Work samples


Year 10

Above satisfactory

Genetic inheritance in Brassica rapa

Summary of task

Students were asked to perform a multi-generational study on the genetic inheritance of two different traits in the species Brassica rapa, a variety of the canola plant. Students were provided with two sets of seeds that had resulted from crossbreeding two distinctly different parental types of this plant species. The two sets of seeds represented the first- and second-generation offspring of the parent plants (referred to as F1 and F2 hybrids).

Students were asked to investigate plant height and stem colour of the hybrid plants. They were given the following information about the genetic makeup of the parent plants:

  • For the gene which controls plant height there are two alleles, (T) which is dominant and is expressed as a tall stem, and (t) which is recessive and is expressed as a shorter stem (dwarfism).
  • For the gene which controls stem colour there are two alleles, (P) which is dominant and gives a purple stem, and (p) which is recessive and gives a green stem.
  • The parents of the F1 hybrids are homozygous dominant for one trait, and homozygous recessive for the other.
  • Plants growing from the F1 seeds can be considered the parents of those growing from the F2 seeds (the F2 hybrids are plants whose parents are genetically the same as the F1 hybrids).

Students were asked to first grow plants from the F1 seeds by following a set of instructions and observe and record their physical traits (phenotypes). They were then asked to determine their genotypes from these observations.

Based on their results for the F1 genotypes, students were then asked to predict the probable genotypes and phenotypes of the F2 generation. After growing and observing the plants grown from the F2 seeds, they were asked to compare their predictions with their actual results and submit a report of the experiment using a given template. Students were provided with the raw data from each class in the year and they were asked to consider the combined results in their analysis. The report template contained section headings and several guiding questions for the discussion.

This task was given at the end of a teaching and learning unit on genetics in which students had learned about the role of genes, chromosomes and DNA in the processes governing genetic inheritance. Students had studied Gregor Mendel’s experiments and they were explicitly taught how to use monohybrid and dihybrid Punnett squares to predict the characteristics of organisms. During the practical lesson they worked in teams of three or four to grow the plants and observe and measure their characteristics. The report was completed as an individual take-home assignment.

Achievement standard

By the end of Year 10, students analyse how the periodic table organises elements and use it to make predictions about the properties of elements. They explain how chemical reactions are used to produce particular products and how different factors influence the rate of reactions. They explain the concept of energy conservation and represent energy transfer and transformation within systems. They apply relationships between force, mass and acceleration to predict changes in the motion of objects. Students describe and analyse interactions and cycles within and between Earth’s spheres. They evaluate the evidence for scientific theories that explain the origin of the universe and the diversity of life on Earth. They explain the processes that underpin heredity and evolution. Students analyse how the models and theories they use have developed over time and discuss the factors that prompted their review.

Students develop questions and hypotheses and independently design and improve appropriate methods of investigation, including field work and laboratory experimentation. They explain how they have considered reliability, safety, fairness and ethical actions in their methods and identify where digital technologies can be used to enhance the quality of data. When analysing data, selecting evidence and developing and justifying conclusions, they identify alternative explanations for findings and explain any sources of uncertainty. Students evaluate the validity and reliability of claims made in secondary sources with reference to currently held scientific views, the quality of the methodology and the evidence cited. They construct evidence-based arguments and select appropriate representations and text types to communicate science ideas for specific purposes.

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