of eyepiece lens

x

magnification of objective lens

=

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What’s the magnification?

A student uses the microscope to look at cells on a slide.

  • The eyepiece lens has a magnification of 10x
  • The objective lens has a magnification of 4x

A

4x

B

10x

C

14x

D

40x

eyepiece lens

objective lens

What is the magnification of the cells seen using the microscope?

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Moss safari

The simple moss squeeze

  1. Take the soaked moss sample and, using a blunt mounted needle (or similar), agitate the moss surface. This will dislodge organisms living within the moss.
  2. Using your fingers, squeeze the moss from the base (rhizoid end) to the tips of the stems. Collect the moss squeeze sample in a small dish.
  3. Collect the moss squeeze using a pipette.

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Microscope Safety

  • Avoid getting the microscope wet.
  • Do not touch the glass part of the lenses with your fingers.
  • Always lift the microscope by the arm and carry with one hand underneath.
  • Let your teacher know if you break a slide or coverslip.

Eyepiece lens

Objective lens

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Using a microscope

  1. Turn the turret until the lowest power objective lens clicks into position.
  2. Place the slide on the stage and fasten it with the stage clips.
  3. Look from the side and turn the focus knob to move the objective lens closer to the stage (note which way is up and which way is down). Stop before the objective lens touches the slide.
  4. Look through the eyepiece.
  5. Turn the focus knob until the image is sharp and clear.
  6. Move the mirror to reflect more light through the sample, if needed.
  7. Turn the turret until the medium power objective lens clicks into position, then re-focus the image.
  8. When finished, use the focus knob to move the objective lens away from the stage, and then remove the slide from the stage.

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How many of the big 5 can you find?

Draw a diagram of what you can see on page 33 and label any coloured areas with the name of the colour. Do not colour it in. Can you guess what any of the parts you can see are?

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7B1.5 Using the microscope

Microscope: an instrument for viewing objects that cannot be seen with the naked eye

Magnification: How much bigger something appears compared with its actual size

Task: draw and label a plant cell and an animal cell

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Answer the questions on page 27

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The speed of light = 300 000 000 m/s

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The size of the coronavirus = 0.00000001 m

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The distance to Mars = 203 000 000 000 m

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The diameter of a helium atom = 0.00000000014m

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  • In science we have to use a lot of very very big numbers and a lot of very very small numbers.
  • These numbers are long: e.g. Jupiter is 365000000 miles away from Earth. Some cells are around 0.00003m wide.
  • This makes them difficult to write, so we need an easy way of writing down long numbers.

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We use prefixes:

To convert units to the next smallest unit in the table, multiply by 1000:

  • E.g. 10mm x 1000 = 10,000µm

To convert units to the next largest unit in the table, divide by 1000:

  • E.g. 500m ÷ 1000 = 0.5km

µ is a Greek letter ‘mu’. We use it to abbreviate ‘micro’, because ‘m’ is used for milli and ‘M’ is used for ‘mega’. Practise writing the Greek letter µ

X

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Think of rulers

  • 1 millimetre (mm) is one thousandth of 1 metre, 1 micrometre (μm) is 1 millionth of 1 metre and so on.
  • We can also say that the nucleus is 6µm (6 micrometres) wide.
  • The prefix ‘micro’ means one millionth, so 1 µm is one millionth of 1 metre.
  • This thing: µ is a Greek letter ‘mu’. We use it to abbreviate ‘micro’, because ‘m’ is used for milli and ‘M’ is used for ‘mega’.

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The speed of light = 300 Mm/s

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The size of the coronavirus = 10 nm

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The distance to Mars = 203 Gm

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The diameter of a helium atom = 0.14 nm

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Decimal

With prefix

1000m

1 km

0.025 m

2.5 cm

0.0003 m

………….. mm

0.000007 m

…………… μm

0.00721 m

………….. mm

…………………………… m

4.2 nm

………………………….. m

50.5 μm

…………………………… m

……………. μm

0.00003 m

0.03 mm

30 µm

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Decimal

With prefix

1000 m

1 km

0.025 m

2.5 cm

0.0003 m

0.3 mm

0.000007 m

7 μm

0.00721 m

7.21 mm

0.000 000 0042 m

4.2 nm

0.000 0505 m

50.5 μm

0.000 000 241 m

0.241 μm

0.00003 m

0.03 mm

30 µm

Answer the questions on page 28 & 29

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Comparing microscopes

What type of microscope do we use in class?

