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Tamil Nadu HSE First Year Biology study materials
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Tamil Nadu HSE First Year Biology practice questions

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Question 1Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

In the binomial name Mangifera indica, what does the second word 'indica' denote?

  1. The specific epithet Correct answer.
  2. The genus name
  3. The author citation
  4. The family name

Explanation

Binomial nomenclature gives each species a two-word Latin name: the first word is the genus (here Mangifera) and the second is the specific epithet (indica). The specific epithet alone never names a species; it is meaningful only when written together with its genus.

Question 2Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which taxonomic category lies immediately below class in the standard hierarchy of Linnaean classification?

  1. Family
  2. Order Correct answer.
  3. Phylum
  4. Species

Explanation

The descending sequence is kingdom, phylum (division in plants), class, order, family, genus, species. Order therefore comes directly after class, and family follows order.

Question 3Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

A scientist discovers an organism with a true nucleus, peptidoglycan-free cell walls, and no membrane-bound organelles other than the nucleus. Into which kingdom of the five-kingdom system does it most suitably fall?

  1. Fungi
  2. Protista Correct answer.
  3. Plantae
  4. Monera

Explanation

Possession of a true nucleus places the organism among eukaryotes, so Monera is excluded. Among eukaryotes, unicellular or simple eukaryotic forms that are neither multicellular plants nor typical absorptive fungi are grouped in Protista under the five-kingdom scheme.

Question 4Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

The term 'taxon' is best defined as which of the following?

  1. The total number of species in a habitat
  2. A group of organisms recognised as a formal unit at any rank Correct answer.
  3. The study of the rules of naming organisms
  4. The key used to identify unknown specimens

Explanation

A taxon is any taxonomic group at any level of the hierarchy, whether it is a species, a genus, a family or a kingdom. Taxonomy is the science that deals with the description, identification, nomenclature and classification of such groups.

Question 5Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

In the five-kingdom classification, the kingdom Monera is characterised chiefly by which feature?

  1. Absence of a nuclear membrane Correct answer.
  2. Presence of chlorophyll b
  3. Presence of chitin in the cell wall
  4. Presence of a nuclear membrane

Explanation

Monera comprises prokaryotic organisms such as bacteria and cyanobacteria, whose genetic material is not enclosed by a nuclear membrane. All other four kingdoms consist of eukaryotes with a membrane-bound nucleus.

Question 6Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which sequence correctly arranges the following taxa from the most inclusive to the least inclusive?

  1. Family, order, class, genus
  2. Class, order, family, genus Correct answer.
  3. Order, class, family, genus
  4. Genus, family, order, class

Explanation

In the Linnaean hierarchy each category contains the ones below it, giving the order kingdom, phylum, class, order, family, genus, species. Hence class is broader than order, which is broader than family, which is broader than genus.

Question 7Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

A specimen is a multicellular, photosynthetic organism with cellulose cell walls and embryos that develop within the parent plant body. Which kingdom is the most appropriate placement?

  1. Protista
  2. Fungi
  3. Plantae Correct answer.
  4. Monera

Explanation

Cellulose walls, photosynthesis and, above all, embryo retention within the parent plant body are defining features of kingdom Plantae. Fungi are heterotrophic absorbers and Monera are prokaryotic, while Protista are chiefly unicellular or lack true embryos.

Question 8Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which statement about the three-domain system of classification is accurate?

  1. It replaces the kingdom Protista with the domain Bacteria.
  2. It separates archaebacteria and eubacteria into two domains alongside Eukarya. Correct answer.
  3. It groups all eukaryotes together with the archaebacteria in one domain.
  4. It recognises only two domains, Prokarya and Eukarya.

Explanation

The three-domain system divides cellular life into Archaea, Bacteria and Eukarya, chiefly on the basis of ribosomal RNA sequence differences and cell-envelope features. It elevates the prokaryotes to two separate domains rather than keeping them as a single kingdom Monera.

