What is the difference between a prokaryotic and eukaryotic cell?

Prokaryotic cells (e.g., bacteria) lack a nucleus and membrane-bound organelles, while eukaryotic cells (e.g., plant and animal cells) have a nucleus and organelles like mitochondria and the endoplasmic reticulum. Prokaryotes are generally smaller and have circular DNA, whereas eukaryotes have linear DNA packaged into chromosomes.

How do enzymes speed up chemical reactions?

Enzymes lower the activation energy of a reaction by binding to the substrate at the active site, forming an enzyme-substrate complex. This stabilises the transition state, allowing the reaction to proceed faster. The induced-fit model suggests the active site changes shape slightly to accommodate the substrate.

What is the role of mitosis in the body?

Mitosis is responsible for growth, repair, and asexual reproduction. It produces two genetically identical daughter cells, allowing organisms to increase cell number for tissue growth and to replace damaged or dead cells. For example, skin cells undergo mitosis to heal wounds.

How does a mutation in DNA affect protein synthesis?

A mutation changes the DNA sequence, which can alter the mRNA codon during transcription. This may lead to a different amino acid being incorporated into the polypeptide chain during translation, potentially changing the protein's structure and function. For instance, a point mutation in the gene for haemoglobin causes sickle cell disease.

What is the difference between competitive and non-competitive inhibition?

Competitive inhibition occurs when a molecule similar to the substrate binds to the active site, blocking the substrate. This can be overcome by increasing substrate concentration. Non-competitive inhibition involves a molecule binding to a different site (allosteric site), changing the enzyme's shape so the active site is less effective. This cannot be overcome by adding more substrate.

How do you calculate the phenotypic ratio from a dihybrid cross?

First, determine the parental genotypes (e.g., AaBb x AaBb). Use a 4x4 Punnett square to combine all possible gametes (AB, Ab, aB, ab). Count the resulting genotypes and phenotypes. For two heterozygous traits with complete dominance, the typical phenotypic ratio is 9:3:3:1 (dominant for both, dominant for first only, dominant for second only, recessive for both).

Contemporary Issues in Science

PEARSON

vocational

This subtopic develops learners' ability to investigate pressing scientific issues—such as antimicrobial resistance and plastic pollution—that affect global health and environments. It examines the roles of organisations like WHO, Greenpeace, and industry in shaping scientific agendas, and builds competencies in critically appraising and reporting scientific data and media. Learners will produce structured evaluations, demonstrating their understanding of scientific validity and bias.

Learning Outcomes

Assessment Guidance

Key Skills

Key Terms

Assessment Criteria

Assessment criteria

Pearson Level 3 Alternative Academic Qualification BTEC National in Applied Science (Extended Certificate)

Topic Overview

This unit explores the fundamental principles of cell biology, biochemistry, and genetics that underpin all living systems. You will investigate the structure and function of prokaryotic and eukaryotic cells, the role of organelles, and how cells communicate and divide. Understanding these concepts is essential for careers in healthcare, research, and biotechnology, as they form the basis for diagnosing diseases, developing treatments, and advancing medical technologies.

The unit covers key biochemical processes including enzyme action, DNA replication, protein synthesis, and cellular respiration. You will learn how genetic information is stored, expressed, and inherited, and how mutations can lead to disorders. This knowledge connects to real-world applications such as genetic engineering, cancer research, and personalised medicine, making it highly relevant for both academic progression and vocational pathways.

By mastering this unit, you will develop analytical skills through practical investigations, including microscopy, enzyme assays, and genetic crosses. These hands-on experiences prepare you for further study in biomedical sciences, nursing, or forensic science, and equip you with transferable skills in data analysis and scientific communication.

Key Concepts

Core ideas you must understand for this topic

→Cell structure: differences between prokaryotic and eukaryotic cells, and the functions of organelles like mitochondria, ribosomes, and the Golgi apparatus.
→Enzyme action: lock-and-key and induced-fit models, factors affecting rate (temperature, pH, substrate concentration), and inhibition types (competitive, non-competitive).
→DNA replication and protein synthesis: semi-conservative replication, transcription, translation, and the roles of mRNA, tRNA, and ribosomes.
→Cell division: mitosis (growth and repair) and meiosis (gamete formation), including the stages and significance of genetic variation.
→Genetics: Mendelian inheritance, monohybrid and dihybrid crosses, codominance, sex linkage, and the impact of mutations on phenotype.

