Q36.2-4ITD. - Campbell Biology

Question

Would you expect plant growth to have a Q₁₀ closer to 1 or 3? Why?

Step-by-Step Solution

Answer

The Q₁₀ for plant growth must be closer to 3 because ATP (adenosine triphosphate) is required for macromolecule synthesis. The synthesis of ATP is a chemical process.

Step 1: Temperature coefficient, Q 10

Temperature coefficient Q10 is a factor that increases the rate of a physical process when the temperature is raised by 10°C. It is a value that describes the relationship between the changes in a physical process due to temperature change.

Chemical processes that are sensitive to temperature have Q10 values close to 2 or 3. However, physical processes have Q10 values close to 1. Thus, Q10 is used to conclude about a physiological process being studied.

Step 2: Formula to calculate temperature coefficient, Q 10

The formula to calculate temperature coefficient:

 $Q_{10}={\left(\frac{k_2}{k_1}\right)}^{\frac{10}{t_2-t_1}}$

Where t2 and t1 are higher and lower temperatures, respectively, and k2 and k1 are reaction rates at t2 and t1, respectively. 

Step 3: Q 10 for plant growth is closer to 3

Water uptake by seeds is a physical process, so its Q10 is close to 1. Plants require ATP for macromolecules synthesis for their growth. This explains the fact that initial water uptake by seeds is a physical process.

However, the growth of seedlings eventually into a plant is a chemical process. As a result, Q10 for plant growth must be closer to 3.