A resource aimed at advanced biology students, this worksheet provides some more unusual examples of dihybrid cross genetics including malvidin production in primrose, kernel colour in wheat and fruit colour in squash; all students will be aware of the classic 9:3:3:1 ratio, but they can often struggle when other factors such as codominance are included in the question. This resource is ideal stretch and challenge material for more able students once they have mastered the basics of the dihybrid cross. It is also ideal preparation for the more challenging questions on this topic favoured by most exam boards. Keywords: dihybrid, ratio, cross, genetics

This resource consists of two worksheets aimed at advanced biology students or level 3 applied science students. The first worksheet is a simple review of how an electron microscope functions and the key points about magnification, resolution and TEM/SEM (the image is that of a tapeworm head). The second worksheet is a table comparing electron microscopes with light microscopes. Three different web references are given and students are required to use these to complete the table. At the end of the exercise, they should be able to confidently compare and contrast light microscopes with electron microscopes.

Worksheet that asks students to work through a chi-squared analysis of data from an investigation into PTU tasting ability. Useful as a lesson starter or plenary review on chi-sqaured. Keywords: chi-squared, statistics, PTU, tasting, null hypothesis, probability, degrees of freedom, critical value