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NCEA Level 1 Science 90948 (1.9) — page 1 of 5
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
Achievement
Merit
Excellence
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 tongue rolling.
Variations in the feature (eg rolling or
non rolling) 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 of:
describes either a
gene OR an
allele
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
tongue or nontongue roller
TWO of:
explains the
difference
between a gene
and an allele in
terms of how
they impact on
features
shows the
relationship
between DNA, a
gene and an
allele in a
diagram
explains that the
base sequence
on a gene
determines the
appearance of a
particular
feature.
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.
No= nothing, N1= relevant word, N2= 1 correct statement, A3 1 statement (see ach) A4= 2
statements (see ach) M5 = A4 plus 1 statement from Merit, M6=A4 + 2 Merits statements, E7 M6 + statement from
E with no example, E8 M6 + Statement from E and example given.
Two
Expected Coverage
Achievement
Merit
Excellence
(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.
THREE of:
in (a), states what
a gamete is
in (a), describes
relevant detail of
gametes
chromosome
numbers
in (b), describes
genetic variation
in (b), indicates
TWO of:
in (a), explains why
gametes are
needed for
sexual
reproduction
in (b), explains
how meiosis
produces
genetic variation
in a population
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,
NCEA Level 1 Science 90948 (1.9) — page 2 of 5
(b)
Description of genetic variation:
Genetic variation refers to a variety of
different genotypes for a particular
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.
that the
separation of
alleles/
chromosomes
during meiosis
results in new
combinations of
alleles
in (b), states that
variation aids
survival when
conditions
change.
by referring to
the separation of
alleles which
then allows new
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.
through the
reshuffling of
alleles.
No= nothing, N1= relevant word, N2= 1 correct statement, A3 2 statements (see ach) A4= 3 statements (see ach)
M5 = A4 plus 1 statement from Merit, M6=A4 + 2 Merits statements, E7 M6 + statement from E with no
explanation, E8 M6 + Statement from E and explanation given.
Three
Expected Coverage
Achievement
Merit
Excellence
(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:
Two first individuals who both have a
straight hairline produce a child with a
widow’s peak. If the normal hairline was
recessive they would not be able to
produce a child with a widow’s peak, so
the normal hairline must be dominant
OR other correct evidence from chart.
(b)
Explanation of why Dd:
As female A has a straight hairline
this must mean that she carries at
least one straight hairline allele (D).
Female A and male B have a
widow’s peak boy, which means that
A must have passed on a widow’s
peak allele (d) to the boy as to have
a widow’s peak the boy must have
two recessive alleles, one from each
parent.
THREE of:
in (a), describes
what a dominant
allele OR
relevant punnet
square linked to
pedigree
diagram
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
widows peak and
straight hairline
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.
(c)
Punnett Square:
See Appendix B.
Calculation of probabilities:
Probability of straight hairline = .5 or
2 out of 4 or 50%
Probability of widow’s peak = .5 or 2
out of four or 50%
Explanation of discrepancy:
Random fertilisation of eggs by
sperm means that number of
TWO of:
in (a), explains the
evidence that
shows that
straight hairline
allele is dominant
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.
NCEA Level 1 Science 90948 (1.9) — page 3 of 5
offspring showing a particular
variation will not always match the
probability predicted by a Punnett
square, unless the number of
offspring is quite large.
No= nothing, N1= relevant word, N2= 1 correct statement, A3 2 statements (see ach) A4= 3 statements (see ach)
M5 = A4 plus 1 statement from Merit, M6=A4 + 2 Merits statements, E7 M6 + statement from E about punnet
squares giving a probability, E8 M6 + Statement from E7 and statement about random chance which allele the
gametes will have at fertilisation.
NCEA Level 1 Science 90948 (1.9) — page 4 of 5
Four
Expected Coverage
(a)
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 liver
cell is not a gamete, a mutation in a
liver cell cannot be inherited.
(b)
Explanation of causes of variation:
The variation in beaks of species A
may be due to differences
(mutations) in the sequence of bases
in a particular gene.
Explanation of effect of larger seeds:
Those individuals of bird species A
whose beaks are large will be better
adapted to the increase in the
number of large seeds. They will
survive better and produce more
offspring, increasing the number of
larger beaked birds in the population.
Explanation of fate of poorly adapted
birds: small beaks will not be able to
gain sufficient food. In time these
birds might die off.
Achievement
Merit
Excellence
TWO of:
in (a), correctly
defines or
describes a
mutation
in (a), states that a
liver cell mutation
is not inheritable
(or similar)
in (b), states that
variation is
caused by
changes in
genetic
information
(mutations)
in (b), states that
birds of species
A with larger
beaks are better
adapted to live
on larger seeds
OR that birds
with average or
small beaks will
be poorly
adapted to larger
seeds, (and will
not survive for
long).
TWO of:
in (a), explains why
a mutation in a
liver cell it not
inheritable
in (b), explains what
causes variation
(e.g. variation in
bird species A
will be due to
changes in
genetic material)
in (b), explains
how variation
aids the survival
of the species
(eg,birds of
species A have
different sized
beaks, and when
the environment
becomes more
abundant in
larger seeds and
less abundant in
smaller seeds,
will be better
adapted to the
new conditions
and therefore will
survive).
In (b), links the
explanation of how
genetic variation
arises within a bird
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 larger
seeds, the larger
beaks of some
birds of species A,
means that they
are better adapted
to survive and
reproduce, thus
ensuring the
survival of some
individuals, and
hence the
species).
No= nothing, N1= relevant word, N2= 1 correct statement, A3 1 statement (see ach) A4= 2 statements (see ach)
M5 = A4 plus 1 statement from Merit, M6=A4 + 2 Merits statements, E7 M6 + explanation from E with no link to
more offspring, E8 M6 + Statement from E and links to more offspring.
Judgement Statement
Achievement
Achievement with Merit
Achievement with Excellence
Minimum of:
10 -16
Minimum of:
17-24
Minimum of:
25-32
NCEA Level 1 Science 90948 (1.9) — page 5 of 5
Appendix A
Appendix B
D
d
D
DD
Dd
d
Dd
dd