Karnataka 1st PUC Biology Question Bank Chapter 2 Biological Classification

1st PUC Biology Biological Classification One Marks Questions and Answers

Question 1.
What is a Capsid?
Answer:
The outer protein coat of a virus is called a capsid.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 2.
What are DNA viruses RNA viruses?
Answer:
Viruses which posses DNA as the genetic material are called DNA viruses and those viruses which posses RNA as the genetic material are called RNA viruses.

Question 3.
Which is the nucleic acid found in bacteriophages?
Answer:
Double stranded DNA.

Question 4.
Give an example for symbiotic bacteria.
Answer:
Rhizobium.

Question 5.
Give one example to Nitrifying bacteria.
Answer:
Nitrosomosnas.

Question 6.
Mention the characteristic blue pigment of cyano bacteria.
Answer:
Phycocyanin.

Question 7.
Why protists are Eukaryotes?
Answer:
Protists contain in their cells true nucleus (Nucleus with nuclear membrane) so protists are eukaryotes.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 8.
What is Isogamy/ Anisogamy?
Answer:
Fusion between similar gametes is isogamy, and that is isogamy between dissimilar gametes is anisogamy.

Question 9.
What is an algal bloom?
Answer:
Heavy growth of algae in a water body or their luxurious growth in water is called algal bloom.

Question 10.
Name the pigment that gives golden brown colour to Diatom.
Answer:
Diatomin.

Question 11.
Which organism is commonly called” Pond Silk”?
Answer:
Spirogyra.

Question 12.
What are Saprophytes?
Answer:
Organisms feeding on dead organic matter and obtain their source of food, are called saprobes.

Question 13.
What is Mycelium?
Answer:
Mycelium is the fungal body made up of a group of hyphae.

Question 14.
What are Hyphae?
Answer:
Hyphae are long filamentous, branches of fungal plant body.

Question 15.
Mention any one harmful effect of fungi.
Answer:
They cause diseases in plants (koferoga), animals (Athlete foot) and humans (Aspergillosis).

Question 16.
Why are deuteromycetes named as Imperfect fungi?
Answer:
Deuteromyetes are termed as Imperfect fungi, because only their asexual reproductive stages are known and sexual reproduction is unknown.

17.
State the occurrence and function of the Cilia.
Answer:
Cilia is found in phylum protozoa, and represents locomotor organs

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 18.
Name the locomotor organelles of class Rhizopoda/ Sarcodina?
Answer:
Pseudopodia (false feet).

Question 19.
Who proposed the five kingdom classification?
Answer:
R.H. Whittaker.

Question 20.
Name the two kingdoms in the two kingdom classification?
Answer:
Animal(s) kingdom and plant(s) kingdom.

Question 21.
In what form is the food stored in Euglena?
Answer:
Starch.

Question 22.
What is a Plasmid?
Answer:
Small double stranded circular DNA molecules which are free from nucleoid present in bacteria are called plasmids.

Question 23.
Name two bacterial diseases of plants.
Answer:
(i) Citrus Cancer
(ii) Crown gall disease.

Question 24.
What is a trichome?
Answer:
A Nostoc filament with mucilage is called a trichome.

Question 25.
What are Akinetes?
Answer:
The resting spores or thick-walled cells containing stored food present in a trichome, are called akinetes.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 26.
What are Heterodysts?
Answer:
These .are large, thick walled cells of nostoc trichomes that help for nitrogen fixation and reproduction.

Question 27.
What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?
Answer:
Cyanobacteria are capable of nitrogen fixation and help in water retention. .

Question 28.
What are prokaryotes?
Answer:
The organisms which do not have well organized nucleus in their cells are called prokaryotes.
or
Organisms containing incipient nucleus (Nucleoid) in their cells are called prokaryotes.

Question 29.
Name the five Kingdoms of living organisms?
Answer:
1. Kingdom Monera.
2. Kingdom Protista.
3. Kingdom – Fungi (mycota).
4. Kingdom – Piantae (metaphyta).
5. Kingdom – Animalia (metazoan).

Question 30.
Who proposed five Kingdom classification?
Answer:
R.H. Whittaker (1969).

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 31.
What are Monerans?
Answer:
Prokaryotic organisms are called monerans.

Question 32.
Give an example for Kingdom Monera.
Answer:
Bacteria, Nostoc, Mycoplasma.

Question 33.
What are mycoplasmas?
Answer:
The smallest living organisms without cell walls and which can survive without oxygen are called mycoplasmas.

Question 34.
Give an example for red dianoflagelletes?
Answer:
Gonyaulax.

Question 35.
Give an example for euglenoids.
Answer:
Euglena (photosynthetic protozoan).

Question 36.
Name the Kingdom which includes eukaryotic heteroptrophic organisms?.
Answer:
Kingdom Mycota (Fungi).

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 37.
Give an example for deuteromycetes.
Answer:
(1) Alternaria
(2) Collectotrichum
(3) Trichoderma.

Question 38.
What are the two distinct phases in the life cycles of plants?
Answer:
(1) Haploid gametophytic generation.
(2) Diploid sporophytic generation.

Question 39.
What is alternation of generation?
Answer:
The alternate occurrence of both haploid and diploid sporophytic generations in the life cycle of plants is called, alternation of generation.

Question 40.
Name the Kingdom which includes heterotrophic eukaryotic multi-cellular organisms which lack cell walls?
Answer:
Kingdom Animalia.

Question 41.
Which is the reserve food material of animals?
Answer:
Glycogen of fat.

Question 42.
What is the mode of nutrition in animals?
Answer:
Holozoic (By ingestion of food).

Question 43.
Name the genetic material of viruses?
Answer:
Either DNA or RNA, but never both.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 44.
What is a capsid?
Answer:
The protein coat of viruses is called a capsid.

Question 45.
Why viruses are called obligate parasites?
Answer:
Because viruses can live inside or outside of the body of the host cell.

Question 46.
Name the disease caused by viroids?
Answer:
Potato spindle tuber disease.

Question 47.
What are lichens?
Answer:
Symbiotic associations (mutually useful associations) between allgae and fungi are called lichens.

Question 48.
What is a phycobiont?
Answer:
The algal component of lichen is called phycobiont. It is autotrophic.

