Answer

(b) Protista is a group of all unicellular eukaryotic plants and animals. The organisms included in this group are either photoautotrophs, heterotrophs or parasites.

On the other hand

• Monera includes prokaryotic organisms like bacteria, which are unicellular but not eukaryotic.
• Fungi are eukaryotic but are mostly multicellular; the exception is yeast, which is unicellular.
• Bacteria are prokaryotic organisms, not eukaryotic.

Answer

(a) RH Whittaker (1969), an American taxonomist in order to develop phylogenetic classification divided organism into five kingdoms, i.e.,

(i) Monera

(ii) Protista

(iii) Fungi

(iv) Plantae

(v) Animalia

Whereas, C Linnaeus developed two kingdom classification, i.e.,

(i) kingdom-Plantae

(ii) kingdom-Animalia and Virchow is associated with the discovery of cell theory.

• A Roxberg is not associated with the five kingdom classification.

Answer

(b) Halophiles are organisms that live in areas of high concentration of salts. The name halophiles is originated from the greek word that means ‘salt loving’.

Whereas, heliophytes are the plants that grow best in sunlight and can not survive in salty conditions.

Methanogens are the bacteria that produces methane as a metabolic by products in anaerobic conditions.

Thermoacidophiles are archaebacteria striving under strong acidic environments and high temperatures, but can not tolerate high salt concentrations around them.

Answer

(d) Slime moulds are saprophytic protists, moving along the dead leaves engulfing organic material. These are multinucleated and do not possess cell wall and have naked cytoplasm.

Whereas, monerans are prokaryotes, which include all bacteria. These do not contain naked cytoplasm, protist are a group of eukaryotic organisms, that bear a well defined membrane around cytoplasm, may be uni or multinucleated and fungi lack naked cytoplasm. Their cell has well developed cell wall made of chitin.

Answer

(c) Mycorrhiza is the symbiotic association of fungus with roots of a higher plants like gymnosperms and angiosperms.

The fungus is dependent on plants for food and shelter, while the plants are benefitted by the fungal hyphae as they are involved in absorption of water and dissolved minerals present in the soil debris and makes it available to the plants.

• Lichen: Lichens are the symbiotic association between algae and fungi, not between fungi and higher plant roots.
• Fern: Ferns are a group of plants that belong to pteridophytes, which are vascular plants, and do not form symbiotic associations with fungi in the same way as mycorrhizae.
• BGA: BGA stands for blue-green algae, which are prokaryotic cells and do not form symbiotic associations with the roots of higher plants.

Answer

(b) Dikaryon is a cell containing two nucleus. This results when two somatic cells fuse but their nucleus does not fuse immediately. Meiosis does not result in such conditions.

• (a) Meiosis is arrested: This option is incorrect because the formation of a dikaryon is not related to the arrest of meiosis. A dikaryon is formed when two haploid cells fuse their cytoplasm but not their nuclei, which is a different process from meiosis.

• (c) Cytoplasm does not fuse: This option is incorrect because the formation of a dikaryon specifically involves the fusion of the cytoplasm of two haploid cells.

• (d) None of the above: This option is incorrect because option (b) correctly describes the formation of a dikaryon. Therefore, “None of the above” is not a valid choice.

Answer

(b) MW Beijernek proposed contagium vivum fluidum means contagious living fluid. This phrase was first used to describe virus, characteristic in escaping from the finest mesh available.

DJ Ivanowsky was a Russian Botanist who discovered the filterable nature of viruses and one of the founder of virology.

Stanley Miller was a Jewish American chemist experimented on origin of life.

Robert Hooke was the first to study and record cells using his primitive microscope.

Answer

(c) Lichens are dual organisms which has a permanent symbiotic association of fungus and an alga. The fungal partner is called mycobiont an the algal partner is called phycobiont.

Mycorrhiza is association of fungus with roots, but not with an algae, while BGA is blue green alga a member of Monera having a prokaryotic cell.

• Mycorrhiza: This is an association of fungus with plant roots, but not with algae. Therefore, it does not involve a mycobiont and phycobiont relationship.

• Root: Roots are part of a plant’s structure and do not inherently involve a symbiotic relationship between a fungus (mycobiont) and an alga (phycobiont).

• BGA (Blue-Green Algae): Blue-Green Algae are a type of cyanobacteria, which are prokaryotic organisms. They do not form a symbiotic relationship with fungi to create a mycobiont and phycobiont association.

