Biology Question Bank – 57 MCQs on “Biological Classification” – Answered!

(b) Linnaeus

(c) Theophrastus

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(d) Darwin.

Answer and Explanation:

1. (c): Linnaeus, 1758 developed “Binomial system of nomenclature”, de Candolle gave the term taxonomy. Theophrastus, father of botany, gave names and descriptions of 480 plants in his book. ‘Histuria plantarum’ and Darwin proposed the theory of natural selection or origin of species.

2. The term “New Systematics” was introduced by

(a) Bentham and Hooker

(b) Linnaeus

(c) Julian Huxley

(d) A.P. de Candolle.

Answer and Explanation:

2. (c): The term “New Systematics” was given by Julian Huxley (1940). This classification takes into account the cytological, morphological, genetical, anatomical, palynological and physiological characters.

3. Classification given by Bentham and Hooker is

(a) artificial

(b) natural J U.

(c) phylogenetic

(d) numerical.

Answer and Explanation:

3. (b): Classification given by Bentham and Hooker is Natural System. Monocots were placed after dicots; closely related families were seperated; gymnosperms were placed between dicots and monocots.

4. The causal organism for African sleeping sickness i is

(a) Trypanosoma cruzi

(b) T. rhodesiense

(c) T. tangela

(d) T. gambiense.

Answer and Explanation:

4. (d): Trypanosoma gambiense was first observed by Forde in 1901. It causes African sleeping sickness. The disease, also called trypanosomiasis, is found in western and central parts of Africa. The parasite is transmitted by blood sucking tse-tse fly, Glossina palpalis. Mouth and contractile vacuole are absent. Food is absorbed through the body surface.

The parasite multiplies by fission. In human beings the parasite lives in the blood plasma. It causes trypanosoma fever. It is accompanied by glandular swelling. Later the parasite enters cerebrospinal fluid and damages the brain. It makes the patient lethargic and unconscious. Because of it, the disease is called sleeping sickness. If untreated, the disease leads to death.

5. The vector for sleeping sickness is

(a) housefly

(b) tsetse fly

(c) sandfly

(d) fruit fly.

Answer and Explanation:

5. (b): Trypanosoma gambiense was first observed by Forde in 1901. It causes African sleeping sickness. The disease, also called trypanosomiasis, is found in western and central parts of Africa. The parasite is transmitted by blood sucking tse-tse fly, Glossina palpalis. Mouth and contractile vacuole are absent. Food is absorbed through the body surface.

The parasite multiplies by fission. In human beings the parasite lives in the blood plasma. It causes trypanosoma fever. It is accompanied by glandular swelling. Later the parasite enters cerebrospinal fluid and damages the brain. It makes the patient lethargic and unconscious. Because of it, the disease is called sleeping sickness. If untreated, the disease leads to death.

6. Trypanosoma belongs to class

(a) sarcodina

(b) zoofiagellata

(c) ciliata

(d) sporozoa.

Answer and Explanation:

6. (b): On the basis of locomotory organelles the protozoan protists are divided into four groups : Mastigophora, Sarcodina, Sporozoa and Ciliata. Trypanosoma belongs to class zooflagellata which comes under the group mastigophora. The characteristics are:

(i) These zooflagellates are generally uninucleate, occasionally multinucleate.

(ii) The body is covered by a firm pellicle.

(iii) Nutrition is holozoic, parasitic and saprobic.

(iv) Reserved food is glycogen.

7. Malaria fever coincides with liberation of

(a) cryptomerozoties

(b) metacryptomerozoites

(c) merozoites

(d) trophozoites.

Answer and Explanation:

7. (b): Symptoms of malaria first appear several days after the infection of the malaria parasite in man. This interval of time or the incubation period is utilized by the parasites to increase their progeny. To establish malarial symptoms, it is necessary that a large number of organisms must continue erythrocytic cycle at a time.

A healthy person acquires infection when a female Anopheles mosquito, containing infective stages of parasite (sporozoites) in its salivary glands, bites him for sucking his blood. Once within the numan blood, the sporozoites get into liverto invade the hepatic cells. Here they multiply asexually by schizogony.

