What ecosystem are you talking about ?
Both. You can use it as singular or plural.
The answer is A because they are parts of algae
Answer:
(d) Cell wall
Explanation:
The cell wall is a structure located on the outside of the cell membrane in the cells of plants, bacteria, fungi, and algae. It is a resistant, tough and flexible layer, which has the vital function of supporting the osmotic pressure inside the cell, preventing the cell from lysis when water enters. Besides, it has the function of giving rigidity, support and defining the shape of the cell.
Answer:
An animal with a backbone.
Explanation: