a ppt on biolscirev synopsis

1. Skins and synopsis
Bill Indge

2. Synopsis
Synopsis
The material in this presentation is designed to encourage students to think
about synopsis. The idea behind synoptic questions is to assess students’
understanding of the general principles on which so much of the subject
depends, which is much more important than simple recall of knowledge.
This presentation supports the article ‘Tales from the museum’ by Henry McGhie
in the April 2014 issue of Biological Sciences Review. The presentation is based
on three different exercises; these may be used independently.
The questions and the accompanying mark schemes are available as a separate
Word document.

3. Synopsis
Synopsis is about
• understanding the principles
Taking diffusion as an example, all specifications consider this
topic relatively early in the AS course. An understanding of
diffusion is essential to the understanding of a number of
topics considered later in the course.
Diffusion
Nerve impulses
Gas exchange
Digestion

4. Synopsis
Enzymes
?
Synopsis is about
• understanding the principles
Another such topic is enzymes. Students might wish to think
about specific enzymes that link to different aspects of
physiology.
?
?

5. Synopsis
Acetylcholinesterase
Carbonic
anhydrase
Amylase
Synopsis is about
• understanding the principles
Enzymes

6. Synopsis
What are these principles?
• Diffusion
• Enzymes
• Polymerisation, condensation and hydrolysis
• Osmosis
• Active transport
• Respiration and ATP
• Size and surface-area-to-volume ratio
• Natural selection
• How science works …
?

7. Synopsis
Synopsis is like a
birthday present.
You may not recognise
the wrapping paper but
you know exactly what
is inside.

8. Synopsis
You may not be familiar
with the context but you
should know all about the
principles on which the
question is based.
You may know nothing
about snails…but the
question may be asking you
about selection or
respiration.
Synopsis is about
• relating the principles to new contexts

9. Synopsis
You may know nothing
about possums…but the
question is asking you
about ‘how science works’
and surface-area-to-volume
ratios
You may not be familiar
with the context but you
should know all about the
principles on which the
question is based.
Synopsis is about
• relating the principles to new contexts

10. Synopsis
• Brush-tail possums are
mammals that are native to
Australia.
• They were introduced to New
Zealand mainly in the years
1890 to 1900.
• The total number of possums
released was between 200
and 300.
• Possums are now widespread
in New Zealand and, in
suitable habitats, reach
population densities of up to
30 animals per hectare.
Possums

11. Synopsis
Location Latitude Total length/mm Tail length/mm
Auckland 36°37’ 786 321
Hawke’s Bay 39°43’ 787 322
Wairurapa 40°54’ 780 297
Orongorongo Valley 41°22’ 789 328
Nelson 41°55’ 831 356
Taramakau River 42°45’ 840 n/a
Lengths of male possums from
different parts of New Zealand

12. Synopsis
1(a) The measurements in the table were obtained from
labels attached to museum skins. It would not be reliable
to measure the actual skins. Suggest why. (2 marks)
The process of preparation is likely to lead to a change in length
of the actual skin;
May be stretched/may shrink (as it dries);

13. Synopsis
1(b) Suggest why all the data were collected from
animals of one sex. (2 marks)
Ensures that the data will be comparable;
Because sex is likely to influence size;

14. Synopsis
2 How would you expect mean annual temperature to
vary with latitude? (1 mark)
Mean annual temperature should decrease with latitude;

15. Synopsis
3 The scientists who collected the data in the table
predicted that body size would be positively correlated
with latitude.
(a) Suggest why larger body size would be an advantage
to a possum further south. (3 marks)

16. Synopsis
0 1 2 3 4 5 6
Side length
6
5
4
3
2
1
0
Surface-area-
to-volume
ratio

17. Synopsis
3 The scientists who collected the data in the table
predicted that body size would be positively correlated
with latitude.
(a) Suggest why larger body size would be an advantage
to a possum further south. (3 marks)
A larger animal would have a smaller surface-area-to-volume
ratio;
Would lose less heat;
In colder conditions;

18. Synopsis
Evaluate means judge the worth of something.
• Look for ways in which the data support the prediction.
• Now write the word but
• And look for ways in which the prediction is not supported by
the data.
3 The scientists who collected the data in the table
predicted that body size would be positively correlated
with latitude.
(b) Use the data in the table to evaluate this prediction.
(3 marks)

19. Synopsis
Location Latitude Total length/mm Tail length/mm
Auckland 36°37’ 786 321
Hawke’s Bay 39°43’ 787 322
Wairurapa 40°54’ 780 297
Orongorongo Valley 41°22’ 789 328
Nelson 41°55’ 831 356
Taramakau River 42°45’ 840 n/a
Lengths of male possums from
different parts of New Zealand

20. Synopsis
There is a positive correlation between total length and
latitude/total length increases with latitude;
(but)
If tail length is subtracted from total length;
There is little/no correlation between body length and latitude;
Other factors/factors such as altitude may also affect mean
temperature; 3 max
3 (b) Use the data in the table to evaluate this
prediction. (3 marks)

21. Synopsis
You may know nothing
about peregrines or
sparrowhawks…but the
question is asking you about
‘how science works’ and
food chains and food webs
You may not be familiar with
the context but you should
know all about the principles
on which the question is based.
Synopsis is about
• relating the principles to new contexts
Eggs and pesticides

22. Synopsis
Egg shell
thickness
index
1900 1920 1940 1960 1980
Date
1 Organochlorine insecticides in common use to treat crops
2 Organochlorine insecticides used to treat seeds
3 Partial ban and reduced use of organochlorine insecticides
2.0
1.6
1.2
0.8
Peregrine
Sparrowhawk
1 2 3