Liver schizogony has two phases, pre-erythrocytic and exo-erythrocytic: Pre-crythrocytic phase: After penetrating a hepatic cell each sporozoite becomes a cryptozoite. It grows for a number of days and becomes a spherical and non- pigmented schizont.

It divides by schizogony (multiple fission) and forms a large number of uninucleate cells, the cryptomerozoites. During pre-erythrocytic schi7ogony, blood remains sterile and its inoculation does not produce infection.

Exo-erythrocvic phase: Cryptomerozoites enter fresh liver cells to become metacryptozoites. They undergo schizogony similar to the previous one producing enormous number of metacrypto-merozoites. Metacryptonierozoites, after escaping into blood stream, invade the erythrocytes or red blood corpuscles. This starts the erythrocytic schizogony. With erythrocytic schizogony, the symptom of malaria starts appearing.

8. A bite of Tse-tse fly may pass to humans

(a)Leishmania donovani

(b) Trypanosoma gambiense

(c) Entamoeba histolytica

(d) Plasmodium vivax.

Answer and Explanation:

8. (b): The main vertebrate host is human. The principle invertebrate’s hosts are tsetse fly of the genus Glossina. T. gambiense is transmitted to human by biting of an infected tsetse fly after the cyclic development of the parasite.

9. Artificial system of classification was first used by

(a) Linnaeus

(b) De Candolle

(c) Pliny the Edkr

(d) Bentham and Hooker

Answer and Explanation:

9. (a): Artificial system of classification was first used by Linnaeus. The cryptogams were included in flowering plants. Linnaeus system is known as sexual system of classification. He classified on the basis of number, size and union of sex organs.

10. System of classification used by Linnaeus was

(a) natural system

(b) artificial system

(c) phylogenetic system

(d) asexual system

Answer and Explanation:

10. (b): Linnaeus put forward an “Artificial system” of plant classification which was based on sexual characters like cryptogamia, monoecia, monandria, diandria, polyandria etc. It is commonly also called as sexual system of plant classification.

11. The infective stage of malaria parasite, Plasmodium that enters human body is

(a) merozoite

(b) sporozoite

(c) trophozoite

(d) minuta form.

Answer and Explanation:

11. (b): The infective stage of Plasmodium is a minute organism called sporozoite. When the mosquito bites man, sporozoites present in the salivary gland of female Anopheles mosquito are injected into the blood of the man. These sporozoites are spindle-shaped or sickle- shaped uninucleate organisms capable of wrigging (worm­like) movements. Each sporozoite consists of elastic pellicle, cytoplasm and nucleus.

12. Genetic information in Paramecium is contained in

(a) micronucleus

(b) macronucleus

(c) both micronucleus and macronucleus

(d) mitochondria.

Answer and Explanation:

12. (a): Paramaecium contains a single large macronucleus and one small micronucleus. The macronucleus controls metabolism such as feeding and maintaenance, whereas the macronucleus takes and important role in reproduction and stores genetic information, hence it is also termed as reproductive nucleus whereas macronucleus is termed as vegetative nucleus.

13. Which is true about Trypanosoma?

(a) polymorphic

(b) monogenetic

(c) facultative parasite

(d) non-pathogenic.

Answer and Explanation:

13. (a): Trypanosoma is polymorphic i.e. it has more than one form. It has at least four forms that are recognized on the basis of the positions of kinetoplast and blepharoplast and the course taken by the tlagellum. Two or more such forms occur either in one or both the hosts in the life cycles of various species of Trypanosoma. These i forms are

(i) Leishmanial (amastigote): Round or oval form with a nucleus, blepharoplast and kinetoplast. Flagellum reduced and fibril-like embedded in cytoplasm.

(ii) Leptomonad (promastigote): Body elongate, nucleus large and anteriorly located blepharoplast and kinetoplast. Flagellum short and unattached.

(iii) Crithidial (epimastigote): Body elongate. Blepharoplast and kinetoplast placed immediately anterior to nucleus. Undulating membrane inconspicuous.

(iv) Trypanosomid (trypomastigote): Body elongate and slender. Blepharoplast and kinetoplast situated at or near posterior end. Undulating membrane conspicuous.