Question 9Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

The herbarium sheet of a plant bears the name 'Solanum nigrum L.' What information does the 'L.' convey?

  1. The variety of the species
  2. The author who first validly described the species Correct answer.
  3. The family to which the species belongs
  4. The locality where the specimen was collected

Explanation

An abbreviated author citation after a binomial records the person who first validly published the name. Here 'L.' stands for Linnaeus, the author of Solanum nigrum. It is neither a locality nor a rank indicator.

Question 10Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which of these pairs correctly matches a taxonomic aid with its purpose?

  1. Botanical garden - preservation of dried specimens only
  2. Herbarium - live cultivation of plants for public display
  3. Museum - identification of bacteria by staining
  4. Zoological park - study of wild animals kept in controlled conditions Correct answer.

Explanation

A zoological park maintains wild animals in controlled surroundings for study, education and conservation. Herbaria store dried pressed specimens, botanical gardens cultivate living plants, and museums preserve specimen collections for reference.

Question 11Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Two organisms are placed in the same class but in different orders. Which conclusion follows necessarily?

  1. They must belong to the same phylum. Correct answer.
  2. They must belong to the same species.
  3. They must belong to the same genus.
  4. They must belong to the same family.

Explanation

Because a class is nested within a phylum, any two organisms sharing a class automatically share the phylum above it. They differ at the level of order and may differ at every rank below it, so family, genus and species identity cannot be assumed.

Question 12Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which characteristic is used in the five-kingdom system to separate Fungi from Plantae?

  1. Ability to reproduce sexually
  2. Mode of nutrition and nature of the cell wall Correct answer.
  3. Presence or absence of a nucleus
  4. Presence or absence of a cell wall

Explanation

Both fungi and plants are eukaryotic and walled, so those features cannot separate them. Fungi are heterotrophic absorbers with chitinous walls, whereas plants are photosynthetic autotrophs with cellulose walls, and this combination of nutrition and wall chemistry distinguishes the kingdoms.

Question 13Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which of the following is a correct statement about the kingdom Protista as conceived in the five-kingdom system?

  1. It includes unicellular eukaryotes such as Euglena and Paramecium. Correct answer.
  2. It contains only prokaryotic organisms.
  3. All members are multicellular and photosynthetic.
  4. It includes all fungi with flagellated spores.

Explanation

Protista is a eukaryotic kingdom that collects mainly unicellular or simple eukaryotic organisms, including photosynthetic forms such as Euglena and heterotrophic forms such as Paramecium. It is deliberately a residual group for eukaryotes that are neither plants, animals nor fungi.

Question 14Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

A taxonomist needs to identify an unknown flowering plant using a printed device in which each step offers two mutually exclusive choices. What is this identification aid called?

  1. A flora
  2. A catalogue
  3. A monograph
  4. A dichotomous key Correct answer.

Explanation

A dichotomous key presents a series of paired contrasting statements, each pair called a couplet, so that successive choices narrow the identification to a single taxon. Monographs, floras and catalogues are descriptive compilations rather than stepwise identification tools.

Question 15Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which pairing of scientist and contribution to classification is correct?

  1. Carl Woese - five-kingdom system
  2. Ernst Haeckel - three-domain system
  3. Carolus Linnaeus - two-kingdom system with binomial nomenclature Correct answer.
  4. Robert Whittaker - binomial nomenclature

Explanation

Linnaeus established the two-kingdom scheme (Plantae and Animalia) and gave binomial nomenclature its systematic form. Whittaker proposed the five-kingdom system, Haeckel introduced the kingdom Protista, and Woese developed the three-domain system.

Question 16Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

An organism is unicellular, lacks a membrane-bound nucleus, and possesses a cell wall but no peptidoglycan. Which interpretation is most consistent with the three-domain system?

  1. It is a fungus, because it has a cell wall.
  2. It is an archaeon, because Archaea lack peptidoglycan in their walls. Correct answer.
  3. It is a protist, because it is unicellular.
  4. It is a eubacterium, because all walled prokaryotes belong to Bacteria.

