Organisms and Evolution: overview of SQA Advanced Higher Biology Area 2

Organisms and Evolution is the second area of SQA Advanced Higher Biology. It moves from the molecular focus of Area 1 to whole organisms, populations and their interactions: how biologists sample and classify them, how populations evolve, how reproduction and behaviour are shaped by selection, and how parasites exploit hosts. This page maps the four key areas and shows how they connect.

The four key areas

Field techniques for biologists

Hazards and safe fieldwork, representative sampling with quadrats, transects and point counts, mark-recapture and its assumptions, taxonomy and phylogenetics, model organisms and indicator species.

Evolution

Sources of genetic variation, sexual versus asexual reproduction and the costs of sex, natural and sexual selection, genetic drift with the bottleneck and founder effects, the Hardy-Weinberg principle, co-evolution and hybridisation.

Sex and behaviour

The r and K continuum, parental investment, mating systems, intra- and inter-sexual selection, mate choice and courtship, sexual dimorphism and alternative reproductive behaviours.

Parasitism

The spectrum of symbiosis, parasite life cycles and transmission, definitive, intermediate and vector hosts, immune evasion, behavioural manipulation, social parasitism, epidemiology and control.

How to study Area 2

1. Link variation to selection. Variation from mutation, recombination and fertilisation is the raw material; selection, drift and reproduction then act on it. Treat the area as one connected story.
2. Practise the calculations. Mark-recapture and Hardy-Weinberg questions are common and reward careful, shown working.
3. Use real examples. Bottlenecks, sexual selection and parasite life cycles are best learned through worked examples you can adapt.
4. State assumptions and evaluate. Many marks come from recognising the assumptions of methods such as mark-recapture and why control of parasites is hard.

The key areas in detail

Each key area has its own answer page with worked questions and cross-links. Use the quiz below to check your recall across the whole area, then work through the individual key areas.

For the official course specification

The SQA publishes the full Advanced Higher Biology course specification and past papers at sqa.org.uk. Always revise from the current specification and SQA past papers.