Designing Investigations
Why is calculating a mean from repeated trials essential for enzyme experiments?
it reduces the impact of random error and increases the reliability of results. However, if inconsistent measurement techniques are used, the data may still be invalid.
How could a single base mutation in the template strand alter a protein?
It may change the mRNA codon, leading to a different amino acid, potentially altering protein structure and function.
Why does an enzyme’s tertiary structure determine substrate specificity?
The tertiary structure determines the precise shape of the active site, which must complement the substrate; this shape is stabilized by ionic, hydrogen, and disulfide bonds.
Why does high surface-area-to-volume ratio improve cell efficiency?
It increases the area available for exchange relative to volume, allowing quicker diffusion of nutrients and waste—e.g., microvilli in intestines.
A new sequencing technology allows scientists to collect more accurate genetic data in less time. This changes how DNA profiling is done in forensics. Which SHE concept is best demonstrated and why?
Development: The question highlights how a new technology improves the efficiency of scientific procedures and data analysis. It also leads to improved accuracy in evidence collection, which reflects an evolution in how the science is conducted.
Identify one uncontrolled variable in an osmosis investigation using root cells and explain its impact.
Biological variation in membrane permeability could affect water movement, potentially confounding the results related to solute concentration.
How do post-transcriptional modifications increase protein diversity in eukaryotes?
Through alternative splicing, different combinations of exons can produce multiple proteins from a single gene.
How does guide RNA ensure accuracy in CRISPR-Cas9 editing?
The guide RNA is complementary to the target DNA sequence, directing Cas9 to the exact site for cutting.
How does facilitated diffusion differ from active transport at the molecular level?
Facilitated diffusion uses channel or carrier proteins to move substances down a concentration gradient without energy. Active transport requires ATP to move substances against a gradient.
A scientist submits their findings to an international genetics journal for peer review before publishing. How is this an example of a SHE concept?
Communication and Collaboration: Scientific knowledge is validated through peer review, shared using international conventions, and often involves global scientific dialogue and standardised communication formats.
Design a photosynthesis experiment investigating light wavelength. Include hypothesis, variables, and ethics.
→ Hypothesis: Different light wavelengths will result in varying photosynthesis rates due to pigment absorption differences.
IV: Light wavelength
DV: Oxygen production
CVs: Light intensity, temperature, plant species
Ethics: Avoid long-term exposure to potentially damaging light, use plants responsibly.
Predict the impact of reversing DNA strand orientation during transcription.
Transcription of the incorrect strand would produce an incorrect mRNA sequence, resulting in a non-functional or truncated protein.
*a protein that is shorter than the full-length version due to premature termination of its synthesis during translation.
How do new DNA-editing technologies challenge existing models of gene therapy?
They allow precise, efficient, and potentially safer edits, reducing dependence on viral vectors but raising new ethical, regulatory, and safety concerns.
Design an investigation comparing osmosis in living and dead plant tissues. Predict the results.
Place equal-sized living and boiled (dead) tissues in distilled water and measure mass change. Living cells will gain/lose water; dead cells will show minimal change due to membrane damage.
Gene therapy trials are paused after reports of adverse effects in patients, requiring international teams to adjust their protocols and re-analyse results. What SHE concept is best represented and why?
Communication and Collaboration: Global coordination, revision of methods, and transparent sharing of findings represent how science relies on collaborative problem-solving and information exchange.
You are testing how temperature affects how quickly amylase breaks down starch. You are using iodine, which changes colour when starch is present.
Why would it be better to use a tool like a colorimeter, which measures colour changes using light, instead of just using your eyes?
A colorimeter is a tool that shines light through a liquid and gives a number to show how dark the colour is. This is better than using your eyes because people might see colours differently. Using a colorimeter gives clear, accurate results and helps you see small changes that your eyes might miss. It also means the results are fair and easy to compare between groups.
How can epigenetic modification in a gene’s promoter region lead to cancer?
Hypomethylation of a promoter can cause overexpression of genes involved in cell division, leading to uncontrolled proliferation.
Note *DNA hypomethylation arises mainly from the loss of methylation at normally heavily methylated areas of genome.
Compare PCR and electrophoresis in purpose and mechanism.
PCR amplifies DNA using cycles of heating, cooling, and enzyme activity. Electrophoresis separates DNA fragments by size using an electric field and gel matrix.
Compare the roles of endocytosis and exocytosis in homeostasis.
Endocytosis imports nutrients or removes pathogens; exocytosis expels waste and secretes molecules. Both processes help maintain internal balance.
During climate change research, biologists use modelling software developed by physicists and engineers to analyse ecological impacts. Identify and explain the SHE concept at work.
Influence: This is a clear example of interdisciplinary influence — where scientific understanding in one field (biology) benefits from tools and knowledge in others (physics, engineering, mathematics).
Critique this method: “Place enzyme in test tube and time how long bubbles take to stop.”
This lacks accuracy and trend data. Use a gas syringe to measure oxygen volume at timed intervals. This allows rate calculation and consistent comparison.
Explain the consequence of a mutated tRNA anticodon.
It may pair with the wrong mRNA codon, inserting an incorrect amino acid, potentially producing a malfunctioning or harmful protein.
What might overlapping peaks at two loci in an electropherogram suggest?
Possible contamination (mixed DNA from multiple individuals)
Why do glucose molecules need transport proteins, but oxygen does not?
Glucose is large and polar, requiring carrier proteins. Oxygen is small and nonpolar, allowing it to diffuse directly through the lipid bilayer.
A CRISPR technology designed for treating inherited blindness is being evaluated for rollout. Public concerns emerge around long-term safety, costs, and gene editing ethics. Which SHE concept is most relevant and why?
Application and Limitation: Although the technology offers a promising solution, its social, economic, and ethical implications highlight the need for risk evaluation and monitoring