Back to lessons
Life SciencesGrade 1240 min

Grade 12 Life Sciences Exam Study Guide

Genetics, reproduction, evolution, homeostasis and environment — condensed for exam season.

The big ideas to revise

  1. Genetics: DNA structure, replication, mutations, meiosis and fertilisation, Mendel's monohybrid cross (Punnett squares, 3:1 ratios), sex determination, pedigree charts.
  2. Reproduction: human reproductive systems, menstrual cycle and hormones, fertilisation and implantation.
  3. Evolution: natural selection (variation → selection pressure → differential survival → change over generations), speciation, evidence (fossils, DNA), human evolution from Australopithecus to Homo sapiens.
  4. Homeostasis: osmoregulation (kidney and ADH), thermoregulation, glycaemic control (insulin and glucagon).
  5. Environmental studies: ecosystems and food webs, loss of biodiversity, human impact and rehabilitation.

How to answer

  • Use the exact biological vocabulary in the question.
  • For Punnett squares: always show parents, gametes, offspring genotypes AND phenotypes with a ratio.
  • "Describe" = what happens; "explain" = why/how it happens.

Final tips

Draw and label every diagram you must know from memory: DNA, a neuron, the nephron, the menstrual cycle graph.

Follow along (device voice)

Listen and follow along as each word is spoken

The big ideas to revise 1. Genetics : DNA structure, replication, mutations, meiosis and fertilisation, Mendel's monohybrid cross Punnett squares, 3:1 ratios , sex determination, pedigree charts. 2. Reproduction : human reproductive systems, menstrual cycle and hormones, fertilisation and implantation. 3. Evolution : natural selection variation → selection pressure → differential survival → change over generations , speciation, evidence fossils, DNA , human evolution from Australopithecus to Homo sapiens. 4. Homeostasis : osmoregulation kidney and ADH , thermoregulation, glycaemic control insulin and glucagon . 5. Environmental studies : ecosystems and food webs, loss of biodiversity, human impact and rehabilitation. How to answer - Use the exact biological vocabulary in the question. - For Punnett squares: always show parents, gametes, offspring genotypes AND phenotypes with a ratio. - "Describe" = what happens; "explain" = why/how it happens. Final tips Draw and label every diagram you must know from memory: DNA, a neuron, the nephron, the menstrual cycle graph.