Download File - NCEA Level 3 Biology

BEANZ Practice Examination
Level 3 Biology
Assessment Schedule
2011
Achievement Standard 90717
B 3.5 Describe patterns and processes of evolution
Credits: 3
Assessment of AS 90717 paper:
Students are given a grade for each question. The criteria for awarding question grades
are given in the last row of each questions’ assessment schedule.
The table below indicates how grades are allocated for the Standard.
Total Questions
i.e. maximum grades
possible
4
3 grades total
(A, M or E)
Sufficiency
Minimum
3A
4
3 grades total
(A, M or E)
plus
2 grades to be at M
or E
A + 2M
4
4 grades gained in
total
plus
3 grades to be at M
or E,
plus
2 grades to be at E
A + M + 2E
Question 1
Q1
a.
The ‘Species Problem’
Evidence for
Achieved
Species defined:
group of actively or potentially
interbreeding individuals
separated genetically from
other such groups
OR
group of organisms that
interbreed successfully
(produce fertile offspring) in
natural environments.
Student must make a
decision i.e. are the Black
Stilt and the Pied Stilt the
same species or not?
Either answer is accepted
as long as it is
substantiated i.e. reasons
must be attempted for Merit
Or
student can state that there
is evidence to support
either decision and then
explain.
b.
Students cannot get
‘Achieved’ alone unless an
attempt at an explanation is
made. i.e. no guesses
accepted.
Evidence for
Achieved with Merit
Evidence for
Achieved with Excellence
2 explanations of decision,
these can be for the answer
given or against the other
choice
Same species:
 interbreeding is possible
and F1 hybrids are fertile
(other hybrids exist)
 species have diverged
recently and their
divergence has not yet
reached species level
 continued divergence
(more time) is needed to
establish separate
species status
 etc
Different species:
 Basis of separation into 2
species is morphological
(based on colour) and
habitat information which
is still valid
 Hybrids are present but
their fertility is not known.
There is a suggestion of
reduced fitness which
would inhibit gene flow
 Species have until recent
colonisation had
geographical separation
and interbreeding was
geographically impossible
 etc
Additional information
required is based on the
long term consequences of
interbreeding
i.e.
 F1 hybrids are fertile but if
the offspring of hybrids
show decreasing fertility
with each generation then
gene flow will be limited
and the species must be
considered separate
 Additional genetic or DNA
information about the
degree of genetic
divergence would give
some definitive information
about how different the two
species actually were
 or similar
Any 2 examples described:
 lack of demarcation
between sp and subsp.
eg. ring species

c.



(successful) interbreeding
between related species
in captivity / gardens
when one sp. is
introduced into the
habitat of another
lack of demarcation
between sequential sp.
or
ancient species defined
on the basis of
morphology
Structural barriers to
breeding between
members of the same sp
etc
2 examples explained:
 Neighbouring populations
can interbreed (same
species) but distant ones
cannot
 Animals and plants
removed from their
natural environment often
can interbreed with
related species

Species defined by time,
how can ability of
interbreeding ever be
tested

Interbreeding is prevented
by factors that have been
artificially selected for eg.
between individuals of
large and small dog
breeds
etc

