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A Levels Biology Ch 1-Cell Structure
Exam Questions with Answers
1
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The use of electrons as a source of radiation in the electron microscope allows high resolution to be
achieved because electrons:
A are negatively charged
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C have a very short wavelength
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Answer: C

3
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Complete the following table, which compares light microscopes with electron microscopes
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List ten structures you could find in an electron micrograph of an animal cell which would be absent
from the cell of a bacterium
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nucleus
2
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chromosome

4
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Golgi body
6
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nucleolus
8
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vacuole
10
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Distinguish between the following pairs of terms:
a) magnification and resolution
Answer:
Magnification is the number of times larger an image is compared with the real size of the object
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The greater the resolution, the
greater the detail that can be seen
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c) nucleus and nucleolus
Answer:
Both are organelles found in eukaryotic cells
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The
nucleus controls cell activity while the nucleolus makes ribosome
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d) chromatin and chromosome
Answer:

chromatin and chromosomes both contain DNA and are both found in nucleus
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Chromatin is the form that exists between cell divisions while
chromosomes are formed just before cell division
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Membranes are found in all cells, while envelopes are only in
eukaryotes
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And both are found spreading through cytoplasm of
eukaryotic cells
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smooth
ER makes lipids and steroids while the rough ER transports proteins made by ribosomes on its surface
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prokaryotes are smaller and have few
organelles while eukaryotes have many organelles with division of labor; eukaryotes evolved from
prokaryotes
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List:
a) three organelles each lacking a boundary membrane
Answer: nucleolus, ribosome, centrioles

b) three organelles each bounded by a single membrane
Answer: lysosomes, rough ER, smooth ER, Golgi body

c) three organelles each bounded by two membranes (an envelope)
Answer: nucleus, mitochondrion, chloroplast

8
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a) manufactures lysosomes
Answer: Golgi body;

b) manufactures ribosomes
Answer: nucleolus;

c) site of protein synthesis
Answer: ribosome;

d) can bud off vesicles which form the Golgi body
Answer: ER / rough ER;

e) can transport newly synthesised protein round the cell
Answer: rough ER;

f) manufactures ATP in animal and plant cells
Answer: mitochondrion;

g) controls the activity of the cell, because it contains the DNA
Answer: nucleus;

h) carries out photosynthesis
Answer: chloroplast;

i) can act as a starting point for the growth of spindle microtubules during cell division
Answer: centrosome (accept centriole);

j) contains chromatin
Answer: nucleus;

k) partially permeable barrier only about 7 nm thick
Answer: cell membrane;

l) organelle about 25 nm in diameter
Answer: ribosome / microtubule

9
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Explain why
some of the mitochondria in the electron micrograph below appear roughly circular
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b) The figure below shows a diagram based on an electron micrograph of a secretory cell from the
pancreas
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Some of the proteins are digestive
enzymes of the pancreatic juice
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The arrows show the
route taken by the protein molecules
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Answer:
A protein made on the ribosome is moving into the rough ER
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Vesicles fuse to form the Golgi body
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D Golgi vesicles travel to cell surface membrane, where they fuse with cell surface membrane and are
secreted by exocytosis
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Answer: ribosome
iii) Through which structure must the molecule or structure you named in ii pass to get through the
nuclear envelope?
Answer: nuclear pore
iv) Name the molecule which leaves the mitochondrion in order to provide energy for this cell
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One technique used to investigate the activity of cell organelles is called differential
centrifugation
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This makes organelles sediment (settle) to the bottom of the tubes
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By repeating the process at faster and faster speeds, the
organelles can be separated from each other according to size
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The centrifuge was spun at 1000 g, 10 000 g or
100 000 g (‘g ’ is gravitational force)
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Suggest why this makes it difficult to study mitochondria
using the differential centrifugation technique
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We therefore cannot be sure whether effects due to mitochondria or lysosomes
in any experiments

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