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Assessment Schedule – 2010 Biology: Describe processes and patterns of evolution (90717) Evidence Statement


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NCEA Level 3 Biology (90717) 2010 — page of


Assessment Schedule – 2010

Biology: Describe processes and patterns of evolution (90717)

Evidence Statement

Q

Evidence for Achievement

Evidence for Achievement with Merit

Evidence for Achievement with Excellence

ONE

(a)


ONE of:

Describes types of speciation (a)

Eg penguins could undergo speciation in different places (allopatric speciation) or in the same place by occupying different niches/habitats (sympatric speciation). BOTH types needed

Describes isolating mechanisms for each type (a)

Eg, geographical boundaries could keep birds from interbreeding.
AND
ONE of:

Temporal differences may result in breeding at different times.

Different mating rituals may isolate groups of birds.

Physical differences may make mating impossible.

Hybrid sterility may inhibit breeding.

Hybrid inviability may stop interbreeding.

Hybrid breakdown may prevent interbreeding.

Polyploidy.



Description of types or isolating mechanisms AND explanation of how this leads to speciation for both. (m)

Any 2 RIMs from (a) can be used for M but must have gained A by including both allopatric and sympatric example.

Eg penguins based on different islands are unlikely to mate. Penguins that live in the same place but have different niches will become adapted for their niche. In both situations gene flow is limited, and over time different selection pressures / accumulation of genetic differences result in enough change, so that they cannot interbreed.


Discussion links sympatric and allopatric speciation to isolating mechanisms and gives examples of species for at least one and how post-zygotic and pre-zygotic mechanisms work together. (e)

Eg sympatric speciation is where species don’t interbreed due to niche differences. For instance, they may breed at different times, which means that there is limited gene flow. Eventually, genetic changes will mean they cannot interbreed. Snares and Rockhopper is an example of allopatric speciation, as they live on different islands. Because they now have different crests, the Rockhopper and Snares penguins don’t recognise each other as a mate, which is good, as if they did, the offspring may be infertile, so they have wasted time and energy.



(b)

Names and describes convergent evolution. (a)

Eg convergent evolution is where similar selection pressures result in similar adaptations in species from different ancestors.



Names convergent evolution and explains it, using the examples. (m)

Eg the penguin and seal have different ancestors/ unrelated but both occupy a niche that involves swimming, so both have separately evolved flippers.






(c)

Describes coevolution. (a)

Eg species evolving in response to each other.




Explains coevolution using the example. (m)

Eg as the slowest penguins are predated on, the more agile penguins pass on their alleles, so penguins become more agile overall. As a result, the most successful seals will be the ones that can catch these more agile penguins, and so the more successful seals will pass on their alleles, so both species become more agile.









A – 1Xa

M -2Xm

E – 1Xe

TWO

(a)


Defines natural selection.

Eg natural selection is where the best suited individuals have a greater chance of reproductive success.

The survival of the species is promoted. (a)
Not the survival of the individual

Not ‘survival of fittest’ on it’s own


Explains the natural selection process. (m)

Eg individuals with more suited / better adapted phenotypes will compete more favourably than others that are less suited and are more likely to reproduce, passing on their favourable alleles.

Favourable alleles will increase in frequency within the population.





(b)

Describes the process of speciation AND identifies a relevant isolating mechanism. (a)

Eg when the ancestral species arrived in New Zealand, plants with suitable adaptations moved into available niches. As the species spread across New Zealand, populations became isolated due to mountain barriers and climate differences, as mountain ranges like the Southern Alps developed.


Must specifically mention geological or climatic features or an example as per resource material


Explains how speciation is likely to have occurred and links it to at least one isolating mechanism relevant to the Dracophyllum example. (m)

Eg when the ancestral species arrived in New Zealand, due to variation within the species, plants with slightly different adaptations filled a variety of available niches, leading to adaptive radiation. Populations of the Dracophyllum ancestor became isolated due to mountain barriers and climate differences as mountain ranges, such as the Alps, and glaciations occurred. Certain alleles / phenotypes became selected for in isolated populations, leading to speciation.




Discusses how environmental changes over the past 8million years and natural selection have contributed to evolution of Dracophyllum through speciation / adaptive radiation. (e)

Eg when the ancestral species arrived in New Zealand, due to variation within the species, plants with slightly different adaptations filled a variety of available niches, leading to adaptive radiation. Those that adapted successfully could reproduce. Populations of the same species became separated and small founder populations became established. They became isolated due to geological and climatic changes, for example, as the Southern Alps formed and colder glaciations occurred, resulting in a range of habitats from alpine to warm, damp lowland forests / east coast and west coast differences.

Over time changes in the allele frequencies / mutations occurred, sympatric speciation such as polyploidy incidents occurred, allopatric speciation due to isolation occurred, resulting in a number of separate species being formed due to reproductive differences





A – 1Xa

M – 1Xm

E – 1Xe

THREE

(a)

(b)


Evidence can be from Three (a) or Three (b)

Identifies / defines PE

Eg long periods of stasis with sudden speciation/periods of evolution leading to genetic change.



Answer must make reference to diagram. (a)


Answer for (a) can be used for (b) even without ref to diagram (a)
Any two of:
Defines Gradualism.

Eg gradualism is slow genetic change over a long period of time. (a)


Defines Punctuated Equilibrium.

Periods of stasis with sudden speciation/periods of evolution leading to genetic change.


This can carry across from 3(a)
Describes factors favouring PE

Eg introduction to a new niche / sudden environmental change favours PE. (a)

Describes factors favouring Gradualism

Eg gradually changing conditions (no sudden major events) favours gradualism. (a)

A _ 1Xa




Explanation links definition to how conditions lead to one of PE / gradualism (m).

Eg when conditions change very slowly, the selection pressure is not very intense. This means that while some individuals will have a greater chance of reproductive success, any change in allele frequency will occur over a long period. This results in gradual change of the species.


OR

A lack of sudden environmental changes or a lack of change in niche availablility leads to a slow rate of evolutionary change – gradualism.


OR:

Sudden changes in niche availability or environmental changes can lead to periods of rapid evolutionary change - punctuated evolution.


M – 1Xm



Compares the conditions for both PE and gradualism relating to the example (e).

Eg when conditions change very slowly, the selection pressure is not very intense. This means that while some individuals will have a greater chance of reproductive success, any change in allele frequency will occur over a long period. This results in gradual change of the species, such as in milliganii. This is gradualism. Whereas with the introduction of a species to a new place, such as Dracophyllum to New Zealand, the one species has a number of new niches, each with its own selection pressures – causing sudden speciation, which is punctuated equilibrium.


E – 1Xe








AM = M

AE =E


Judgement Statement

Achievement

Achievement with Merit

Achievement with Excellence


3 A OR 1 A + 1 M

1 A + 2 M

1 A + 1 M + 1 E





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