Q1. Explain cell wall.
Ans1 1. Cell wall is present outer to cytoplasmic membrane.
2. It is rigid in structure and gives shape to the cell.
3. Cell wall makes upto 10-40% of the dry weigh of the cell.
4. Bacterial cells whose cell wall is removed cannot grow or divide like a normal
cell.
Q2. Differentiate between gram positive and gram negative bacteria.
Ans2
GRAM POSITIVE
1. Cell wall appears more thick
and continuous
2. 90% of the cell wall is made up
of peptidoglycan.
3. Teichoic acids are the main
surface antigen
GRAM NEGATIVE
1. Cell wall usually appears think
and three layered.
2. 10% of the cell wall is made uo
of peptidoglycan.
3. Lipopolysacchrides are the
main surface antigen.
Q3. Explain cytoplasmic membrane.
Ans3 1. Cytoplsmic membrane is 7.5 nm thick.
2. It is made up of phospholipids and proteins.
3. 20-30% phospholipids and 60-70% proteins.
4. Phospholipids form bilayer.
5. There are two types of proteins- integral and peripheral protein.
6. Cytoplasmic membrane acts as a hydrophobic barrier to most
water soluble molecules.
7. If cytoplasmic membrane is damaged physically or chemically it may lead to
death of the cell.
Q4. Explain Mesosomes.
Ans4 1. Mesosomes are present in many bacteria especially gram positive
bacteria.
2. There are two types - Central mesosomes and Peripheral
Mesosomes.
3. Central mesosomes are located near the middle of the cell and appear to be
attached to the nuclear material.
4. Peripheral mesosomes are slightly penetrateed into the
cytoplasm.
5. Respiratory activity takes place here.
Q5. Name three groups of photosynthetic bacteria.
Ans5 1. Cyanobacteria
2. Purple bacteria
3. Green bacteria
Q6. Explain lamella and sac.
Ans6 1. Lamellae or sacs, as stated, are the photosynthetic
internal membrane systems formed by the extensions of plasma
membrane.
2. They have similar functions to the chloroplasts of eukaryotes.
3. They may form hollow sacs or get arranged in regular parallel layers or may
form small regular stacks of tubular lamella resembling grana of chloroplasts.