Question

The researchers designed this experiment to test their hypotheses: They grew ragweed plants in growth chambers at three different levels of CO₂:

• the pre-industrial level, 280 µmol mol^-1

• the level in the year 2000, 370 µmol mol^-1

• the level projected for the middle of the 21st century, 600 µmol mol^-1

They then measured the amount of pollen produced by sample plants grown under each condition and determined the concentration of protein allergens in that pollen. Here are the data they collected.

CO2 Level	Pollen Produced per Plant (g)	Allergen Protein Concentration (units mg-1 pollen protein)
280 µmol mol-1	5.0	4490
370 µmol mol-1	11.5	5290
600 µmol mol-1	21.0	8180

Pollen data from L. H. Ziska and F. A. Caulfield. Rising CO₂ and pollen production of common ragweed (Ambrosia artemisiifolia), a known allergy-inducing species: implications for public health. Aust. J. Plant Physiol. 27: 893–898 (2000). Allergen data from Singer, B.D. et al. Increasing Amb a 1 content in common ragweed (Ambrosia artemisiifolia) pollen as a function of rising atmospheric CO₂ concentration. Functional Plant Biology 32: 667-670 (2005).

Use the data table to answer these questions about the experimental results and conclusions. Not all terms will be used.

ResetHelp increases decreases remains the same cannot tell from the data yes no 1. As the CO2 level increases up to 600 µmol mol-1, how does ragweed pollen production change?   2. As the CO2 level increases up to 600 µmol mol-1, how does the ragweed allergen concentration change?   3. If the CO2 level increases above 600 µmol mol-1, how would ragweed pollen production and the allergen concentration change?   4. Do the data support Hypothesis 1 and its prediction--that plants grown at higher CO2 levels will produce more pollen? (yes or no)   5. Do the data support Hypothesis 2 and its prediction--that plants grown at higher CO2 levels will produce higher concentrations of allergens? (yes or no)   6. Do the data prove that increased CO2 levels cause more severe ragweed allergies? (yes or no)

Answer 1

1. As the CO2 level increases up to 600 µmol mol-1, how does ragweed pollen production change? Increases. 2. As the CO2 level increases up to 600 µmol mol-1, how does the ragweed allergen concentration change?  Increases. 3. If the CO2 level increases above 600 µmol mol-1, how would ragweed pollen production and the allergen concentration change? cannot tell from the data. 4. Do the data support Hypothesis 1 and its prediction--that plants grown at higher CO2 levels will produce more pollen? yes. 5. Do the data support Hypothesis 2 and its prediction--that plants grown at higher CO2 levels will produce higher concentrations of allergens? yes. 6. Do the data prove that increased CO2 levels cause more severe ragweed allergies? no.