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NCEA Level 1 Science 90948 (1.9) — page 1 of 4
SAMPLE ASSESSMENT SCHEDULE
Science 90948 (1.9): Demonstrate understanding of biological ideas relating to genetic
variation
Assessment Criteria
Achievement
Merit
Excellence
Demonstrate understanding
requires the student to recognise,
name, draw, give characteristics of,
or an account of genetic variation.
Demonstrate in-depth
understanding requires the student
to explain how or why genetic
variation occurs.
Demonstrate comprehensive
understanding requires the student
to link biological ideas about
genetic variation. It may involve
elaborating, applying, justifying,
relating, evaluating, comparing and
contrasting, or analysing.
Evidence Statement
One
Expected Coverage
Explanation of difference:
A gene is a section of DNA that
codes for a particular feature /protein.
An allele is an alternative form of the
gene.
Drawing of structural relationship:
See Appendix A.
Explanation of determination of
feature and variation:
Along the DNA, base sequences
provide the code for building different
proteins, which then determine
particular features. Specific sections
of the DNA determine individual
features such as flower colour.
Variations in the feature (eg red or
white flowers) are due to (slight)
differences in the sequence of the
bases making up a gene. The
different variations of a particular
gene are called alleles and they
cause the variations in the
phenotypes.
Two
Expected Coverage
(a)
Description of gametes:
A gamete is a sex cell (eg, an egg or
sperm), which has half the normal
number of chromosomes as body
cells.
Explanation of the need for gametes:
It is required in sexual reproduction
to ensure that when a sperm fuses
with an egg, the resulting first cell of
the new organism has the correct
number of chromosomes.
(b)
Description of genetic variation:
Genetic variation refers to a variety of
different genotypes for a particular
Achievement
Merit
TWO of:
TWO of:
 describes either
a gene OR an
allele
 explains the
difference
between a gene
and an allele in
terms of how
they impact on
features
 states that a
gene codes for a
protein which
then determines
a feature
 indicates that a
different base
sequence
(alleles) results
in differing plant
features such as
red or white
flowers.
Achievement
 shows the
relationship
between DNA, a
gene and an
allele in a
diagram
Merit
TWO of:
 in (a), states
what a gamete is
 in (a), explains
why gametes are
needed for
sexual
reproduction
 in (b), describes
genetic variation
 in (b), indicates
that the
separation of
alleles/
chromosomes
Links the
explanation of the
structural
relationship
between DNA,
genes and alleles
with the
explanation of the
production of a
particular feature
and variation within
that feature.
 explains that the
base sequence
on a gene
determines the
appearance of a
particular
feature.
THREE of:
 in (a), describes
relevant detail of
gametes
chromosome
numbers
Excellence
 in (b), explains
how meiosis
produces
genetic variation
in a population
by referring to
the separation of
alleles which
then allows new
Excellence
In (b), links the
explanation of why
genetic variation
within a population
is important for the
survival of the
species with the
explanation of how
inherited variation
is constantly being
generated by the
process of meiosis,
through the
reshuffling of
alleles.
NCEA Level 1 Science 90948 (1.9) — page 2 of 4
trait within a population.
Explanation of role of meiosis:
Meiosis produces gametes with half
the number of chromosomes. This
means that pairs of alleles are
separated at meiosis.
At fertilisation, which sperm fertilise
which egg is due to chance and this
results in new combinations of
alleles.
The advantage of variation to a
species is that it may enable some
individuals to survive if some
threatening event occurs. For
example, if a new disease arrives,
not all individuals will be wiped out.
Three
Expected Coverage
(a)
Explanation of a dominant allele:
A dominant allele is the form of a gene
that is always expressed whether the
individual has one or two copies of that
allele.
Explanation of evidence:
A and B who both have a cleft chin
produce a smooth chin child. If the cleft
chin allele was recessive they would not
be able to produce a child with a smooth
allele, so the cleft chin allele must be
dominant OR other correct evidence
from chart.
(b)
(c)
Explanation of why Dd:
As male A has a cleft chin this must
mean that he carries at least one
cleft chin allele (D). Male A and
female B have a smooth chin boy,
which means that A must have
passed on a smooth chin allele (d) to
the boy as to be smooth chinned the
boy must have two recessive alleles,
one from each parent.
