Because natural selection can only increase or decrease frequency of alleles that already exist in the population
Answer:
Tendon sheaths protect long tendons as they course over and around synovial joints.
Explanation:
Tendon sheaths are tubes of tissue filled with a lubricating fluid that surround the tendons like a tunnel. The tendon sheath prevents the tendon from fraying or being exposed to excessive friction. The inside of the sheath is lined with synovial fluid. This allows the tendon to slide forward and backward. From this we can say that the tendon sheaths protect the long tendons as they travel through the synovial joints.
Some plants cant survive.
They restricted to specific layers hope this helps
