Answer:
subsistence agriculture
Explanation:
The land is limited, cultivation systems are basic, and there is not enough harvest to sell.
Explanation:
If water did not expand when freezing, then it would be denser than liquid water when it froze; therefore it would sink and fill lakes or the ocean from bottom to top. Once the oceans filled with ice, life there would not be possible.
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.
The study of the chemical reactions that take place in all living organisms is called Biochemistry
I belive its called a metric system