Punnett Square:
See Appendix B.
Calculation of probabilities:
Probability of cleft chin = ¾ or 75% or
3 out of 4
Probability of smooth chin = ¼ or
25% or 1 out of four
Explanation of discrepancy:
Random fertilisation of eggs by
sperm means that number of
offspring showing a particular
variation will not always match the
probability predicted by a Punnett
square, unless the number of
offspring is quite large.
during meiosis
results in new
combinations of
alleles
 in (b), states that
variation aids
survival when
conditions
change.
Achievement
combinations of
alleles to occur
at fertilisation
 in (b), explains
that variations in
a population
might allow
individuals to
survive in
changing
conditions and to
pass on the
ability to their
offspring.
Merit
THREE of:
TWO of:
 in (a), describes
what a dominant
allele OR
relevant punnet
square linked to
pedigree
diagram
 in (a), explains
the evidence that
shows that cleft
chin allele is
dominant
 in (b), gives a
reason for the
presence of one
of the alleles of
the genotype
 in (c), completes
the Punnett
Square correctly
 in (c), gives the
correct
probabilities for
cleft chin and
smooth chin.
 in (b), explains
why individual A
must have a
dominant and a
recessive allele
using evidence
from the
pedigree
diagram
 in (c), gives the
correct
probabilities
based on the
completed
Punnet square
parent alleles
and indicates
that these can’t
be used to
predict what an
individual will be.
Excellence
In (c), links the
theoretical
probabilities
derived from the
correctly
completed Punnett
Square with the
explanation of why
the actual
outcomes for
families will not
necessarily match
the predicted
outcomes,
especially when
dealing with small
population
samples.
NCEA Level 1 Science 90948 (1.9) — page 3 of 4
Four
(a)
(b)
Expected Coverage
Achievement
Description of a mutation:
A mutation is a change to the base
sequence of a gene along the DNA
of an organism or a change in the
genetic code.
Explanation of inheritance:
If the mutation occurs in a gamete,
then it would be inherited. As a skin
cell is not a gamete, a mutation in a
skin cell cannot be inherited.
Explanation of causes of variation:
The variation in plants of species A
may be due to differences
(mutations) in the sequence of bases
in a particular gene.
Explanation of effect of reduced light:
Those individuals of plant species A
whose leaves are large will be better
adapted to live under lower light
levels. They will survive better and
produce more offspring, increasing
the number of larger leaves plants in
the population.
Explanation of fate of poorly adapted
plants:
Plants with average or small leaves
will not be able to absorb enough
sunlight and make sufficient food. In
time these plants might die off.
Merit
Excellence
TWO of:
TWO of:
 in (a), correctly
defines or
describes a
mutation
 in (a), explains
why a mutation
in a skin cell it
not inheritable
 in (b), explains
what causes
variation (e.g.
variation in plant
species A will be
due to changes
in genetic
material)
 in (a), states that
a skin cell
mutation is not
inheritable (or
similar)
 in (b), states that
variation is
caused by
changes in
genetic
information
(mutations)
 in (b), states that
plants of species
A with larger
leaves are better
adapted to live
under lower light
levels OR that
plants with
average or small
leaves will be
poorly adapted to
low light levels,
(and will not
survive for long).
 in (b), explains
how variation
aids the survival
of the species
(eg, plant of
species A have
different sized
leaves, and
when the
environment
becomes more
shaded some
plants will be
better adapted to
the new
conditions and
therefore will
survive).
In (b), links the
explanation of how
genetic variation
arises within a
plant species with
the explanation of
how that genetic
variation aids
survival of the
species in a
changing
environment (eg,
when
environmental
conditions are
changed to lower
light levels, the
larger leaves of
some plants of
species A, means
that they are better
adapted to survive
and reproduce,
thus ensuring the
survival of some
individuals, and
hence the
species).
Judgement Statement
Achievement
Achievement with Merit
Achievement with Excellence
Minimum of:
2A
Minimum of:
2M
Minimum of:
2E
NCEA Level 1 Science 90948 (1.9) — page 4 of 4
Appendix A
Appendix B
D
d
D
DD
Dd
d
Dd
dd