23. Synopsis
The eggs are museum specimens/valuable/cannot be
replaced;
The index does not involve breaking them/measuring the
thickness involves breaking them;
1 The egg shell thickness index was calculated from the
formula:
thickness index = mass of egg shell (mg)
length × breadth of egg (mm)
(a) Suggest why this index was used rather than
measuring the actual thickness of the egg shell. (2 marks)

24. Synopsis
1 The egg shell thickness index was calculated from the
formula:
thickness index = mass of egg shell (mg)
length × breadth of egg (mm)
(b) The mass of the egg shell was divided by its length ×
breadth. Explain why it was necessary to divide by the
length × breadth. (1 mark)
The mass of the egg shell will depend on the size of the
egg/length × breadth gives a measure of the egg size;

25. Synopsis
2 Both the peregrine and the sparrowhawk feed on
birds. Use your knowledge of food chains and food webs
to explain:
(a) how organochlorine insecticides used to treat seeds
enter the tissues of a sparrowhawk (1 mark)
(b) why the concentration of organochlorine insecticide
in the tissues of a peregrine falcon is much higher than
the concentration on the seeds (2 marks)

26. Synopsis
The food chains involved in this question
Seeds  Wood pigeon  Peregrine falcon
Seeds  Chaffinch Sparrowhawk

27. Synopsis
(Transfer through the food chain) via an intermediate seed-
eating bird/appropriate example;
2 Both the peregrine and the sparrowhawk feed on
birds. Use your knowledge of food chains and food webs
to explain:
(a) how organochlorine insecticides used to treat seeds
enter the tissues of a sparrowhawk (1 mark)

28. Synopsis
Insecticide taken up by primary consumer/example from
part (a) and accumulates/not broken down in tissues;
Primary consumer eats many seeds so higher concentration in
its tissues;
Process repeated in secondary consumer; max 2
2 Both the peregrine and the sparrowhawk feed on
birds. Use your knowledge of food chains and food webs
to explain:
(b) why the concentration of organochlorine insecticide
in the tissues of a peregrine falcon is much higher than
the concentration on the seeds (2 marks)

29. Synopsis
3 In a scientific paper published in 1977, the biologist
R. K. Murton pointed out that many biologists assumed
egg shell thinning was harmful. They considered that if
a population lays eggs with thin shells and at the same
time is declining, there must be a causal relationship.
(a) Suggest how egg shell thinning may lead to lower
breeding success. (1 mark)
Eggs with thinner shells are more likely to be broken
(during incubation).

30. Synopsis
(b) Explain why a decline in number of birds may not
necessarily be caused by egg shell thinning. (2 marks)
Another factor may be involved;
Which might be linked to both decline in birds and egg-shell
thinning;

31. Synopsis
You may know nothing
about tigers…but the
question is asking you
about selection,
mitochondria and DNA.
You may not be familiar with
the context but you should
know all about the principles on
which the question is based.
Synopsis is about
• relating the principles to new contexts
Tigers

32. Synopsis
1 Preservation of genetic variability in rare or
endangered species may help them to survive. Use your
knowledge of natural selection to explain why. (2 marks)
Some forms may be at an advantage/be better adapted;
If there is a change in the environment of the organism;

33. Synopsis
2 In order to assess tiger genetic variation, it was
important that samples were taken from tigers that
originally came from different geographical areas.
Explain why it was important that these tigers did not
come from the same geographical area. (2 marks)
If they came from the same area they would be more likely to
be genetically similar;
Because they might be related/might be adapted to similar
conditions/might have had the same ancestors;
We need to know about all tigers; max 2

34. Synopsis
3 The mutation rate in mtDNA is faster than that in
nuclear DNA because of differences in the DNA repair
systems. Suggest how these differences could result in
a slower mutation rate in nuclear DNA. (2 marks)
Mutations in nuclear DNA may be removed/repaired (by the
repair system);
System only found in nucleus/not found in mitochondria;

35. Synopsis
4 If a tiger was born in a zoo, it may be useful to know
the origin of the female parent if its mtDNA is to be
studied. Explain why. (2 marks)

36. Synopsis
Male
gamete
Zygote
Female
gamete
Chromosomes
and cytoplasm
Chromosomes

37. Synopsis
This will tell you the geographical origin of its mtDNA;
Because it is inherited from its mother;
4 If a tiger was born in a zoo, it may be useful to know
the origin of the female parent if its mtDNA is to be
studied. Explain why. (2 marks)

38. Synopsis
5 Suppose there were five sites on an mtDNA molecule
where it could be cut by the restriction enzyme. How
many pieces of DNA would result? Explain your answer.
(2 marks)
Five;
Because mtDNA is circular;

39. Synopsis
6 A polymorphic site is a site on a DNA molecule where
the sequence of bases is different in different animals.
(a) A particular restriction enzyme may cut the DNA
from one leopard but not from another at a particular
site. Explain why. (3 marks)
Sequence of bases is different;
Only a specific sequence fits/binds;
With active site of a particular enzyme;

40. Synopsis
50
40
30
20
10
0
Number
of
polymorphic
sites
for
this
enzyme
(b) Explain how the graph supports the
suggestion that the tigers that are alive
today have descended from very few
animals. (3 marks)

41. Synopsis
50
40
30
20
10
0
Number
of
polymorphic
sites
for
this
enzyme
(b) Alleles/different forms of gene may be lost
from population as it gets smaller;
Tigers descended from this population will have
little genetic diversity;
Graph shows no polymorphic sites;
10 000 years is a short time so few mutations
producing differences in DNA; max 3