Answer

(a) Virus contains DNA or RNA as genetic material and a protein coat, whereas viroids have no protein coat, but only RNA as their nucleic acid. This is the reason why viroids are carried inside viruses. e.g., hepatitis-D is a viroid that is carried in the capsid of hepatitis-B virus.

• (b) Presence of low molecular weight RNA in virus, but absent in viroid: This is incorrect because viroids actually consist of low molecular weight RNA, whereas viruses can have either DNA or RNA as their genetic material, not specifically low molecular weight RNA.

• (c) Both (a) and (b): This is incorrect because option (b) is incorrect. Viroids do have low molecular weight RNA, and viruses can have either DNA or RNA, not specifically low molecular weight RNA.

• (d) None of the above: This is incorrect because option (a) is correct. Viroids lack a protein coat and consist only of RNA, while viruses have a protein coat and can contain either DNA or RNA.

Answer

(c) Plasmogamy means fusion of protoplasm and karyogamy means fusion of nucleus. These two events lead to the formation of zygote (2n) which is diploid structure where meiosis takes place.

• Option (a) is incorrect because karyogamy (fusion of nuclei) cannot occur before plasmogamy (fusion of protoplasm). Plasmogamy must occur first to bring the nuclei together.

• Option (b) is incorrect because meiosis (reduction division) cannot occur before plasmogamy and karyogamy. Meiosis happens after the formation of the diploid zygote, which is formed by plasmogamy and karyogamy.

• Option (d) is incorrect because meiosis cannot occur before karyogamy and plasmogamy. Meiosis takes place after the diploid zygote is formed through plasmogamy and karyogamy.

Answer

(d) In five kingdom classification of Whittaker, non-cellular organisms like viruses and viroids are not mentioned. Viruses did not find a place in classification since they are not truly ’living’ and hence, they are considered as non-cellular.

• Monera: Includes all unicellular prokaryotes called bacteria, in which viruses cannot be included.
• Protista: Includes all eukaryotic unicellular plants and animals, and viruses do not fit this classification.
• Fungi: Are heterotrophic/parasitic, cellular organisms devoid of chlorophyll, which does not describe viruses.

Thinking Process

Phycomycetes is a lower group of fungi which shows diversity in its habitat Most of the are saprophytes and only few are parasites.

Answer

(c) All of these

Explanation:

Phycomycetes are a diverse group of fungi that exhibit a range of habitats and lifestyles:

(i) They are found in aquatic habitats: Many phycomycetes, such as species of water molds (e.g., Saprolegnia), thrive in aquatic environments where they use water for dispersal of their zoospores.

(ii) They can be found on decaying wood: Phycomycetes include saprophytic fungi that decompose organic matter like wood.

(iii) They thrive in moist and damp places: Moist environments are suitable for many phycomycetes due to their need for water for dispersal and reproduction.

(iv) They can exist as obligate parasites on plants: Some phycomycetes are known pathogens of plants, causing diseases such as Phytophthora infestans (potato late blight) and Peronospora viticola (downy mildew of grapes).

Answer

Cyanobacteria are used in agricultural crop improvement because of their adicity to fix atmospheric nitrogen and make it available to the plants. This improves the yield of the crops and also reduces the cost of application of nitrogen fertilisers. e.g., Anabena and Nostoc.

Thinking Process

Identification, classification and nomenclature is based on the morphological characters of an organism. One has to study the characters very throughly, by taking the help of taxonomly.

Answer

All unicellular eukaryotic organisms form a link between plants, and animals. There organisms possess a well defined nucleus with membrane bound organelles and reproduce either sexually or asexually.

The it presence of two flagella one placed longitudanally and other transversely in a furrow between wall plates makes this organisms to be placed under Kingdom-Protista.

Answer

The five kingdom classification, that is proposed by $\mathrm{RH}$ Whittaker is based upon cell structure, body structure (unicellular, multicellular), nutrition (autotrophic, heterotrophic) reproduction and way of living either aquatic, terrestrial, or arial and phylogenetic relationship.

So, it is more useful as compared to two kingdom system of classification which does not distinguish between prokaryotes and eukaryotes and no other kingdom except plant and animal are identified.

Answer

Polluted water bodies possess high algal growth due to the presence of nutrient. These nutrients increase the rapid growth of water plants, i.e., algae especially Nostoc and Oscillitoria, etc., and result in colonies. These colonies are generally surrounded by a gelatinous sheath and furtherleads to the formation of blooms in water bodies.

