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Topic 3: The voice of the genome

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are cells structured and how do they divide to produce new cells?

The ultrastructure of eukaryotic and prokaryotic cells, the functions of the main organelles, and the events of the cell cycle and mitosis.
An Edexcel A-Level Biology B (Salters-Nuffield) answer on cell structure and the cell cycle, covering eukaryotic and prokaryotic ultrastructure, organelle functions, and the stages of mitosis.
12 min answer →

How is gene expression controlled, and how can the environment affect which genes are active?

The control of gene expression by transcription factors, the role of epigenetic modifications such as DNA methylation and histone modification, and how the environment can affect the phenotype.
An Edexcel A-Level Biology B (Salters-Nuffield) answer on gene expression and epigenetics, covering the control of transcription by transcription factors, epigenetic modifications such as DNA methylation and histone modification, and how environment affects phenotype.
9 min answer →

How does meiosis produce genetic variation and how does fertilisation restore the chromosome number?

The events of meiosis, how crossing over and independent assortment generate genetic variation, the role of gametes and fertilisation, and the difference between meiosis and mitosis.
An Edexcel A-Level Biology B (Salters-Nuffield) answer on meiosis and fertilisation, covering the events of meiosis, crossing over and independent assortment, the role of gametes and fertilisation, and how meiosis differs from mitosis.
9 min answer →

How do unspecialised cells become specialised, and how might stem cells be used in medicine?

The nature and types of stem cells, how cells become specialised and organised into tissues and organs, and the potential uses and ethical issues of stem cells.
An Edexcel A-Level Biology B (Salters-Nuffield) answer on stem cells and differentiation, covering the types of stem cells, how cells differentiate and organise into tissues and organs, and the potential uses and ethical issues of stem cells.
9 min answer →