Tiypanosoma is digenetic i.e. it completes its life cycle in two hosts. It is an obligate parasite and is pathogenic.

14. Amoebiasis is prevented by

(a) eating balanced food

(b) eating plenty of fruits

(c) drinking boiled water

(d) using mosquito nets.

Answer and Explanation:

14. (c): Amoebiasis can be prevented by drinking boiled water as it mainly occurs by ingestion of cysts of E. histolytica in food or drinks. The contamination of food or drinks occurs by (i) unhygienic habits of food handlers who by habit scratch the anus and then put the fingers in the food which they serve, (ii) habit of defecating in open fields causing contamination of vegetables and then washing the bottom in ponds causing the contamination of water, (iii) transmission of cysts from stools to food and drinks by flies and cockroaches. So, one should take following preventive measures:

(I) Proper sanitation of roads, streets, lanes and open drains.

(II) Purification of drinking water (by boiling).

(III) Proper disposal of sewage.

(IV) Covering of the food articles by the traders.

(V) Chemical trcatent of huma faeces to be used as fertilizer.

15. Plasmodium, the malaria parasite, belongs to class

(a) sarcodina

(b) ciliata

(c) sporozoa

(d) dinophyceae.

Answer and Explanation:

15. (c): These protozoans are adapted to parasitic mode of life. All of them are endoparasites. Locomotory organelles (cilia, flagella. pseudopodia, etc.) are absent. Organelles connected with ingestion are absent. Nutrition is parasitic (absorptive). Sexual reproduction takes place through syngamy.

It is followed by spore formation, hence sporozoans. Life cycle consists of two distinct asexual and sexual phases. They may be passed in one (monogenetic) or two different hosts (digenetic).

16. Linnaeus evolved a system of nomenclature called

(a) mononomial

(b) vernacular

(c) binomial

(d) polynomial

Answer and Explanation:

16. (c): Binomial nomenclature is the formal system of naming species. The essence of it is that each species name is in (modern scientific) Latin and has two parts, so that it is also sometimes popularly known as the ‘Latin name of the species’, although this terminology is frowned upon by biologists, who prefer the phrase scientific name.

17. Basic unit or smallest taxon of taxonomy/ classification is

(a) species

(b) kingdom

(c) family

(d) variety.

Answer and Explanation:

17. (a): Basic unit or smallest taxon of taxonomy/ classification is species. Species is a group of individuals that remain relatively constant in their characteristics; can be distinguished from other species and do not normally interbreed.

18. A taxon is

(a) a group of related families

(b) a group of related species

(c) a type of living organisms

(d) a taxonomic group of any ranking.

Answer and Explanation:

18. (d): The word taxon signify a taxonomic group of any rank which represents the real biological organisms included in a category. The term taxon was coined by Adolf Meyer (1926) for animals and H.J Lam (1948) used this term in plant Science.

19. Who discovered Plasmodium in R.B.C. of human beings?

(a) Ronald Ross

(b) Mendel

(c) Laveran

(d) Stephens.

Answer and Explanation:

19. (c): Laveran discovered that malaria is caused by protozoan parasite (Plasmodium) in 1880. He discovered Plasmodium and got Nobel Prize in 1907.

Sir Ronald Ross in 1897, a doctor in Indian Army, established that malaria parasite is transmitted by the bite of a female Anopheles mosquito and in 1902; he got Nobel Prize for this discovery.

20. Malignant tertian malaria parasite, belongs to class

(a) Plasmodium falciparum

(b) P. vivax

(c) P. ovale

(d) P. malariae.

Answer and Explanation:

20. (a): Plasmodium falciparum is the greatest killer of human beings over most parts of Africa and elsewhere in tropics. It causes malignant (or pernicious or cerebral or tropical) tertian malaria.

This malaria is most harmful. Plasmodium vivax causes benign tertian malaria. Plasmodium malariae causes quartan malaria. Plasmodium ovale is the rarest of the four species which infect man and it causes mild tertian malaria.

21. African sleeping sickness is due to

(a) Plasmodium vivax transmitted by Tsetse fly

(b) Trypanosoma lewsii transmitted by Bed Bug

(c) Trypanosoma gambiense transmitted by Glossina palpalis

(d) Entamoeba gingivalis spread by Housefly.

