Biological Classification Chapter-Wise Test 6

Correct answer Carries: 4.

Wrong Answer Carries: -1.

A prokaryotic organism possesses chlorophyll a, forms a gelatinous sheath around its colony and may fix atmospheric nitrogen in specialised cells. Which group does it belong to?

Euglenoids
Dinoflagellates
Slime moulds
Cyanobacteria
4

Cyanobacteria are photosynthetic prokaryotes containing chlorophyll a. Their colonies are generally surrounded by a gelatinous sheath, and some forms, such as Nostoc and Anabaena, fix atmospheric nitrogen in heterocysts.

An aquatic microscopic organism floats passively in water and has a wall formed by two overlapping, silica-containing shells. Which further conclusion is correct?

It is a dinoflagellate and possesses stiff cellulose plates.
It is a diatom and contributes to diatomaceous earth.
It is a euglenoid and has a protein-rich pellicle.
It is a slime mould and forms a plasmodium.
2

The organism is a diatom. Diatoms are microscopic plankton whose walls form two thin, overlapping shells embedded with silica. The accumulated deposits of these indestructible walls form diatomaceous earth.

A freshwater protist has no cell wall, possesses a flexible protein-rich covering and has one short and one long flagellum. How will it behave when sunlight is unavailable?

It will prey on smaller organisms as a heterotroph.
It will form fruiting bodies bearing spores.
It will fix atmospheric nitrogen in heterocysts.
It will produce basidiospores.
1

The described organism is a euglenoid. Euglenoids have a flexible pellicle and two unequal flagella. They photosynthesise in sunlight but behave as heterotrophs by preying on smaller organisms when sunlight is unavailable.

A marine photosynthetic protist possesses stiff cellulose plates and two flagella, one longitudinal and one transverse. What may result if red-coloured members multiply rapidly?

A red tide that may kill fishes
Formation of diatomaceous earth
Production of methane from dung
Formation of a fungal ascocarp
1

These features identify a dinoflagellate. Red dinoflagellates such as Gonyaulax may multiply so rapidly that the sea appears red. Toxins released by such large populations may kill marine animals, including fishes.

A fungus has aseptate, coenocytic mycelium. Its motile or non-motile asexual spores are produced inside a sporangium, and sexual reproduction produces a zygospore. To which class does it belong?

Ascomycetes
Basidiomycetes
Phycomycetes
Deuteromycetes
3

Phycomycetes possess aseptate and coenocytic mycelium. Their asexual spores are motile zoospores or non-motile aplanospores produced endogenously in sporangia, while fusion of gametes produces a zygospore.

A fungus has branched, septate mycelium. It produces conidia externally on conidiophores and sexual spores internally in sac-like structures. Which combination correctly identifies its class and sexual structure?

Basidiomycetes—basidium
Phycomycetes—sporangium
Deuteromycetes—heterocyst
Ascomycetes—ascus
4

The fungus belongs to Ascomycetes. Its asexual conidia are produced exogenously on conidiophores, while sexual ascospores are produced endogenously inside sac-like asci. The asci are arranged in ascocarps.

A fungus has branched, septate mycelium, generally lacks asexual spores and forms four spores externally after karyogamy and meiosis in a specialised structure. Which statement is correct?

It is an Ascomycete, and the specialised structure is an ascus.
It is a Basidiomycete, and the specialised structure is a basidium.
It is a Phycomycete, and the specialised structure is a sporangium.
It is a Deuteromycete, and the specialised structure is a conidiophore.
2

The features identify a Basidiomycete. Karyogamy and meiosis occur in the basidium, generally producing four basidiospores externally. The basidia are arranged in fruiting bodies called basidiocarps.

Only the asexual and vegetative phases of a fungus are known, and it reproduces by conidia. What should happen if its sexual stage is later discovered?

It should be moved from Deuteromycetes to the class to which its sexual form belongs.
It should remain permanently in Deuteromycetes.
It should be transferred to Kingdom Protista.
It should be classified as a viroid.
1

Deuteromycetes include fungi for which only the asexual or vegetative stages are known. When the sexual stage is discovered and its relationship is established, the fungus is moved to the appropriate fungal class, often Ascomycetes or Basidiomycetes.

Three infectious agents are examined: X contains nucleic acid enclosed by a capsid, Y is free low-molecular-weight RNA without a protein coat, and Z consists of abnormally folded protein. Which identification is correct?

X—viroid; Y—prion; Z—virus
X—prion; Y—virus; Z—viroid
X—bacterium; Y—virus; Z—fungus
X—virus; Y—viroid; Z—prion
4

A virus contains RNA or DNA protected by a protein capsid. A viroid consists of free, low-molecular-weight RNA and lacks a protein coat. A prion is an infectious agent made of abnormally folded protein.

Which sequence correctly arranges the major discoveries associated with tobacco mosaic virus from earliest to latest?

Stanley crystallised viruses → Ivanowsky recognised the filterable agent → Beijerinck demonstrated infectivity
Beijerinck demonstrated infectivity → Stanley crystallised viruses → Ivanowsky recognised the filterable agent
Ivanowsky recognised the filterable agent → Beijerinck demonstrated infectivity of the extract → Stanley crystallised viruses
Diener discovered viroids → Ivanowsky recognised the filterable agent → Stanley proposed five kingdoms
3

Ivanowsky recognised the filterable agent causing tobacco mosaic disease in 1892. Beijerinck showed in 1898 that infected plant extract could infect healthy plants. Stanley demonstrated in 1935 that viruses could be crystallised.

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