NEET Biology Biological Classification MCQs Set 22

Answer: (b) Gas vacuoles

Explanation:
1. Gas vacuoles are the inclusion bodies of blue-green, purple and green photosynthetic bacteria.
2. They help the cells float at the right depth for light.
3. Contractile vacuoles belong to protozoa, while centrioles and microtubules are eukaryotic structures.

Teacher's Note:
1. Remember gas vacuoles as the floating devices of prokaryotes.
2. Link inclusion bodies with prokaryotes only.

Answer: (b) They lack heterocysts

Explanation:
1. Cyanobacteria are photoautotrophs with chlorophyll a, like green plants, and they form blooms in polluted water.
2. Many filamentous forms such as Nostoc and Anabaena possess specialised heterocysts for nitrogen fixation.
3. So the statement that they lack heterocysts is incorrect.

Teacher's Note:
1. Heterocysts are the nitrogen-fixing cells of filamentous cyanobacteria.
2. In incorrect-statement questions, test each option separately.

Answer: (c) They have free RNA without protein coat.

Explanation:
1. Viroids are infectious agents smaller than viruses.
2. They consist of a free RNA molecule of low molecular weight and have no protein coat.

Teacher's Note:
1. Viroid = naked RNA, virus = nucleic acid plus protein coat.
2. Viroids were discovered by T.O.
3. Diener.

Answer: (c) Sporozoites

Explanation:
1. The sporozoite is the infective stage of Plasmodium that is injected into the human blood by a female Anopheles mosquito.
2. Gametocytes are taken up by the mosquito, and trophozoites develop inside red blood cells.

Teacher's Note:
1. Sporozoites enter humans while gametocytes enter the mosquito.
2. Keep the direction of transfer clear to avoid mix-ups.

Answer: (a) Chlorella and Spirulina

Explanation:
1. Chlorella and Spirulina are unicellular (Spirulina is a microscopic blue-green alga used with it as single cell protein) and are used as single cell protein.
2. Laminaria, Sargassum, Gelidium and Gracilaria are multicellular seaweeds, and Volvox is colonial.

Teacher's Note:
1. Chlorella and Spirulina are the classic single cell protein sources.
2. Remember them as the unicellular algae pair.

Answer: (a) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)

Explanation:
1. Halophiles live in salty areas, thermoacidophiles in hot springs, methanogens in the guts of ruminants and cyanobacteria in aquatic environments.
2. The matching is therefore a-iv, b-i, c-iii, d-ii.

Teacher's Note:
1. Archaebacteria are extremophiles, so link each group with its harsh habitat.
2. Methanogens produce biogas from cattle dung.

Answer: (a) Saccharomyces

Explanation:
1. Mycobacterium, Nostoc and Oscillatoria are bacteria or cyanobacteria and are prokaryotes.
2. Saccharomyces is a unicellular yeast, a fungus, so it is eukaryotic.

Teacher's Note:
1. Yeast is the only eukaryote in this list.
2. Prokaryotes lack a membrane bound nucleus and organelles.

Answer: (c) Pseudopodia are locomotory and feeding structures in Sporozoans

Explanation:
1. Pseudopodia are locomotory and feeding structures of amoeboid protozoans, not sporozoans, which have no locomotory structures.
2. The other statements are correct; mushrooms belong to Basidiomycetes and all eukaryotic kingdoms have mitochondria.

Teacher's Note:
1. Sporozoans such as Plasmodium have an infectious spore-like stage and no locomotory organs.
2. Match each protozoan group with its locomotory structure.

Answer: (c) Agaricus

Explanation:
1. In Basidiomycetes such as Agaricus, karyogamy and meiosis in the basidium produce four basidiospores borne exogenously.
2. Neurospora and Saccharomyces form ascospores endogenously inside asci, and Alternaria is a deuteromycete with no sexual stage.

Teacher's Note:
1. Basidiospores are exogenous, ascospores are endogenous.
2. This difference is a frequent exam point.

Answer: (b) Diatoms

Explanation:
1. Diatoms are the chief producers in the oceans.
2. They are microscopic, photosynthetic chrysophytes with silica shells.

Teacher's Note:
1. Diatomaceous earth is made of their silica walls.
2. Diatoms are the main primary producers of oceans.

Answer: (d) having two types of nuclei

Explanation:
1. Ciliates are protozoans that move by cilia, and they have two types of nuclei, a macronucleus and one or more micronuclei.
2. Flagella, contractile vacuoles and pseudopodia occur in other protozoans too.

Teacher's Note:
1. Think of Paramecium: large macronucleus and small micronucleus.
2. Dual nuclei are the unique feature of ciliates.