Answer and Explanation:

21. (c): Trypanosoma gambiense is the parasitic zoo flagellate which causes one of the deadliest ailments in human beings called sleeping sickness or trypanosomiasis. The disease is common in humid and subhumid zones of the African continent. The disease is transmitted by shade loving tsetse fly (Glossinapalpalis) which acts as the vehicle that carries the culprit protozoan parasite.

22. In Amoeba and Paramecium osmoregulation occurs through

(a) pseudopodia

(b) nucleus

(c) contractile vacuole

(d) general surface

Answer and Explanation:

22. (c): In Amoeba and Paramecium osmoregulation occurs through contractile vacoule. Osmoregulation is a phenomenon in which contractile vacuole plays an important role in maintaining the water balance of the cell. Paramaecium contains two contractile vacuoles which have fixed position.

One contractile vacuole is present near the anterior end while another is present towards posterior end of the body. Each contractile vacuole is surrounded by 5-12 radial canals. Excess of water is transferred from the cytoplasm to the radial canals. The latter pour water into the contractile vacuole. The contractile vacuole expels water outside the body.

Thus the contractile vacuoles and radial canals are for osmoregulation. In Amoeba the endoplasm, at its posterior end, contains a single, clear rounded and pulsating contractile vacuole, filled with a watery fluid and enclosed by a unit membrane. Surrounding this membrane is a region containing many tiny feeder vacuoles and mitochondria. It helps in the osmoregulatory and excretory activities of the animal.

23. A group of plu.nts or animals with siuilar traits of any rank is

(a) species

(b) gcr.us

(c) order

(d) taxon.

Answer and Explanation:

23. (d): A taxon (plural taxa) or taxonomic unit, is a name designating an organism or group of organisms. A taxon is assigned a rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships.

24. An important criterion for modern day classification is

(a) resemblances in morphology

(b) anatomical and physiological traits

(c) breeding habits

(d) presence or absence of notochord.

Answer and Explanation:

24. (b): Taxonomy and classification are a part of the broader field of systematics which is the study of diversity of organisms. Classification of a part of systematics as it lists the unique characters of each taxon.

25. The part of life cycle of malaria parasite Plasmodium vivax, that is passed in female Anopheles is

(a) sexual cycle

(b) pre-crythrocytic schizogony

(c) exoerythrocytic schizogony

(d) post-erythrocytic schizogony.

Answer and Explanation:

25. (a): Plasmodium has two hosts.

(i) Female Anopheles mosquito: Here the sexual phase of the malaria parasite occurs and it is considered the definitive host of material parasite, (ii) Human beings: Here the asexual phase of malaria parasite occurs. It is considered as the intermediate host. Options (b), (c) and (d) are the stages of the asexual phase of Plasmodium.

26. The term phylum was given by

(a) cuvier

(b) haeckel

(c) theophrastus

(d) linnaeus.

Answer and Explanation:

26. (a): The term phylum was given by Cuvier.

27. Sequence of taxonomic categories is

(a) class-phylum-tribe-order family- genus species

(b) di vision-class-family-tribe-order-genus- species

(c) division-class-order-family-tribe-genus- species

(d) phylum-order-class-tribe-family-genus- species

Answer and Explanation:

27. (c): To construct the hierarchy of classification, one or more species are grouped into a genus, one or more of genera into a family, families are clubbed into order, order into class, classes into phylum and various phyla into kingdom.

28. If all ponds and puddles arc destroyed, the organism likely to be destroyed is

(a) Leishniania

(b) Trypanosoma

(c) A scar is

(d) Plasmodium.

Answer and Explanation:

28. (d): Plasmodium is digenetic i.e. it completes its life cycle in two hosts, asexual cycle in man and sexual cycle in Anophelesmosquito. The breeding place of this mosquito is ponds, marshes, swampy areas etc. So, if all the ponds and puddles are destroyed, Anopheles will not be able to survive leading to destruction of its parasite, Plasmodium.