Question 49.
What is a mycobiont?
Answer:
The fungal component of lichen is called mycobiont. It is heterotrophic.

1st PUC Biology Biological Classification Two Marks Questions and Answers

Question 1.
List the general characters of Monera.
Answer:
General characteristics of kingdom monera are:
(1) They are unicellular, but some show short chains / filaments / colonies.
(2) Their cell structure is typically prokaryotic.
(3) Plasma membrane gets infolded as the mesosomes.
(4) Cell wall is made of murein. ,
(5) Photosynthetic pigments associated with membranes forming lamellae / thylakoids choloroplasts are absent.

Question 2.
Write any two living and non-living characters of virus.
Answer:
Living characters:
(a) Like organisms they contain protein and nucleic acid.
(b) Like organisms they undergo mutation.
Non – living characters:
(i) They are non cellular.
(ii) They do not show metabolism.

Question 3.
‘Write a note on bacteriophages.
Answer:
The virus which infect bacteria and cause diseases are called bacteriophages. They have DNA as their genetic material. They are distinguished into T-odd phages as well as T-even phages.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 4.
Explain Heterocyst.
Answer:
The large barrel shaped thick walled cell present in a trichome is called an heterocyst It is terminal or intercalary in position. The terminal heterocyst contains a single polar nodule and a single polar pore whereas intercalary heterocyst contains two polar nodules and two polar pores. Heterocysts contain nitrogenase enzyme which helps in nitrogen fixation.

Question 5.
List any four divisions , of the Kingdom protista based on morphology.
Answer:
Division:
1. Pyrophyta;
2. Chrysophyta
3. Euglenophyta
4. Protozoa.

Question 6.
Write any two distinguishing characters of Fungi.
Answer:
(i) Fungi are nonphotosynthetic saprophytes.
(ii) Fungal body is called mycelium and it is made up of branched or unbranched septate or aseptate filaments called hyphae.

Question 7.
Give four characters of Protozoa.
Answer:
Characters of Protozoa are as follows :
(1) These organisms are unicellular and possess uninucleate or binucleate conditions. When binucleate, one nucleus is larger (Macronucleus) and other one small (Micronucleus).
(2) Locomotion is by pseudopodia, cilia or flagella.
(3) Nutrition is holophytic or holozic or saprophytic or parastitic.
(4) Reproduction takes place by binary fission or multiple fission.

Question 8.
Give two characteristics of kingdom Monera.
Answer:
(i) All monerans are prokaryotes, unicellular or multicellular.
(ii) They contain cytoplasm with incipient nucleus and do not contain mitochondria,Endoplasmic reticulum, golgi body etc, but ribosomes are present.

Question 9.
Give two characteristics of kingdom Metaphyta.
Answer:
(i) Members of this kingdom are plants and they are multicellular, eukaryotes, chlorophyllous (photosynthetic) and has body shows tissues and organ grade of construction.
(ii) They store starch as their reserve food material.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 10.
Give two characteristics of kingdom Metazoa.
Answer:
(i) Members of this kingdom are animals and they are multicellular, eukaryotes and the animal body shows tissues and organ level of construction.
(ii) They are heterotrophs and show locomotion.

Question 11.
Discuss how classification systems have undergone several changes over a period ‘of time?
Answer:
The earliest classification systems were based on simple and easily observable characters like usage of food, shelter and clothing. They are called as artificial systems. Later on they started using classifications in which many morphological characters were used. Such classifications were called as Natural systems. After Darwinism was propounded phylogenetic classification was proposed, which is based on evolutionary relations and morphological characters.

Question 12.
What is the nature of cell-walls in diatoms?
Answer:

  • The cell wall, is called as frustule and it is impregnated with silica, which makes fine characteristic designs. Therefore these are called as jewels of plantkingdom.
  • The cell wall consists of two overlapping halves like a soap case.
  • The outer lid-like part is called epitheca and the lower part is called hypotheca.
  • The cell wall of dead diatoms accumulate and forms diatomaceous earth at the bottom of the ocean floor.
  • They reproduce asexually by binary fission (cell division). Sexual reproduction is by the formation of gametes, that involves meiosis and the fusion product develops into an auxospore.

Question 13.
Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify.
Answer:
Excessive growth of cyanobacteria in nutrient enriched water body are called algal blooms. They result in depletion of Oxygen content of water causing BOD. They are oceanic blooms of mostly red coloured dinoflagellates like Gonyaulax. Red tides spread for several kilometres in the sea.

Question  14.
Plants are autotrophic. Can you think of some plants that are partially heterotrophic?
Answer:
Euglena, Bladderwort, Venus fly trap etc.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question  15.
What do the terms phycobiont and mycobiont signify?
Answer:
Phycobiont is the algal component of a lichen. It manufactures food by photosynthesis for itself and the mycobiont. Mycobiont is the fungal component of a lichen. Mycobiont forms the protective covering of the lichen, attaching structures, absorbing structures and part of the interior thallus. Mycobiont is in symbiotic association with phycobiont.

Question  15.
Are chemosynthetic bacteria autotrophic or heterotrophic?
Answer:
Chemosynthetic bacteria are autotrophic as they can manufacture organic food from inorganic raw materials, with the help of chemical energy obtained by them by oxidising inorganic chemicals present in their environment.

Question  16.
Name the 5 kingdoms of living organisms?
Answer:
1. Monera.
2. Protista.
3. Fungi (Mycota).
4. Plantae (Metaphyta).
5. Animalia (metazoa).

Question 17.
Name the fungi which belongs to basidiomycetes.
Answer:
(1) Agaricus(mushroom).
(2) Ustilago(smurt).
(3) Puccinia(rust fungus).

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 18.
Write the four characters of Phycomycetes?
Answer:

A. Class : Oomycetes

  • They have coenocytic -aseptate and multinucleate-mycelia. Mostly they are parasites, while a few are saprotrophs. Parasitic forms produce haustoria for deriving nutrition from the host cells.
  • Asexual reproduction is by zoospores or aplanospores. Sexual reproduction is either by gametic fusion eg: Synchitrium (isogamous) and Allomyces (anisogamous) or by gametangiaL contact as in Albugo, Phyrophihora, etc.

