Question

free-response questions (frqs) - 32 minutes: question 1 (10 points maximum) (4.a.6) plants lose water from their aboveground surfaces in the process of transpiration. most of this water is lost from stomata, microscopic openings in the leaves. excess water loss can have a negative effect on the growth, development, and reproduction of a plant. severe water loss can be fatal. environmental factors have a major impact on the rate of plant transpiration. transpiration rate versus temperature temperature (°c) 20 23 27 28 transpiration rate (mmol/m²·sec) 1.5 3 5 4.5 a) using the data above and the grid provided, draw a graph showing the effect of temperature on the rate of transpiration. explain the shape of the curve from 23 - 28 degrees. (up to 5 points; 3 points for graph, 1 point for description of curve, and 1 point for explanation of change)

Explanation:

Step1: Identify variables

The independent variable is temperature and the dependent variable is transpiration rate.

Step2: Plot points

On the x - axis (temperature in °C) plot 20, 23, 27, 28 and on the y - axis (transpiration rate in mmol/m²·sec) plot 1.5, 3, 5, 4.5 respectively and connect the points.

Step3: Analyze curve from 23 - 28 degrees

From 23 - 27 degrees, the transpiration rate increases. This is because higher temperatures increase the kinetic energy of water molecules, causing more water to evaporate from the stomata. From 27 - 28 degrees, the transpiration rate decreases. This could be due to the closure of some stomata as a protective mechanism against excessive water loss at high temperatures.

Answer:

A graph with temperature on the x - axis and transpiration rate on the y - axis should be plotted with points (20, 1.5), (23, 3), (27, 5), (28, 4.5) connected. The curve from 23 - 27 degrees rises due to increased kinetic energy of water molecules and from 27 - 28 degrees it falls possibly due to stomatal closure to prevent excessive water loss.