Answer

Chemosynthetic bacteria are capable of oxidising various inorganic substances such as nitrates, nitrites and ammonia and use the energy released for their ATP production. So, they are autotrophs and not heterotrophs.

Answer

The common or vernacular names changes with the change in place, causing confusion regarding the identification of specific specimen, whereas the complex scientific names are in latin and universally accepted and understood.

Hence, scientific names are preferred over the common vernacular names.

Answer

Viruses are considered as living when they are inside a host but outside any host they are referred to as non-living due to their

(a) inert nature

(b) inability to reproduce

(c) lack of cellular organisation

(d) inability for growth and cell division

These characters potraited by viruses make them identical to non-living organisms. Viruses are considered a connecting link between living and non-living organisms.

Answer

In the five kingdom classification given by Whittaker four kingdom belongs to eukaryotes, i.e., Protista, Fungi, Plantae and Animalia, except for the kingdom-Monera that belongs to prokaryotes.

Eukaryotic organism are those that possess

(i) An organised nucleus

(ii) Possess double envelop system

(iii) Presence of cell wall

(iv) Membrane bound organelles are present.

Thinking Process

Discuss cellular composition of diatoms and formation of ‘diatomaceous earth.

Answer

Diatoms and desmids are inducted under chrysophytes, kingdom-Protista. These are the main producers in the ocean. They prepare food not only for themselves but also for the other life forms in the ocean. This is the reason they are also called as ‘pearls of ocean. Body of diatoms is covered by siliceous shell known as frustule.

‘Diatomaceous earth’ is the accumulation of large deposits of diatoms that forms a siliceous covering extending for several $100 \mathrm{~m}$ formed in billions of years. The material obtained from these deposits is used in polishing and filteration of oils and syrups.

Answer

The fruiting bodies in Agaricus known as basidiocarps form a concentric ring like structure from the mycelium present in the soil. These basidiocarps resemble button in shape and develop to form a ring like structure.

This fairy ring structure in Agaricus have reported stimulation of plants productivity. This rings are infact fruiting bodies of this fungus and the diameter of this fairy ring increases every year due to spread of mycelium.

Answer

Neurospora fungus was selected to be a very good tool in genetics because this fungus can be grown easily under laboratory conditions by providing ‘minimal medium’ like inorganic salts, carbohydrates source and vitamin (biotin).

Also under X-ray treatment the mutations can be easily introduced in the fungal cells and meiotic division can be easily seen.

Answer

Although the two are vastly different from each other. They still bear some common characters, on the basis of which they are introduced in eubacteria of kingdom-Monera. These characters are as follows

(i) Both the groups do not possess well defined nucleus.

(ii) Nucleus lacks nucleous and nuclear membrane.

(iii) DNA (genetic material) lies freely in the cytoplasm.

(iv) They possess $70 \mathrm{~S}$ type of ribosomes.

Answer

Ascomycetes Consist of sporangial sac called ascus. Asci (singular-ascus) may occur freely or get aggregated with dikaryotic mycelium to form the fruitification called ascocarps. The fruitification formed by asci are like

(i) Apothecium is a cup like structure, e.g., Peziza.

(ii) Perithecium flask shaped, e.g., Neurospora.

Perithecium

(iii) Cleistothecium closed with a slit, e.g., Penicillium

Cleistothecium

Answer

On the basis of locomotary organ Trypanosoma is included under flagellated protozo It resembles Protista on the basis of following characters

Trypanosoma gambiens

(i) Possess unicellularity

(ii) Possess asexual reproduction, i.e., by binary fission.

(iii) Possess centrally located nucleus and also contain an prominent nucleus endosome.

(iv) Reserve food material is in the form of granules, such characters possessed by Trypanosoma made it to be included under kingdom-Protista.

Answer

Role of Fungi

Fungi are cosmopolitan in occurrance being present in air, water, soil over and inside animals and plants. The branch of biology dealing with the study of fungi is known as Mycology.

(i) Few fungi are used as nutritious and delicious food. e.g., Agaricus compestris

(ii) Saprophytic fungi lives upon dead organic matter and breaks complex substances into simple ones, that are absorbed by plants as nutrients.

(iii) Some fungi like Absidia, mucor and Rhizopus possess soil binding properties and make the soil good for cultivation.

