Biological Classification Chapter-Wise Test 21

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which activity of heterotrophic bacteria is directly useful in food production?

Making curd from milk
Producing red tides
Forming diatomaceous earth
Producing basidiospores
1

Some heterotrophic bacteria are useful in converting milk into curd. Other beneficial roles mentioned for these bacteria include antibiotic production and nitrogen fixation in the roots of legumes.

Why are the boundaries of Kingdom Protista described as not well defined?

Protists are all multicellular organisms.
The same organism may be viewed differently by different biologists.
Protists lack a well-defined nucleus.
All protists are obligate parasites.
2

The limits of Kingdom Protista are not sharply defined because an organism regarded as a photosynthetic protist by one biologist may be considered a plant by another. Protista includes single-celled eukaryotes.

Which statement correctly describes the ecological importance of diatoms?

They are the main decomposers of forest litter.
They produce methane in ruminants.
They are responsible for wheat rust.
They are the chief producers in the oceans.
4

Diatoms are photosynthetic chrysophytes and are described as the chief producers in the oceans. Their silica-containing cell walls also accumulate over long periods to form diatomaceous earth.

What is present on the outer surface of dinoflagellate cells?

A protein-rich pellicle
A silica shell made of two overlapping halves
Stiff cellulose plates
A chitinous fungal wall
3

Dinoflagellates possess stiff cellulose plates on the outer surface of the cell. Their colour may appear yellow, green, brown, blue or red depending on the principal pigments present.

Which statement correctly describes the spores of slime moulds?

They lack walls and are dispersed through water only.
They possess true walls and are dispersed by air currents.
They are produced exogenously on basidia.
They germinate only inside a host cell.
2

Slime-mould spores possess true walls, are extremely resistant and can survive for many years under adverse conditions. They are dispersed by air currents.

Which set includes only vegetative methods of reproduction in fungi?

Fragmentation, fission and budding
Conidia, ascospores and basidiospores
Plasmogamy, karyogamy and meiosis
Zoospores, oospores and zygospores
1

Fungi may reproduce vegetatively by fragmentation, fission and budding. Spore formation is classified separately as asexual or sexual reproduction depending on the type of spore produced.

Which sequence correctly represents the major events of the fungal sexual cycle?

Karyogamy → plasmogamy → mitosis
Plasmogamy → karyogamy → meiosis
Meiosis → plasmogamy → budding
Fission → karyogamy → fragmentation
2

The fungal sexual cycle involves plasmogamy, the fusion of protoplasms; karyogamy, the fusion of nuclei; and meiosis in the zygote, which produces haploid spores.

Which statement about asexual reproduction in Basidiomycetes is correct?

Conidia are always produced in large numbers.
Zoospores are formed inside sporangia.
Budding is the only mode of reproduction.
Asexual spores are generally absent, but fragmentation is common.
4

In Basidiomycetes, asexual spores are generally not found. Vegetative reproduction by fragmentation is common, while sexual reproduction ultimately results in the formation of basidiospores.

Which statement about bacteriophages is correct?

They infect fungi and usually contain RNA.
They are protein-only infectious agents.
They infect bacteria and are usually double-stranded DNA viruses.
They lack a protein coat.
3

Bacteriophages are viruses that infect bacteria. They are usually double-stranded DNA viruses, and their nucleic acid is protected by a protein coat called the capsid.

Which statement correctly describes the usual genetic material of plant viruses?

They generally contain single-stranded RNA.
They always contain both RNA and DNA.
They generally contain only double-stranded DNA.
They contain no nucleic acid.
1

Viruses that infect plants generally possess single-stranded RNA as their genetic material. In contrast, animal viruses may contain single- or double-stranded RNA or double-stranded DNA.

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