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Cell theory
The microscope was invented in about 1590 by a Dutch spectacles maker called Zacharias Janssen.
As microscopes have become more powerful, scientists have learnt more about cells. Robert Hooke
(1635-1703)
was an English scientist who first saw and drew the shapes of some dead plant cells.
In 1665 he published his discovery in a book (Micrographia)
so that others could see what he had
found.
Franz Meyen (1804-1840)
was a German scientist. He read Hooke's book and did observations of
his own. He found that the insides of living plant cells contained chloroplasts. Smaller parts found
inside a cell are called organelles.
Robert Brown (1773-1858),
a Scottish scientist, first observed another organelle in the cells of
orchid plants - the nucleus. In 1833 he wrote a 'paper' about it. A paper is an article describing a
scientific discovery and how it was made. Papers are collected together and published in 'journals'.
Scientists buy journals to find out what other scientists have done. One famous journal today is
called Nature.
Matthias Schleiden (1804-1881),
a German scientist, read Brown's paper and did many careful
observations. He found that there were nuclei in all plant cells.
In 1838 Schleiden was having dinner with his friend Theodor Schwann (1810-1882).
Schwann about his discovery. Immediately
He told
Schwann went back to his lab and looked at some
slides of animal tissue. He saw nuclei, and when he looked very closely he could just about see
the cell surface membranes. He had discovered that animals also had cells. This led him to write
a book in which he described cell theory - his theory that all living things are made of cells. (A
theory is a scientific idea that can be tested by doing experiments.)
1 a What are organelles?
b In what part of a cell are organelles found?
c What organelle do plant cells have that animal cells do not?
d What organelle do both plant and animal cells have?
2 a In the passage there are three ways in which the scientists shared information.
What are
these three ways?
b How else might scientists share information
today?
3 a In what year were plant cells discovered?
b In what year were animal cells discovered?
c Why do you think animal cells were discovered after plant cells?
4 a What is the 'cell theory'?
b Do you think that scientists still believe this theory today?
c Why do you think this?
I CAN... • describe what
the cell theory is • recall what an organelle is
• obtain relevant information from texts • describe how science is communicated.
Exploring Science
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© Pearson Education Limited 2008
Shaped for the job
Name
_
Class
_ Date
_
Cells are different shapes because they do different jobs.
Draw lines to match up each picture with the name of the cell and its job. One has been done for you.
Picture
Name
Job
muscle cell
strands wave
about to move
things
root hair cell
it can change
length
ciliated
epithelial cell
it takes water
from the soil
palisade cell
it carries
signals
nerve cell
it has lots of
chloroplasts to
help the plant
make food
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I CAN... • recognise
that cells can have different shapes depending on their functions
• describe the functions of some specialised cells.
Exploring Science
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© Pearson Education Limited 2008
Cell division
Name
_ Class
Date
_
_
1 Is it living? Complete the questions we ask to see if something is living using words from the box
below. Use each word only once.
I
energy
excrete
a Can it
grow
move
nutrition
reproduce
sense
I
itself or parts of itself?
b Does it need
(food)?
c Can it
(get rid of waste substances)?
d Can it
(make more organisms just like itself)?
e Can it
what is happening and react?
f Can it respire using food and oxygen for
9 Can it -----------
?
bigger?
2 Complete the sentences by unscrambling the words in the ovals.
a For whole plants and animals to get bigger, they need to make more
c
e
\
b Plants and animals make more cells by cell
_
.
,
I
.
n
c When a cell divides, the two new cells are called
cells.
u
d
r
I CAN... • recall the seven life processes • describe what happens in cell division.
Exploring Science
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© Pearson Education Limited 2008
Different (ells for different jobs
Name
_
Class
_
Date
_
Draw lines to match the pictures of cells with their correct names and jobs. The drawings are not
to scale.
palisade cell
can carry
signals around
the body
root hair cell
carries oxygen
white blood
cell
used by plants
to reproduce
nerve cell
helps your
body defeat
diseases
red blood cell
takes in water
pollen grain
has cilia that
can move
things
ciliated
epithelial cell
makes food for
a plant
I CAN... • recognise
that cells can have different shapes depending on their functions
• describe the functions of some specialised cells.
