Species and courtship behaviourAQA A-Level Biology: Mind map

Exam questions on Species and courtship behaviour

1. A horse has 64 chromosomes in each body cell and a donkey has 62. A horse and a donkey can mate and produce a healthy offspring called a mule. A mule has 63 chromosomes in each body cell. Mules have never been reported to produce offspring of their own.
   Explain why the horse and the donkey are classified as separate species even though they can mate.2 marks
2. Two closely related species of fruit fly live in the same forest. In species P, the male produces a courtship song by vibrating one wing, with pulses 40 milliseconds apart. In species Q, the male's song has pulses 70 milliseconds apart. In a laboratory test, females of species P accepted a male for mating after hearing a song with 40 millisecond pulses, but almost never after hearing a song with 70 millisecond pulses.
   Explain why courtship behaviour is a necessary precursor to successful mating.2 marks
3. Two species of firefly live in the same meadow. The males of each species fly at night and give a pattern of flashes that is different in each species. A female on the ground replies with a single flash after a fixed delay. A researcher imitates the flash pattern of species X with a torch. Females of species X replied on 85% of the occasions, but females of species Y, a related species, replied on only 6% of the occasions.
   Explain the role of the flash patterns in species recognition in the fireflies.3 marks