Total for Q 1
3a
Assessment
for Q 1
Student gains
Achieved
for this question if:
 2 of 3 opportunities for
‘A’ are answered
correctly.
Minimum
2a
2m
Student gains
Achieved with Merit
for this question if:
 2 of 3 opportunities for ‘A’
are answered correctly
and
 1 of 2 opportunities
for ‘M’ are answered
correctly.
1a + 1m
1e
Student gains
Achieved with Excellence
for this question if:
 2 of 3 opportunities for ‘A’
are answered correctly
 1 of 2 opportunities for ‘M’
are answered correctly
and
 the opportunity for ‘E’ is
answered correctly.
1a + 1e
Question 2
Q2
a.
b.
c.
Recent Speciation in Salsify
Evidence for
Achieved
Speciation defined:
any process that
promotes divergence
and leads to the
formation of a new
species
Evidence for
Evidence for
Achieved with Merit
Achieved with Excellence
Speciation must be sympatric
because:
For allopolyploids to occur crosspollination (between the parental species)
is required which means the parent must
be growing in the same habitat i.e.
sympatric (in the same place).
NB it is not sufficient to simply explain
what sympatric means.
Description or implication
Explanation explains that
of what makes a plant a
polyploidy exhibit ‘hybrid
successful weed:
vigour’.
eg.
i.e. because they contain a
Allopolyploids have the ability
wider range of genetic
to compete, grow more
material from 2 parental
quickly and spread in habitats species they are able to cope
where environmental factors
with more extreme conditions
that are less ideal or more
and usually have higher
likely to be limiting
growth rates
Description of allopolyploid Explanation of how
Reproductive Isolating
stated or implied:
allopolyploids arise (are
Mechanisms OR their
produced):
importance discussed:
a polyploid that contains
genetic material from 2 (or
One of 2 mechanisms
Allopolyploids are a ‘new’
more) parental species.
explained
species because they are
1. Fusion (fertilisation) that ‘reproductively isolated’ from
involves 2 nonother species (including their
disjoined gametes
parental species by hybrid
infertility. This means that
i.e. 2 gametes with 2n
chromosomes (that have any fertilisation between a 4n
not separated at meiosis) species (gametes 2n) and a
form a 4n zygote
2n species (gametes n) will
2. A polyploid that results
result in a 3n hybrid, which
from the doubling of
will be infertile.
chromosome number
RIMs are important because
in an otherwise infertile they prevent gene flow
hybrid at the first mitosis between the 2 populations.
after fertilisation
This in turn allows divergence
(effectively a 2n zygote
to occur / action of selective
becomes a 4n zygote)
pressures or natural selection.
(2 ideas; no gene flow and
divergence)
Total for Q 2
3a
3m
Assessment
for Q 2
Student gains
Achieved
for this question if:
 2 of 3 opportunities for
‘A’ are answered
correctly.
Student gains
Achieved with Merit
for this question if:
 2 of 3 opportunities for ‘A’
are answered correctly
 2 of 3 opportunities M’ are
answered correctly.
Minimum
2a
2m
1e
Student gains
Achieved with Excellence
for this question if:
 3 of 3 opportunities for ‘A’
are answered correctly
 2 of 3 opportunities for ‘M’
are answered correctly
and
 the opportunity for ‘E’ is
answered correctly.
1a + 1m + 1e
Question 3
Q3
a.
Divergence or Convergence? - The Lord Howe Tree Lobster
Evidence for
Evidence for
Achieved
Achieved with Merit
Bottleneck
Explanation of how or why genetic
effect defined diversity is reduced (short-term effect):
or described.
Small number of individuals will only carry a
Loss of
smaller number of genes present in the
genetic
original larger population (some alleles may
diversity due
be lost altogether)
to small
This will lead to a loss of genetic diversity
population
(assuming the population regains its former
size.
size)
OK if student
uses the term
Genetic drift.
b.
Divergence
and
Convergence
both
described:
Divergence:
Evolution in
which 2 or
more species
evolve from a
common
ancestor
Convergence:
Evolution in
which 2 or
more
unrelated
species (no
common
ancestor)
evolve similar
adaptations in
response to
similar niche
requirements
Total for Q 3
Assessment
for Q 3
Minimum
Evidence for
Achieved with Excellence
Discussion of long-term
consequences for the
recovering population
If population size recovers, lack
of diversity may limit adaptive
potential (until new variations
appear due to mutations,
independent. assortment,
crossing over &/or
recombination).
Conversely some alleles that were rare may i.e.
become more common because (by
population will initially not have
chance) they were over-represented in the
the genetic diversity that will allow
small population
it to respond to environmental
changes.
Outline the conditions that would have been
2 or more types of
necessary for both mechanisms to occur
evidence is evaluated:
Divergence:
Anatomical features
and ecology i.e.
Any 2 or more conditions
 Common ancestor that disperses and colonises morphology, adaptations
and niche. These are
new islands
superficially similar (due
 mechanism that prevents gene flow between
to convergence) although
populations, e.g. geographic separation
they appear to be due to
 different adaptive forces / natural selection
divergence.
forces acting on different populations
 sufficient time is needed for the accumulation of DNA analysis
Genetic evidence
sufficient genetic differences
indicates
that these
 resulting genetic changes developing in
insects
had
different
isolated populations leading to divergence (2
ancestors
/
origins.
different but related species)
Morphological similarities
 etc
can
be generated and
Convergence:
selected
for in genetically
Any 2 or more conditions
different
ways

