Evaluation Questions Flashcards
(3 cards)
Ecologists investigated the effect of two fish species, the redband parrotfish and the ocean surgeonfish, on algal growth on an artificial reef. They made this artificial reef by submerging many large concrete blocks at a depth of 16–18 metres off the coast of Florida. They attached four large wire cages, A, B, C and D, to each block and populated the cages as shown.
B, p value = 0.841
C, p value = <0.001
D, p value = 0.634
significant decrease with C compared to A
no significant difference with B and D compared to A
less than 0.05 probability that difference is due to chance
species of algae unknown
natural reef growth may differ
evaluate the use of 2,4,D herbicide on a wheat crop that contains wild oats as a weed.
2,4-D is a selective herbicide that kills some species of plants but not others. 2,4-D disrupts
cell-surface membranes but the extent of disruption differs in different species.
Scientists investigated the effect of 2,4-D on wheat plants (a crop) and on wild oat plants (a
weed).
They grew plants of both species in glasshouses. They put plants of each species into one of two
groups, W and H, which were treated as follows:
* Group W - leaves sprayed with water
* Group H - leaves sprayed with a solution of 2,4-D.
After spraying, they cut 40 discs from the leaves of plants in each group and placed them in
flasks containing 10 cm3
de-ionised water. After 5 minutes, they calculated the disruption to
cell-surface membranes by measuring the concentration of ions released into the water from the
leaf discs.
FOR
1. 2,4-D causes an increase in release of ions from wild oat cells AND 2,4-D does
not affect / has little effect on the release of ions from wheat cells; (therefore it is a good herbicide)
2. (For wheat) Difference is less than LSD / 7 so difference is not significant;
OR
(For wild oats) Difference is more than LSD / 10 so difference is significant;
3. Loss of ions from cells (likely to) lead to cell / plant death/damage;
OR
Disruption of cell membrane (likely to) lead to cell / plant death / damage;
AGAINST
4. No evidence here about death of plants as a result of this ion loss;
5. No evidence here of other ecological/environmental impact;
