Patterns, relationships, conclusions, hypotheses and further investigation
Write three features of a strong answer.
Describe the enzyme-style graph. Avoid vague words like “it” and “they”. Replace them with nouns.
“It goes up then down.”
“As temperature increases, the rate increases then decreases.”
“As temperature increases from 10°C to 40°C, the rate increases from 1 to 6 cm³/min. After 40°C the rate decreases.”
Question: Calculate the gradient between 0 and 10 minutes.
m = gradient
c = y-intercept, where the line crosses the y-axis
For a straight-line graph, this can help describe the mathematical relationship between variables.
For a curve, the rate of change at one point is found using a tangent.
Explain why a tangent is needed for rate at one point on a curve.
Press start to begin.
First, scientists can decide whether data appears to support a hypothesis by looking at the pattern.
To be more confident, they can use mean and standard deviation to judge whether differences between groups are likely to be meaningful.
Think about spread, variation and overlap.
Dataset: 12, 15, 15, 18, 20
Standard deviation measures how spread out data is around the mean.
9, 10, 10, 11, 10
4, 8, 10, 12, 16
Dataset: 8, 10, 10, 12, 15
Use this sample standard deviation formula:
| Value, x | x − mean | (x − mean)² |
|---|---|---|
| 8 | -3 | 9 |
| 10 | -1 | 1 |
| 10 | -1 | 1 |
| 12 | 1 | 1 |
| 15 | 4 | 16 |
| Total | 28 |
Write one sentence about spread and reliability.
Scientists often compare the mean and standard deviation range for two groups.
If the mean ± SD ranges do not overlap, the groups are more likely to be genuinely different.
If the mean ± SD ranges overlap, the difference between means may be due to variation in the data.
Hypothesis: Fertiliser increases plant growth.
| Group | Mean height (cm) | Standard deviation (cm) | Mean ± SD range |
|---|---|---|---|
| No fertiliser | 12 | 2 | 10 to 14 |
| Fertiliser | 18 | 3 | 15 to 21 |
Question: Do the SD ranges overlap? What does this suggest about the hypothesis?
Data helps us decide whether a hypothesis is supported, but it may not prove something is always true.
Example: If pondweed produces more oxygen at higher light intensity, does that conclusion apply to all plants in all conditions?
List two reasons a conclusion might not apply everywhere.
“Caffeine increases reaction time because the people who drank coffee reacted faster.”
| Group | Mean reaction time (ms) | Number of participants |
|---|---|---|
| No caffeine | 280 | 3 |
| Caffeine | 240 | 3 |
Click each term and add the definition to your notes.
Create a “how to interpret scientific data” guide.
Describe the trend in the enzyme graph using data and scientific vocabulary.
For the line y = 3x + 4, identify the gradient and y-intercept.
An experiment used one species, five repeats and a narrow temperature range. Suggest two improvements.
Answer each question. Your score will appear at the end.