Robert Hooke’s book Micrographia was a best seller as it contained drawings such as cork. The term cell came from the latin word cella which means storeroom or small container in English.

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Light microscopes

Thin specimens

Requires staining

Magnification limited to distance of 0.5 Wavelengths for good resolution

Most commonly used

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Light microscopes

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Resolution

Low Magnification

Good Resolution

High Magnification

Poor Resolution

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Transmission Electron Microscopes

Thin specimens

Uses heavy positive ions for staining

Beam of electrons

Far greater range of magnification with much improved resolution

Expensive, used mostly in research

Magnification 500,000

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Transmission electron microscopes

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Scanning electron microscopes

Beam of electrons hitting surface thus 3D image

Crystal clear resolution at high magnifications

Specimens coated in heavy gold ions

Expensive, used mainly in research and specialist labs

Magnification 100,000

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Can you guess what these magnified images are?

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Scanning electron microscopes

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Can you guess what it is?

Chilly

11/20

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Can you guess what it is?

Sharp

12/20

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Can you guess what it is?

Clean teeth

13/20

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Can you guess what it is?

Hook you up

14/20

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Can you guess what it is?

Molar

15/20

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Can you guess what it is?

Season and spice

16/20

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Can you guess what it is?

Attracted to the light

17/20

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Can you guess what it is?

Killer of the sea.

18/20

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Can you guess what it is?

Vital erythrocytes

19/20

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Can you guess what it is?

I see you

20/20

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Can you guess what it is?

Strum me

Bonus

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Microscope Safety

  • Avoid getting the microscope wet.
  • Do not touch the glass part of the lenses with your fingers.
  • Always lift the microscope by the arm and carry with one hand underneath.
  • Let your teacher know if you break a slide or coverslip.

Eyepiece lens

Objective lens

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Using a microscope

  1. Turn the turret until the lowest power objective lens clicks into position.
  2. Place the slide on the stage and fasten it with the stage clips.
  3. Look from the side and turn the focus knob to move the objective lens closer to the stage (note which way is up and which way is down). Stop before the objective lens touches the slide.
  4. Look through the eyepiece.
  5. Turn the focus knob until the image is sharp and clear.
  6. Move the mirror to reflect more light through the sample, if needed.
  7. Turn the turret until the medium power objective lens clicks into position, then re-focus the image.
  8. When finished, use the focus knob to move the objective lens away from the stage, and then remove the slide from the stage.

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7B1 Start here

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Calculating actual size

The measured size is 70 mm

The magnification of the picture is x500

x500

Actual size = 70/500 = 0.14mm

= 140μm

A

I M

Answer the questions on page 36

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Cheek cell slide preparation�

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Cheek cell slide preparation�

  1. Gently scrape the inside of your cheek with a sterile cotton bud.
  2. Now smear the scrapings onto the middle of a clean microscope slide.
  3. Place your used cotton bud in a beaker of disinfectant.
  4. Place a drop of dilute methylene blue on top to stain the cells.
  5. Place a coverslip over the cells, lowering it carefully to avoid air bubbles.
  6. Draw and label what you can see using a sharp pencil.
  7. Draw clear, simple, two-dimensional line diagrams without shading.
  8. Label any coloured areas with the name of the colour. Do not colour in.

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Cheek cell drawing�

X10 eyepiece lens

X10 objective lens

What is the actual size of the cheek cell?

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Onion Slide Preparation

  1. Take a piece of onion and gently peel off a single layer (very thin).
  2. Lie the onion onto a clean slide.
  3. Cover the onion with Iodine to dye it.
  4. Gently place a cover slip over the onion and iodine being very careful not to get any air bubbles in.
  5. View your slide under the microscope.

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Looking at the Onion Cells

2. Draw and label what you can see using a sharp pencil.

  • Draw clear, simple, two-dimensional line diagrams without shading.
  • Label any coloured areas with the name of the colour. Don’t colour in.

1. Focus the microscope using the lowest magnification (eyepiece magnification x objective magnification-10x X 25x =250x total magnification)

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Onion cell drawing�

x 10 eyepiece lens

x 40 objective lens

20 mm

0.8 mm

What is the actual size of the onion cell?

