Final answer:
Gram-positive bacteria are characterized by their thick peptidoglycan wall, single plasma membrane, and ability to retain the crystal violet stain, appearing blue (dark purple), with various antibiotics effective against them.
Step-by-step explanation:
The true statements about gram-positive bacteria are that they have a thick peptidoglycan wall, a single plasma membrane, stain blue (dark purple) with crystal violet, and can be treated with antibiotics such as penicillin, fluoroquinolones, and sulfa-antibiotics. The peptidoglycan wall is not located in the periplasmic space and gram-positive bacteria do not have an inner and outer cell membrane but rather a single plasma membrane. After the primary stain of crystal violet, a gram-positive bacterium stains blue (dark purple), indicating a thick layer of peptidoglycan, and it will retain this color even after a counterstain like safranin is applied given its ability to resist decolorization by alcohol or acetone. Treatments with antibiotics such as penicillin, which inhibits cell wall synthesis, fluoroquinolones, and sulfa-antibiotics that inhibit different metabolic pathways within bacterial cells, are often effective against gram-positive bacteria.
The statements that are true about gram-positive bacteria are:
Thick peptidoglycan wall: Gram-positive bacteria have a thick cell wall composed of multiple layers of peptidoglycan.
Stains blue (dark purple) with crystal violet: When Gram-stained, gram-positive bacteria retain the crystal violet dye and appear blue or dark purple.
Can be treated with penicillin: Penicillin is effective against gram-positive bacteria as it targets their peptidoglycan cell wall.