Breadth and depth of curriculum are important for success in science teaching and learning. Curriculum theorists recommend less breadth and more depth than overloaded, superficial science curricula. This study investigates breadth and depth in the official biology syllabi in the seventh to eighth or ninth years in four diverse jurisdictions, Kenya, South Africa, British Columbia (Canada) and Singapore. Breadth was the number of generic topics included in each syllabus. Depth comprised focus, meaning the proportion of statements devoted to each topic, and demand, meaning the complexity and abstractness of each topic. High-performing jurisdictions, British Columbia and Singapore, have contrasting profiles of breadth and depth, with British Columbia having low breadth, high focus and high demand, while Singapore has high breadth, low focus and lower demand than British Columbia. Low-performing South Africa has high breadth, some focus but lower demand than the high-performing jurisdictions. Kenya has low breadth, high focus, but low demand. Breadth, focus and demand are independent parameters of biology syllabus. High-performing jurisdictions have higher demand but not focus nor breadth than South Africa and Kenya. The British Columbia syllabus best fits the appeal for less breadth and more depth.