The is a defining characteristic of bacteria which is not found in eukaryotes and is therefore a good choice for chemotherapeutic agents.

peptidoglycan

Explanation:

The cell wall of most of bacteria is composed of peptidoglycan. peptidoglycan is a polymer of amino acids and sugar molecules. It is also used to distiguish between gram negative and gram positive bacteria by gram staining technique.

Peptidoglycan is important for the integrity of bacterial cell as well as for binary fission. Several antibiotics such as Penicillin interfere with the formation of peptidoglycan. Bacterial resistance is increasing for antibiotics by the mutation in gene transpeptide. This mutation in gene decreases the interaction of antibiotic with bacteria.

Lysozymes found in our tears aslo act as antibacterial by attacking the bacterial peptidoglycan.

Peptidoglycan cell wall

Explanation:

Peptidoglycan forms the structural framework of bacterial walls, by forming a 3-D mesh-like layer  from peptides  and its Glycan strands in the cell wall.This provides  strength and protection to bacterial, resisting  the  tugor  pressure    from osmotic potential  of the surrounding cytoplasm.

Gram +, bacteria have more peptidoglycan layers in their cell walls lay down  than other forms of bacteria. Penicillin(a chemotherapeutic agents )is susceptible to peptidoglycan, and therefore kills bacteria by breaking down the peptidoglycan in the cells walls, destroying the 3-D mesh-like layer, therefore disrupting the structural framework.

This perforated the cell wall. The high osmotic potential of surrounding cytoplasm drives water in by osmosis, thus  the cell swells and bursts. killing the bacterial.

Eukaryotes lack peptidoglycan cell wall, and therefore chemotherapeutic agents do not affect Eukaryotes through the plasma membrane.

b. heterotroph

explanation:

a and c are the answeres