Name:
Cells
Practice sheet
A2 Building blocks
Homework
HELP
1 a Copy the diagram of a plant cell below.
b Add labels to name each part shown.
c One very important part of the cell has been missed off the
diagram. Draw it in and label it.
d One part of the cell looks green under a microscope.
i
Which part looks green?
ii What makes it look green?
CORE
2 a Copy and complete the table below to compare plant cells
and animal cells. (Do not include stored food.)
Structures found only in
plant cells
Structures found in both
plant and animal cells
b Write sentences to explain the function of the following
parts of a cell:
i
cell membrane
ii nucleus.
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
Sheet 1 of 2
A2
Building blocks (continued)
Homework
EXTENSION
These questions are about how microscopes have helped to
develop our modern understanding of how living things work.
Read the passage, and then answer the questions about it.
In the early seventeenth century, people thought that an animal or plant had to be
complete to be alive. If you cut off a flower and stood it in water in a vase, for example,
it was no longer alive. This idea was called vitalism. We do not believe this idea now,
partly because microscopes have enabled us to see parts of living things that are too small
to be seen with the naked eye.
In 1670, a Dutchman called Antoni von Leeuwenhoek made a microscope with just one
lens. He could look at objects such as the legs of flies and butterfly wings with it.
Scientists thought it was a wonderful invention. A few years later a British scientist
called Robert Hooke added a second lens, so making the first compound microscope.
This could magnify things even better, and it allowed him to see that cork is made from
tiny boxes, which he called cells. All these microscopes are light microscopes, because
they work by shining a light up through the specimen on the microscope stage, into the
lens and eventually into our eye.
In the nineteenth century, Matthias Schlieden and Theodor Schwann looked at hundreds
of animals and plants and found that they were all made from cells. Schwann also
discovered that cells could divide to make new cells. This showed that cells are alive, so
the old vitalist theory was disproved. In 1858, Rudolph Virchow stated a new theory.
Virchow’s theory says: ‘Every animal (and plant) appears as a sum of its vital units, each
of which bears in itself the complete characteristics of life.’
Nearly one hundred years later, in 1932, a German engineer called Ernst Ruska built the
first electron microscope. This uses electrons instead of light, and can reach very high
magnifications. Now it is possible to see right inside cells to look at the fine detail of the
parts they contain and which make them work.
3 What makes a compound microscope different from the one
built by Antoni von Leeuwenhoek?
4 Why does a specimen need to be thin to see it under a light
microscope?
5 Who discovered that cells can reproduce to make new cells?
6 Why do you think that Robert Hooke is considered to be an
important figure in the world of animal and plant science?
7 Rudolph Virchow talked about ‘vital units’ in his theory. What
do you think we would call these ‘vital units’ today?
8 After Robert Hooke invented the first compound microscope,
it was another hundred years or so before scientists stated a
new theory about cells. Suggest two reasons why it might
have taken them so long.
9 A light microscope has an eyepiece lens of ×10 magnification,
and three objective lenses of ×10, ×50 and ×100. Calculate
the magnification produced by each combination of eyepiece
and objective lenses. Show your working.
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
Sheet 2 of 2