Question

Match the system with the conditions described.

are purple when using the Gram staining technique

      [ Choose ]            Gram negative            Gram-negative            neither cell type            Gram positive            both cell types      

contains endotoxins as part of cell wall structure

      [ Choose ]            Gram negative            Gram-negative            neither cell type            Gram positive            both cell types      

contains peptidoglycan as part of cell wall structure

      [ Choose ]            Gram negative            Gram-negative            neither cell type            Gram positive            both cell types      

Staphylococcus aureus

      [ Choose ]            Gram negative            Gram-negative            neither cell type            Gram positive            both cell types      

Escherichia coli

      [ Choose ]            Gram negative            Gram-negative            neither cell type            Gram positive            both cell types      

Match the system with the conditions described.

Location where you are most likely to find halotolerant microbes

      [ Choose ]            The lower respiratory system            The upper digestive system            The lower digestive tract            The upper respiratory system            The skin      

location of the mucociliary escalator

      [ Choose ]            The lower respiratory system            The upper digestive system            The lower digestive tract            The upper respiratory system            The skin      

Location of microbe able to produce strong urease enzymes.

      [ Choose ]            The lower respiratory system            The upper digestive system            The lower digestive tract            The upper respiratory system            The skin      

very high numbers of Gram negative microorganisms because of the abundance of nutrients

      [ Choose ]            The lower respiratory system            The upper digestive system            The lower digestive tract            The upper respiratory system            The skin      

Where you are more likely to find microaerophiles

[ Choose ]            The lower respiratory system            The upper digestive system            The lower digestive tract            The upper respiratory system            The skin      

Answer 1

1. While using Gram staining, the bacteria that remains purple is known as Gram positive bacterium. It is because of the thick layer of peptidoglycan that retains the crystal violet stain (which gives purple color). On adding iodine (mordant), it forms a complex with crytsal violet. On application of alcohol, the peptodoglycan shrinks due to which the complex gets retained in there and stains purple even after applying counter stain-safranin.

Hence, the correct option is Gram positive

About the incorrect options-

Gram negatives appear pink during Gram staining. So, it is only Gram positive that appears purple, not both of them

2. The endotoxins are a part of cell wall structure of Gram negative bacteria. The Gram negative bacteria have an outer membrane of lipopolysaccharide. It contains three components - lipid A, R polysaccharide and O-antigen. It is the lipid A , which is responsible for providing toxicity entity to the bacteria by forming endotoxins.

Hence, the correct option is Gram negative.

About the incorrect options-

The Gram postives do not have LPS layer, so endotoxins are only formed by Gram negatives.

3. The peptidoglycan layer is present in both Gram positive and Gram negative bacterium with varying concentrations. The Gram positive bacteria have thick peptidoglycan layer (20-80nm) whereas it is comparativelt thinner in Gram negative bacteria (7-8nm); but it is present in both cell types.

Hence, the correct option is - both cell types.

4. Staphlylococcus aureus is Gram positive

5. Escherichia coli is Gram negative

Hope it helps

PLEASE LEAVE LIKES :)