Exploring Science
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.
© Pearson Education Limited 2008
Human organs 1
Name
Class
_
Date
_
Match up the picture of the organ with its name and its job. One of these has been done f~r you.
Picture
I (AN...
Exploring Science
Name
Job
lungs
controls the
body
brain
for breathing
liver
pumps blood
heart
makes and
destroys
substances
intestines
breaks up food
stomach
breaks up food
and digests it
• recall the names and functions
~edition
1
of some human organs.
© Pearson Education Limited 2008
Organ parts
Name
~--
1
Class
_
Date
_
2
4
Down
Across
1 The job of the heart is to
2 The heart is made up of nerve, fat and
_
tissue.
_
blood around the body.
3 The heart is made up of different
4 The heart has some
tissue
in it.
2 a Draw lines from the plant to the correct label.
A root
B stem
C leaf
b Which organ holds the plant in place?
I CAN... • recall the names and functions
Exploring Science
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edition
_
of some organs • recall what organs are made of.
2
© Pearson Education Limited 2008
How fossil fuels were made
1 Cut out all the boxes. Sort out the pictures and statements into the ones that apply to:
a oil and gas b coal.
2 Put the pictures and statements in order, and stick them into your book.
I CAN... • describe
A
how fossil fuels were formed.
c
B
.'
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oil and gas
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...
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More layers of the
mud squashed
the fossils. Heat
from inside the
Earth turned the
mud into rock and
turned the plant
fossils into coal.
The plants and
animals fell to the
sea bed when
they died and got
buried in mud and
sand. The mud
stopped them
rotti ng away .
••
~--------------+--------------+--------------+--------------i
K
J
When the plants
died they were
buried in mud.
The mud stopped
them rotting away.
Exploring Science
~edition
Coal was formed
from dead plants
that lived long
ago.
Oil and gas were
formed from tiny
plants and animals
that lived in the
sea millions of
years ago.
371
L
More layers of
mud buried the
dead animals, and
they turned into
oil and gas. The
oil and gas get
stuck under a layer
of caprock which
will not let them
through.
© Pearson Education Limited 2008
Fossil fuels 1
Name
_
Class
_ Date
_
Some of these statements about fuels and energy are true and some are false.
Tick the boxes to show which statements are true and which are false.
Write a correct version of each false statement.
True
lOur
00
bodies need fuel.
2 Living sustainably means harming the things around you.
3 Using energy resources may be contributing
False
to global cooling.
·0 0
00
4 Natural gas, oil and electricity are fossil fuels.
0 0
5 Coal is formed from the remains of plants.
0 0
6 Oil and natural gas take hundreds of years to form.
00
7 Fossil fuels are renewable fuels.
0 0
8 Oil is the fossil fuel that will run out first.
0 0
9 Electricity is not a fuel because it is made using other fuels.
0 0
10 Oil is a called a fossil fuel because it has fossils in it.
0 0
I CAN... • recall what
fossil fuels are and how they were made
• recall what renewable and non-renewable resources are.
Exploring Science
~edition
372
© Pearson Education Limited 2008
--
Energy resources
Name
_
Class
_ Date
_
1 Underline three renewable energy resources:
coal
oil
biomass
wind
natural gas
hydroelectric power
2 The missing words in these statements are shown jumbled up at the end of each statement.
a Nuclear power stations use a metal called
. (um a ruin)
b Uranium is dangerous because it can cause illnesses like
_
(can rec)
c Renewable energy resources will
run out. (nerve)
d Solar cells turn energy from the Sun directly into
e A
. (tricycle tie)
can be powered by a solar cell. (ocular talc)
f Solar panels can be used to provide
to homes. (wheat rot)
9 Solar power can be used to generate
to turn water into
if the heat from the Sun is used
. (eelcityric, meats)
h A biomass fuel is one made from
or
waste.
(st plan, laminas)
Wood is an example of a
fuel. (aim boss)
j Geothermal power uses the heat from underground
. (corks)
k There are not many hydroelectric power stations in the UK because we do not have many
high mountains with trapped
. (we rat)
I CAN... • give some examples of non-renewable
Exploring Science
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and renewable energy resources.
© Pearson Education Limited 2008