Answer: (d) All fungi possess a purely cellulosic cell wall

Explanation:
1. Fungi are heterotrophic, eukaryotic and may be unicellular (yeast) or multicellular.
2. Their cell wall is made of chitin and polysaccharides, not purely of cellulose.

Teacher's Note:
1. Fungal wall is chitin, plant wall is cellulose.
2. Words like purely or only often make a statement false.

Answer: (d) Archaebacteria

Explanation:
1. Methanogens, which produce methane in marshes and ruminant guts, are archaebacteria.
2. Dinoflagellates and slime moulds are protists, and eubacteria are true bacteria.

Teacher's Note:
1. Archaebacteria include methanogens, halophiles and thermoacidophiles.
2. Their cell wall lacks peptidoglycan.

Answer: (d) Their RNA is of high molecular weight

Explanation:
1. Viroids lack a protein coat, are smaller than viruses and cause infections such as potato spindle tuber disease.
2. Their RNA is of low molecular weight, not high.

Teacher's Note:
1. Viroid RNA is short and naked.
2. Check numeric or size words in the options.

Answer: (c) Eubacteria are also called false bacteria

Explanation:
1. Cyanobacteria are also called blue-green algae, golden algae (desmids) are chrysophytes and Phycomycetes are algal fungi.
2. Eubacteria are the true bacteria, so calling them false bacteria is wrong.

Teacher's Note:
1. Eubacteria means true bacteria.
2. Learn the alternate names used in the Whittaker five kingdom scheme.

Answer: (a) Lichens

Explanation:
1. Lichens, a symbiotic association of algae and fungi, are pioneer colonisers on bare rocks.
2. They release acids that help to form soil for later species.

Teacher's Note:
1. Lichens start primary succession on rocks.
2. They are also pollution indicators.

Answer: (d) Mycoplasma

Explanation:
1. Mycoplasma lacks a cell wall and is the smallest living cell, able to survive without oxygen.
2. Nostoc, Aspergillus and Funaria all have cell walls.

Teacher's Note:
1. Mycoplasma is pleomorphic and wall-less.
2. It is resistant to penicillin because it lacks a cell wall.

Answer: (a) Alternaria – sexual reproduction absent – Deuteromycetes

Explanation:
1. Alternaria is a deuteromycete in which sexual reproduction is absent.
2. Mucor is a zygomycete, Agaricus is a saprophytic basidiomycete and Phytophthora has aseptate mycelium but is an oomycete (phycomycete).

Teacher's Note:
1. Deuteromycetes are called imperfect fungi.
2. Learn one example for each fungal class.

Answer: (d) Anabaena

Explanation:
1. A true nucleus is absent in prokaryotes.
2. Anabaena is a cyanobacterium, whereas Mucor, Vaucheria and Volvox are eukaryotes.

Teacher's Note:
1. Blue-green algae are prokaryotic bacteria despite the name.
2. Look for cyanobacteria among algae lists.

Answer: (b) Ectocarpus

Explanation:
1. Ectocarpus is a brown alga whose male gametes are flagellated.
2. Spirogyra and Anabaena have no flagellated gametes, and red algae such as Polysiphonia have non-motile male gametes.

Teacher's Note:
1. Red algae lack flagellated stages altogether.
2. Brown algae have biflagellate gametes.

Answer: (b) Archaebacteria

Explanation:
1. Archaebacteria live in extreme habitats such as deep sea hydrothermal vents, hot springs and salt lakes.
2. Blue-green algae need light, which does not reach the deep sea.

Teacher's Note:
1. Think of extremes: deep sea, hot springs and salty lakes belong to archaebacteria.
2. Photosynthetic forms are limited to lit surface waters.

Answer: (c) Cycas

Explanation:
1. Cyanobacteria such as Anabaena live in the coralloid roots of Cycas, apart from paddy fields.
2. Psilotum, Pinus and Equisetum do not have such an association.

Teacher's Note:
1. Coralloid roots of Cycas house cyanobacteria.
2. Anabaena azollae lives in Azolla fern.

Answer: (d) Fungi

Explanation:
1. Among the groups listed, fungi have the highest number of species, ahead of algae, lichens, and mosses with ferns.

Teacher's Note:
1. Fungi are the most numerous group among the plant-like groups listed.
2. Learn the biodiversity figures from the NCERT chapter.

Answer: (a) Chromatophores

Explanation:
1. Cyanobacteria have pigment-containing membranous extensions of the plasma membrane called chromatophores.
2. Heterocysts are nitrogen-fixing cells, and basal bodies and pneumatophores are unrelated.

Teacher's Note:
1. Chromatophores hold the photosynthetic pigments of cyanobacteria.
2. Since they lack chloroplasts, these extensions do the job.