Answer:
One
Explanation:
In a controlled experiment only one variable is changed at a time, while the others are kept the same/controlled so changes can be observed and a causation can be determined.
Could be anything that can help represent the cell membrane visually
The correct answer is option C, that is, the presence of the nuclear membrane.
Cyanobacteria is a phylum of bacteria that attain their energy via the process of photosynthesis, and are the only photosynthetic prokaryotes possessing the tendency to generate oxygen. As a prokaryote, they are devoid of the nuclear membrane.
Euglena refers to a single cell flagellate eukaryote. It comes under the class Euglenoidea. The species of Euglena are witnessed in salt water and in freshwater. Being a eukaryote, they possess nuclear membrane.
Cells don't grow very big because they have to be able to diffuse through material easily. Also, when cells are small and plentiful they are easy to replace when damaged.
