Genetics and ecosystems official content revision notes

Genetics and Ecosystems Revision Note

Key Concepts in Genetics

• Genotype vs. Phenotype: The genotype is the genetic makeup of an organism, while the phenotype is the observable characteristics resulting from the genotype and environmental influences.
• Terminology: Understand the terms dominant, recessive, codominant, homozygous, and heterozygous to describe genetic traits.
• Genetic Diagrams: Be able to construct and interpret genetic diagrams for monohybrid and dihybrid crosses, including those involving sex-linkage and autosomal linkage.
• Chi-Squared Testing: Use chi-squared tests to compare observed and expected phenotypic ratios, assessing the significance of genetic crosses.

Population Genetics

• Population Definition: A population consists of organisms of the same species in a specific space and time that can interbreed.
• Gene Pool and Allele Frequency: The gene pool is the total collection of genes in a population, and allele frequency refers to how often a particular allele appears in that gene pool.
• Hardy-Weinberg Principle: Understand the conditions under which this principle applies and use the Hardy-Weinberg equation to calculate allele, genotype, and phenotype frequencies.

Variation and Natural Selection

• Phenotypic Variation: Differentiate between genetic and environmental causes of phenotypic variation.
• Natural Selection: Explain how differential survival and reproductive success lead to evolution, including stabilising, directional, and disruptive selection.
• Genetic Drift and Founder Effects: Understand how these concepts affect small populations and contribute to genetic variation.
• Speciation: Explain how reproductive isolation can lead to the formation of new species.

Ecosystems and Ecology

• Ecosystem Components: Describe populations, communities, ecosystems, and ecological niches, and how they interact.
• Factors Affecting Population Size: Analyze the effects of abiotic (non-living) and biotic (living) factors on population dynamics.
• Succession: Explain the process of ecological succession and the characteristics of climax communities.
• Conservation Methods: Evaluate various conservation strategies and ecosystem management practices.