Economic Importance:
They cause the following diseases in plants :
(i) Phytophihora infestans – Late blight of potato.
(ii) Albugo candida – White rust of crucifers.
(iii) Pythium – Damping-off disease in many crucifers.

B. Class: Zygomycetes

  • Plant body is unicellular coenocytic mycelium.
  • They are obligate saprotrophs.
  • Asexual reproduction occurs by aplanospores, which are formed within the sporangium (called also as sporangiospores).

Economic Importance:
Rhizopus stolonfer is heterothallic.
Rhizopus and Mucor grow on any fruit, vegetable or organic food and cause their spoilage.
Note: Class oomycetes and class zygomycetes were included under class phycomycetes.

Question 19.
Write the characters of Ascomycetes?
Answer:

  • These are commonly called sac-fungi. They may be unicellular (e.g. yeast) or multicellular.
  • Organisms are saprotrophic and parasitic.
  • Mycelium is septate and septa are porous.
  • Asexual reproduction is by formation of conidia, which are cut off exogenously on a
    conidiophore, in a basipetal succession.
  • Sexual reproduction is by gametangial fusion (yeast), or gametangial contact (Pyronema) or
    Spermatization (Neurospora) or somatogamy (Peziza).

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 20.
Who discovered viroids?
Answer:
T.O. Diener.

1st PUC Biology Biological Classification Three Marks Questions and Answers

Question 1.
State two economically important uses of
(a) heterotrophic bacteria
(b) archaebacteria.
Answer:
(a) 1. Parasitic bacteria: They depend on living cells of plants and animals. They cause disease in plants, animals and human beings.
2. Saprophytic bacteria: They depend on dead organic matter and bring about decomposition of the organic matter.
3. Symbiotic bacteria: The relationship between two partners where both are mutually benefited.
e.g: Rhizobium in the root nodule of legume plant.

(b) (1) Biogas formation from dung using Methanobacterium and Methanococcus.
(2) Minerals like molybodenum are extracted from poor ores through bioleaching with the help of sulpholobus.

Question 2.
How are viroids different from viruses?
Answer:
Viruses:
(1) They larger than viroids.
(2) They have a protein coat.
(3) Genetic material consists of DNA or RNA.
(4) If RNA present, has a high molecular mass.

Viroids:
(1) They are smaller than viruses.
(2) They lack a protein coat.
(3) They are RNA particles.
(4) Their RNA has a lower molecular mass.

Question 3.
Describe briefly the four major groups of Protozoa.
Answer:
Phylum : Protozoa
This phylum is divided into four classes based on the locomotory structures:
(1) Sarcodina : Locomotion is by pseudopodia. e.g. Amoeba, Entamoeba.
(2) Sporozoa : No structure for locomotion, but is carried toward by the body fluid. e.g. Plasm odium.
(3) Flagellata: Locomotary organelle is flagella e.g. Giardia.
(4) Culata: Locomotary organelle is cilia e.g. Paramaecium.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 4.
What are the characteristic features of Euglenoids?
Answer:
Phylum: Euglenophyta:

  • Members of this phylum are fresh water, flagellate and motile forms.
  • A single flagellum is found at the anterior end.

The flagellum develops from basal granule and an eye spot or stigma is present near to it.

  • The cells have an elastic pellicle that gives a definite shape to the cell.
  • Euglena is photosynthetic when optimum light is available and is non-photosynthetic in the
    absence of light and engulfs the food materials. Hence it is described as myxotroph.
  • Contractile vacuoles help in osmoregulation.
  • Reserve food occurs in the form of paramylum starch.
  • Asexual reproduction is by longitudinal binary fission.

1st PUC Biology Biological Classification Five Marks Questions and Answers

Question 1.
Explain the types of bacteria based on their mode of Nutrition.
Answer:
Nutrition:
Based on the mode of nutrition bacteria are of two groups:
(i) Autotrophs
(ii) Heterotrophs.

Certain bacteria which can synthesise their own food are called as autotrophic bacteria. They are of two types:-

  • Photosynthetic bacteria: They synthesise carbohydrates with the help of sunlight and C02 like green plants eg: Green bacteria (Chlorobium), purple bacteria (Rhodospirullum).
  • Chemosynthetic bacteria: They are bacteria that can prepare their food by using the energy liberated from oxidation of inorganic substances.

e.g: Nitrifying bacteria: Nitrosomonas and nitrococcus can oxidize Ammonia to nitrite. Species of nitrobacter can oxidize nitrite to nitrate.

  • Sulphur bacteria: Thiothrix oxidizes H2S to sulphur, which is further oxidized to Sulphuric acid, Iron bacteria i.e., ferrobacillus oxidize ferrous iron to ferric iron.
  • Heterotrophic bacteria: They do not synthesise their own food. They may be parasities saprophytic or symbiotic.

Question 2.
Give the general features and classification of Protista with examples.
Answer:
Protista:
All the organisms belonging to this kingdom are unicellular and eukaryotic; the cells possess all membrane-bound cell organdies like mitochondria, chioropiasts, endopiasmic reticulum, lysosomes, etc.

This kingdom is classified as follows :
(a) Phylum Protozoa includes unicellular and holozoic organisms (Protozoan protista).
(b) Myxomycota includes saprotrophs and decomposers (Decomposer protista).
(c) Dinoflagellata.
(d) Chrysophyta and
(e) Euglenophyta are called photosynthetic protists.
Most of the members are aquatic and others prefer to grow in moist and humid conditions.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Question 3.
Give an account of the distinguishing characters of Fungi.
Answer:
Fungi.
Fungi are eukaryotic, achiorophyllous organisms which are but, generally multicelluar a few
are unicellular (yeast).

  • The fungal body consists of long, slender, thread-like structures called hyphae, which form a
    network called mycelium.
  • The hyphae have a cell wall made up of chitin.
  • They may be aseptate and multi-nucleate le., coenocytic or septate.
  • All fungi are heterotrophs -they are saprotrophs or parasites or live as symbionts in the roots
    of higher plants (mycorrhizae) and in lichens (mycobiont). They reproduce vegetatively by fragmentation, fission or budding.
  • Asexual reproduction is by formation of zoospores as in Suprolegnia and Pythium by aplanospor&sporangiospores formed endogenously (within the sporangium) as in Rhizopus
    and Mucor or by conidia, which are produced exogenously on the swollen tip of the conidiophore as in Penicillium and Aspergillus.