29. Schizont stage of Plasmodium occurs in human cells

(a) erythrocytes

(b) liver cells

(c) erythrocytes and liver cells

(d) erythrocytes, liver cells and spleen cells.

Answer and Explanation:

29. (c): Schizont stage of Plasmodium occurs in human erythrocytes and liver cells. Within the human blood the sporozoites, circulates about half an hour and enters into the liver cell. The kupffer cells of the liver clear the sporozoites from the blood stream and kill many of the organisms. A fraction of sporozoites escape destruction, however, and penetrate the hepatocytes where they take up the residence. Here they multiply by schizogony.

30. Linnaeus is credited with

(a) binomial nomenclature

(b) theory of biogenesis

(c) discovery of microscope

(d) discovery of blood circulation.

Answer and Explanation:

30. (a): Binomial nomenclature of scientific naming was first given by C. Linnaeus (1735) in his book System a Naturae and later in “Species Plantarum” (1753). He used two Latin words for any organism, the first being generic name and the second is specific name. The generic name begins with capital letter and the species name with small letter.

31. The protists have

(a) only free nucleic acid aggregates

(b) membrane bound nucleo proteins lying embedded in the cytoplasm

(c) gene containing nucleoproteins condensed together in loose mass

(d) nucleoprotein in direct contact with the rest of the cell substance.

Answer and Explanation:

31. (b): Protists include all unicellular and colonial eukaryotes except those of green and red algae. They are broadly divided into three groups – photosynthetic, slime moulds and protozoans. The protistan cells are typically eukaryotic having membrane bound organelles like mitochondria, chloroplasts, Golgi bodies, endoplasmic reticulum, nucleus etc. Nucleus is well defined. Protists can be uninucleate, binucleate or multinucleate. The genetic material is linear DNA, enclosed by nuclear envelope, complexed with proteins and organised into distinct chromosomes.

32. Phylogenetic classification is one which is basea

(a) overall similarities

(b) utilitarian system

(c) habits of plants

(d) common evolutionary descent.

Answer and Explanation:

32. (d): Phylogenetic systems of classification bring out evolutionary relationships of organisms. Phylogenetic
systems of classification came into existence after acceptance of doctrine of evolution and natural selection propounded by Charles Darwin in his book “On the origin of Species” by means of Natural Selection. Darwin had put forward the view that the present day plants/animals originated from some ancestral ones after undergoing some periodical changes.

So the phylogenetic classification is based on the evolutionary descent of a group of organisms and the relationships are depicted through a phylogram and a cladogram.

33. Tobacco mosaic virus (TMV) genes are

(a) single stranded RNA

(b) double stranded DNA

(c) proteinaceous

(d) double stranded RNA.

Answer and Explanation:

33. (a): Tobacco Mosaic Virus is a ribovirus and contains single stranded RNA. It was proved by the experiments ofFrankel Conart that RNA is the genetic material in this virus. It does not contain any DNA and is composed of 6 % RNA surrounded by a hollow cylinder of portion subunits.

Double stranded RNA is found in Reovirus and Tumor virus.

Retroviruses have two copies of single stranded RNA.

34. The tailed bacteriophages are

(a) motile on surface of bacteria

(b) non-motile

(c) motile on surface of plant leaves

(d) actively motile in water.

Answer and Explanation:

34. (a): The tailed bacteriophages contain a hollow helical tail which serves both as cell attachment organ and as a tube that facilitates the entry of nucleic acid into the host cell. The tail consists of tail plate and the caudal fibres.

35. BGA (blue green algae) is included in which of the following groups?

(a) bryophytes

(b) prokaryotes

(c) protista

(d) fungi.

Answer and Explanation:

35. (b): According to Whittaker’s system, blue green algae are placed in kingdom monera which is the kingdom of prokaryotes. This is because they lack nucleus, DNA is naked and is folded variously to form nucleoid in the centre of the protoplast. In addition they lack membrane bound organelles including endoplasmic reticulum and ribosomes are of 70s type. So they are included under prokaryotes.

36. ‘Taxon’ is the unit of a group of

(a) order

(b) taxonomy

(c) species

(d) genes.

