The major causes of death that account for the large differences in life exxpectancy between less developed and more developed countries are b. infectious and parasitic diseases.
G1 phase - growth
S - DNA replication
G2 - growth and preparation to divide
Mitosis - cell division
Checkpoints are important because cells are checked to make sure they have grown/replicated DNA correctly
oxygen and air are abiotic
Answer: It's about things happen
Explanation: