Answer:
1.ans Phylogenetic Trees
Scientists use a tool called a phylogenetic tree to show the evolutionary pathways and connections among organisms. A phylogenetic tree is a diagram used to reflect evolutionary relationships among organisms or groups of organisms.
2.ans Binomial Nomenclature Rules
The entire two-part name must be written in italics (or underlined when handwritten). The genus name is always written first. The genus name must be capitalized. The specific epithet is never capitalized
3.ans Dichotomous Key
A dichotomous key is a tool created by scientists to help scientists and laypeople identify objects and organisms. Typically, a dichotomous key for identifying a particular type of object consists of a specific series of questions.
 
        
             
        
        
        
The most common pathogen then carry is protozoa , that causes malaria 
        
             
        
        
        
Answer:
The answer is autotrophs
Explanation:
During the early days of the Earths life there was no oxygen but there was plenty of CO2 which the autotrophs took and used as food while discarding the excess which was the oxygen.