Explanation

Among prokaryotes, Archaea are distinguished by cell walls that lack peptidoglycan, whereas bacterial walls typically contain it. A unicellular organism without a nuclear membrane is prokaryotic, so Protista and Fungi, both eukaryotic, are excluded.

Question 17Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Species A and species B are placed in the same genus, while species C is placed in a different genus of the same family. Which statement is necessarily true?

  1. A and C belong to the same species.
  2. A and B share more recent common ancestry with each other than either does with C. Correct answer.
  3. B and C belong to the same order but different families.
  4. A, B and C all belong to the same class but different phyla.

Explanation

Because genus is a narrower category than family, species sharing a genus are grouped more closely than species placed in separate genera of the same family. This reflects the hierarchical nesting on which classification is based, so A and B are more closely related to each other than to C.

Question 18Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

Which statement best explains why morphological classification alone can mislead taxonomists?

  1. Morphological classification ignores the kingdom level entirely.
  2. Unrelated organisms may converge on similar forms under similar selection pressures. Correct answer.
  3. Morphological characters are never heritable and so cannot be used.
  4. Morphology can be studied only in extinct organisms.

Explanation

Convergent evolution can produce similar body forms in lineages that are not closely related, such as the streamlined shape of fish and dolphins. For this reason modern taxonomy supplements morphology with molecular, biochemical and developmental evidence before drawing phylogenetic conclusions.

Question 19Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

A new species is described and its name is to be validly published. Which practice conforms to the International Code of Nomenclature?

  1. Naming the species after the author alone, using a single word.
  2. Publishing the binomial in a local newspaper without a Latin description.
  3. Using a polynomial of several descriptive words as the species name.
  4. Providing a Latin diagnosis and depositing a type specimen in a recognised collection. Correct answer.

Explanation

Valid publication of a new plant name requires, among other things, a description or diagnosis in Latin or English as the Code allows, designation of a nomenclatural type, and effective publication in a recognised scientific medium. A single word or a descriptive polynomial does not satisfy the binomial requirement.

Question 20Diversity of Living World (taxonomy, classification, kingdoms, nomenclature)

A researcher studying a museum collection finds that a preserved specimen carries the label 'holotype'. What does this designation signify for the species concerned?

  1. It is a specimen collected later and chosen to represent the species when no original material survives.
  2. It is merely a duplicate of the type specimen kept in a second herbarium for safety.
  3. It is a specimen used only to demonstrate the species in a teaching collection.
  4. It is the single specimen designated by the original author as the name-bearing type of the species. Correct answer.

Explanation

Under the International Code of Nomenclature, the holotype is the one specimen or illustration that the original author designates as the permanent reference point attached to a new species name. All other specimens are compared with it, so the name is fixed to that material even if later workers revise the group.

Question 21Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

In the life cycle of a moss plant, the structure that produces spores by meiosis is the

  1. capsule of the sporophyte Correct answer.
  2. rhizoid
  3. antheridium of the gametophyte
  4. protonema

Explanation

In bryophytes the sporophyte is the diploid generation, and its capsule contains spore mother cells that undergo meiosis to give haploid spores. The gametophyte structures such as antheridia produce gametes by mitosis, not spores. Hence the capsule is the only spore-forming organ listed.

Question 22Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Red algae are placed in the class Rhodophyceae mainly because they possess

  1. chlorophyll b as the sole pigment
  2. silica shells called frustules
  3. the accessory pigment phycoerythrin Correct answer.
  4. flagellated zoospores in all stages

Explanation

Rhodophyceae are characterised by the red accessory pigment phycoerythrin, which masks the green of chlorophyll a and gives the thallus its red colour. Chlorophyll b is typical of green algae, frustules of diatoms, and red algae lack flagellated stages entirely. Thus only phycoerythrin is a defining feature of the class.

