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
(c) Mud higher up the shore receives fresh water draining from the
land. Ragworms are able to survive in this mud because they can
tolerate the absorption of water into their tissues. Explain what
causes a ragworm to absorb water when higher up the shore.
66. The drawings show two dogwhelks taken from two different
populations. Dogwhelk A came from a sheltered shore and dogwhelk B
from a shore exposed to heavy wave action. The dogwhelks attach
themselves to rocks with a muscular foot which comes out through the
aperture. The shell length : aperture length ratios (L/A) were
calculated. The mean and standard deviation for each population are
,shown under the drawings.
mean L/A ratio = 1.91 mean L/A ratio = 1.78
standard deviation = 0.19 standard
deviation = 0.10
, (a) Describe how you would collect a random sample of each
population.
(b) What do the standard deviations tell you about the two
populations of
dogwhelks? .....................................................................................
................................................
(ii) the standard
deviations. .........................................................................
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