The question
Name: ______________________ Date: ____________ Same genotype, different environments (4 points)
Experimental setup
Yarrow cuttings at three temperatures
Yarrow is a flowering plant that grows from sea level to high mountains. A student has one yarrow plant collected near the coast. She plans to take 36 cuttings from it, root them, and grow 12 cuttings in each of three growth chambers set to 10 °C, 18 °C and 26 °C. After 10 weeks she will measure the height of each plant, in centimeters.
(a) State the null hypothesis for this investigation. [1 point]
(b) Identify the independent variable and one variable that should be held constant across the growth chambers, and justify holding that variable constant. [1 point]
(c) Explain why the student uses cuttings from one plant rather than seeds collected from many plants. [1 point]
(d) The student finds that the plants are tallest at 18 °C and shortest at 10 °C. Predict the heights of plants grown from cuttings of the 10 °C plants if they were then moved to 18 °C for another 10 weeks of new growth, and justify your prediction. [1 point]