page 14 19. During an investigation into foraging behaviour, a student studied prey selection by shore crabs feeding on mussels. The student observed the crabs feeding and measured the length of each mussel predated on by the crabs over several days. The results were compared with another study where the energy expended by a crab to open a mussel of a specific size was compared to the energy content of the mussel to allow the energy gained per unit of foraging time to be calculated. The results are shown in the graph. average number of mussels eaten per day length of mussel (mm) energy gain (Joules per unit of foraging time) Key mussels eaten energy gain 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 What conclusion can be drawn from the results? A Shore crabs don’t select prey on the basis of size. B As prey size increases, foraging becomes less efficient. C As prey size increases, foraging becomes more efficient. D Shore crabs tend to select prey sizes that make foraging more efficient. 20. Which of the following characteristics is most likely to be found in an r‑selected species? A Produce a large number of small offspring B Most offspring reach adulthood C Have a longer generation time D High level of parental care [END OF SECTION 1. NOW ATTEMPT THE QUESTIONS IN SECTION 2 OF YOUR QUESTION AND ANSWER BOOKLET] page 15 [BLANK PAGE] DO NOT WRITE ON THIS PAGE