<h2>
Answer:</h2>
The scientist started to study relationships among various groups of organisms <u>C. by using genetic analyses</u>.
<h2>
Explanation:</h2>
The following features were used to study about the relationships between different groups of organism:
- External morphology
- Similarities in structure
- Genetic analysis
- Chemical composition
The molecular similarities in the structure of RNA, DNA, and proteins help to establish the relationship of relationships between different groups of organisms. This was studied through testing the samples obtained by organisms using genetic analyses.
Answer:
B) Help produce oxygen
C) Help make foods
D) Help break down dead materials
Explanation:
B - Life on Earth <em>depends</em> on protists since they are the ones who supply us with oxygen.
C - Provide food to other living organisms in food chains/webs.
D - Even, recycle important nutrients just for other life forms to use (some protists may also be decomposers; as they also release nutrients into the environment).
