Curriculum Portal

neurologyYou need to know

• Asexual reproduction involves one parent and produces offspring that are genetically identical clones, except when mutations occur.
• Sexual reproduction involves the fusion of male and female gametes, produces genetically varied offspring, and usually involves two parents.
• Mitosis produces two genetically identical diploid body cells for growth, repair and asexual reproduction.
• Meiosis produces four genetically different haploid gametes by halving the chromosome number.
• In meiosis, variation is produced because chromosomes are shuffled and gametes receive different combinations of alleles.
• DNA is a polymer made of two strands twisted into a double helix, with bases paired as A with T and C with G.
• A gene is a section of DNA that codes for the order of amino acids in a protein.
• Chromosomes are long DNA molecules found in the nucleus, and the genome is the complete set of genetic material in an organism.
• An allele is a different version of a gene; dominant alleles are expressed with one copy, while recessive alleles are expressed only when two copies are present.
• A genotype is the combination of alleles an organism has, while a phenotype is the observable characteristic caused by genes and the environment.
• The human genome is important because it can help scientists identify genes linked to disease, develop targeted treatments, trace human migration, and understand inherited disorders.
• In humans, biological sex is usually inherited through sex chromosomes: females are XX and males are XY, so the sperm determines the sex of the offspring.
• Cystic fibrosis is caused by a recessive allele and can cause thick sticky mucus in the lungs and digestive system.
• Polydactyly is usually caused by a dominant allele and results in a person being born with extra fingers or toes.
• Genetic screening is testing DNA, cells or embryos to identify alleles linked to inherited disorders.
• Variation between organisms can be caused by genetic differences, environmental differences, or a combination of genetic and environmental factors.
• Mutations are changes in DNA, and they can be harmful, beneficial or have no effect on phenotype.
• Natural selection occurs when individuals with advantageous characteristics are more likely to survive, reproduce and pass on their alleles.
• Selective breeding is the process where humans choose organisms with desirable characteristics to breed over many generations.
• Genetic engineering transfers a useful gene from one organism into another organism’s genome, often using enzymes and vectors such as plasmids.

• Compare asexual and sexual reproduction by referring to number of parents, gametes, genetic similarity of offspring, and amount of variation.
• Compare mitosis and meiosis by stating the number of divisions, number of cells produced, chromosome number, genetic similarity, and biological purpose.
• Construct and complete a Punnett square using parental genotypes, possible gametes, offspring genotypes, phenotype ratios, and probability predictions.
• Interpret a family tree by identifying affected individuals, carriers where possible, and likely dominant or recessive inheritance patterns.
• Represent variation data from a population using an appropriate graph, such as a bar chart for discontinuous data or a line graph/histogram for continuous data.
• Evaluate embryo screening by weighing medical benefits against economic costs, social impacts and ethical concerns.
• Explain evolution by natural selection using variation, competition, survival advantage, reproduction, inheritance of alleles, and change in allele frequency over generations.
• Explain antibiotic resistance by linking random mutation, survival of resistant bacteria, reproduction, spread of resistance, and reduced effectiveness of antibiotics.
• Interpret evolutionary trees by identifying common ancestors, closest relatives, branching points and relative times of divergence.
• Write a species name using the binomial naming system, with the genus first, the species second, and appropriate capitalisation.