9. Pili originate from the plasma membrane. They are more often involved in
adherence to surfaces, which facilitates infection. One specialized type of
pilus (sex pilus) helps in the transfer of genetic material between the
bacterial cells. This process is called conjugation.
Fimbriae is another name of “short attachment pili.” They adhere to the
host’s surface, allowing bacteria to colonise and infect the host. The
bacteria with fimbriae are known as fimbriate bacteria.
16. Explanation
The polysaccharide (PS) capsule of the human
pathogenic fungus Cryptococcus neoformans is
a beautiful structure, which appears in India Ink
preparations as a translucent region. The
capsule is the most important virulence factor
of C. neoformans, contributing approximately
25% of the total virulence composite.
19. Explanation
The rigid layers of fungal cell walls contain complex
polysaccharides called chitin and glucans (unlike the
cell walls of plants, which contain cellulose).
Chitin is probably the second most
abundant polysaccharide in nature
Chitin is a modified polysaccharide that contains
nitrogen; it is synthesized from units of N-acetyl-D-
glucosamine. These units form covalent β-(1→4)-
linkages.
25. Explanation
Chlamydomonas and spirogyra are two green algae.
Chlamydomonas is a unicellular eukaryotic algae. Spirogyra
are photosynthetic and they belong to the kingdom Plantae.
These are Eukaryotic.
27. Explanation
African Trypanosomiasis, also known as “sleeping
sickness”, is caused by microscopic parasites of the species
Trypanosoma brucei. It is transmitted by the tsetse fly
(Glossina species)
Leishmaniasis is a parasitic disease caused by
the Leishmania parasite. This parasite typically lives in
infected sand flies.
Amoebiasis, or amoebic dysentery, is an infection of
the intestines caused by a parasitic amoeba
Entamoeba histolytica.
Malaria is caused by the Plasmodium parasite. The parasite
is spread to humans through the bites of infected
mosquitoes.
29. Explanation
Red algae, or Rhodophyta from Ancient
Greek (rhódon) 'rose', and (phutón) 'plant'), are one of
the oldest groups of eukaryotic algae. They are
eukaryotic red-colored algae that may be multicellular
or unicellular and colonial. The red colour of these
algae results from the pigments phycoerythrin and
phycocyanin; this masks the other pigments,
Chlorophyll a (no Chlorophyll b), beta-carotene and a
number of unique xanthophylls.
33. Explanation
The contractile vacuole complex is a membrane-bound osmoregulatory
organelle of fresh water protozoa such as Paramecium. As the name
suggests, it expands and contracts. The function of the contractile
vacuole is to pump water out of the cell through a process called osmo
regulation, the regulation of osmotic pressure. It maintains the shape
and internal pressure of the cell.
35. Explanation
Protozoans reproduce by binary fission as well as by
multiple fission.
The outer surface layer of some protozoa, termed a
pellicle (stiff but flexible), is sufficiently rigid to
maintain a distinctive shape.
41. Explanation
Archaebacteria:
Archaea contain a cell wall composed of various
polysaccharides and proteins.
Archaebacteria has a well-defined cell wall that is not made
of peptidoglycans like its eubacterial counterpart.
Pseudopeptidoglycan (also known as pseudomurein; PPG
hereafter) is a major cell wall component of some
Archaea that differs from bacterial peptidoglycan in
chemical structure, but resembles bacterial peptidoglycan
in function and physical structure.
It provides rigidity and protection from the harsh outer
environment.
43. Explanation
These are primitive unicellular organisms that belong
to prokaryotes.
The organisms in Domains Bacteria and Archaea are
prokaryotic, meaning that their cells do not have a true
nucleus, but rather have a nuclear region. Archaea and
Bacteria do not possess membrane-bound organelles.
Archaea thrive in many different extremes: heat, cold,
acid, base, salinity, pressure, and radiation.
45. Explanation
The archaeal lineage may be the most ancient that
exists on earth.
No archaea are known to use photosynthesis.
Halophiles can be found mostly in the domain
Archaea but not all are halophiles, they also include
thermophiles, psychrophiles, halophiles, acidophiles,
and alkaliphiles.
They are the most ancient and are called living fossils.
So they are the oldest living beings.
49. Explanation
Geosmin is a natural bicyclic terpene with an earthy
odor. The human nose can detect it at concentrations
in air as low as 5 ppt.
Geosmin is produced by various blue-green algae
(cyanobacteria) and filamentous bacteria in the
class Actinomyces, and also some other prokaryotes
and eukaryotes.
In the soil, geosmin production is attributed to a single
genus of bacteria, called Streptomyces.
51. Explanation
Frankia is a representative genus of nitrogen-fixing (N2-
fixing) actinobacteria.
Frankia is a genus of nitrogen-fixing bacteria that live in
symbiosis with actinorhizal plants, similar to the
Rhizobium bacteria found in the root nodules.
Azospirillum is a Gram-negative, nitrogen-fixing bacterial
genus.
Clostridium are capable of nitrogen fixation and are an
anaerobic bacterium, it is the first known free-living
nitrogen-fixing bacterium.
Anabaena belongs to the genus of filamentous
cyanobacteria which are known for their nitrogen-fixing
abilities.
53. Explanation
Actinomycetes are Gram positive, aerobic,
and filamentous bacteria.
Actinomyces species may form endospores.
Actinomycete spores are formed either by subdivision
of existing hyphae by fragmentation or swelling or by
endogenous spore formation.
55. Explanation
Penicillins are a group of β-lactam antibiotics
originally obtained from Penicillium moulds,
principally P. chrysogenum and P. rubens.
Clinically useful natural products originated from
Streptomyces are not just confined to antibiotics, but
also include antifungals (e.g., amphotericin B),
antivirals (e.g., boromycin), antiparasitics (e.g.,
ivermectin), antitumorals (e.g., doxorubicin),
anti‐hypertensives (e.g., pikromycin), and
immunosuppressants.