Answer and Explanation:

36. (b): Taxon refers to all the categories in the taxonomic hierarchy. It may be a kingdom, class, order, family, genus or species. It is any level of grouping of organisms. Each of these categories has been divided further into intermediate categories like subkingdom, subdivision, superclass, subgenus, subspecies etc. This term was coined by ICBN in 1956.

37. What is the genetic material in influenza virus?

(a) double helical DNA

(b) RNA

(c) single helix DNA

(d) none of these.

Answer and Explanation:

37. (b): Influenza viruses are spherical in shape measuring about 800-1200A in diameter. It has a protein capsid that encloses a single stranded RNA. The single stranded RNA is generally linear and constitutes about 10% of the virus particle. RNA is genetic material in other viruses like poliomyelitis, foot and mouth disease virus and tobacco mosaic virus etc.

38. Viruses possess

(a) ribosomes to synthesize protein

(b) organelle for its vitamin mechanism

(c) either DNA or RNA

(d) none of these.

39. In the five kingdom system of classification, which single kingdom out of the following can include blue-green algae, nitrogen fixing bacteria and methanogenic archaebacteria?

(a) plantae

(b) protista

(c) monera

(d) fungi.

Answer and Explanation:

39. (c): R.H. Whittaker had proposed a five kingdom system of biological classification in 1969. It is based on complexity of cell structure, body organization and mode of nutrition. The kingdom monera includes all prokaryotes. They are basically unicellular with peptidoglycan in cell wall. Naked circular DNA coiled to form nucleoid without association with histones, ribosomes 70s, thylakoids present in photoautotrophs but other membrane bound organelles are absent.

These are heterotrophic, phototrophic or chemotrophic in their mode of nutrition. The blue-green algae, nitrogen fixing bacteria and methanogenic archaebacteria are all unicellular prokaryotes so they are included in the kingdom monera.

40. The book ‘Genera Plant arum’ was written by

(a) Engler & Prantl

(b) Bentham & Hooker

(c) Bessey

(d) Hutchinson.

Answer and Explanation:

40. (b): Bentham and Hooker in their monumental work Genera Plantarum (1862-1883) have provided elaborate keys for the easy identification of202 natural orders and genera. Engler and Prantl wrote Die naturlichen pflanzen familien. Huchinson wrote a book titled “The Families of Flowering Plants.”

41. A system of classification, in which a large number of traits are considered, is

(a) natural system

(b) phylogenetic system

(c) artificial system

(d) synthetic system.

Answer and Explanation:

41. (a): There are three systems of classification – artificial, natural and phylogenetic. In the natural system of classification the organisms are arranged on the basis of all known taxonomic characters instead of one or first few. These include morphological, anatomical, cytological, and physiological and biochemical characters of the organisms.

The artificial system is based on one or a few characters that are easily observable. The phylogenetic system tries to organize organisms on the basis of their genetic and phylogenetic relationships besides taxonomic characters.

42. Which of the following is less general in characters as compared to genus?

(a) species

(b) division

(c) class

(d) family.

Answer and Explanation:

42. (a): A taxonomic hierarchy is the sequence of arrangement of taxonomic categories in a descending order during the classification of an organism. There are seven obligate categories – kingdom, division, class, order, family, genus and species. Species is the lowest category while kingdom is the highest category.

The number of common characters is maximum in case of organisms placed in the lowest category. Number of common characters decreases with the rise in category. Species are the smallest group of individuals which can be recognized by ordinary methods as groups and which arc consistently and persistently different from other groups because their characters are less general.

43. Cauliflower mosaic virus contains

(a) ss RNA

(b) ds RNA

(c) ds DNA

(d) ss DNA.

Answer and Explanation:

43. (c): Cauliflower mosaic virus contain ds DNA. It is circular and shows semidiscontinuous type of replication.

44. In five kingdom system, the main basis of classification of

(a) structure of nucleus

(b) mode of nutrition

(c) structure of cell wall

(d) asexual reproduction.

Answer and Explanation:

44. (b): Whittaker’s system is based on the following three criteria –

• complexity of cell structure.

• complexity of the body organization.

• mode of nutrition.