(iv) They also provide pest resistence, e.g., Empusa, Ferinosa, etc.

(v) Yeast (Saccharomyces) has the property of fermentation, thus used in alcohol and dough preparation.

Answer

Algae and their spores exhibit enormous diversity and they vary greatly in their level of specialisation. Asexual reproduction by spores and their types are described below

(a) By Zoospores These are mobile flagellated spores. In which protoplasm of each vegetative cell undergoes repeated longitudnal division either into 2 or 4 rarely 8 or 16 daughter protoplast. The parent cell loses its flagella, before the onset of division.

After the last series of division, each daughter protoplast secretes a cell wall and neuromotor apparatus that develops two flagella, eyespots and contractile vacuoles.

Thus, each of the daughter cell formed resembles the parent cell in all aspects except the small size.

Formation of zoospores is very common under favourable conditions.

(b) By Aplanospores These are the non-motile spores. They are asexually formed with in a cell, in this the protoplast withdraws itself from the parent wall, rounds up and develops into aplanospores which may either germinate directly or may divide to produce zoospores.

Aplanospore of Spirogyra

(c) In this, the protoplasm withdraws from the cell wall, rounds up an develop a thick wall under unfavourable condition. These resting spores are called as hypnospores. They are red in colour due to presence of haematochrome. e.g., Vaucheria, Ulothrix.

(d) Akinetes These are special vegetative thick walled cells present in the filaments which remain under dorment state and return to germination under favourable condition and can also with stand unfavourable condition as Spirogyra.

(e) Statospores This are thick walled spores produced in diatoms.

(f) Neutral Spores In some algae, the protoplast, of vegetative cells directly functions as spores called as neutral spores (e.g., Ectocarpus).

Answer

All photosynthetic organisms contain one or more organic pigments that are capable of absorbing visible radiations, which will initiate the photochemical reaction of photosynthesis. Three major classes of pigments found in plants and algae are the chlorophylls, the carotenoids and the phycobilins.

Carotenoid and phycobilins are called accessory pigments since, the quanta (packets of light) absorbed by these pigments can be transferred to chlorophyll.

The diversity of light harvesting pigments in alga implies that the common ancestor was primitive and that no close affinity exist between blue, green, red, brown, golden brown and green algae, to use their common names.

The characteristic pigments of different classes are mentioned below

Answer

Algae

Some 70 species of marine algae are used for food, chemical and medicinal purpose.

Fungi

The role of fungi was established in early history yeast have been used in making of bread and alcohol since, the beginning of cultivation the discovery of penicillin, that marked the beginning of a new approach to microbial diseases in human health.

More recent approaches include the application of hydrophins to surfaces leading to biocompatibility of implants and to emulsion formation improving drug delivery.

Products of fungi in medicine, chemical and food are

Answer

Peat is an organic fuel consisting of spongy material formed by the partial decomposition of organic matter, primarily plant material in wetlands such as swamps ferns and mosses. The development of peat is favoured by warm, moist climatic conditions.

The main producers of peat Sphagnum most occurs in bogs. The accumulation of Sphagnum plant in due course of time lead this plant to get hardened and change into peat.

Peat is used in preparation of ethyl alcohol, peat, tar, ammonia, paraffin, etc. Peat is also used in covering the roots during transportation. This enormous value shown by peat for man kind makes it as an important domestic fuel and economic source for man kind.

Answer

Classification has been a centre piece of biology ever since Linnaeus, providing a frame work on which existing knowledge can be organised and predictions about unknown traits can be made.

But the basis of biological classification has gone through a series of upheavals over the last 3 centuries, from being considered a plan in mind of the creator, to the neutral assessment of over all similarity, to a reflection of evolutionary niches and finally to a phylogenetic mapping of the tree of life. e.g., in two kingdom classification their are two groups, i.e., Plantae and Animalia.

These groups are made on the basis of structural and cellular difference like plant possess cell wall, central vacuole, whereas animals lack cell wall and central vacuole but the drawback in this system classification is that eukaryotic and prokaryotic organisms like Euglena, bacteria and fungi are not included in this kingdom classification.

That are later added in three kingdom classification that in (kingdom-Protista) finally 1969, Whittaker purposed five kingdom classification.

These classifications are done on the basis of increase in understanding regarding organism by the advancements made in scientific techniques and by observing minute detailing that has led this classification more detailed and scientifically correct.