ideas you need from ks3 what are our bodies built...

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A 1 C e l l s

layers of muscle

circular muscle

Cells of the circularmuscle are long, thinand relaxed.

Cells of the circularmuscle are short, fatand contracted.

contractedcircular muscle

Ideas you need from KS3

What are our bodies builtfrom?

Robert Hooke was the first person to see what plants andanimals are made of. This was 300 years ago. He lookedat parts of plants and animals using a microscope.

He found that both plants and animals are made up oflots of tiny parts like bricks in a wall. He called themcells.

1 What is the basic unit of all animals and plants?

2 a Measure the length of one of the plant cells in the picture.

b How long is the plant cell in real life?

3 Why do we need a microscope to see cells?

Tissues

A tissue is a group of cells with the same shape and job.Different tissues do different jobs.

Muscle cells group together to form muscular tissue.

4 What does muscular tissue do?

5 What type of cells make up muscular tissue?

Muscle cells can contract, or get shorter. As a muscle getsshorter, it causes movement or a change of shape.

6 How does muscular tissue move food down thegullet to the stomach?

Photograph of plant leaf cells taken through amicroscope. They are magnified 350 times.

This athlete isusing musculartissue to moveher body.

When the circular muscles contract, they move the food along the gullet.

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livergullet

stomach

pancreas

smallintestine

largeintestine

The human digestive system breaks down andabsorbs food.

Other tissues have different jobs

Muscle cells are shaped so that thetissue can do its job. Other tissues inthe body have different jobs, so theircells are different shapes.

7 Look at the picture. Draw the shapes of a musclecell and a gland cell from thestomach. Remember to labelthem.

Some of the organs in the digestive system contain glandular tissue. This makes digestive juices, which helpto break down food. Other glandular tissues in the bodymake other useful juices. For example, sweat glands make sweat.

8 Copy and complete the sentence.

In the stomach, tissue churns thefood and mixes it with juicesmade by the tissue.

Organs and organ systems

Different tissues join together to make an organ. Several organs work together in an organ system. Each organ system in the body does particular jobs.

9 List six organs in the digestive system.

10 What are the jobs of the digestive system?

gland cells

muscle cells

REMEMBER

You need to be able to relate thestructure of more types of cells to their jobs in a tissue or an organ in the way that you did on these pages.

The stomach is one of the organs of the digestive system. It contains glandular and muscular tissue.






cell membrane

nucleus

cytoplasm

mitochondrion

ribosome

red blood cells

side viewof a redblood cell

capillary– a narrowblood vessel

A human white blood cell.

Red blood cells are unusual because their nucleidisappear when they are fully formed. These cellsare full of a substance called haemoglobin thatcan join with oxygen. This means they can carryoxygen around the body. They release it in partsof the body that have a low oxygenconcentration.

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1 What are cells like?

Your body is made of billions of cells. Larger organisms likehumans have more cells than smaller organisms like ants.Some organisms have only one cell.

Most animal cells, including human cells, have these parts

a nucleus which controls everything that happens inthe cellcytoplasm where most of the cell’s chemical reactionshappena cell membrane to control which substances pass inand out of the cell, and also holds the cell togethermitochondria that release energy in respirationribosomes for making proteins (protein synthesis), including the enzymes that make chemical reactionshappen in cells.

1 Draw a table with these headings.

Complete the table to show the five cell parts shown.

Some cells look different

Cells may be different shapes and sizes but they still have anucleus, cytoplasm and cell membrane. They may alsohave other parts that are needed to do their jobs. We say that the cells are specialised to do their jobs.

2 How is a red blood cell specialised to do its job?

Cell part What it does






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Nerve cells have to carry impulses between the centralnervous system and other parts of the body.

3 How is a nerve cell specialised to do its job?

Cells that line the oviducts have hairs

Egg cells are released from an ovary and travel down anoviduct to the womb. Each oviduct is lined with special cells.

These cells have tiny hairs which move forwards andbackwards.

4 Make a large copy of cell X. Label the nucleus,cytoplasm and cell membrane.

5 Why do the cells lining an oviduct have tiny hairson their surface?

nervecell

This carries thenerve impulses.up to 1.5m long

long nerve fibre

nerveending

egg cell cell X

REMEMBER

Some cells are very long

stimulus

receptor

sensory neurone

central nervoussystem

effector(muscle or gland)

motor neurone

Inside an oviduct.

What you need to remember Copy and complete using the key words

What are cells like? Most human cells are made up of the same basic parts.Cells have a which controls everything that happens in the cell.It is the cell that controls the passage of substances in and out of the cell.Most of the chemical reactions in a cell take place in the .For example, most energy release in respiration happens in and proteinsynthesis happens in in the cytoplasm. These and other chemical reactions in cells are controlled by .

You need to be able to use your skills and knowledge to match specialised cells to the jobs that they do in tissues and organs or the whole organism.






Cells from a cork oak tree.

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A 1 C e l l s

2 How are plants built?

The first cells ever seen are shown in the drawing on theright. Robert Hooke drew them more than 300 years ago.

