AQA GCSE Biology (Triple) - Paper 2: Inheritance, Variation and Evolution

Vocabulary flashcards based on key concepts from AQA GCSE Biology (Triple) covering inheritance, variation, and evolution.

Sexual reproduction

The fusion of male and female gametes (sperm and egg) to produce genetically different offspring.

Asexual reproduction

Reproduction involving only one parent; offspring are genetically identical to the parent.

Meiosis

A type of cell division that produces four genetically different haploid gametes from one diploid cell.

DNA

A polymer made of two strands forming a double helix, carrying the genetic information.

Gene

A small section of DNA on a chromosome that codes for a specific sequence of amino acids.

Genome

The entire genetic material of an organism.

Importance of understanding the human genome

It helps identify genes linked to disease, understand inherited disorders, and trace human evolution.

Alleles

Different versions of the same gene.

Dominant alleles

Show their effect even if one copy is present.

Recessive alleles

Only show their effect if two copies are present.

Genotype

The genetic makeup (alleles) of an individual.

Phenotype

The physical expression of the genotype.

Homozygous genotype

Two identical alleles (e.g., BB or bb).

Heterozygous genotype

Two different alleles (e.g., Bb).

Punnett square

A diagram used to predict the probability of different genotypes and phenotypes in offspring.

Polydactyly

An inherited disorder caused by a dominant allele, resulting in extra fingers or toes.

Cystic fibrosis

An inherited disorder caused by a recessive allele, characterized by thick mucus affecting the lungs.

Sex determination in humans

Determined by sex chromosomes: XX = female, XY = male.

Causes of variation in organisms

Genetic variation (mutations, sexual reproduction) and environmental factors.

Mutation

A random change in DNA that can affect how genes work; most have little or no effect.

Evolution

The gradual change in inherited characteristics of a population over time through natural selection.

Selective breeding

A process where humans breed plants or animals for desired characteristics.

Genetic engineering

Modifying the genome of an organism by introducing a gene from another organism.

Advantages of genetic engineering

Includes disease resistance and increased yield.

Disadvantages of genetic engineering

Includes ethical concerns and risks to biodiversity.

Cloning

The production of genetically identical individuals from a single parent.

Extinction

When no members of a species remain alive.

Evidence supporting evolution

Includes fossil records and studies of antibiotic resistance in bacteria.

Binomial system of classification

A universal naming system giving each organism a two-part Latin name (genus and species).

Organism classification

Into hierarchical groups: kingdom, phylum, class, order, family, genus, species.

Theory of natural selection

Developed by Charles Darwin to explain how species evolve.

Main principles of natural selection

Variation exists, competition for resources, better-adapted individuals survive and reproduce.

Fossils

Remains of organisms from millions of years ago, formed by mineral replacement of organic material.

Incompleteness of the fossil record

Due to soft-bodied organisms decomposing quickly or fossils being destroyed.