How should a results table be laid out?

The independent variable goes in the first column and the dependent variable, with its repeats and mean, in the columns to its right, and every column heading gives the quantity and its unit.

Why are units written in the column headings of a results table rather than beside each value?

The unit applies to every value in the column, so giving it once in the heading, for example "Time / s", keeps the table clear.

How many decimal places should raw data in a results table be recorded to?

Every value of the same measurement should have the same number of decimal places, matching the resolution of the apparatus used.

How many significant figures should a calculated result be given to?

No more than the least precise measurement used in the calculation, because a result cannot be more precise than the data it came from.

Calculate the mean rate of water uptake when three potometer readings are 2.4, 2.7 and 2.6 mm/min.

Mean = (2.4 + 2.7 + 2.6) ÷ 3 = 7.7 ÷ 3 = 2.566…, given as 2.6 mm/min to 2 significant figures to match the data.

Round 0.004872 mm to 2 significant figures.

0.0049 mm: the leading zeros are not significant, so the first two significant figures are 4 and 8, and the following 7 rounds the 8 up to 9.

OCR A-Level Biology H420

Cell Structure

Topic overview Microscopy, slide preparation and staining Biological drawings, magnification and resolution Eukaryotic cell ultrastructure The secretory pathway and the cytoskeleton Prokaryotic and eukaryotic cells compared

Biological Molecules

Topic overview The properties of water Monomers, polymers and the elements of life Monosaccharides and disaccharides Polysaccharides and their functions Lipids Amino acids and protein structure Globular and fibrous proteins Inorganic ions The biochemical tests Colorimetry and chromatography

Nucleotides and Nucleic Acids

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Enzymes

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Biological Membranes

Topic overview Membrane structure and the fluid mosaic model Factors affecting membrane permeability Diffusion, active transport, endocytosis and exocytosis Osmosis and water potential

Cell Division, Cell Diversity and Cellular Organisation

Topic overview The cell cycle Mitosis and observing it in root tips Meiosis Specialised cells Tissues, organs and organ systems Stem cells and differentiation

Exchange Surfaces

Topic overview Surface area to volume and the features of an exchange surface The mammalian gas exchange system Ventilation and lung volumes Gas exchange in fish and insects Dissecting and examining gas exchange tissue

Transport in Animals

Topic overview Why animals need transport systems Arteries, veins and capillaries Tissue fluid and lymph The structure of the mammalian heart The cardiac cycle and control of the heartbeat The electrocardiogram Transporting oxygen and carbon dioxide Oxygen dissociation curves and the Bohr effect

Transport in Plants

Topic overview Xylem, phloem and vascular tissue Transpiration and the potometer Water uptake and movement up the xylem Xerophytes and hydrophytes Translocation

Communicable Diseases, Disease Prevention and the Immune System

Topic overview Pathogens and how disease is transmitted Plant defences and non-specific animal defences Phagocytes and phagocytosis The specific immune response Antibodies Types of immunity Vaccination Medicines and antibiotic resistance

Biodiversity

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Classification and Evolution

Topic overview The taxonomic hierarchy and binomial naming The five kingdoms and the three domains Phylogeny and the evidence for evolution Variation and adaptation Natural selection and resistance

Communication and Homeostasis

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Excretion as an Example of Homeostatic Control

Topic overview Excretion and nitrogenous waste The liver: structure and function The structure of the kidney The nephron Ultrafiltration Selective reabsorption and the loop of Henle Osmoregulation and ADH Kidney failure, dialysis and transplant Urine testing and monoclonal antibodies

Neuronal Communication

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Hormonal Communication

Topic overview Hormones and the adrenal glands The pancreas and the islets of Langerhans Controlling blood glucose Diabetes and its treatment

Plant and Animal Responses

Topic overview Tropisms and plant responses to stress and herbivory Plant hormones and their commercial uses The nervous system and the brain Reflex actions and the knee jerk reflex Fight or flight and the control of heart rate The structure of skeletal muscle The neuromuscular junction and the sliding filament model

Photosynthesis

Topic overview Photosynthesis and chloroplast structure Photosynthetic pigments and chromatography The light-dependent stage The Calvin cycle Limiting factors

Respiration

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Cellular Control

Topic overview Gene mutations and their effects The lac operon Transcription factors and post-transcriptional control Homeobox and Hox genes Mitosis and apoptosis Oncogenes, tumour suppressor genes and cancer

Patterns of Inheritance

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Manipulating Genomes

Topic overview DNA sequencing and bioinformatics DNA profiling, PCR and gel electrophoresis Genetic engineering: restriction enzymes and vectors Genetic modification, its ethics, and gene therapy

Cloning and Biotechnology

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Ecosystems

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Populations and Sustainability

Topic overview Population size and limiting factors Predator-prey cycles and competition Conservation and preservation Sustainable timber production and fishing Human impacts and how they are controlled

Practical Skills and Mathematical Requirements

Topic overview Planning investigations and choosing apparatus Recording and presenting data Gradients, intercepts and logarithmic scales Averages, spread and statistical tests Evaluating experiments and uncertainty Estimates, symbols and biological calculations

Practical Skills and Mathematical Requirements

Recording and presenting data

3 things to know
Components 01, 02 and 03

Overview

Recall questions on laying out results tables with units in the headings, decimal places and significant figures, standard form and unit conversions, the units of a rate, and choosing bar charts, histograms and line graphs.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

Why is 5.0 × 10⁻³ written with a zero after the decimal point rather than as 5 × 10⁻³?

Process

When should data be presented as a bar chart?

Process

When should a line graph or a scattergram be used?

Questions from this subtopic

Each one with the model answer underneath.

1
How should a results table be laid out?
Model answer
The independent variable goes in the first column and the dependent variable, with its repeats and mean, in the columns to its right, and every column heading gives the quantity and its unit.
2
Why are units written in the column headings of a results table rather than beside each value?
Model answer
The unit applies to every value in the column, so giving it once in the heading, for example "Time / s", keeps the table clear.
3
How many decimal places should raw data in a results table be recorded to?
Model answer
Every value of the same measurement should have the same number of decimal places, matching the resolution of the apparatus used.
4
How many significant figures should a calculated result be given to?
Model answer
No more than the least precise measurement used in the calculation, because a result cannot be more precise than the data it came from.
5
Calculate the mean rate of water uptake when three potometer readings are 2.4, 2.7 and 2.6 mm/min.
Model answer
Mean = (2.4 + 2.7 + 2.6) ÷ 3 = 7.7 ÷ 3 = 2.566…, given as 2.6 mm/min to 2 significant figures to match the data.
6
Round 0.004872 mm to 2 significant figures.
Model answer
0.0049 mm: the leading zeros are not significant, so the first two significant figures are 4 and 8, and the following 7 rounds the 8 up to 9.

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