Blog Week 10: Question, Marking Criteria and Sample Answer

Outcome: H7

Module: 9.8: Communication

Dot point: 9.8.1.2

QUESTION:

Explain the difference between a polymorphism and a clinal gradation using an example from human phenotypes. (3 marks)

MARKING GUIDELINES	Marks
• Clearly shows, using a relevant example of human phenotype, why and how a polymorphism is different from a clinical gradation	3
• Defines polymorphism and Clinal gradation and provides an example from human phenotypes	2
• Defines polymorphism and/or clinical gradation OR ·       Provides an example from human phenotypes	1

SAMPLE ANSWER:

Polymorphism is having more than one form of a genetically determined characteristic such as the obvious colour of the skin or the not so obvious ABO blood group. Polymorphic differences between people occur as selective adaptions to different environments.

clinal gradation is the gradual change in the gene frequency from one geographic region to another and occurs in all the most commonly observed human characteristics as seen in skin colour and eye colour.

An example of polymorphism and clinal gradation is the gradual increase in the frequency of blonde haired, blue-eyed people as you move from the Mediterranean to the counties of Scandinavia. While eye colour and skin colour are both polymorphic and therefore relay on the genetically determined characteristics, the clinal gradation, or change in gene frequency across geographic regions, that occurs is because of the surrounding environment where different genetic factors have an advantage.

REFLECTION:

WOW this took longer than expected! As my module this week was 9.8: The Human Story, I had to visit sources of information and previous exam questions to assist me with my determination of what question I wanted to ask. I chose to assess dot point 9.8.1.2 and decided not to change the question too much from the dot point. My only issue was with the verb. I chose to assess “explain” but I was not sure whether I should have used “compare” or “contrast” however I wanted the students to briefly explain bot polymorphism and Clinal gradation and therefore provide and/or how they are different, with the use of an example so I chose to stick with “explain”.

I also chose to assess the Outcome H7 – Biological diversity and have the students analyse the impact of natural and human processes on biodiversity. I did not know if I should have extended the question to a 5 mark and have the students discuss how the increasing movement of people around the world, with the ever increasing travelling of humans, affects Clinal gradation and they could therefore address the specific component of the outcome which looks at the impact of human processes on diversity.

After writing this question, I came to the conclusion that in order to construct a good question it is imperative to have a thorough knowledge of the content of the syllabus.

Reference:

NSW Board of Studies (2009). Biology Stage 6 Syllabus. Sydney: Board of Studies