NCEA Level 2 Science (90772) 2010 — page 1 of 2
Assessment Schedule – 2010
Science: Describe the factors and processes involved in the evolution of New Zealand’s
plants and animals (90772)
Evidence Statement
Question
ONE
TWO
Achievement
Achievement with Merit
Achievement with Excellence
Identified different defence
mechanisms at TWO of the three
life stages:
TWO defence mechanism
described and explained in
relation to that predator.
• young seedling – camouflage /
hard to see
• young tree – unpalatable /
difficult to eat / chew
• adult tree – too high.
Colour of seedling same as
background so predator could not
see the seedling in order to
browse on it.
AND / OR
Young tree leaves spiky so
unappealing / too difficult for
predator to eat.
AND/OR
Adult tree leaves above reach of
browser so cannot be eaten.
Discuses and links changes in
defence mechanisms at all
THREE stages and how they
would prevent predation by the
moa, (or other herbivores)
increasing reproductive success,
(chances of passing on genes /
mating / producing offspring etc).
Founder effect described: New
population started with few
individuals and / or a different
gene pool.
AND
ONE factor that could cause a
change in either gene pool
described.
Eg:
• Mutations can lead to new traits
/ alleles being formed.
• Bottleneck is a reduction in
population size due to a large
proportion of original
population being wiped out.
• The gene pool can change due
to genetic drift / random
changes in the gene pool.
• Natural selection / selection
pressures can affect the gene
pools of both populations.
NOT
Any statement about isolation as
isolation itself does not affect a
gene pool.
Founder effect described and
TWO factors affecting gene pool
explained:
different selection pressures due
to different environmental
conditions selecting for certain
beneficial traits can change allele
frequencies.
OR
different mutations could occur in
each population and be passed on
adding new alleles to the
population.
OR
A bottleneck could occur in either
population due to a catastrophic
event causing a decrease in
population size therefore
decreasing genetic diversity.
OR
Genetic drift can have significant
effect on a small population
causing allele frequencies to
change randomly.
Eg, seedling uses camouflage so
that it can’t be seen and therefore
eaten. Those who survive to form
young trees have unpalatable
leaves that are unpleasant for the
moa to eat. These will be browsed
on less as a result. Once an adult,
the tree can have many leaves as
these are now out of the moa’s
reach and are therefore not eaten.
Having reached adulthood the tree
can reproduce, passing on the
genes for these useful defence
mechanisms.
Discuss the founder effect as
providing a small population or
non representative gene pool on
which two explained factors act.
The concept that the populations
must be genetically isolated over
a long period of time / many
generations in order for a
speciation event to occur must be
implicit in the response.
NCEA Level 2 Science (90772) 2010 — page 2 of 2
THREE
Survival of pōhutukawa limited
by harsh environmental factors.
OR
Selection pressures cause some
individuals to die out, (or others to
survive).
OR
Selection against certain alleles
reduces diversity in gene pool.
OR
Alleles selected against would be
lost from the gene pool
Plants that could not tolerate high
salt / low fresh water / strong winds
and poor soil would not survive.
AND their genes could not be
passed on to the next generation,
(become less common in the gene
pool).
OR
Plants that could tolerate high salt
/ low fresh water / strong winds
and poor soil would survive.
AND their genes would be passed
on to the next generation,
(become more common in the
gene pool).
Discusses that the gene pool of
the pōhutukawa has less diversity
due to the action of natural,
(directional), selection removing
less desirable alleles from the
gene pool as a consequence of
decreased reproductive success in
those individuals.
OR
Discusses differences or a change
in allele frequencies in the gene
pool as a result of lost alleles due
to selection and gain of alleles
due to mutation or selection.
FOUR
Identifies that:
Explains that isolation as a result
of the Southern Alps prevents
gene flow between populations.
OR
Explains that different selection
pressures on the two populations,
isolated by the southern alps,
cause distinct gene pools to form.
Considers isolation, (and its
geological cause), and differing
selection pressures causing
distinct gene pools and links both
merit statements together in a way
that explains new species
formation.
Fault / plate movement causes
uplift / mountain building /
orogeny, (of Southern Alps).
AND
Mountains geographically
separate populations.
AND
Isolation leads to speciation.
Eg, the Alpine Fault caused uplift
/ mountain building and the koura
was geographically isolated by
this formation leading to two
different species.
Eg, as the Alpine Fault was
formed, the Southern Alps were
also formed creating geological
boundaries that separated the
koura. This prevented gene flow.
This separation meant two distinct
species arose due to the different
environmental conditions /
selection pressures affecting the
gene pools in different ways.
Eg, the Alpine Fault formation
and the rise of the Southern Alps
separated the koura into two
areas. Isolation prevents gene
flow between populations. So
accumulated differences are not
shared.
Different environmental
conditions acted as different
selection pressures and so
different traits were selected for
which led to two different species
of koura evolving.
Judgement Statement
Achievement
Achievement with Merit
Achievement with Excellence
3A
2M+1A
2E+1A