Learning Objectives

What you need to know and understand

1. Investigate contemporary scientific issues that impact the global population and environment.2. Examine the effect different organisations have on contemporary science.3. Understand how to evaluate and report scientific information.

Assessment Criteria

Key criteria assessors look for in your portfolio

Award credit for selecting and interpreting scientific data from credible, varied sources (e.g., peer-reviewed journals, government databases) to support arguments.
Expect a balanced analysis that considers multiple stakeholder perspectives (social, ethical, economic) and acknowledges the complexity of the issue.
Credit for consistent and accurate referencing (e.g., Harvard style) to acknowledge sources and avoid plagiarism.
Look for explicit evaluation of the reliability and validity of sources, including recognition of potential bias or methodological limitations.
Reward effective communication: clear structure, appropriate scientific terminology, and logical progression from investigation to conclusion.

Assessment Guidance

Guidance for achieving higher grades

💡Use analytical frameworks like PESTLE (Political, Economic, Social, Technological, Legal, Environmental) to structure your evaluation and ensure comprehensive coverage of impacts.
💡Cross-reference at least three high-quality sources for each key claim to demonstrate robust research skills and reliability.
💡Practise writing concise summaries of complex scientific issues in your own words to enhance clarity and avoid plagiarism.
💡Allocate time proportionally: spend at most 30% on description, with the remainder on analysis, evaluation, and conclusion to address higher-grade criteria.
💡Before submission, check that you have addressed every command verb in the assignment brief (e.g., investigate, examine, evaluate) with explicit evidence.
💡When answering questions on enzyme kinetics, always sketch a graph showing the effect of temperature or pH, and label the optimum point. Use specific data from the investigation to support your explanation.
💡For genetics problems, write out the parental genotypes clearly, then use a Punnett square to show the cross. State the genotypic and phenotypic ratios explicitly, and include a sentence interpreting the results.
💡In essay-style questions, use correct terminology (e.g., 'semi-conservative replication' not 'copying') and link concepts together. For example, explain how a mutation in DNA can affect protein structure and function.

Common Mistakes

Common errors to avoid in your coursework

Confusing correlation with causation when interpreting data, leading to flawed conclusions.
Relying uncritically on non-academic sources (e.g., blogs, social media) without verifying credibility.
Failing to distinguish between scientific evidence and opinion, treating all claims as equally valid.
Presenting a one-sided argument that ignores counter-evidence or opposing viewpoints, missing the 'evaluate' command.
Producing descriptive reports that summarise information rather than analysing and synthesising it to meet assessment criteria.
Students often think that all enzymes are proteins, but some RNA molecules (ribozymes) also catalyse reactions. Remember that the definition of an enzyme is a biological catalyst, not exclusively a protein.
A common mistake is confusing mitosis and meiosis: mitosis produces two identical diploid cells, while meiosis produces four genetically different haploid cells. Focus on the number of divisions and the outcome.
Many students believe that DNA replication occurs during interphase, but they forget that it happens specifically in the S phase. Ensure you link the cell cycle stages to the correct events.

Frequently Asked Questions

Common questions students ask about this topic

Before You Start

Prior knowledge that will help with this topic

•Basic knowledge of cell structure from GCSE Biology, including the differences between plant and animal cells.
•Understanding of the principles of diffusion, osmosis, and active transport as methods of membrane transport.
•Familiarity with the concept of genes and chromosomes from Key Stage 4 science.

Key Terminology

Essential terms to know

1. Investigate contemporary scientific issues that impact the global population and environment.2. Examine the effect different organisations have on contemporary science.3. Understand how to evaluate and report scientific information.

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Contemporary Issues in Science

Assessment criteria

Topic Overview

Key Concepts

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Assessment Criteria

Assessment Guidance

Common Mistakes

Frequently Asked Questions

Before You Start

Key Terminology

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Related Topics in PEARSON vocational Applied Science

Component 1

Biomedical Science