Question 23Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

The chief photosynthetic pigment of brown algae such as Sargassum is

  1. phycoerythrin
  2. fucoxanthin Correct answer.
  3. phycocyanin
  4. chlorophyll d

Explanation

Phaeophyceae owe their olive-brown colour to fucoxanthin, a xanthophyll accessory pigment that masks chlorophyll a and c. Phycocyanin is a blue pigment of cyanobacteria and red algae, while phycoerythrin is red. Chlorophyll d occurs in red algae, so fucoxanthin is the correct pigment.

Question 24Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

In pteridophytes the gametophyte is best described as

  1. a free-living, independent prothallus Correct answer.
  2. a dependent structure retained on the sporophyte
  3. the dominant photosynthetic plant body
  4. a haploid spore-producing capsule

Explanation

In ferns and other pteridophytes the haploid gametophyte is the small green prothallus, which lives independently and bears antheridia and archegonia. It is not retained on the sporophyte, is not the dominant phase, and does not produce spores. The dominant leafy plant is the diploid sporophyte.

Question 25Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

The ovules of gymnosperms are described as naked because they

  1. contain no embryo sac
  2. lack an integument
  3. are borne on the upper surface of megasporophylls without an ovary wall Correct answer.
  4. are produced inside a closed ovary

Explanation

Gymnosperm ovules are exposed on the surface of megasporophylls and are not enclosed within an ovary wall, which is why the group is called naked-seeded. They do possess an integument and a megaspore that develops into the female gametophyte. Enclosure inside a closed ovary is the angiosperm condition.

Question 26Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Double fertilisation, involving syngamy and triple fusion, is a characteristic event of

  1. angiosperms Correct answer.
  2. gymnosperms
  3. pteridophytes
  4. bryophytes

Explanation

In angiosperms one male gamete fuses with the egg (syngamy) and the second fuses with the two polar nuclei to form triploid endosperm (triple fusion). This twin event is unique to flowering plants. Gymnosperms show only syngamy, and bryophytes and pteridophytes fertilise with a single sperm in water.

Question 27Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

A student finds a plant with vascular tissue, free-living gametophyte and leaves bearing sporangia on the underside. The plant most probably belongs to

  1. pteridophytes Correct answer.
  2. red algae
  3. gymnosperms
  4. bryophytes

Explanation

Presence of vascular tissue combined with an independent gametophyte and sporangia borne on leaves (sporophylls) identifies a pteridophyte such as a fern. Bryophytes lack true vascular tissue, gymnosperms have dependent gametophytes and seeds, and red algae are non-vascular. Hence the specimen is a pteridophyte.

Question 28Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

The protonema stage in the life cycle of a moss develops directly from

  1. a germinating spore Correct answer.
  2. a vegetative bud on the capsule
  3. a fertilised egg
  4. a fragment of the seta

Explanation

When a haploid moss spore germinates it first forms a branched green filament called the protonema, which later bears leafy gametophores. The zygote develops into the sporophyte, not the protonema. Capsule and seta belong to the sporophyte, so neither can give rise to a protonema.

Question 29Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Heterocercal tails, in which the two lobes of the caudal fin are unequal, are seen in

  1. Cyclostomata
  2. Chondrichthyes Correct answer.
  3. Osteichthyes
  4. Amphibia

Explanation

Cartilaginous fishes such as sharks possess a heterocercal tail with a larger upper lobe, a feature associated with their cartilaginous skeleton and ventral mouth. Bony fishes generally have homocercal tails, and cyclostomes and amphibians lack this caudal fin form. Thus the feature belongs to Chondrichthyes.

Question 30Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Which feature distinguishes the class Phaeophyceae from Chlorophyceae?

  1. Occurrence of cellulose cell walls
  2. Presence of fucoxanthin and mannitol Correct answer.
  3. Occurrence of starch as reserve food
  4. Presence of chlorophyll a

Explanation

Brown algae contain fucoxanthin along with chlorophyll a and c, and store the carbohydrate mannitol (often as laminarin). Green algae contain chlorophyll a and b and store starch, but both groups share chlorophyll a and cellulose walls. Hence only the pigment and reserve-food combination separates Phaeophyceae.

