Answer:The answer is tiny organisms known as cyanobacteria, or blue-green algae.
Explanation:
These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and oxygen increase. Additionally, some sources you could use that I used to answer this question was 
https://www.scientificamerican.com/article/origin-of-oxygen-in-atmosphere/
 
        
             
        
        
        
Critical thinking is the term defined as the mental process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and evaluating information to reach an answer or <span>conclusion.</span>
        
             
        
        
        
Answer:
The influx of calcium ions.
Explanation:
The influx of calcium ions at a certain point produces phase of the action potential also called depolarization which results in the ion movement changes the membrane potential from negative to positive inside the cell.
In action potential, calcium ions may control gene transcription, cell excitability, and neurotransmitter release. In chemical synapses, the influx of calcium ions leads to vesicles filled with neurotransmitters move to the surface of the cell, and into the synaptic cleft release their contents.
 
        
             
        
        
        
These would be the elements in row 2 the alkaline metals. Elements in a row usually share many qualities such as electon reactivity as well as similar characteristics like the fact that many alkaline metals are considered Cations, ions with positive charges. Some examples are beryllium and calcium. 
        
             
        
        
        
Answer:
Dr. Stott's belief about that the 9-year-olds will advance in knowledge based on instructions is based on the theory of cognitive development, proposed by Lev Vygotsky.
Explanation:
Theory of cognitive development -also called the socio-cultural theory of cognition- was put forward by the Russian-Jewish psychologist Lev Vygotsky, in which he expresses the influence of the socio-cultural environment on the learning process.
<u>For Vygotsky, children possess innate basic skills, such as attention, sensation, memory and perception, which develop over time</u>.
The process of cognitive development implies that the development of each child's basic skills requires the guidance of an adult, since -although there are skills that he does not understand or has not developed- he can learn them with the appropriate guidance and instructions.