On the basis of these criteria, Whittaker divided organisms into five kingdoms. These five kingdoms are monera, protista, algae, fungi and animalia. In the five kingdom classification all, prokaryotes have been placed in kingdom monera, all unicellular eukaryotes in kingdom protista, fungi (except slime moulds and water moulds) in their separate kingdom while kingdom plantae and kingdom animalia have been retained for multicellular, autotrophic and multicellular holozoic organisms respectively.

45. Biosystematics aims at

(a) the classification of organisms based on broad morphological characters

(b) delimiting various taxa of organisms and establishing their relationships

(c) the classification of organisms based on their evolutionary history and establishing their phylogeny on the totality of various parameters from all fields of studies

(d) identification and arrangement of organisms on the basis of their cytological characteristics

Answer and Explanation:

45. (c): Biosystematics is the study of identification, nomenclature classification and relationships amongst living beings. In other words, it is the study of diversity of organisms, their comparative and evolutionary relationships based on comparative anatomy, ecology, physiology, biochemistry and other fields.

46. In which kingdom would you classify the archaea and nitrogen-fixing organisms, if the five-kingdom system of classification is used?

(a) plantae

(b) fungi

(c) protista

(d) monera

Answer and Explanation:

46. (d): The kingdom monera includes all prokaryotes. They are basically unicellular but can be mycelial, colonial and filamentous. They contain peptidogycan in cell wall. Naked circular DNA coiled to form nucleoid without association with histones, ribosomes 70s, thylakoids present in photoautotrophs but other membrane bound 1 organelles are absent. Nutrition is of various types – parasitic, chemoautotrophic, photoautotrophic and saprobic.

Some monerans have the ability to fix nitrogen. Due to presence of these characters in arehaea and nitrogen- fixing organisms they are placed under monera.

All others fungi, plantae, protists and animalia are eukaryotic.

47. Phenetic classification is based on

(a) the ancestral lineage of existing organisms

(b) observable characteristics of existing organisms

(c) dendrograms based on DNA characteristics

(d) sexual characteristics

Answer and Explanation:

47. (b): Phenetic classification is a type of numerical taxonomy. In this type of classification the organisms are arranged according to overall similarity of existing organisms based on available characters.

It is also called adansonian taxonomy because the same was first attempted by Adanson (1763), of course on the basis of external traits only. Numerical taxonomy evolved around 1950.

It has received impetus with the availability of calculating machines and computers. In numerical taxonomy as many characters as possible are employed for evaluating degree of similarity and difference. All characteristics used in analysis are given equal weightage and importance.

A proper selection of characters, their organisation and analysis in the light of current knowledge is key to success of this method. A lot of subjectivity can creep in depending upon the judgement of the biosystematist. No weightage is given to the quantity of the character present.

48. Species are considered as

(a) real basic units of classification

(b) the lowest units of classification

(c) artificial concept of human mind which cannot be defined in absolute terms

(d) real units of classification devised by taxonomists

Answer and Explanation:

48. (a): Species is a natural population or group of natural populations of individuals which are genetically distinct and reproductively isolated with similar essential morphological traits. Species is also a genetically closed system because its members do not interbreed with members of other species. Species is lowest or basic taxonomic category, e.g., mango {Mangifera indica), potato (Solanum tuberosum), lion (Panthera Leo).

Here indica, tuberosum, Leo are species of genera Mangifera, Solatium and Pantera respectively. All other taxonomic categories are defined and described in relation to species. For example, a genus is a group of species and a subspecies or a variety is a part of species. New species originate from already existing species. Species is considered basic unit of taxonomy since in the greater majority of cases we do not have intraspecific names.

49. Viruses are no more “alive” than isolated chromosomes because

(a) they require both RNA and DNA

(b) they both need food molecules

(c) they both require oxygen for respiration

(d) both require the environment of a cell to replicate

Answer and Explanation:

49. (d): Viruses contain a protein coat that encloses a single type of nucleic acid, either RNA or DNA. They multiply only inside the living host cells and for this they take over the machinery of the host cell. They lack cell division and enzymes for protein synthesis. They do not have cell 01 ganclles like mitochondria, Golgi complex, lysosomes ribosomes etc. so they cannot live or reproduce separately.

