In a strain of soybeans, high oil content (H) in seeds is dominant to low oil content (h)  and four seeds in a pod (F) is dominant to two seeds in a pod (f).  A farmer crosses  two soybean plants, both with high oil content and four seeds in a pod.  The offspring have a phenotypic ratio of 9 : 3 : 3 : 1.

Identify the genotypes of the soybean plants with high oil content and four seeds in a pod that were used in the cross.

In a strain of soybeans, high oil content (H) in seeds is dominant to low oil content (h)  and four seeds in a pod (F) is dominant to two seeds in a pod (f).  A farmer crosses  two soybean plants, both with high oil content and four seeds in a pod.  The offspring have a phenotypic ratio of 9 : 3 : 3 : 1.

Determine the genotypes of the gametes and offspring using a Punnett grid.

In a strain of soybeans, high oil content (H) in seeds is dominant to low oil content (h)  and four seeds in a pod (F) is dominant to two seeds in a pod (f).  A farmer crosses  two soybean plants, both with high oil content and four seeds in a pod.  The offspring have a phenotypic ratio of 9 : 3 : 3 : 1.

Identify the phenotypes of each part of the phenotypic ratio.

Deduce the reason for the person developing as a female.

Determine, with a reason, whether this karyotype shows that non-disjunction has occurred.

 HhFf HhFf  / (both) HhFf;

all gametes shown correctly on Punnett grid;
all offspring genotypes correct;

 Award [1] for any two correct phenotypes.

no Y chromosome.

yes as there is only one X chromosome/chromosome missing/only 45 chromosomes

Most wrote the correct genotype, though there were a surprising number that did not follow notation conventions such as writing HFhf or using linkage notation. 

The majority of students could answer this question. Where students were not answering correctly, it was due to a lack of conceptual understanding of segregation; i.e. writing gametes as HH or ff for example.

This question was most commonly answered correctly.

Approximately half of students answered this correctly.   A number did not recognize the condition for determining a female was the absence of the Y chromosome rather than the presence of the X chromosome.

This was more commonly answered correctly than i).  Here a common misunderstanding was that nondisjunction could only be present if additional chromosomes were present rather than if one were missing.