← Combined Science syllabus

SingaporeCombined Science

Biology: Genetics and Ecology

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What is DNA, where are genes kept, and how do cells divide to grow and to make gametes?

Describe the structure and role of DNA, genes and chromosomes, and compare mitosis and meiosis as types of cell division
A focused answer to the O-Level Combined Science outcome on DNA and cell division. DNA, genes and chromosomes, the role of DNA in coding for proteins, and a comparison of mitosis for growth and meiosis for gametes.
9 min answer →

How does energy flow through an ecosystem, and how is carbon recycled between organisms and the air?

Describe the flow of energy through food chains and food webs, explain why food chains are short, and outline the carbon cycle
A focused answer to the O-Level Combined Science outcome on ecology. Food chains and webs, producers and consumers, energy loss between trophic levels, pyramids of numbers, and the carbon cycle of photosynthesis, respiration and combustion.
9 min answer →

How do human activities pollute and damage the environment, and what can reduce that impact?

Describe the effects of human activity on the environment including pollution, the enhanced greenhouse effect and deforestation, and outline ways to reduce the impact
A focused answer to the O-Level Combined Science outcome on human impact. Air and water pollution, the enhanced greenhouse effect and global warming, acid rain, deforestation and its effects, and measures to reduce environmental damage.
9 min answer →

How are characteristics passed from parents to offspring, and how do we predict the results of a genetic cross?

Use the terms gene, allele, dominant, recessive, genotype and phenotype to explain monohybrid inheritance, and use genetic diagrams to predict the offspring of a cross
A focused answer to the O-Level Combined Science outcome on inheritance. Genes and alleles, dominant and recessive, genotype and phenotype, and using a genetic diagram (Punnett square) to predict the ratios of offspring in a monohybrid cross.
10 min answer →