A grounds team tests a selective weedkiller on three equal areas of a grass sports field. At the start, each area contains 50 broad-leaved weeds.

Each area is sprayed with the same volume of liquid. All other conditions are kept the same.

After four weeks, the team counts the broad-leaved weeds and estimates the percentage of the ground covered by grass.

Spray applied	Number of broad-leaved weeds after four weeks	Ground covered by grass (%)
Water only	45	95
0.5 g auxin per dm³	15	92
2.0 g auxin per dm³	5	78

The grounds team wants to reduce the number of broad-leaved weeds as much as possible while maintaining at least 90% grass cover.

Calculate the percentage decrease in the number of broad-leaved weeds in the water-only area and in the area treated with 0.5 g auxin per dm³. Explain why the difference between these percentages can be attributed to auxin.

Evaluate which spray the grounds team should use.

A grounds team tests a selective weedkiller on three equal areas of a grass sports field. At the start, each area contains 50 broad-leaved weeds.

Each area is sprayed with the same volume of liquid. All other conditions are kept the same.

After four weeks, the team counts the broad-leaved weeds and estimates the percentage of the ground covered by grass.

Spray applied	Number of broad-leaved weeds after four weeks	Ground covered by grass (%)
Water only	45	95
0.5 g auxin per dm³	15	92
2.0 g auxin per dm³	5	78

The grounds team wants to reduce the number of broad-leaved weeds as much as possible while maintaining at least 90% grass cover.

Evaluate which spray the grounds team should use.

6.3 Plant hormones

Question 39

Markscheme

6.3 Plant hormones

Question 39

Markscheme

6.3 Plant hormones

Question 39

6.3 Plant hormones Questions

6.3 Plant hormones

Question 39

6.3 Plant hormones Questions