Question 4.
Explain the useful aspects of Fungi.
Answer:
Fungi are useful in the following ways:
(i) Fungi as food : Mushrooms and morels are rich in protein, vitamin and mineral contents and so are used as food.
(ii) Fungi as decomposers: Since most of them are saprophytes they decompose dead organic matter and help in recycling.
(iii) Fungi in the drug industry: Many fungi are used in the drug industry to extract useful antibiotics, eg: Penicillium notatum.
(iv) Fungi and biological control: Several parasitic nematodes are controlled by fungi.

Question 5.
Draw a neat labelled diagram of T4 phage and explain its structure.
OR
Describe the structure of a bacteriophage with a neat labelled sketch.
Answer:
1st PUC Biology Question Bank Chapter 2 Biological Classification .4
Head : It is polyhedral in shape with a length of 950 A and breadth of of 650 A. The capsule of the head is made up of 2000 identiçal protein sub units called capsomere. The head encloses within it tightly coiled as DNA which forms the core inside the head. It is about 53 microns in length. Below the head, connecting the head to tail is the collar. It is ring like.

Tail: The tail consists of a needle like core tube (tail core) which is surrounded by contractile tail sheath. The tail sheath is made up of 144 sub units arranged in 24 rings around the core. The tail at its posterior ends with an hexagonal base of the tail called the Tail plate base plate. It has six pointed pegs spikes at its 6 corners. On its upper surface, there are six long folded tail fibres arising from its six corners.

Question 6.
Classify bacteria based on the number and position of flagella.
Answer:
(1) Peritrichous – Many flagella arising from various points on the surface of the cell.
(2) Amphitrichous – With tufts of flagella at two opposite ends.
(3) Lophotrichous With a tuft of flagella at one point (end).
(4) Monotrichous – With a single polar flagellum.
(5) Atrichous – Without flagella.

Question 7.
Explain the types of bacteria based on their mode of Nutrition.
Answer:
Based on nutrition, bacteria are classified into the following types.
(i) Growth: Growth is defined as art irreversible increase in the number of cells and or

1st PUC Biology Question Bank Chapter 2 Biological Classification

1. Autotrophic bacteria: They synthesize their own food. They are further classified into two types. .
A. Photoautotrophic bacteria: These autotrophs synthesize their food by absorbing light energy. They contain b’acteriochlorophyll and bacteriovirdin’to absorb light energy. eg: Green sulphur bacteria like chlorobium and purple sulphur bacteria like chromatium.

B. Chemoautotrophic bacteria: These autotrophs utiiize (utilises) chemical energy of chemical substances from nature. Example: Nitrifying bacteria, sulphur bacteria etc.
Note: Some bacteria use H2S as their source of energy, so O2 is not liberated.

2. Heterotrophic bacteria: They do not synthesize their own food but obtain food by any of the two methods.
(a) Saprophytic method.
(b) Parasitic method.
Those bacteria that obtain their food by feeding on dead organic matter, are called saprophytic bacteria.
Those bacteria that obtain their food by living inside or outside the body of other organisms are called parasitic bacteria.

Question  8.
Give a comparative account of the classes of Kingdom Fungi under the following categories:
(i) mode of nutrition.
(ii) mode of reproduction.
Fungi Mode of nutrition Mode of reproduction

(1) Phycomycetes (oomycetes and zygomycetes) Obligate parasites on plants or decaying on wood in moist and damp places. Asexual reproduction by zoospore or alpanospores (non motile).

1st PUC Biology Question Bank Chapter 2 Biological Classification

(2) Ascomycetes saprophytic (yeast) decomposers parasitic or coprophilous (growing on dung) Asexual spores are conidia produced exogenously on the special mycelium called conidiophores. Sexual spores are called ascospores produced endogenously in sac like asci.

(3) Basidiomycetes saprophytes or parasites. Asexual spores not found. Vegetative reproduction by fragmentation is common. Sex organ are absent, but plasmogamy is brough by fusion of two vegetivite or somatic cells of different strains or genotypes.

(4) Deuteromycetes
Ci. mainly decomposers and a few parasites. Only asexual or vegetative phase of these fungi are known. Asexual reproduction by formation of stalk like outergrowth called conidia, which germinates. with highly evolved angiosperms in Plant Kingdom

1st PUC Biology Biological Classification Text Book Questions and Answers

1. Two Kingdom Classification:
• According to this system of classification, all organisms are classified into plants (those which are autotrophs, have a cell wall and do not move) and animals (those which are heterotrophs and holozoic in nutrition and are able to move).

• Linnaeus named these two kingdoms as Plantae and Animalia. But later it was found that two-kingdom classification was not sufficient for the following reasons :
(i) Prokaryotes and eukaryotes have been grouped together, e.g, Bacteria and Cyanobacteria were placed under Plant Kingdom.

(ii) Heterotrophs and autotrophs were placed together.
e.g, Fungi, which are heterotrophs were placed with plants. Euglena, which has chlorophyll was placed under protozoa, that are heterotrophs.

(iii) It did not differentiate between unicellular and multicellular organisms. E.g. Protozoans are unicellular organisms, but were placed with multicellular animals.

(iv) Simple organisms were placed with highly complex organisms, e.g. Protozoans were placed with human beings in Animal Kingdom. Bacteria (prokaryotes) were placed Archaea bacteria are characterized by possessing cellwalls without peptidoglycan (a substance found in the wall of eubacteria). The lipids in their plasma membrane are unusual and are branched.

This unusual lipid make up is probably related to the extreme environments to which they have adapted. The phototrophic forms use the pigment bacteria rhodopsin (instead of bacteriochlorophyll used by eubacteria).

Archae bacteria are of the following types:
Methanogens:Methane producing anaerobes present in bogs and swamp plants.
Halophiles: found in high salinity and use’ salt gradients to generate high energy ATP molecules.
Thermo-acidophils: Can survive at high temperature around 80° and low pH.