Question 31Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

In a gymnosperm such as Pinus, the endosperm that nourishes the embryo is

  1. diploid sporophyte tissue of the seed coat
  2. haploid female gametophyte tissue formed before fertilisation Correct answer.
  3. triploid and formed after triple fusion
  4. formed from the fusion of two polar nuclei

Explanation

Gymnosperm ovules store food in the haploid female gametophyte, which develops before fertilisation and is therefore pre-fertilisation tissue. Triple fusion and polar nuclei exist only in angiosperms, where endosperm is triploid. The seed coat is diploid maternal sporophyte tissue and is not nutritive endosperm.

Question 32Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Which combination correctly matches an algal class with its stored food and a representative genus?

  1. Chlorophyceae - starch - Spirogyra Correct answer.
  2. Rhodophyceae - mannitol - Sargassum
  3. Chlorophyceae - mannitol - Polysiphonia
  4. Phaeophyceae - starch - Ulothrix

Explanation

Green algae (Chlorophyceae) store starch and include Spirogyra, a filamentous form with spiral chloroplasts. Mannitol is characteristic of brown algae, and Sargassum belongs to Phaeophyceae. Ulothrix is green, and Polysiphonia is a red alga, so only the first pairing is fully correct.

Question 33Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

The sporophyte of a liverwort differs from that of a moss chiefly in that the liverwort sporophyte

  1. produces seeds after fertilisation
  2. has an independent photosynthetic habit
  3. possesses a capsule with elaters and a very short seta Correct answer.
  4. bears stomata on its capsule wall

Explanation

Liverwort sporophytes are simple, with a capsule containing elaters and a short seta, and they remain attached to the gametophyte. Moss capsules have stomata and a longer seta, while independence and seed production are not bryophyte features at all. Thus the elater-bearing capsule with short seta is the distinguishing point.

Question 34Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

A plant shows circinate vernation of young leaves, a rhizome with ramenta and kidney-shaped sporangia on the leaf margin. It is most likely

  1. a green alga such as Chara
  2. a cycad such as Cycas
  3. a moss such as Funaria
  4. a fern such as Adiantum Correct answer.

Explanation

Circinate vernation, scales called ramenta on the rhizome and marginal sporangia are classic fern features, seen in Adiantum. Mosses have no vascular tissue or circinate leaves, cycads bear seeds and cones, and Chara is a non-vascular alga. The specimen is therefore a fern.

Question 35Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

In angiosperms the embryo sac is formed from the megaspore mother cell through meiosis followed by three mitotic divisions. The number of nuclei in the mature embryo sac of the common Polygonum type is

  1. sixteen
  2. two
  3. four
  4. eight Correct answer.

Explanation

The functional megaspore undergoes three mitotic divisions without wall formation, giving eight nuclei: three antipodal, two polar and three at the micropylar end (egg plus two synergids). Four nuclei would result from only two divisions, and sixteen from four. Hence the mature Polygonum-type sac contains eight nuclei.

Question 36Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Which statement about the plant body of brown algae such as Laminaria is correct?

  1. It is unicellular and flagellated throughout life
  2. It is a thallus differentiated into holdfast, stipe and frond Correct answer.
  3. It has true roots, stems and leaves with vascular tissue
  4. It consists of a protonema and leafy gametophores

Explanation

Brown algae are multicellular thallophytes whose body is a thallus, often differentiated into a holdfast for attachment, a stipe and a flattened frond. They lack true roots, stems, leaves and vascular tissue. A protonema with leafy gametophores is a moss feature, and Laminaria is not unicellular.

Question 37Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

A student claims that a particular plant is a pteridophyte because it shows alternation of generations. Which reasoning best evaluates this claim?

