It is the presence of oxygen-bound hemoglobin that makes it bright red
Release of a neurotransmitter across the synapse is triggered by the entry of Ca++ into the presynaptic axon. No Ca++ entry means no transmission across the synapse.
Answer:
Answer B. Endosymbiosis
Explanation:
Early protists were first eukaryotic organisms and had several membrane bound organelles. The anaerobic protists evolved by acquiring purple bacteria. The purple bacteria have the ability to carry out aerobic cellular respiration. The endosymbiont transformed into mitochondria in due course of evolution. Similarly, the photosynthesizing protists were evolved by endosymbiosis of cyanobacteria which in turn was transformed into chloroplast during further evolution.
