Tag: bacteria; benefits and harmful effects
Questions Related to bacteria; benefits and harmful effects
Sex factor of bacteria is
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RNA
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Sex pili
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F-factor
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Chromosome replicon
F-factor is also called as fertility factor. It is the sex factor of bacteria. It allows the transfers of genes from one bacterium carrying the factor to another bacterium lacking the factor by the process of conjugation. It is found in some bacteria only.
Which is not true of bacterial cell wall?
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Not antigenic
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Provides shape to bacterium
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Not stainable with simple dyes
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Made of mucopeptide
Murein of bacterial cell wall is derivative of
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Vitamin
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Fat
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Organic acid
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Sugar
The bacterial cell wall is made up of Peptidoglycan or murein. It is a polymer that is made up of sugars and amino acids. The sugar component is made up of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). NAM is then attached to an amino acid chain of L-alanine, D-glutamic acid, diaminopimelic acid (DAP) and D-alanine.
Bacterial cell membrane is made up of
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Chitin
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Cellulose
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Proteins and phospholipids
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Fats
Bacteria is a unicellular prokaryotic organism. It has a cell wall around the cell membrane. The bacterial cell membrane is made up of proteins and phospholipids. the proteins in are randomly distributed in the phospholipid bilayer of the cell membrane.
Teichoic acid is present in cell wall of
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Bacteriophage
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Mycoplasma
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Nostoc
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Pneumococcus
Some bacteria have a capsule outside cell wall. It is made of
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Protein
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Cellulose
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Fat
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Mucopolysaccharide
Some bacteria have a capsule outside cell wall. It is made up of mucopolysaccharide. The functions of mucopolysaccharide are;
- It enhances the ability of bacteria to cause disease.
- It protects cells from engulfment by macrophages.
- It protects cells from desiccation.
Why is a capsule advantageous to a bacterium?
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It provides means of locomotion
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It allows bacteria to "hide" from host's immune system
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It allows the bacterium to attach to surface
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It protects the bacterium from desiccation.
- Bacterial capsule usually consists of a polysaccharide layer that lies outside the cell envelope. The capsule is found in both gram-positive and gram-negative bacterium.
- The capsule is considered as virulence factor because it enhances the ability of bacteria to cause disease. It protects the bacterial cell from engulfment by macrophages.
- Capsules also contain water which protects the bacterium from desiccation.
Ageing is slow or absent in
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Plants
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Parrot
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Monkeys
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Hydra
The ageing is very slow or is not seen with the human eye in unicellular organisms but they do age. They undergo constant spontaneous DNA damage that can lead to the death of cells when it no longer able to reproduce. Plants and parrot are multicellular organisms with the higher level of complexity. The complexity is such that cell divisions are limited and when the cell is not able to divide, it ages with the decay of organelles and finally dies. So these organisms do age and die after a perticular period of time. but Hydra is the only species that does not age and lose its capability to reproduce. So we can say that ageing is slow or absent in hydra.
Select the wrong statement of a bacterial cell
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Mesosome is formed by extensions of plasma membrane into cell
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Pili are elongated tubular structures made up of a protein
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Flagellum is composed of filament, hook and basal body
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Ribosomes are about 30 nm by 50 nm in size
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Fimbriae are small bristle like fibres sprouting out of cell.
Which one of the following is absent in eukaryotes?
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Nucleolus
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Plastid
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Mesosome
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Ribosomes
- Mesosomes are absent in eukaryotes.
- Mesosomes refers to the folded invaginations in the plasma membrane of prokaryotes or bacterial cells.
- Its main function is to increase the surface area of the plasma membrane.
- When the surface area of the membrane is increased it helps to carry out the cellular respiration more efficiently.
- So, the correct answer is 'Mesosome'.