1 Why do you think he called them cells?

2 Draw a line 1 centimetre (cm) long. About 400 plantcells will fit along this line. Now use a sharp pencilto mark off each millimetre along your line. How many cells will fit into a space of 1 mm?

We know now that all plants are made up of cells.

Do all cells look the same?

Some things are the same in all cells, but other things aredifferent. Look at the plant cells and the animal cell.

3 Write down three parts you can see in both types ofcell.

4 Which part can you see in all three of the plant cellsbut not in the animal cell?

5 Write down the two parts you can see in some, butnot all, of the plant cells.

All plant cells have cell walls made of cellulose. This makes the cells stronger and more rigid. The permanent spaces in plant cells, called vacuoles, arefilled with a watery fluid called cell sap.

6 Make a large, labelled copy of the plant cell withchloroplasts. Draw some mitochondria and ribosomesin the cytoplasm. Remember to label them.

cell wall

vacuole full of cell sap

cell wall

chloroplast

cell membrane

cytoplasm

nucleus

cell membrane

An animal cell.

Three plant cells.

nucleus

cytoplasm

These little spaces that bees make for their youngand for storing honey are called cells.






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Why don’t all plant cells have chloroplasts?

Chloroplasts contain chlorophyll. This is what gives plantstheir green colour. Chlorophyll absorbs light energy so thatplants can make food. Chlorophyll is made only in the light.After a few weeks in the dark, it disappears from the cells.

Look at the pictures of the lawn.

7 a What happens to the grass under the tent? b Why does this happen?

8 Root cells do not have chloroplasts. Why not?

9 Look at the picture of a section cut through a stemof a plant. Only the outer layer is green. Why isn’t it green in the middle?

Potatoes are the underground stems of potato plants. They grow under the ground so they are not green, but theygo green in the light.

The bad news: the green parts of potatoes are poisonous. The good news: you would have to eat a lot to make you ill.

10 How should you store potatoes so they don’t go green?

A slice across a stem.

before

after

What you need to remember Copy and complete using the key words

How are plants built?Plant cells have cell walls to make them . They often have permanent spaces called . These are filled with a liquidcalled cell . Some plant cells have to absorb the light energy that plants use to makefood.






palisadelayer

spongylayer

guard cell

xylem

vein

phloem

upperepidermis(skin)

lowerepidermis(skin)

chloroplast

to leaves

water and mineral ions from roots

woodymaterial tomake cellwalls strong

This partwas onecell.

A slice across a leaf.

Xylem vessels are made of dead cells. The pattern of woody material varies.

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3 The cell for the job!

All plants are made from tiny parts called cells. But not allplant cells are the same. You can see this if you cut a slicethrough part of a plant.

1 You would need to look at the slice under amicroscope. Why is this?

Different jobs in a plant are done by different kinds of cells.A group of cells with the same shape and job is called atissue.

2 Write down three kinds of tissue shown in the leafsection.

3 What job does a leaf do?

4 Which of the tissues can make food? Give a reason for your answer.

5 In which part of a leaf is most of the food made?

The leaves, stems and roots of plants are called organs.Organs are made of more than one kind of tissue.

Why do leaves have veins?

Plants use veins to transport substances. Veins are made oftwo main kinds of tissue. The first is called xylem tissue.(You say this word ‘zy-lem’.)

In xylem tissue, there are rows of dead cells with the endsmissing. They form a long tube like a drinking straw. Water travels up xylem tissue from the roots.

Look at the drawing of xylem tissue.

6 What else besides water travels from the roots to thestems and leaves through the xylem tissue?

7 Xylem tissue also does another job. What do you think this job is?

REMEMBER

Only plant cells which havechloroplasts can use light energy to make food.






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The second kind of tissue is called phloem. (You say this word ‘flo-em’.)

Look at the drawing of phloem tissue.

8 Write down two differences between xylem andphloem tissue.

Phloem carries sugar from where it is made to other partsof the plant.

9 a Which part of a plant does phloem carry sugar from?

b Where does phloem carry sugar to?

Where are the transport tissues?

10 Copy the drawings of slices of a root and a stem. Then colour in the tissue which transports water.Use a different colour for the tissue which carries sugar. Add a key to show what your colours mean.

sugar from leaves

sugar to storage organsand growing regions

cytoplasm

end wall likea sieve

nucleus

epidermis(skin)

xylem

phloem

Phloem tissue is made of living cells.

Slice of a root. Slice of a stem.

chloroplast

Cell is dividing.

Wall made of woodymaterial –the rest of this cell isdead.

starchgrain

DC

A B

Nucleus hasdividedinto two.

What you need to remember

The cell for the job!There is nothing new for you to remember in this section.

What other kinds of plant cells are there?

Other plant cells do other jobs. We say that they arespecialised to do particular jobs.

11 What do you think each of the cells on the right is specialised to do? Choose from:

supportstoragemaking new cellsphotosynthesis (making food).

Give a reason for each answer.

You need to be able to look at a cell and work out its job like you did in question 11.






ideas you need from ks3 what are our bodies built...

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