Explain why individual amino acids are soluble in water, and why not all peptides are water soluble?

Question

Explain why individual amino acids are soluble in water, and why not all peptides are water soluble?

Answer 1

one aminoacid may be soluble in water because:  first all aminoacids have a amino group and a carboxilic group and these groups are polars so they make to aminoacids be partially soluble in water, second: all aminoacids have side grupo or R group so then if this R group is polar ( for example -OH for serine , or -COOH for glutamic acid) so these aminoacis are even more soluble in water...

But the peptides are made by few aminoacids this mean that not all are polar necesarly so the peptides are less soluble in water, it means that the solubility of a peptide is based on the polarity of R groups from its aminoacids.