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Troubleshooting

  • Check that the mirror reflects light through the stage and that light can be seen when looking down the microscope before trying to locate a specimen. Check that the lowest objective lens is clicked properly in place. Have pupils used too much stain when making their slide? Draw out excess stain from under the cover slip using a paper towel.
  • See step 1. Move slide around until you see something move across the field of view. It might be fuzzy, this is fine. When you see something, try to focus in on it using the coarse focus first, then the fine focus. START WITH OBJECTIVE LENS CLOSE TO SLIDE AND FOCUS BY WINDING IT UP, NOT DOWN.
  • Does it move when I move the slide? If not, clean the lens. If this doesn’t work, switch microscopes.
  • Is it perfectly round? Is the inside a paler colour than the surrounding stain? If so it’s probably a bubble. If lots are present, make slide again carefully.

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7B1 Start here

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7B1.6: How Multicellular Organisms are Organised

Answer the starter questions on page 37

  1. A cell is the smallest structural unit of living things.

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Calculating actual size

The measured size is 70 mm

The magnification of the picture is x500

x500

Actual size = 70/500 = 0.14mm

= 140μm

A

I M

Answer the questions on page 36

Page 36

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Cheek cell drawing�

X10 eyepiece lens

X10 objective lens

What is the actual size of the cheek cell?

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Keywords

Definition

multicellular organism

 

 

Tissue

 

 

organ

 

 

 

organ system

A living thing that is made of many cells

 

 

A group of cells of the same type working together

 

Structure made up of a group of tissues, working together to perform specific functions.

 

A group of different organs, which all work together to do a particular job

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7B1.6: How Multicellular Organisms are Organised

We will learn how multicellular organisms are organised in a hierarchy of increasingly complex structures, from individual cells up to complete organisms

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1. The smallest structural unit of living things

  1. What is a cell?
  2. Draw and label a typical plant cell
  3. Draw and label a typical animal cell

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Body cells

Which statement about the human body is the most accurate?

A

The body contains cells.

B

The body is a cell.

C

The body is made up of cells.

D

Cells are only found between the organs.

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Cell needs

The cells of humans and other animals need particular things to stay alive.

How would you join the boxes to explain what animal cells need and what they do with it?

Oxygen

Glucose

Water

What animal cells need

React it with glucose to provide energy.

React it with oxygen to provide energy.

Use it to store and transport dissolved substances.

What animal cells do with it

A

B

C

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Cells, tissues and organs

The bodies of humans are made up of cells, tissues, organs and organ systems.

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From cells to systems…

  • Cells are the basic building blocks of all living things. They are microscopic.

getting bigger

  • Cells can form tissues. Tissues are groups of cells working together to do a job.

getting bigger

  • Organs are made from one or more types of tissues grouped together. E.g brain, liver, heart

getting bigger

  • Organ systems are made from groups of organs working together. E.g. nervous system, digestive system

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Cells, tissues and organs

Read the statements in the table.

What is your decision for each statement?

1

Cells contain organs that carry out life processes.

2

Cells, tissues and organs are roughly the same size.

3

Tissues are made up of cells.

4

Organs are made up of tissues.

5

Plants are also made up of tissues.

I am sure this is right

I think this is right

I think this is wrong

I am sure this is wrong

6

Plants do not have organs.

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Put the following things in order from smallest to largest:

organism

organ systems

tissues cells

organs

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Put the following things in order from smallest to largest:

cells, tissues, organs, organ systems, organism

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Talking about cells, tissues and organs

Some children discuss their ideas about cells, tissues and organs.

Amber

I think cells contain organs such as lungs for respiration.

Kate

The organs in your body are made up of tissues.

Mia

Humans, other animals and plants are all made up of tissues.

Dan

Cells, tissues and organs must be roughly the same size.

Harry

I’m sure body tissues are made up of cells.

Tyler

I’m sure plants don’t have organs!

In pairs, discuss the answers to the questions on page 39

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Talking about cells, tissues and organs

To talk about in your group:

1 Who do you agree with?

2 Who do you disagree with, and why?

3 How would you explain the right ideas to these children?

Amber

I think cells contain organs such as lungs for respiration.

Kate

The organs in your body are made up of tissues.

Mia

Humans, other animals and plants are all made up of tissues.

Dan

Cells, tissues and organs must be roughly the same size.

