Protists that have a pellicle are surrounded by
silica dioxide
calcium carbonate
carbohydrates
proteins

proteins

Explanation:

Protists are unicellular eukaryotic organisms. As eukaryotes, they carry an individualized, delimited nucleus and well-defined cytoplasmic organelles. The Protista kingdom is made up of protozoa and certain unicellular algae. Among the protists that have a pellicle, such as Euglena, there is the presence of protein film organized spirally around the cytoplasm. This film is very flexible and allows the constant change of the shape of these organisms. These organisms are found in freshwater puddles with a lot of organic matter and are considered bioindicators of pollution in this kind of environment.

answer-

the statement that f(x) = |x+a| + b has exactly one x-intercept is sometimes correct.

solution-

it solely depends on b, whether the function will have one or two or zero x intercept.

this plot of the given function, f(x) = |x+a| + b will be the basic absolute value graph i.e v shape, with vertex translated to (-a, b), instead of origin.

1-   if b is zero, the graph will have exactly one x-intercept, at x= -a

2- if b is positive, the whole graph will be above the x-axis, hence it will have no x-intercepts.

3- if b is negative, the graph will be below the x-axis, hence it will have two x-intercepts.

∴ the statement is sometimes true.