  1. The claim is invalid, because alternation of generations occurs in all plants Correct answer.
  2. The claim is valid, because alternation of generations occurs only in pteridophytes
  3. The claim is invalid, because pteridophytes lack a gametophyte stage
  4. The claim is valid, because the gametophyte is dominant in pteridophytes

Explanation

Alternation of a haploid gametophyte with a diploid sporophyte is a general feature of the plant kingdom, including bryophytes, pteridophytes, gymnosperms and angiosperms. It therefore cannot diagnose a pteridophyte specifically. Pteridophytes do have a gametophyte, but it is small and free-living, not dominant.

Question 38Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

In a moss, the sporophyte is nutritionally dependent on the gametophyte. Which structural feature best explains this dependence?

  1. The sporophyte lacks chlorophyll and remains attached by a foot embedded in the gametophyte Correct answer.
  2. The sporophyte possesses a well-developed vascular connection to the soil
  3. The gametophyte draws food from the sporophyte through the seta
  4. The sporophyte has an independent root system that absorbs water from soil

Explanation

The moss sporophyte has little or no chlorophyll and stays attached to the gametophyte by a foot that absorbs water and nutrients; some mosses are partly photosynthetic but remain structurally dependent. It has no roots and no independent vascular connection to soil. The direction of supply is from gametophyte to sporophyte, not the reverse.

Question 39Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

Cycas and Pinus are both gymnosperms, yet they differ in that only Pinus

  1. produces seeds
  2. bears ovules in cones rather than on megasporophylls borne on a trunk Correct answer.
  3. has a dominant sporophyte generation
  4. possesses archegonia in the female gametophyte

Explanation

In Cycas the megasporophylls are loosely arranged and ovules sit on their margins near the apex of the trunk, whereas in Pinus ovules are borne on ovuliferous scales of well-defined female cones. Both produce seeds, have a dominant sporophyte and retain archegonia in the female gametophyte. Thus cone organisation is the discriminating feature.

Question 40Plant Kingdom (algae, bryophytes, pteridophytes, gymnosperms, angiosperms)

An angiosperm ovule is described as anatropous. The feature that defines this condition is that the

  1. ovule is straight with the micropyle opposite the funicle
  2. micropyle lies close to the funicle because the ovule is bent through 180 degrees Correct answer.
  3. ovule is attached laterally with the micropyle directed away from the funicle
  4. ovule is curved so that the embryo sac becomes horseshoe-shaped

Explanation

In an anatropous ovule the body is bent through about 180 degrees so that the micropyle comes to lie near the funicle and the chalaza. A straight ovule with micropyle opposite the funicle is orthotropous, while a horseshoe-shaped embryo sac describes the campylotropous curvature. Lateral attachment with the micropyle turned away does not define the anatropous type.

Question 41Animal Kingdom (invertebrate and vertebrate classification, body plans)

In the classification of the animal kingdom, which phylum is characterised by the presence of a notochord at some stage of the life cycle?

  1. Arthropoda
  2. Echinodermata
  3. Mollusca
  4. Chordata Correct answer.

Explanation

The notochord is the defining feature of the phylum Chordata, appearing at least in the embryonic stage. Echinoderms, arthropods and molluscs are non-chordates that never develop a notochord at any stage.

Question 42Animal Kingdom (invertebrate and vertebrate classification, body plans)

Which of the following animals possesses a body cavity that is not lined by mesoderm, so the visceral organs lie in an unlined space?

  1. Starfish
  2. Ascaris Correct answer.
  3. Earthworm
  4. Cockroach

Explanation

Ascaris is a pseudocoelomate: the body cavity is not completely lined by mesoderm, and the internal organs lie loose in the blastocoel. Earthworm and cockroach are true coelomates, while starfish is also a coelomate with a mesoderm-lined cavity.

Question 43Animal Kingdom (invertebrate and vertebrate classification, body plans)

The presence of a cellular-level body organisation, where cells are arranged in loose aggregates without true tissues, is characteristic of which phylum?

