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Cells Homework 1
1. What is a cell?
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2. List the five structures found in an animal cell.
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3. The diagram below shows a plant cell.
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a) Which three arrows point to structures which are found in plant cells and not animal
cells?
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b) Which arrow is pointing to the mitochondria?
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c) What is the function of the mitochondria?
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4. Carefully read the following passage.
The living part of every plant cell is neatly packaged within a plant cell wall. The chief
chemical substance of a plant cell wall is cellulose. However, plant cell walls are not made
up of cellulose alone. Plants have developed a cell wall which is complicated. The cell
walls of a growing plant are built up from at least six different sugars; at least two
structural proteins; about twenty different enzymes and small quantities of many other
substances. Cell walls are complex structures and this complexity must be important to
plant life. Cell walls, therefore, must not be seen simply as “cardboard boxes”.
Cell walls can be removed from plant cells by treating the cells with appropriate digestive
enzymes in sugar solution. The resulting cells, now without their walls, can remain alive
for several days and are called protoplasts. They differ from the original cell in several
ways, including;
1) Neighborliness – they are freely floating independent cells instead of being organised
together in tissue;
2) Size – they have no fixed volume. When put into pure water, they swell and burst.
Normal plant cells cannot swell beyond a certain size when placed in pure water.
The diagrams below show the structure of a normal leaf cell and a protoplast
Answer the following questions which relate to the passage.
a) Identify three components of a plant cell wall.
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b) When making a protoplast, what does the digestive enzyme do?
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c) Why should cell walls not be thought of as “cardboard boxes”?
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d) What is a protoplast?
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