For questions 33-40, write one word that best completes each sentence.
Write your answer on the lines below the text.
There is an example at the beginning (0).
The porcupine’s prickly defence
Porcupines are slow-moving nocturnal creatures that are no pushover (0) for a predator. Since they don't run towards a predator to attack, their quills, can reach 30 centimetres in length, must easily detach and penetrate tissue. They can also be hard to remove of their microscopic barbs, say scientists.
North American porcupines are famed for unique defence as they carry 30,000 quills on their backs. Tiny backward-facing barbs studding the tip of each quill have been found to reduce penetration force and maximise staying power. our knowledge this is the first demonstration of a highly engineered system that achieves polar-opposite dual functionality.
In order to understand the quills perform their remarkable dual function, researchers analysed them under a microscope. The team found that the quills with barbs required 60-70 % less force to penetrate muscle tissue those without barbs. But when came to removing the quills, the barbs played the opposite role with the microscopic structures acting as anchors in the tissue.
conjunction with the porcupine's large strong claws, the stiff quills of the tail are used as a brace to help it stay attached to tree limbs, so while resting on a branch, a porcupine will flatten itself and appear to be a tree nest.
Online pripreme za maturu i instrukcije za srednju školu. Dostupno 24/7.