unrelated ancestors present on different
Other evidence:
islands
eg

unoccupied niches are available
Genetic comparisons with

similar adaptations evolve because they
possible ancestors
occupy similar niches
Fossils evidence

populations are subject to similar selective
(possible but not likely)
pressures (similar environments)
etc

etc
acceptable if evaluated
2a
Student gains
Achieved
for this question if:
 both opportunities for
‘A’ are answered
correctly.
2a
2m
Student gains
Achieved with Merit
for this question if:
 both opportunities for ‘A’
are answered correctly
and
 1 of 2 opportunities for ‘M’
is answered correctly.
1a + 1m
2e
Student gains
Achieved with Excellence
for this question if:
 both opportunities for ‘A’
are answered correctly
 both opportunities for ‘M’
are answered correctly
and
 1 of 2 opportunities for ‘E’
is answered correctly.
1m + 1e
Question 4
Q4
a.
The Evolution of Fresh-water Eels
Evidence for
Achieved
Title has 2 parts and must
be descriptive:
1. Divergence / Phylogeny etc
of
2. freshwater Eels / genus
Anguilla.
Or similar
mtDNA is inherited from one
(female) parent only.
i.e. mtDNA is inherited via
the direct female line.
b.
Dispersal and colonisation
both described
Movement to new geographic
area and establishment of
breeding population there.
c.
i.
Evidence for
Achieved with Merit
Evidence for
Achieved with Excellence
mtDNA can only change by mutation
(mutations are more common than in
nuclear DNA due to the lack of repair
mechanisms)
or
mtDNA is not subject to
recombination and is thus inherited
unchanged (except for accumulated
mutations).
Circumstances explained (at least
one explanation needed):
 juveniles are carried by ocean
currents to new river systems
(explanation involves colder
currents, slower growth, longer
juvenile period and longer time
for migration to fresh water)
 movement to Africa and Oceania
is possible because oceans are
connected but movement to
Atlantic occurred before Africa
moved to its present position –
Indian, Mediterranean, Atlantic
were connected.
 New breeding population was
isolated from the parental
population i.e. geographically,
temporally due to temps and
growth rates etc or some other
feasible mechanism.
 etc
Divergence and
speciation defined or
implied
Or
Natural selection
defined or implied
c.
Mechanism of speciation
explained:
Geographic separation of
populations prevents gene
flow. As a result of different
natural selection pressures
the gene pools diverge until
different species result
Or
Mechanisms of Natural
Selection explained
In geographically separate
areas gene pools respond to
the different selection
pressures that operate in
those areas (examples
include temperature and food
sources etc. temp causes
slower juvenile growth etc)
ii.
Elaboration of present day
distribution. One of the following
elaborated on:
 Majority of species occur in the
Indo-Pacific because
it is the centre-of-origin of the
genus and because geographic
isolation (and prevention of gene
flow between populations) is more
easily achieved in tropical areas
where migration distances are
shorter due to faster growth rates.
 In temperate areas greater
distances between populations are
needed to achieve isolation
because juveniles spend more time
at sea and can cover greater
distances – carried by currents.
Hence Africa 1 sp. only and N.
Atlantic 2 sp. only
 Many areas do not have any eel
species despite oceanic
connections eg S Atlantic, N and E
Pacific. Reasons could include:
o lack of ocean currents that
encourage dispersal to those
areas
o distances are too great so that
even if currents were suitable
the time involved would be too
great and juveniles need to
migrate into freshwater
o lack of suitable spawning areas
with suitable ocean currents
that carry migrating juveniles to
suitable freshwater habitats
and adults back to the
spawning areas. i.e. round-trip
migration is not possible
o etc.
Total for Q 4
4a
3m
Assessment
for Q 4
Student gains
Achieved
for this question if:
 3 of 4 opportunities for
‘A’ are answered
correctly.
Student gains
Achieved with Merit
for this question if:
 3 of 4 opportunities for ‘A’
are answered correctly
and
 2 of 3 opportunities for ‘M’
are answered correctly.
Minimum
3a
1a + 2m
1e
Student gains
Achieved with Excellence
for this question if:
 3 of 4 opportunities for ‘A’
are answered correctly
 2 of 3 opportunities for ‘M’
are answered correctly
and
 the opportunity for ‘E’ is
answered correctly.
1a + 1m + 1e