(B) Eubacteria:
Bacteria are the smallest and most primitive cellular organism. They are microscopic and often regarded as germs.
Bacteria are cosmopolitan in distribution and found in all environments i.e, soil, air and water. They also occur in plants and animals, both in living and dead.
Bacteria are unicellular organisms and they exist in various forms (shapes). Four major forms of bacteria exist in nature.

1. Coccus form: These are spherical in shape. Cocci forms may occur singly, in pairs, in a clamp or in chains. Accordingly, they are named as:
Monococcus – Occur singly (Micrococcus).
Diplococcus – Occur in pairs (Diplococcus pneumamiae).
Staphylococcus – Occur in groups (Streptococcus pyrogenes).

2. Bacillus form: These are rod shaped. They may occur singly, in pairs or in chains, i.e. Bacillus, Diplobacilli, Streptobacilli.
3. Spirillum form: These bacteria have spirally coiled bodies, eg: Treponema, Rhodo spirillum.
4. Vibrio form: These are comma shaped, eg: Vibrio cholerae.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Flagellation In Bacteria:

Many bacterial forms (bacillus and spirillum) posses thread like flagella for locomotion. Based on the number and position and the flagella, bacteria have been divided into the following groups:
(a) Monotrichous – with single flagellum.
(b) Lophotrichous – with more than one flagellum arising from one end.
(c) Amphitrichous – with flagella arising from the opposite ends.
(d) Peritrichous – with flagella distributed all around the cell.

Cell Structure:
Bacteria are prokaryotic in nature. A typical bacterial cell reveals the following details:
1. Cell wall: The bacterial cell is surrounded by distinct rigid cell wall which is tough and flexible. It contains a mixed polymer called peptidoglycan (mucopolysaccharide and mucopolypeptide). Many bacterial cells secrete a slimy / mucilaginous envelop surrounding the cell wall known as capsule / slimelayer (made up to mucopolysaccharides). This capsule is highly resistant to adverse environmental conditions and to chemicals Capsulated forms are usually pathogenic.

Structure Of Bacteria Cell
1st PUC Biology Question Bank Chapter 2 Biological Classification .1

2. Plasma membrane: Beneath the cell wall lies a thin plasma membrane made up of phospholipids, proteins and trace quantities of polysaccharides. The plasma membrane is selectively permeable and it limits the protoplasm. The plasma membrane shows infoldings or invaginations forming mesosomes. Mesosomes are the sites of respiration.

3. Cytoplasm: Cytoplasm is granular and even in its distribution. It contains 70s ribosomes, stored food granules such as volutin, glycogen and fats and incipient nucleus (circular DNA). In addition cytoplasm may show smaller circular DNA structures known as ‘plasmids’.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Based on the staining properties, eubacteria is of two types, namely Gram positive and Gram negative bacteria

Nutrition:
Based on the mode of nutrition bacteria are of two groups:
(i) Autotrophs
(ii) Heterotrophs.
Certain bacteria which can synthesise their own food are called as autotrophic bacteria. They are of two types:-
(a) Photosynthetic bacteria: They synthesise carbohydrates with the help of sunlight and C02 like green plants eg: Green bacteria (Chlorobium), purple bacteria (Rhodospirullum).

(b) Chemosynthetic bacteria: They are bacteria that can prepare their food by using the energy liberated from oxidation of inorganic substances. e.g: Nitrifying bacteria: Nitrosomonas and nitrococcus can oxidize Ammonia to nitrite. Species of nitrobacter can oxidize nitrite to nitrate.

  • Sulphur bacteria: Thiothrix oxidizes H2S to sulphur, which is further oxidized to Sulphuric acid, Iron bacteria i.e., ferrobacillus oxidize ferrous iron to ferric iron.
  • Heterotrophic bacteria: They do not synthesise their own food. They may be parasities saprophytic or symbiotic.

(a) Parasitic bacteria: They depend on living cells of plants and animals. They cause disease in plants, animals and human beings.

(b) Saprophytic bacteria: They depend on dead organic matter and bring about decomposition of the organic matter.

(c) Symbiotic bacteria: The relationship between two partners where both are mutually benefited.
e.g: Rhizobium in the root nodule of legume plant.

Reproduction:
Bacteria reproduce through vegetative, asexual and sexual methods:-
1. Vegetative reproduction: It takes place by two ways: Fission and Budding.
Fission: It is the most common type of reproduction in bacteria. Fission is a simple type of cell division in which the bacterial cell enlarges and the protoplasm divides into two portions by two grooves from opposite sides. These grooves deepen and meet at the center, dividing a single cell into two. Thus, it is binary fission.
Budding: In this method, an outgrowth is produced by bacterial cell which eventually separates and forms a daughter cell.

2. Asexual reproduction:
This takes place by endospore formation and conidia.
Endospore: During unfavourable conditions, bacilli form resting spores called endospores. During this process they shrink and a thick wall is secreted to form a thick walled spore. These spores can withstand unfavourable or adverse environmental conditions and on return of favourable conditions, germinate to form new bacterial cells. Conidia: Certain filamentous bacteria (streptobacilii) show the formation of conidiospores or stalk like outgrowth on the cell surface, called conidiophores. Each conidium / conidiospore germinates to form a new bacterium.

3. Sexual reproduction:
Sexual reproduction in bacteria takes place by genetic recombination. In this process there is the transfer of only a small portion of the genome from one cell (donor) to another (recipient) forming a new genome in the recipient.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Sexual reproduction is of three types, namely:
1. Conjugation.
2. Transformation.
3. Transduction.

Economic Importance Of Bacteria

Beneficial effects of bacteria:
(1) As natural Scavengers: They decompose dead parts of animals, plants and other organic matters into simpler inorganic matters,
e.g.: Proteus, Clostridium, bacillus etc.
Gloiogica

(2) As fermenting agents:
eg: Vinegar (acetic acid) is obtained from alcohol by fermentation in the presence of bacterium Acetobacter aceti.

(3) Retting of fibres: Retting is a technique of separating fibres of commercial importance from stems of fibre yielding plants.

