The table below shows observations from a seedling nursery. Young bean plants were grown in trays. Some trays were gently touched with a soft brush for ten ...
Question 1 Report
The table below shows observations from a seedling nursery. Young bean plants were grown in trays. Some trays were gently touched with a soft brush for ten seconds each day, while others were not touched. After 14 days, students measured the mean stem length. All trays received equal volumes of water, the same mineral solution and equal periods of light. The students were investigating a response to touch in plants.
| Condition | Number of plants | Mean stem length after 14 days / cm |
|---|---|---|
| Touched daily | 24 | 9.8 |
| Not touched | 24 | 13.1 |
(a) Identify the independent variable. [1]
(b) Calculate the difference between the mean stem lengths. [1]
(c) Describe the conclusion supported by the results. [2]
(d) Explain why equal volumes of water were used. [2]
(e) Suggest one reason for using 24 plants in each condition. [1]
Answer Details
(a) Whether plants were touched daily / touch treatment [1] (b) 13.1 - 9.8 = 3.3 cm [1] (c) Touched plants had shorter stems [1]; daily touch reduced mean stem growth / length [1] (d) Water affects plant growth / cell turgor [1]; keeping it equal means any difference is due to touch rather than water [1] (e) To improve reliability / reduce effect of unusual individual plants [1]
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