HKDSE Biology: four compulsory topics, four electives of which you take two, and free practice questions

Which topics does HKDSE Biology cover?

Eight in total: four compulsory and four electives. The compulsory part runs from molecules and cells out to whole ecosystems, and every candidate studies all of it. The electives each take one strand of the compulsory material further, and a school normally enters its candidates for two of the four.

• Cells and Molecules of Life (compulsory): molecules of life, cellular organisation, movement of substances across membranes, the cell cycle and division, cellular energetics
• Genetics and Evolution (compulsory): basic genetics, molecular genetics, biodiversity and evolution
• Organisms and Environment (compulsory): nutrition and gas exchange in plants and animals, transport, reproduction and growth, coordination and response, homeostasis, ecosystems
• Health and Diseases (compulsory): personal health, disease and its transmission, the body's lines of defence
• Human Physiology: Regulation and Control (elective): water balance, temperature regulation, regulation of blood gases, hormonal control of the reproductive cycle
• Applied Ecology (elective): human impact on the environment, pollution control, conservation and global issues
• Microorganisms and Humans (elective): microbiology, the use and genetics of microorganisms, the harm they do
• Biotechnology (elective): modern biotechnological techniques, applications, bioethics

Do you have to choose which electives to revise?

Your school chooses, and you revise the two you are entered for. That is why a revision app that carries only a subset is a gamble: a student moving school, or one whose school changes its pairing, loses half the elective material. Our bank covers all four electives as well as all four compulsory topics, so the choice never has to be made at the point of buying. The free questions below sample every one of the eight.

Why does this page not state the paper structure, the timings or the marks?

Because we have not verified them against a current official document, and a wrong number here would defeat the purpose of the page. Figures circulating online for the number of multiple-choice questions in Paper 1 are usually taken from one year's actual paper, which is not a rule that binds the next sitting. The topic framework is stable and publicly documented, so that is what this page states. For paper structure, timings, marks and the assessment framework, go to the HKEAA and to your school, and treat any third-party page that states them confidently, including a competitor's, with suspicion unless it cites the document.

What actually catches Biology candidates out?

Terminology across two languages, and comparisons that look interchangeable and are not. A student who learned the concept in Chinese still has to name it in English, and 基因型 against 表現型, 超濾 against 重吸收, 柵狀葉肉 against 海綿葉肉 all have exact English counterparts that the paper expects. The second trap is a definition that is nearly right: an enzyme described as 'used up' rather than 'recovered unchanged', a homozygote described as 'carrying two alleles' without the word 'identical'. Multiple-choice is very good at catching precisely that, which is why the free questions below lean on it.

• Genotype and phenotype: what an organism carries against what you can observe
• Homozygous and heterozygous: two identical alleles against two different ones
• Ultrafiltration and reabsorption: different structures of the nephron doing different jobs
• Palisade and spongy mesophyll: where photosynthesis mainly happens, and why position matters
• Denatured and inhibited: a permanent change of shape against a temporary loss of activity

Where do these questions come from?

They are original. Every question, option, explanation, flashcard and topic note is written by RiverMap Learning to the topic framework in the publicly available Biology Curriculum and Assessment Guide (Secondary 4 to 6), 2007, updated November 2015. No HKEAA past paper question, marking scheme or textbook content is reproduced. Scientific facts are not copyrightable, and the published topic framework is used only to align coverage. Each item is checked by a second AI model from a different family, disagreements are settled by hand, and Chinese terminology is checked against the usage in Hong Kong textbooks.

Is RiverMap Learning connected to the HKEAA or the EDB?

No. RiverMap Learning is not affiliated with, endorsed by or sponsored by the Hong Kong Examinations and Assessment Authority, the Education Bureau, the Curriculum Development Council or any school. These pages and the app are independent revision material. The app reports how well you are doing on its own practice questions; that is not a grade, and HKDSE levels are awarded by standards-referenced reporting each year rather than by a fixed mark.