Voice of the Genome | Edexcel A-Level Biology A (Salters-Nuffield) (9BN0)

Voice of the Genome

194 questions
16 subtopics
Topics 1 to 4, examined on all three papers
Paper 1, Paper 2 and Paper 3

Covers the cell as a unit: the ultrastructure of prokaryotes and eukaryotes, mitosis and meiosis, gametes and fertilisation, stem cells and how gene expression makes one cell different from another..

It covers prokaryotic cells, eukaryotic organelles and their functions, identifying organelles in an electron micrograph, protein secretion, and levels of organisation, microscopy: the graticule, magnification and standard form, the cell cycle and the stages of mitosis, core practical: the root tip squash, meiosis, linkage and sex linkage, the structure of sperm and egg cells, fertilisation: the acrosome and cortical reactions, totipotency, pluripotency and sources of stem cells, the ethics and risks of stem cell therapy, differential gene expression and specialisation, the lac operon, epigenetics: DNA methylation and histone modification and polygenic inheritance, continuous variation and statistics.

Sample questions from Voice of the Genome

Answer each one closed book first, then open the answer.

Prokaryotic cells

What is the function of the capsule found in some prokaryotic cells?

Show the answer
It acts as a protective layer outside the cell wall.
Identifying organelles in an electron micrograph

Describe the appearance of rough endoplasmic reticulum in an EM image.

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Flattened membrane sacs with dark dots (ribosomes) on the surface.
Microscopy: the graticule, magnification and standard form

Convert 0.0045 into standard form.

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4.5 × 10⁻³
Core practical: the root tip squash

Why is the root tip tissue macerated or softened during preparation of a squash?

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To break down cell walls and separate cells, making them easier to spread into a single layer.
The structure of sperm and egg cells

Why do sperm cells have numerous mitochondria in the midpiece?

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To provide ATP for the movement of the tail/flagellum.
Totipotency, pluripotency and sources of stem cells

Define totipotency.

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The ability of a cell to differentiate into any cell type in an organism, including extraembryonic tissues such as the placenta.
Differential gene expression and specialisation

What process produces mRNA from specific genes during differential gene expression?

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Selective gene transcription.
Epigenetics: DNA methylation and histone modification

What is epigenetics?

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Heritable changes in gene expression that occur without changes to the DNA sequence itself.

The 16 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Prokaryotic cells	Recall questions on the cell wall, capsule, plasmids, flagella, pili and mesosomes, and on how prokaryotic DNA and ribosomes differ from eukaryotic.	10
Eukaryotic organelles and their functions	Recall questions on the nucleus, ribosomes, endoplasmic reticulum, mitochondria, lysosomes, centrioles and the Golgi apparatus.	9
Identifying organelles in an electron micrograph	Recall questions on what each organelle looks like under the electron microscope.	9
Protein secretion, and levels of organisation	Recall questions on the route a protein takes from ribosome to cell surface, and on cells, tissues, organs and systems.	12
Microscopy: the graticule, magnification and standard form	Recall questions on using a graticule, the magnification formula and rearranging it, and on standard form.	8
The cell cycle and the stages of mitosis	Recall questions on interphase and the mitotic phase, why mitosis matters, and what happens in prophase, metaphase, anaphase and telophase.	14
Core practical: the root tip squash	Recall questions on preparing a root tip squash, the stains used, and why root tips are suitable.	8
Meiosis, linkage and sex linkage	Recall questions on how meiosis generates variation through crossing over and independent assortment, and on loci, linked genes and sex linkage.	15
The structure of sperm and egg cells	Recall questions on the acrosome, the flagellum, mitochondria, the zona pellucida and the cortical granules.	12
Fertilisation: the acrosome and cortical reactions	Recall questions on what triggers each reaction, and on how polyspermy is prevented.	12
Totipotency, pluripotency and sources of stem cells	Recall questions on self-renewal, the potency of embryonic and adult stem cells, and where each is found.	11
The ethics and risks of stem cell therapy	Recall questions on the arguments over using embryos, induced pluripotent stem cells, and the risks of rejection and tumour formation.	8
Differential gene expression and specialisation	Recall questions on why cells with the same genome become different, and on the specialised cells produced.	10
The lac operon	Recall questions on the structural genes, promoter, operator and regulatory gene, and on what happens when lactose is present and absent.	16
Epigenetics: DNA methylation and histone modification	Recall questions on how methylation and histone acetylation change gene expression, and on why the changes persist.	12
Polygenic inheritance, continuous variation and statistics	Recall questions on polygenic inheritance, multiple alleles and continuous variation, the mean, median, mode, range and standard deviation, the Student’s t-test and Spearman’s rank correlation coefficient, and choosing the right statistical test.	28

Voice of the Genome is 194 of the 1,892 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.