(4) Importance of bacteria in genetic engineering: Invitro manipulation of gene by humans to get a desired character or product from a biological source, is called genetic engineering.

(5) Importance of bacteria in mineral extraction: Certain bacteria play an important role in the extraction of minerals from low grade ores.

(C) Cyanobacteria:

  • These are unicellular, multicellular, colonial or form trichomes.
  • Single cell or colonies are surrounded by a gelatinous sheath called mucilage.
  • Cells are prokaryotic and have a cell wall of peptidoglycan.
  • All members are autotrophs and cany out photosynthesis. They are aerobes.
  • Thylakoid membranes photosynthetic lamellae are distributed in the cytoplasm.
  • Most of them have the capacity to fix atmospheric nitrogen: Filamentous forms have heterocysts for nitrogen fixation, e.g. Nostoc, Anabaena.
  • Reproduction is by binary fission in unicellular forms: In trichomes /filamentous forms, it is by fragmentation to form short chains of cells called hormogonia. Each hormogonium grows into an adult trichome.
  • Sexual reproduction and motile cells have not been reported.

Economic Importance:

  • Many of them are used as bio-fertilizers because, of their nitrogen fixing capacity, e.g. Nostoc, Aulosira, Anabaena.
  • Spirulina is unicellular and spiral-like; it is cultured and used as cattle-feed and human food, for it is rich in proteins. It is called as single called protein.

(D) Mycoplasma
These were discovered by Nocard and Roux (1998).
They are the smallest known prokaryotes, which lack a cell wall. They were first isolated from the cattle suffering from pleuropneumonia and hence named as Pleuropneumonia-like organisms (PPLO).
They are highly pleuomorphic i.e., They can alter on vary their shape and size in response to environmental conditions.

1st PUC Biology Question Bank Chapter 2 Biological Classification

They cause pneumonia and urethritis in animals.
In plants they cause diseases like bunchy top of banana, little leaf of brinjal, witches broom of legumes, etc.

II. Kingdom – Protista
• All the organisms belonging to this kingdom are unicellular and eukaiyotic; the cells possess all membrane-bound cell organelles like mitochondria, chloroplasts, endoplasmic reticulum, lysosomes, etc.
This kingdom is classified as follows :
(a) Phylum Protozoa includes unicellular and holozoic organisms (Protozoan protista).
(b) Myxomycota includes saprotrophs and decomposers (Decomposer protista).
(c) Dinoflagellata.
(d) Chiysophyta and
(e) Euglenophyta are called photosynthetic protists.
Most of the members are aquatic and others prefer to grow in moist and humid conditions.

(A) Phylum : Protozoa
This phylum is divided into four classes based on the locomotory structures:
(1) Sarcodina : Locomotion is by pseudopodia, e.g. Amoeba, Entamoeba.
(2) Sporozoa : No structure for locomotion, but is carried toward by the body fluid, e.g. Plasmodium.
(3) Flagellata : Locomotary organelle is flagella e.g. Giardia.
(4) Ciliata : Locomotary organelle is cilia e.g. Paramaecium.

(B) Phylum: Myxomycota
The members of this phylum show features of plants (production of spores which have cell wall) and animals (mode of nutrition and somatic organisation). They are commonly called slime moulds and are of two types:
(i) Acellular slime moulds and
(ii) Cellular slime moulds.

The differences between the two groups are as follows:
(i) Acellular slime mould:-
(i) The vegetative phase is a diploid, multinucleate plasmodium.
(ii) Spores are formed after meiosis.
(iii) The zygote germinates involving only mitotic divisions and form the plasmodium.
e.g. Stemonites, Physarum.
(ii) Cellular slime mould:-
The vegetative phase is a haploid pseudoplasmodium with amoeba-like cells. Spores are formed after mitosis.
The zygote germinates involving meiosis and form a pseudoplasmodium. e. g. Dictyostelium

(C) Phylum : Dinoflagellata:
Dinoflagellates are unicellular and have a cellulosic cell wall, divided into plates, which give the organisms an armoured appearance. They have two flagella. One lies in the longitudinal direction, while the other lies transversely in the furrow between the cell wall plates. Sexual reproduction is almost unknown.
Other examples of this phylum are Glenodinium, Noctiluca, Ceratium, etc.

1st PUC Biology Question Bank Chapter 2 Biological Classification

(D) Phylum: Chrysophyta: .
Organisms belonging to this phylum are commortly called as diatoms(previously known as golden brown algae) and desmids.
1st PUC Biology Question Bank Chapter 2 Biological Classification .2
They are both marine and freshwater, and constitute the major phytoplanktons.
They float on the surface of the water body, because of the storage lipids in them.
The diatoms may be bilaterally symmetrical (Pennate diatoms) or radially symmetrical (centric diatoms).

  • The cell wall, is called as frustule and it is impregnated with silica, which makes fine characteristic designs. Therefore these are called as jewels of plantkingdom.
  • The cell wall consists of two overlapping halves like a soap case.
  • The outer lid-like part is called epitheca and the lower part is called hypotheca.
  • The cell wall of dead diatoms accumulate and forms diatomaceous earth at the bottom of the ocean floor.
  • They reproduce asexually by binary fission (cell division). Sexual reproduction is by the formation of gametes, that involves meiosis and the fusion product develops into an auxospore.

Economic Importance:

  • Diatoms form the major phytoplanktons of the oceans and account for 80% of the biomass production in the ocean.

Diatomaceous Earth is used :

  • as absorbent for liquid nitroglycerin to make explosives.
  • for filtering the liquids in sugar factories.
  • as an inert extender in paints, as an insulator in boilers and blast furnaces.
  • in the powdered form as abrasive in silver polish and in the manufacture tooth paste.

1st PUC Biology Question Bank Chapter 2 Biological Classification

(E) Phylum: Euglenophyta:

  • Members of this phylum are fresh water, flagellate and motile forms.
  • A single flagellum is found at the anterior end.
  • The flagellum develops from basal granule and an eye spot or stigma is present near to it.
  •  The cells have an elastic pellicle that gives a definite shape to the cell.
  •  Euglena is photosynthetic when optimum light is available and is non-photosynthetic in the absence of light and engulfs the food materials. Hence it is described as myxotroph.
  • Contractile vacuoles help in osmoregulation.
  • Reserve food occurs in the form of paramylum starch.
  • Asexual reproduction is by longitudinal binary fission.
  • Sexual reproduction has not been reported.
  • Under unfavourable conditions, cells develop a thick-wall around themselves called as cyst wall, e.g . Euglena, Distirna, Peranema.

