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Data analysis review packet.
1. Scientists examined the teeth of a group of related species of cichlid fishes in Lake
Tanganyike, Africa, to determine their evolutionary relationship. The group
contained six species from two genera, Perissodus and Haplotaxodon. The chart
shows the number of teeth per jaw of these two species and indicates whether each
is adapted to feed in shallow water or deep water. Species from the genus
Perissodus are known for their unique feeding habit of eating the scales out of other
fish.
a. Using the information on the graph above, state the mean number of teeth on the
upper jaw of P. straeleni. (1 point)
15 teeth
b. Using the information on graph above, compare the teeth on the upper and lower
jaw of P. elaviae and P. hecqui (2 points).
The mean number of teeth on the upper jaw of P. elaviae is lower (17) compared to
the P. hecqui (29). But P. hecqui has a larger standard deviation.
The mean number of teeth on the lower jaw of P. elaviae is lower (26) compared to
the P. hecqui (31). Again, P. hecqui has a larger standard deviation.
There is no significant difference between the number of teeth on the lower jaw of
the two species due to over lapping error bars.
c. Using your own knowledge of evolution to answer this question. P. elaviae and H.
microlepis both evolved from a common ancestor. Suggest how they became different
species. (3 points)
Gene pools of the two populations must become separated for speciation to occur.
The two populations must have become reproductively isolated as a result of
behavioural, temporal or geographic isolation.
2. Hummingbirds have long narrow beaks that have adapted to collect nectar from
flowers. Nectar provides energy in the form of sugar, but has very low
concentrations of other nutrients. Therefore, hummingbirds also have to catch flying
insects in order to have a balanced diet. They catch the insects by flying with their
beaks wide open towards the insects. Scientist have used high-speed video to study
the success rate for catching insects. The pie charts below show the results,
according to which part of the beak the insect touches first.
a. Using the information in the graphs above, which part of the beak first touched
by insects, is the most likely to result in the hummingbird eating the insect? (1
point)
The closer to the base the insect touches the higher the success rate.
Birds that feed only on insects have a different shape of beak from the
hummingbirds.
b. Use your knowledge of evolution to predict, with a reason, the shape of beak in
a species of bird that feeds only on flying insects. (2 points).
Short or wide shape BECAUSE longer beak does not increase the chance of
catching insects. Wide beak gives a greater chance of catching insect or decreases
to chance of dropping/losing the insect once it has been caught. The beak will be
larger so there is more chance of catching the insect.
Hummingbirds also beat their wings really fast to keep their bodies steady near a
flower while it collects the nectar. This unusual flight behaviour is called hovering.
Scientists took measurements to investigate hovering in four different hummingbird
species. The body mass and maximum frequency of wing beats were measured. The
velocity of the wing tips was measured when the wings were beating at their
maximum. The mean results are shown in the table below.
c. Use the data in the table as part of your answer to this question. State the
relationship between body mass and maximum frequency of wing beats. (1
point).
There is a negative relationship, the lower the wing beat frequency the greater
the body mass.
d. Hummingbirds are the smallest birds in the world, with adult masses ranging
from approximately 2g to 20g. Using the data in the table and your own
knowledge, suggest a possible reason why hummingbirds with a mass above 20g
have not evolved. (1 point).
Larger the body mass the lower the maximum frequency of wing beats per
second. It is likely that hummingbirds over 20g would not be able to hover.
3. Yeast is a microorganism. The yeast species Metschnikowia bicuspidate is a parasite
of a species of zooplankton Daphnia dentifera. Biologists monitored the infections of
D. dentifera population in a series of lakes in Indiana (USA). An increase in nitrogen
compounds dissolved in the lakes causes the phytoplankton populations to increase.
D. dentifera feed on phytoplankton.
The graph shows the:
 Relationship between nitrogen levels dissolved in the water and the size of
the parasite epidemic in the D. dentifera population.
 Relationship between the size of the parasite epidemic in the D. dentifera
population and the change in resistance (established by comparing the
infection of the D. dentifera populations before and after the epidemic).
d. Using the information on ONE of the graphs above, state the value of the change in
resistance to the parasite when the parasite epidemic size is 14 arbitrary units. (1 point)
0.0 arbitrary units. (although answers between -0.05 and +0.05 are also acceptable)
e. Using the information on BOTH graphs, suggest a possible relationship between total
nitrogen and parasite epidemic size. (1 point)
As the levels of nitrogen increase so does the epidemic size. There is a positive correlation.
f.
Using your own knowledge about the theory of NATURAL SELECTION, outline how
an increase in the size of the parasite epidemic in the D. dentifera will result in the
evolution of increased resistance to the parasite. (2 points)
High epidemic sizes are associated with high populations of D. dentifera.
The greater the population size of D. dentifera, the more likely there will be genetic
variation/mutations in the population.
Some of the variations may include greater resistance to the parasite, the resistant
individuals have a greater chance of reproducing and passing on the resistance gene to
the next generation.
Predatory fish tend to eat infected D. dentifera more than uninfected D. dentifera.
g. Using your own knowledge of evolution and natural selection, predict the effect the fish
predators may have on the level of resistance to the parasite in the D. dentifera populations.
(2 points)
The number of resistant D. dentifera will increase because the fish will be eating those
infected. This will reduce the epidemic over time.
4. Obesity (excessive weight) is recognised as a global health problem and has been
correlated with a large number of health issues, diseases and deaths. Fructose is
widely used as a sweetener in many foods and drinks and has been linked to an
increase in obesity.
In a study, mice were divided into four groups. Each group was given the same
amount of food and either a soft drink with a different sweetener or water.
h. Using the graph above, describe the overall trend in body fat accumulation for the four
groups of mice. (1 point)
All four group accumulated fat over time.
i.
Using the graph above, suggest compare the body fat accumulation between the four
groups of mice. (2 points)
Body fat accumulation increased over time for all four groups.
Fructose caused the most accumulation of fat AND water caused the least.
Sucrose and artificial sweetener/diet soft drink had the same increase.
Sucrose, artificial sweetener and water did not start accumulating fat until 20 days while
fructose increased from the beginning.
As it has been shown that high triglyceride (a type of fat) levels correlate to obesity,
another study was undertaken with humans. Over a ten-week period, one group was
given glucose-sweetened drinks and the other fructose-sweetened drinks.
Triglyceride levels in blood were measured throughout the study.
j.
Using the information in the graph, compare the results for glucose-sweetened drinks
and fructose-sweetened drinks over the 10-week period. (2 points)
Glucose fed group has little/no increase in triglycerides while fructose fed group has a large
increase.
Glucose fed group has more consistency compared to the fructose fed group.
More triglycerides in the fructose fed group than glucose fed group from week 2 to 10.