in this bundle there are more than 5000 aqa a level biology questions and if you do every question and memorise the mark scheme you will get that A* without a doubt
(a) In a study of one population of moose, 72 animals were trapped and marked with ear tags.
They were then released. One month later, fieldworkers examined 120 moose and found
that 14 of these had ear tags.
Use these figures to calculate the size of the moose population. Show your working.
Answer:............................
(2)
(b) Isle Royale is a large island in Lake Superior. Moose first colonised this island in 1900. At
the time they had no predators on the island. Wolves, which are predators of moose, were
introduced to the island in 1950. The graph shows the moose population from 1900.
I s la n d c o lo n is e d W o lv e s
b y m oose in tro d u c e d
3000
2000
M oose
p o p u la tio n
1000
0
1900 1910 1920 1930 1940 1950 1960 1970
D a te
(i) Suggest an explanation for the changes in the moose population before the
introduction of the wolves.
2. Spruce trees produce very large numbers of seeds. Most of these seeds die immediately,
releasing nitrogen compounds into the soil. Swedish scientists investigated the effects of this on
the growth of pine seedlings, in areas where the forest floor was free of moss plants and in areas
where moss plants grew.
(a) Describe the part played by soil bacteria in making the nitrogen in compounds in the dead
spruce seeds available to pine seedlings.
(b) In areas where the forest floor was free of moss plants, the pine seedlings grew better in
plots with added spruce seeds than they did in control plots. In areas in which moss plants
grew, the difference in growth of the pine seedlings in plots with added spruce seeds was
not statistically significant from those in the control plots. Suggest an explanation for the
effect of the moss plants on the growth of the pine seedlings.
(b) The contours on the graph represent 0%, 50% and 100% survival for C. septemspinosa in
aerated water over a range of temperatures and salinities (salt content of sea water).
30
5 0 % s u rv iv a l
25 0%
s u rv iv a l
T e m p e ra tu re 20
/ °C 1 0 0 % s u rv iv a l
15
10
5
0 5 10 15 20 25 30 35 40 45
P e rc e n ta g e s a lin ity
(i) What are the upper and lower limits of temperature for 100% survival of
C. septemspinosa?
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