Tag: botany

Questions Related to botany

The large holes in "swiss-cheese" are due to production of large amount of $CO _2$ by a bacterium named?

botany option b: biotechnology and bioinformatics gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Lactobacillus

  2. Saccharomyces cerevisiae

  3. Propionibacterium sharmani

  4. Streptococcus

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Correct Option: A

Teichoic acid is present in 

botany living world and classification of microbes gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Gram +ve bacteria

  2. Gram -ve bacteria

  3. Spirochaete

  4. Actinomycetes

Show answer
Correct Option: A
Explanation:

Teichoic acids are found within the cell wall of Gram-positive bacteria. The main function of teichoic acid is to provide rigidity to the cell wall by attracting cations, such as magnesium and sodium.

Which one of the following dyes cannot be used for staining chromatin material?

botany living world and classification of microbes gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Acetocarmine

  2. Crystal violet

  3. Haematoxylin

  4. Schiff's reagent (Feulgen stain)

Show answer
Correct Option: B
Explanation:

Crystal violet dye is used as a histological stain and in Gram's method of classifying bacteria.
Rest all other dyes in option as acetocarmine, haematoxylin and Schiff's reagent are used to stain chromosome.
Thus, the correct answer is option B.

All the following statements are true about exotoxins except 

botany living world and classification of microbes gram staining microbiology: organisms in industry cell wall and cell membrane

  1. They are protein in nature.

  2. Are heat labile.

  3. Produced by Gram + positive bacteria.

  4. Are highly antigenic.

Show answer
Correct Option: C
Explanation:

An exotoxin is a toxin secreted by bacteria. An exotoxin can cause damage to the host by destroying cells or disrupting normal cellular metabolism. Exotoxin is secreted during lysis of the cell. 

The main difference between Gram +ve and Gram -ve resides in the composition of 

botany living world and classification of microbes gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Cilia

  2. Cell wall

  3. Cell membrane

  4. Cytoplasm

Show answer
Correct Option: B
Explanation:

The Gram-negative cell wall is characterized by presence of outer membrane, a thinner peptidoglycan layer and extensive periplasmic space surrounding the peptidoglycan. The uppermost layer of the outer membrane has lipopolysaccharide, while the innermost layer is a typical lipid layer. Presence of membrane channels formed by porin proteins in outer membrane impart make them less penetrable as compared to Gram positive cells. Gram positive cells are characterized by presence of single thick layer of cell wall which is made up of peptidogycan, teichoic acid and lipoteichoic acid. They lack outer membrane and porin and have narrow periplasmic space. Plasma membrane is the unit membrane in both, Gram positive and Gram negative bacteria, present beneath cell wall with primarily phospholipids (making up about 30–40% of the membrane mass) and proteins (60–70%). The dense gelatinous solution surrounded by plasma membrane is cytoplasm which has same composition in both, Gram positive and Gram negative cells. Cilia are the eukaryotic structures which are absent in bacteria as they are prokaryotic. 

Thus, the correct answer is option B.

A prokaryotic cell lacks 

botany cell and cell organelles gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Cell wall

  2. Cell membrane

  3. Cytoplasm

  4. Nucleolus

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Correct Option: D
Explanation:

A prokaryotic cell lacks a nucleolus. A prokaryote is a single-celled organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelles. All the intracellular water-soluble components are located together in the same volume enclosed by the cell membrane, rather than in separate cellular compartments.

Difference in Gram +ve  and Gram -ve bacteria is due to

botany option b: biotechnology and bioinformatics gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Cell wall

  2. Cell membrane

  3. Ribosome

  4. Cytoplasm

Show answer
Correct Option: A
Explanation:

The cell wall of certain bacteria shows a characteristic reaction to the stain devised by C. Gram. Those bacteria which retain the stain are known as Gram positive and those which do not retain the stain are called Gram negative.

  • The cell wall in bacteria contains peptidoglycan, a polymer of N-acetyl glucosamine, N-acetyl muramic acid and amino acids.
  • Gram-positive cell walls contain a thick layer of peptidoglycan that encircles the cell.
  • Gram-negative cell walls contain a thin layer of peptidoglycan between the cytoplasmic membrane and the outer membrane.

Bacterial cell wall is composed of peptidoglycan, a complex of oligosaccharides and proteins.        The oligosaccharide component consist of _________

botany option b: biotechnology and bioinformatics gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Linear chain of alternating NAG and NAM linked by ${\alpha}$ (1 -4) linkage

  2. Linear chains of alternating NAG and NAM linked by ${\beta}$ (1-4) linkage.

  3. Linear chain of glucose linked by $4{\beta}$ (1-4) linkage.

  4. Linear chain of glucose linked by ${\alpha}$ (1-4) linkage

Show answer
Correct Option: B
Explanation:

The oligosaccharide component of bacterial cell wall consists of linear chains of alternating NAG and NAM linked by ${\beta}$ (1-4)linkage.

Gram-negative bacteria that cause infections, when stained,  do not retain the crystal violet stain, which tells the researcher that

botany option b: biotechnology and bioinformatics gram staining microbiology: organisms in industry cell wall and cell membrane

  1. The peptidoglycan layer is thick and the bacteria are resistant to antibiotics.

  2. The peptidoglycan layer is very thin and the bacteria is susceptible to antibiotics.

  3. The peptidoglycan layer is very thin and the bacteria are resistant to antibiotics.

  4. The peptidoglycan layer contains an impermeable lipid layer.

Show answer
Correct Option: C
Explanation:

The peptidoglycan layer of the gram negative bacteria are thin and are also referred to as the cell envelope. The layer is wavy and provides resistance to antibiotics. They are more virulent as compared to Gram positive bacteria

So, the correct answer is 'The peptidoglycan layer is very thin and the bacteria are resistant to antibiotics'

Which one of the following is not a characteristic of Gram positive bacteria?

botany living world and classification of microbes gram staining microbiology: organisms in industry cell wall and cell membrane

  1. Cell wall is smooth

  2. Mesosomes are distinctively prominent

  3. Basal body of flagellum contains 2 rings

  4. Outer membrane is present

Show answer
Correct Option: D
Explanation:

Outer membrane and periplasmic space are absent in Gram positive bacteria but present in Gram negative bacteria. The outer membrane in Gram negative bacteria is made up of lipopolysaccharides.