Harry

I’m sure body tissues are made up of cells.

Tyler

I’m sure plants don’t have organs!

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A

B

C

D

G

Organs of the human body

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Looking at the torso model

  • Your teacher will show you the model torso. Fill in your table as you go.
  • They will describe the functions of the organs and tell you which organ system they belong to.
  • Use the information already in your table and listen to your teacher to complete your table.
  • Thomas the torso could be Thomasina! We can’t tell! Why not?
  • Are any other organ systems missing from Thomas/Thomasina?

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If the torso is not available….

  • Paste this link into chrome to view body systems info clip. 8 minutes 21sec long.

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Name of organ system

Function of organ system

Examples of organs, structures and tissues in this system

To regulate (control) the functions of the body using fast electrical signals

Respiratory (breathing) system

Heart, veins, arteries, capillaries, blood

To support the body, protect organs and allow movement

Endocrine glands (e.g. pituitary, adrenal, thyroid), pancreas, testes, ovaries. Organs that the hormones control are called ‘target organs’.

Digestive system

To produce gametes (sex cells) and allow reproduction (to make babies)

Kidneys, bladder

To maintain constant internal conditions, barrier against infection

To destroy pathogens (bad microorganisms) and prevent future infection

Bone marrow, blood, skin

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Name of organ system

Function of organ system

Examples of organs, structures and tissues in this system

Nervous system

To regulate (control) the functions of the body using fast electrical signals

Brain, spinal cord (these make up the central nervous system), peripheral nervous system

Respiratory (breathing) system

To inflate the lungs so that oxygen can be absorbed into the blood via diffusion

Lungs, rib cage and intercostal muscles, diaphragm

Cardiovascular system

To transport oxygen and food to every cell and remove waste substances.

Heart, veins, arteries, capillaries, blood

Skeletomuscular system

To support the body, protect organs and allow movement

Bones, muscles, tendons, ligaments

Hormonal (or endocrine) system

To regulate (control) the functions of the body using hormones (chemical messengers)

Endocrine glands (e.g. pituitary, adrenal, thyroid), pancreas, testes, ovaries. Organs that the hormones control are called ‘target organs’.

Digestive system

To break down food into smaller molecules so that it can be absorbed into the blood

Mouth, stomach, intestines, liver

Reproductive system

To produce gametes (sex cells) and allow reproduction (to make babies)

Ovaries, testes, uterus, cervix, sperm duct, vagina, penis

Excretory system

To remove toxic waste products from the blood

Kidneys, bladder

Skin

To maintain constant internal conditions

Skin

Immune (lymphatic) system

To destroy pathogens (bad microorganisms) and prevent future infection

Bone marrow, blood, skin, lymph nodes, spleen

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Body parts

The diagram shows some organs in the human body.

A

B

C

D

E

F

G

H

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Body parts

  1. Which part pumps blood around the body?

  • What is the name of the part you chose in question 1?

A

B

C

D

E

F

G

H

A

Heart

B

Intestine

C

Lung

D

Stomach

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Body parts

  1. Which part absorbs oxygen from air?

  • What is the name of the part you chose in question 3?

A

Heart

B

Intestine

C

Lung

D

Stomach

A

B

C

D

E

F

G

H

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Body parts

  1. In which part does most of the digestion of food take place?

  • What is the name of the part you chose in question 5?

A

Heart

B

Intestine

C

Lung

D

Stomach

A

B

C

D

E

F

G

H

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Body parts

  1. In which part is food stored and churned?

  • What is the name of the part you chose in question 7?

A

Heart

B

Intestine

C

Lung

D

Stomach

A

B

C

D

E

F

G

H

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Extension

  • Imagine that you are one of the organs that we have looked at today. You must apply for a job in the relevant organ system.
  • Write to the brain describing the qualities that you have that make you the best organ to work as part of that organ system.
  • E.g. you are the heart:

Dear Mr Brain,

I am applying for the role of the heart in the cardiovascular system. I am well-suited for this role as I am a double pump, and can pump blood around both body and lungs.

I am made of strong cardiac muscle, and my left ventricle is particularly large, strong and adapted for pumping blood all around the body.

I have valves to prevent blood flowing the wrong way.

I work well as part of a team and make good connections with both veins and arteries.

Yours sincerely,

Harriet Heart