50. Tobacco mosaic virus is a tubular filament of size

(a) 300 x 10 nm

(b) 300 x 5 nm

(c) 300 x 20 nm

(d) 700 x 30 nm

Answer and Explanation:

50. (c): TMV is rod shaped measuring 300 20 nm. It is made of RNA and proteins.

51. Which one of the following statements about viruses is correct?

(a) viruses possess their own metabolic system

(b) all viruses contain both RNA and DNA

(c) viruses are obligate parasites

(d) nucleic acid of viruses is known as capsid

Answer and Explanation:

51. (c): Viruses contain a protein coat known as capsid which encloses a single type of nucleic acid, either RNA or DNA. They do not have enzymes for protein synthesis. They multiply only inside the living host cell and for multiplication they take over the machinery of the host cell. Thus viruses are obligatory intercellular parasites.

52. Phenetic classification of organisms is based on

(a) observable characteristics of existing organisms

(b) the ancestral lineage of existing organisms

(c) dendogram based on DNA characteristics

(d) sexual characteristics.

Answer and Explanation:

52. (a) Refer to Explanation 47

53. Viruses that infect bacteria multiply and catise their lysis, are called

(a) lysozymes

(b) lipolytic

(c) lytic

(d) lysogenic.

Answer and Explanation:

53. (c): Viruses like bacteriophage T4 undergo lytic cycle that involves lysis of bacteria. The replication cycle of bacteriophage T4 consists of following phases –

(i) Adsorption of the phage to bacterial or host cell. Then the viral genetic material penetrates into the host cell.

(ii) Eclipse period involves the synthesis of new phage DNA and proteins.

(iii) Maturation involves the assembly of phage DNA into the protein coat.

(iv) Lysis of host cell occurs and releases infective progeny phases.

54. Which of the following statements is not true for retroviruses?

(a) DNA is not present at any stage in the life cycle of retroviruses

(b) Retroviruses carry gene for RNA-dependent DNA polymerase

(c) The genetic material in mature retroviruses is RNA

(d) Retroviruses are causative agents for certain kinds of cancer in man.

Answer and Explanation:

54. (a): Retroviruses contain RNA as genetic material and this RNA is converted to DNA using enzyme reverse transcriptase.

55. One of the most important functions of botanical gardens is that

(a) they provide a beautiful area for recreation

(b) one can observe tropical plants there

(c) they allow ex-situ conservation of germ plasm

(d) they provide the natural habitat for wild life.

Answer and Explanation:

55. (c): Ex situ conservation means “offsite conservation”. It is the process of protecting endangered species of plants and animals by removing it from an unsafe or threatened habitat and placing it or part of it under the care of humans. Botanical gardens serve as ex situ conservation of germplasm of different plants, to maintain rare and endemic plant species and also to provide recreation and knowledge about plants to a comnian man.

56. ICBN stands for

(a) International Code of Botanical Nomenclature

(b) International Congress of Biological Names

(c) Indian Code of Botanical Nomenclature

(d) Indian Congress of Biological Names.

Answer and Explanation:

56. (a): The International Code of Botanical Nomenclature (ICBN) is a set of rules and recommendations dealing with the formal botanical names given to plant. The foundations of ICBN are given in book written by C. Linnaeus named Philosophia Botanica. It is independent of zoological nomenclature, i’lie rank of species is basic and relative orders of the ranks of taxa are as: species, genus, tribe, family, order, series, class, division and kingdom.

The different ranks or categories have following specific endings of their names as division – phyla, class, and family-aceae.

57. Which one of the following is a slime mould?

(a) Physarum

(b) Thiobacillus

(c) Anabaena

(d) Rhizopus.

Answer and Explanation:

57. (a): Slime moulds are peculiar protista that normally take the form of amoebae, but under certain conditions develop fruiting bodies that release spores, superficially similar to the sporangia of fungi.

The order physarales include Physarum species. The fruiting bodies (sporangia) are characterized by the presence of abundant amount of calcium salt. The order comprises 142 species which are placed under 12 genera. Physarum polycephalam is the best known. The somatic phase is multinucleate, diploid holocarpic Plasmodium which is the product of syngamy.

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