Biological Classification Chapter-Wise Test 7

Correct answer Carries: 4.

Wrong Answer Carries: -1.

An organism is prokaryotic, photosynthetic and may occur as a unicellular, colonial or filamentous form. Which additional feature would support its identification as a cyanobacterium?

A protein-rich pellicle instead of a cell wall
Chlorophyll a and a gelatinous sheath around colonies
Two overlapping silica-containing shells
A well-defined nucleus and membrane-bound organelles
2

Cyanobacteria are photosynthetic prokaryotes containing chlorophyll a. They may be unicellular, colonial or filamentous, and their colonies are generally surrounded by a gelatinous sheath. Some forms also fix atmospheric nitrogen in heterocysts.

A microorganism lives in the gut of a cow and contributes to biogas formation from dung. Which classification and habitat association are correct?

Halophilic archaebacterium—extremely salty areas
Methanogenic archaebacterium—ruminant gut and marshy areas
Thermoacidophilic eubacterium—polluted water
Cyanobacterium—hot springs and deep oceans
2

Methanogens are archaebacteria found in marshy areas and in the gut of ruminants such as cows and buffaloes. They produce methane and are responsible for biogas formation from the dung of these animals.

A microscopic aquatic eukaryote has two flagella, stiff cellulose plates and photosynthetic pigments. Which observation would most strongly identify it as a dinoflagellate rather than a euglenoid?

The two flagella are one short and one long.
One flagellum is longitudinal and the other is transverse.
The organism lacks a cell wall and possesses a pellicle.
It becomes heterotrophic when deprived of sunlight.
2

Most dinoflagellates possess two differently oriented flagella: one lies longitudinally and the other transversely in a furrow between the cellulose plates. Euglenoids instead have a flexible pellicle and two flagella described as one short and one long.

A protist lives in water, moves using thousands of short structures and directs food-bearing water into a gullet. Which organism and locomotory structure are correctly matched?

Amoeba—pseudopodia
Trypanosoma—flagella
Paramoecium—cilia
Plasmodium—spore-like locomotory structures
3

Paramoecium is a ciliated protozoan. Coordinated movement of its numerous cilia directs water containing food into the gullet. Amoeboid protozoans use pseudopodia, while flagellated protozoans possess flagella.

A fungus has aseptate, coenocytic mycelium and produces motile spores inside a sporangium. Which combination correctly identifies its class and spore?

Ascomycetes—conidia
Basidiomycetes—basidiospores
Phycomycetes—zoospores
Deuteromycetes—ascospores
3

Phycomycetes possess aseptate and coenocytic mycelium. Their motile asexual spores are zoospores, whereas their non-motile asexual spores are aplanospores. Both are produced endogenously inside a sporangium.

Two fungi both possess branched, septate mycelium. Fungus X produces ascospores inside asci, whereas fungus Y produces basidiospores externally on basidia. Which classification is correct?

X—Phycomycetes; Y—Deuteromycetes
X—Ascomycetes; Y—Basidiomycetes
X—Basidiomycetes; Y—Ascomycetes
X—Deuteromycetes; Y—Phycomycetes
2

Ascomycetes produce sexual ascospores endogenously inside sac-like asci. Basidiomycetes produce basidiospores exogenously on basidia. Both groups generally possess branched, septate mycelium.

A fungus is initially placed in Deuteromycetes because only conidia and its vegetative mycelium are known. Its sexual stage is later found to produce ascospores. What is the appropriate taxonomic action?

Retain it permanently in Deuteromycetes.
Transfer it to Ascomycetes.
Transfer it to Basidiomycetes.
Place it in Kingdom Protista.
2

Deuteromycetes contain fungi whose sexual stages are not known. Once a sexual stage is discovered, the fungus is moved to the class to which that stage belongs. Production of ascospores identifies the sexual form as an Ascomycete.

An infectious agent is smaller than viruses, consists of low-molecular-weight RNA and lacks a protein coat. Which additional statement is correct?

It is a prion associated with mad cow disease.
It is a viroid first associated with potato spindle tuber disease.
It is a bacteriophage containing double-stranded DNA.
It is a virus whose capsid contains capsomeres.
2

The described agent is a viroid. T. O. Diener discovered it while investigating potato spindle tuber disease. A viroid consists of free, low-molecular-weight RNA and lacks the protein coat present in viruses.

An infectious agent contains no nucleic acid and consists of an abnormally folded protein. Which disease association is consistent with the chapter?

Malaria in humans
Bovine spongiform encephalopathy in cattle
Potato spindle tuber disease
Tobacco mosaic disease
2

The agent is a prion, an infectious abnormally folded protein. Prions are associated with bovine spongiform encephalopathy, or mad cow disease, in cattle and its analogous variant, CJD, in humans.

A composite organism disappears from a highly polluted locality. Examination shows that its autotrophic partner prepares food while its heterotrophic partner provides shelter and absorbs water and minerals. What is the organism?

A mycorrhiza
A lichen
A slime mould
A cyanobacterial colony
2

The organism is a lichen, a mutually beneficial association between an algal phycobiont and a fungal mycobiont. The alga prepares food, while the fungus provides shelter and absorbs water and minerals. Lichens do not grow in polluted areas and therefore act as pollution indicators.

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