What is the significance of the red blood cell being anucleate?

Which mantle is under the crust the upper mantle or the lower mantle i think it's upper let me know if i'm right

Identify the type of energy used in each action. the flexing of an arm muscle: a signal transduction process by a neuron: a ball at the top of a hill: 1. electrical energy 2. mechanical energy 3. gravitational potential energy

Which best describes meiosis? a. it produces cells that are identical to the original cell b. it is responsible for the replacement of damaged skin cells c. it is responsible for growth of the organism d. it produces male and female sex cells