III. Kingdom -Fungi:
Fungi are eukaryotic, achlorophyllous organisms which are but, generally multicelluar a few are unicellular (yeast).

  • The fungal body consists of long, slender, thread-like structures called hyphae, which form a network called mycelium.
  • The hyphae have a cell wall made up of chitin.
  • They may be aseptate and multi-nucleate i.e., coenocytic or septate.
  • All fungi are heterotrophs -they are saprotrophs or parasites or live as symbionts in the roots of higher plants (mycorrhizae) and in lichens (mycobiont).
  • They reproduce vegetatively by fragmentation, fission or budding.
  • Asexual reproduction is by formation of zoospores as in Saprolegnia and Pythium by aplanospores/sporangiospores formed endogenously (within the sporangium) as in Rhizopus and Mucor or by conidia, which are produced exogenously on the swollen tip of the conidiophore as in Penicillium and Aspergillus.

Sexual reproduction is of the following types :

(a) Fusion of gametes leading to zygote formation. (Planogametic fusion).
(b) Gametangial contact, to form oospore (gametangia are antheridia and oogonial).
(c) Gametangial fusion, to form zygospore.
(d) Spermatization, where a modified spore called spermatium functions as the male gamete.
(e) Somatogamy, that involves fusion between vegetative/somatic cells of hyphae of opposite mating strains.

Kingdom Fungi is divided into five classes, based on the following characters:
(a) Morphology of mycelium
(b) Mode of spore formation.
(c) Mode of sexual reproduction and
(d) Nature of fruiting bodies.

1st PUC Biology Question Bank Chapter 2 Biological Classification

A. Class : Oomycetes

They have coenocytic -aseptate and multinucleate-mycelia. Mostly they are parasites, while a few are saprotrophs. Parasitic forms produce haustoria for deriving nutrition from the host cells.

Asexual reproduction is by zoospores or aplanospores. Sexual reproduction is either by gametic fusion eg: Synchitrium (isogamous) and Allomyces (anisogamous) or by gametangial contact as in Albugo, Phytophthora, etc.

Economic Importance:
They cause the following diseases in plants :
(i) Phytophthora infestans – Late blight of potato.
(ii) Albugo Candida – White rust of crucifers.
(iii) Pythium – Damping-off disease in many crucifers.

B. Class: Zygomycetes

  • Plant body is unicellular coenocytic mycelium.
  • They are obligate saprotrophs.
    Asexual reproduction occurs by aplanospores, which are formed within the sporangium (called also as sporangiospores).

1st PUC Biology Question Bank Chapter 2 Biological Classification

Economic Importance:

  • Rhizopus stolonifer is heterothallic.
  • Rhizopus and Mucor grow on any fruit, vegetable or organic food and cause their spoilage.
    Note: Class oomycetes and class zygomycetes were included under class phycomycetes.

C. Class: Ascomycetes

  • These are commonly called sac-fungi. They may be unicellular (e.g. yeast) or multicellular.
  • Organisms are saprotrophic and parasitic.
  • Mycelium is septate and septa are porous.
  • Asexual reproduction is by formation of conidia, which are cut off exogenously on a conidiophore, in a basipetal succession.
  • Sexual reproduction is by gametangial fusion (yeast), or gametangial contact (Pyronema) or Spermatization (Neurospora) or somatogamy (Peziza).

Economic Importance:

  • Yeast is employed in bakeries and breweries (for alcohol fermentation). Penicillium notatum is are employed in the production of penicillin an antibiotic.
  • Morels (Morcella) and buffels are edible. Neurospora crassa is widely used for biochemical and genetic researches. Penicillium is used for flavouring cheese.
  • Claviceps causes the disease ergot of rye.

D. Class: Basidiomycetes

  • These are commonly called club-fungi or bracket fungi.
  • They grow in the soil on logs, tree barks or as parasites.
  • The mycelium is much branched, and the hyphae are septate; and septa are porous/ perforated.
  • No asexual spore formation has been reported.
  • Sexual reproduction is by somatogamy, which involves fusion between two cells of hyphae of different mating strains.
  • There is a prolonged dikaryotic phase in the life-cycle. Later karyogamy and meiosis occur in each of the dikaryons and they become the basidia.
  • Each basidium forms four basidiospores exogenously on its upper end.
  • The basidia are arranged into fruiting bodies called basidiocarps.
  •  Each basidiospore gives rise to a mycelium on germination.

Economic Importance:

  • Ustilago causes smut disease. Puccinia causes rust of wheat and other cereals.
  • Polyporus decomposes wood. Agaricus (mushroom) is edible.

1st PUC Biology Question Bank Chapter 2 Biological Classification

E. Class : Deuteromycetes

  • These fungi are commonly called as fungi imperfect because sexual reproduction is absent or not known and some of them resemble ascomycetes while some others resemble basidiomycetes.
  • They reproduce asexually by spores called conidia. -The mycelium is branched and septate.
  • Some are saprotrophs and as decomposers help in nutrient/mineral cycling. e.g: Alternaria solani.
  • Early blight of potato, Colletotrichum falcatum – Red rot of sugar cane. Arthrobotrus is a predatory fungus, that feeds on nematodes.

Lichens

  • Lichens are composite organisms, composed of algae and certain fungi that live in symbiotic biotic association.
  • The algal partner is called phycobiont and the fungal partner is called mycobiont.
  • The algae prepare food, while the fungus provides protection and helps in absorption of nutrients and water.