  1. Cnidaria
  2. Porifera Correct answer.
  3. Platyhelminthes
  4. Annelida

Explanation

Sponges (Porifera) show the cellular level of organisation, as their cells are loosely arranged without forming true tissues. Cnidarians show tissue-level organisation, while platyhelminths and annelids show organ and organ-system levels respectively.

Question 44Animal Kingdom (invertebrate and vertebrate classification, body plans)

Which of the following features is used to distinguish a diploblastic animal from a triploblastic animal?

  1. The presence or absence of a vertebral column
  2. The presence or absence of segmentation
  3. The number of germ layers present in the embryo Correct answer.
  4. The type of body symmetry shown by the adult

Explanation

Diploblastic animals have only two germ layers (ectoderm and endoderm), while triploblastic animals have three, including mesoderm. The vertebral column, symmetry and segmentation are unrelated criteria used for other levels of classification.

Question 45Animal Kingdom (invertebrate and vertebrate classification, body plans)

In the phylum Arthropoda, the body is divided into which three regions in insects such as the cockroach?

  1. Head, neck and trunk
  2. Head and trunk
  3. Cephalothorax and abdomen
  4. Head, thorax and abdomen Correct answer.

Explanation

Insects possess a body divided into head, thorax and abdomen, with three pairs of legs attached to the thorax. Cephalothorax and abdomen describe crustaceans and arachnids, while head and trunk describe many annelids.

Question 46Animal Kingdom (invertebrate and vertebrate classification, body plans)

Which class of vertebrates is characterised by a body covered with dry, cornified scales and a heart with an incomplete ventricular septum?

  1. Osteichthyes
  2. Reptilia Correct answer.
  3. Aves
  4. Amphibia

Explanation

Reptiles have dry, cornified skin with scales and a heart with an incomplete ventricular septum, allowing some mixing of blood. Amphibians have moist skin, birds have a four-chambered heart, and bony fishes have a two-chambered heart.

Question 47Animal Kingdom (invertebrate and vertebrate classification, body plans)

The presence of a water-vascular system with tube feet for locomotion is a distinguishing feature of which phylum?

  1. Mollusca
  2. Annelida
  3. Echinodermata Correct answer.
  4. Arthropoda

Explanation

Echinoderms possess a unique water-vascular system, which is a part of the coelom and operates the tube feet used in locomotion and feeding. The other phyla lack this system and use different locomotory structures.

Question 48Animal Kingdom (invertebrate and vertebrate classification, body plans)

A student observes an animal with a soft, unsegmented body, a mantle covering the visceral hump and a radula in the mouth. To which phylum does it belong?

  1. Nematoda
  2. Platyhelminthes
  3. Annelida
  4. Mollusca Correct answer.

Explanation

The mantle, visceral hump and rasping radula are diagnostic features of the phylum Mollusca. Annelids are segmented, platyhelminths are flattened and acoelomate, and nematodes are cylindrical pseudocoelomates without a mantle.

Question 49Animal Kingdom (invertebrate and vertebrate classification, body plans)

Which of the following correctly pairs an animal with its type of body symmetry?

  1. Cockroach - asymmetry
  2. Starfish - radial symmetry in the adult Correct answer.
  3. Hydra - bilateral symmetry
  4. Earthworm - radial symmetry

Explanation

Adult echinoderms such as the starfish exhibit radial symmetry, although their larvae are bilaterally symmetrical. Earthworms and cockroaches are bilaterally symmetrical, and Hydra shows radial symmetry.

Question 50Animal Kingdom (invertebrate and vertebrate classification, body plans)

Which feature of the phylum Annelida is directly responsible for its name?

  1. The body contains a notochord
  2. The body bears jointed appendages
  3. The body is covered with a calcareous shell
  4. The body is divided into metamerically arranged segments Correct answer.

Explanation

The name Annelida refers to the ring-like segments (annuli) that give the body its metameric segmentation. Jointed appendages are characteristic of arthropods, shells of molluscs, and the notochord of chordates.