Higher Biology 2025, Question 12: F1 hybrids, range bars and animal welfare

01What the introduction is really telling you

Milk yield is the dependent variable and the goats'' genetic group is the independent variable. There is very little detail given about F1 hybrids, which is usually a hint that the definition will be tested later in the question.

02Read the bar chart properly

The final paragraph tells you there are 10 goats in each group and each bar is an average. The bars on top of the bars represent range, though that is not always the case. And the y-axis starts at 300, not 0.

03Part (a): individual goats means range bars

You are asked about individual goats across the whole dataset, not one genetic group, so use the extremes of the range bars. The lowest is 520 litres per year in parent breed 2, the highest is 730 in the F1 hybrids, so the difference is 210 litres per year.

The follow-up asks how you know an average was taken from the graph. Your instinct is to check the y-axis label, but the answer is the range bars. If you skim past "from the graph", you will wrongly quote the 10 goats mentioned in the introduction.

04Part (b): why the F2 generation varies

The key detail is that the decrease in milk yield is only seen in some individual goats. When an F2 generation is bred from a pair of F1 hybrids, uniformity is lost and much greater variation appears, some individuals produce less, some the same, some more.

The answer is simply: the F2 generation will show greater variation.

05Part (c): advantages of intensive farming

This is course-specification recall. Read carefully and give both an advantage and one relating to the farmer. Acceptable answers include more cost effective, leading to greater profits; less labour intensive; less land required; and higher productivity because production is faster.

06The two-topic link question

Fewer than 25% of candidates answered this correctly, because it needs information from two separate parts of the course. From animal welfare: overcrowding is common in intensive farms. From symbiosis: parasites spread by direct contact. The mark is in the link, in the overcrowded environment created by an intensive farm, parasites are more likely to spread between hosts by direct contact.

07The last mark

The final part is straight recall: hysteria. The green-bordered paragraph is there to tell you which part of your course knowledge to answer from, "altered levels of activity" is lifted directly from the course specification. Skim that and you will either find the question much harder than it is, or invent a new answer that earns nothing.