Key learning 1: transmission of heritable characteristics from one generation to the next involves DNA and genes

Key learning 2: the theory of evolution by natural selection explains the diversity of living things and is supported by a range of scientific evidence

Watch the clip and test yourself afterwards with the quiz

Dominant: an allele that masks the presence of of a recessive allele in the phenotype

Recessive: an allele that is masked in the phenotype by the presence of a dominant allele

Allele: alternate forms or varieties of a gene

Phenotype: the observable characteristics of an individual organism

Genotype: the genetic make-up of an individual

For more key terms click here

Predict simple ratios of offspring genotypes and phenotypes in crosses involving dominant/recessive gene pairs or in genes that are sex-linked

Click the link below for a range of tutorial videos and resources on Mendelian genetics including Punnet squares, ratios and probabilities. 

Evidence to support the theory of Evolution includes:

• fossils
• comparative anatomy (homologous structures)
• genetic and biochemical evidence

Describe the role of DNA as the blueprint for controlling the characteristics of organisms

Deoxyribonucleic acid (DNA) is found in the nucleus of cells and contains the instructions required for an organism to grow, develop, survive and reproduce. It does this by controlling protein synthesis and the production of enzymes. 

The basic building block of DNA is a nucleotide. 

DNA can:

• determine the kind of cell formed (muscle, blood, nerves, etc...)
• determine the kind of organism (buttercup, giraffe, human, etc...)
• 1 gene codes for 1 trait
• We have 2 genes (alleles) for each characteristic

Click here for a brief overview of genetics

Use models and diagrams to represent the relationship between DNA, genes and chromosomes. 

Click below to watch a video on the relationship between DNA, genes and chromosomes. 

Mutations: changes in the bases of genes, or to chromosomes. 

Represent patterns of inheritance of a simple dominant/recessive characteristic through generations of a family

This video below, available via ClickView, covers Punnet Squares, sex linkage, and crossing over. It also introduces Pedigree Analysis using examples of autosomal and sex-linked  inheritance. 

Test yourself by completing the resource activities before, during and after watching the video. 

This ClickView video reviews the structure of DNA and the relationship between DNA, genes and chromosomes. 

Nucleotide molecules:

• consist of a phosphate group + deoxyribose sugar + nitrogen base
• arrange to form the double helix shape
• pair up according to the nitrogen bases (adenine-thymine, and cytosine-guanine)

Mitosis: cell division in body cells for growth and repair. It produces two identical cells. 

Recognise that genetic information passed on to offspring is from both parents by meiosis and fertilisation. 

Meiosis: cell division in gonads that creates 4 non-identical sex cells or gametes (sperm and egg)

Fertilisation occurs during sexual reproduction when a male sex cell (sperm) unites with a female sex cell (egg) to produce an offspring. 

Variation within species is due to meiosis and/or random fertilisation. 

Describe mutations as changes in DNA or chromosomes and outline the factors that contribute to causing mutations. 

A mutagen is any agent capable of altering the structure of DNA within our cells. 

Watch the video below, available via ClickView, and complete the resource activities before, during and after the clip. 

Log in via ClickView to view the following video on Natural Selection