Lichens are of the following three types:

(i) Crustose Lichens:- These lichens have a flat thallus, that is closely appressed to the substratum and looks like a crust. E.g: Graphis, Lecanora, Rhizocarpon.
(ii) Foliose Lichens:- These lichens have a flat, dorsiventral leaf-like thalli. They are attached to the substratum by rhizoid-like structures, called rhizines. e.g. Parmelia, Peltigera, Physcia.
(iii) Fruticose Lichens:-
These have cylindrical, much-branched thalli, that gives a bushy appearance. The thallus may be erect or pendent, but attached to the substratum, by their basal ends. e.g. Usnea, Cladonea, Evemia.

mycorrhizae
• Mycorrhizae are symbiotic association between certain fungi and the roots of higher plants (myco -fungus; rhiza -root); it means fungus-roots.
• Mycorrhizae are of two types:
(i) Ectomycorrhizae and
(ii) Endomycorrhizae.

(i) Ectomycorrhizae:-

  • In this type, the fungal mycelium lives on the surface of the roots, forming a mantle. Such roots lack root hairs.
  • Certain hyphae penetrate into the root cortex.

(ii) Endomycorrhizae:-
In this type, the fungus lives within the root and does not form a mantle of tissue outside. The fungus helps in decomposing the organic matter in the vicinity of roots and provides nutrients to the root. It helps in absorption and retains the absorbed nutrients also. It provides protection to the roots.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Viroids
These are the small infectious self replicating RNA particles lacking protein coat. These were discovered by T.O. Diner and Raymer in 1967.
Each viroid is composed of 250 – 370 nucleotides and folds upon itself to become a double stranded rod shaped particle. The rod shaped particle shows intrastrand base pairing and interseparated unpaired loops.
Diseases caused by Viroids:
Viroid causes several diseases of plants namely:
1. Potato Spindle Tuber Disease (PSTD).
2. Citrus exocortis.
3. Chrysanthemum chlorotic mottle.
4. Chrysanthemum stunt.

Viruses
General characters of Viruses:
Viruses are regarded as ‘living entities’ since they exhibit living character when they occur within a host cell as intracellular parasites. When they are outside a living system, they exhibit non-living characters.
The living characters are:
1. They occur as obligate parasites and can grow and reproduce within a host cell.
2. They occur in definite forms and contain genetic material -either DNA or RNA.
3. They are pathogenic and cause infectious diseases like other pathogenic organisms.
4. They show sensitiveness to heat and cold, like other organisms.

The non-living characters are:
1. They exhibit a cellular nature i.e., they lack protoplasmic bodies such as cell wall, cell membrane, cytoplasm, nucleus, mitochondria, golgi bodies, E.R, ribosomes etc.
2. They cannot grow and multiply when they are outside the host cell., They look inert.
3. They do not show cellular metabolism like respiration.
4. They can be isolated, crystallised and stored like any other chemicals.

Note:
Shape:Viruses may be rod shaped, spherical, tadpole, tetrahedral, octahedral or icosahedral.
Size: Viruses are measured in nanometer units. Size of viruses varies from 30 to 350 nm. eg: Pox virus – 300 nm, foot and mouth vims – 30 nm, psittacosis – 300 nm.

Structure: A typical virus consists of a central core of nucleic acid either DNA or RNA, surrounded by protective protein coat called capsid. The nucleic acid constitutes the viral genome and may be either
single stranded or double stranded and exist in either circular or linear form. Capsid is composed of a number of protein sub units called capsomeres.
1st PUC Biology Question Bank Chapter 2 Biological Classification .3

Extra information:
Classification of viruses:
Classification of virus is a controversial subject. In 1948 Holmes, divided the order Virales into 3 groups (sub orders) based on their hosts and type of nucleic acid they posses.

1. Plant viruses (phytophaginae):-
These viruses attack plants, particularly higher plants lie angiosperms. Some of them attack certain lower plants. eg: Cyanophages infect B.G algae, Mycophages infect fungi.

1st PUC Biology Question Bank Chapter 2 Biological Classification

These are mostly RNA viruses but some of them are DNA viruses,
eg: Tobacco mosaic virus (TMV) – single stranded DNA.

Wound Tumour virus – Double stranded RNA.
Cauliflower mosaic virus and Dahlia mosaic virus – Double stranded DNA viruses.

2. Animal viruses (Zoophaginae):-
These infect animals. Their genome may be either DNA or RNA. eg: RNA virus: DNA virus:
Eg: RNA virus:
Herpes virus
Retro virus

DNA virus:
Pox virus
Herpes virus
Papova virus.

3. Bacterial viruses (Bacteriophaginae):
Those viruses which infect bacteria are called as bacteriophages.
eg: T – even phages like T2, T4, T6, T8…………….. T16
T – odd phages like Tl, T3 …………….. T17
9B Phage, MS-2 Phage- RNA viruses,
φ × 174 → SS DNA virus y
φ > 6 → ds RNA Phage.

Bacteriophage:
The viruses which infect bacteria are known as Bacteriophages or Bacteria eaters Bacteriophages were discovered by Twort and de’Herelleh Types of Bacteriophages:
Bacteriophages are broadly classified into several T – phages:
T – even Phages eg: T2, T4, T6 Phage.
T – odd Phages eg: T1 ,T3, T5 Phage.
The much studied phage is the T4 phage affecting the E.coli bacterium. It is also known as coli phage.

1st PUC Biology Question Bank Chapter 2 Biological Classification .4
Head : It is polyhedral in shape with a length of 950 A and breadth of of 650 A. The capsule of the head is made up of 2000 identical protein sub units called capsomere. The head encloses within it tightly coiled as DNA which forms the core inside the head. It is about 53 microns in length. Below the head, connecting the head to tail is the collar. It is ring like.

1st PUC Biology Question Bank Chapter 2 Biological Classification

Tail: The tail consists of a needle like core tube (tail core) which is surrounded by contractile tail sheath. The tail sheath is made up of 144 sub units arranged in 24 rings around the core. The tail at its posterior ends with an hexagonal base of the tail called the Tail plate base plate. It has six pointed pegs spikes at its 6 corners. On its upper surface, there are six long folded tail fibres arising from its six corners.

IV. Kingdom -Plantae
It includes multicellular plants which are photosynthetic in nature

V. kingdom animalia
It includes multicelluar animals with cellular, tissue, organ or organ system grade of body organisation.
Note : Kingdom animalia and Kingdom plantae are discussed in the next two chapters.

1st PUC Biology Question Bank with Answers

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