Tag: botany

Questions Related to botany

Which of the following stain/s is used by Hans Christian Gram to classify bacteria as gram negative and gram positive bacteria?

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

  1. Carbolfuchsin

  2. Saffronin

  3. Crystal violet

  4. All of the above

Show answer
Correct Option: D
Explanation:

Hans Christian Gram used carbolfuchsin, safranin, and crystal violet to classify bacteria as gram positive and gram negative.

So, the correct option 'all of the above'.

During Gram's stain

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

  1. All bacteria whether Gram (+)ve or (-)ve, take crystal violet stain

  2. Only Gram +ve bacteria take crystal violet stain

  3. Only Gram (-)ve bacteria take crystal violet stain

  4. Gram (+)ve bacteria lose this stain after alcohol treatment and take red stain of safranin

Show answer
Correct Option: B
Explanation:

  1. Gram staining distinguishes between the Gram-positive and Gram-negative bacteria on the basis of the composition of the cell wall.
  2. Gram-positive bacteria have a thick layer of peptidoglycan which helps to retain stain.
  3. The Gram-positive bacteria is first treated with Gram stain which is retained by them. After staining they are treated with alcohol to decolourize. 
  4.  Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell. 
  5. When they are stained by saffranine, they are unable to take the stain and appears blue. 
  6. Gram staining bacteria take up the Gram stain but they are unable to retain them due to the thin layer of peptidoglycan.
  7. When they are exposed to alcohol, decolourizer dissolves the lipids in the cell walls, which allows the crystal violet-iodine complex to leach out of the cells.
  8. When stained with safranin, they take the stain and appears red in colour.
So, the correct answer is 'Only Gram +ve bacteria take crystal violet stain'.

Which of the following is not the layer of chemically complex cell envelope of prokaryotic cells?

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

  1. Glycocalyx

  2. Chromatophore

  3. Cell wall

  4. Cell membrane

Show answer
Correct Option: B
Explanation:
Chromatophores are the pigment-containing and light-reflecting cell. They have no contribution to the protection and structure of the cells. Thus, they are not present in the chemically complex cell envelop of prokaryotic organisms.
Glycocalyx surrounds the cell membrane of bacteria. It is a glycoprotein and glycolipid layer.
Cell wall is the outer most layer of the plant cell. It is composed of cellulose.
Cell membrane is made up of lipids and proteins.
So, the correct answer is 'Chromatophore'.

In which of the following bacteria, cell membrane invaginates and gets folded inside the cell forming mesosomes?

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

  1. Salmonella

  2. Pseudomonas

  3. Rhizobium

  4. Bacillus

Show answer
Correct Option: D
Explanation:

Cell membrane invaginates and gets folded inside the cell forming mesosomes in bacillus because mesosomes are present only in the gram-positive organisms. All the other bacteria are gram-negative organism.

So, the correct answer is 'Bacillus'.

Cell wall is chemically made up of peptidoglycan and lipopolysaccharides in

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

  1. Gram Positive bacteria

  2. Protists

  3. Mycoplasma

  4. Gram Negative bacteria

Show answer
Correct Option: D
Explanation:

Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the gram-staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane. They are an important medical challenge, as their outer membrane protects them from many antibiotics (including penicillin); detergents that would normally damage the peptidoglycans of the (inner) cell membrane; and lysozyme, an antimicrobial enzyme produced by animals that form part of the innate immune system. Additionally, the outer leaflet of this membrane comprises a complex lipopolysaccharide (LPS) whose lipid A component can cause a toxic reaction when these bacteria are lysed by immune cells. 

So, the correct answer is D.

A culture of Mycobacterium leprae was subjected to alkaline ethanol extraction prior to acid-fast staining. The colour of the culture following staining will be

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

  1. Red

  2. Green

  3. Yellow

  4. Blue

Show answer
Correct Option: A
Explanation:
A culture of Mycobacterium leprae was subjected to alkaline ethanol extraction prior to acid-fast staining. The colour of the culture following staining will be red because it is an acid-fast bacteria as it contains a large amount of lipoidal material in their cell wall which prevents penetration of decolorizing solution.

So, the correct answer is 'Red'.

Gram positive bacteria are more rigid than Gram negative bacteria because of the 

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

  1. presence of multiple layers of peptidoglycan

  2. lack of D-amino acids in their cell wall

  3. presence of N-acetylgalactosamine in the peptidoglycan backbone

  4. presence of lipopolysaccharide

Show answer
Correct Option: A
Explanation:
Because gram-positive bacteria are surrounded by layers of peptidoglycan which is many times thicker than is found in the gram negatives. Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which is surrounded by an outer membrane containing lipopolysaccharide which is not present in gram-positive bacteria.

So, the correct answer is 'presence of multiple layers of peptidoglycan'.

Mesosomes were taken as

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

  1. Golgi bodies

  2. Plastids

  3. Mitochondria

  4. Endoplasmic recticulum

Show answer
Correct Option: C
Explanation:

In the vesicle of mesosomes, the respiratory enzymes and the components of electron transport such as ATPase, dehydrogenase, cytochrome are present in low amount. So, they were considered anologous to mitochondria for their respiratory function. 

So, the correct option is 'Mitochondria'.

Which of the following statements is false?

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

  1. Bacteria glycocalyx differ in composition and thickness among diffrent bacteria.

  2. Bacterial envelope has a layered structure and each layer has a distinct function but they act as a single structure

  3. Bacteria are organelle less and contains ribosomes

  4. Number and arrangements of flagella is variable in bacteria.

Show answer
Correct Option: A

____________ is a microbial bio-control agent.

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

  1. Pseudomonas

  2. Penicillium

  3. Bacillus thuringiensis

  4. Clostridium

Show answer
Correct Option: A
Explanation:

Pseudomonas are aerobic, gram-negative bacteria, ubiquitous in agricultural soils, and are well adapted to growing in the rhizosphere. Pseudomonads possess many traits that make them well suited as biocontrol and growth-promoting agents.