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Right choice is (a) True

To ELABORATE: RNA of the viroids is of low MOLECULAR WEIGHT when compared to viruses. Viroids are comparatively smaller than viruses. They also lack PROTEIN sheath that is FOUND in viruses.

Correct answer is (a) Venom

Best explanation: The word “Virus” refers to venom or POISONOUS. It was first TERMED by a DUTCH microbiologist named Martinus Beijerinck in 20^th century. Dmitri Ivanowsky discovered VIRUSES for the first time.

The correct CHOICE is (a) SINGLE stranded RNA

Easy explanation: Viruses that infect plants called as plant viruses have single stranded RNA. Animal viruses contain a single/ double stranded RNA or a double stranded DNA. BACTERIOPHAGES have double stranded DNA.

Correct option is (a) T.O. Diener

To ELABORATE: T.O. Diener discovered viroids in 1971. He found that these infectious agents are smaller than VIRUSES and are the main cause for potato spindle TUBER DISEASE.

Correct OPTION is (b) IVANOWSKY

The explanation is: Ivanowsky discovered viruses as micro-organisms on tobacco plant and are smaller than bacterium. Later M W Beijerinek TERMED them as “Viruses” which means venom or POISON. W M Stanley for the first time proved that viruses are crystalline like structures and these crystals are made of protein RICH sheaths.

Correct answer is (a) Acquired Immuno Deficiency SYNDROME

Easy explanation: AIDS stands for Acquired Immuno Deficiency Syndrome and is caused by a virus called HUMAN Immunodeficiency Virus (HIV). Symptoms of this disease INCLUDE night sweats, LOSS of apetite, diarrhoea, loss of eye sight and malaise etc.

Correct choice is (d) Potato SPINDLE tuber DISEASE

Easy explanation: Mumps, small pox, HERPES and influenza are caused due to viruses. Whereas, T.O.Diener in 1971 discovered that potato spindle tuber disease is caused by set of pathogens that are similar to viruses and named them as VIROIDS.

Right choice is (B) They don’t grow in polluted regions

To EXPLAIN: The co-existence of ALGAE with FUNGUS is called lichens. Lichens are the best examples of symbiotic association. They are also good indicators of pollution as they don’t grow in polluted regions.

Right answer is (a) Viruses contain DNA WHEREAS viroids don’t contain DNA

Best explanation: Viruses contain both RNA and DNA whereas viroids contains. Viruses contain protein coat whereas viroids don’t contain protein coat. Viruses are FOUND in BACTERIA, animals and PLANTS but viroids only in plants.

Correct ANSWER is (B) Viruses are not living organisms

To elaborate: UNLIKE organisms in the other five kingdoms which are living, viruses are non-living organisms. They don’t even have basic unit of LIFE i.e. cell. Hence, they are not categorized in any of the kingdoms.

The correct option is (c) Viruses can perform all of their metabolic ACTIVITIES except REPRODUCTION when outside a living host

Explanation: Viruses can’t perform any of the metabolic activities when outside a living host. So, they are non-living ORGANISMS. Viruses don’t even consist of a CELL and so acellular. They are in fact smaller than that of a bacterium and can even infect them.

Right choice is (b) False

To EXPLAIN I would say: Viroids are smaller than viruses. Viroids don’t contain PROTEIN coat WHEREAS viruses do contain. Both viroids and viruses are pathogenic i.e. both of them CAUSE diseases.

The correct ANSWER is (B) Proteins

Easy explanation: Viruses don’t CONTAIN cell and instead have GENETIC material made of nucleic acids and a protein sheath covering it which is made of proteins. This protein sheath is called capsid and is made of BASIC units called as capsomeres.

Correct answer is (a) BACTERIOPHAGES

For explanation I would say: Viruses are smaller when COMPARED to BACTERIUM. Viruses can infect bacterium are called bacteriophages. Bacteriophages contain double STRANDED DNA (Deoxy ribonucleic acid).

Right OPTION is (a) Obligate parasites

For explanation I would say: VIRUSES are an example of obligate parasites. Viruses can’t perform any of their metabolic ACTIVITIES when they are outside a LIVING host. As SOON as they enter a living host they replicate and perform their metabolic activities. Therefore, they are an example of obligate parasites.

Correct answer is (a) Digestive tract of HUMANS

To EXPLAIN I would SAY: ESCHERICHIA coli is a rod-shaped bacterium present in the digestive tract of warm-blooded ANIMALS like human beings and is responsible for the indigestion problems in humans.

The correct answer is (c) CYANOBACTERIA are chemosynthetic autotrophs

To explain: Cyanobacteria CONTAIN chlorophyll which helps to perform PHOTOSYNTHESIS and in turn enrich the oxygen levels in the ATMOSPHERE. The word “cyano” in cyanobacteria means blue-green algae and therefore they are also CALLED as blue-green algae.

The correct choice is (b) Heterotrophic mode of nutrition

Best explanation: Parasites obtain food from the HOST. HETEROTROPHS obtain food from autotrophs. Saprophytes feed on dead and decay matter. Autotrophs PREPARE their own food either by USING light energy or chemical energy. Pseudomonades are Heterotrophs.

Right answer is (b) GUTS of COW

The explanation: Methanogens are RESPONSIBLE for production of methane. These are present in marshy AREAS like guts of a cow which HELPS in production of biogas from cow dung.

The correct CHOICE is (b) Chemical energy

The explanation: Bacteria adopt DIFFERENT modes of nutrition like photosynthetic, chemosynthetic, saprophytic and parasitic. Chemosynthetic autotrophs prepare their own FOOD by obtaining energy from organic SUBSTANCES.

The correct option is (a) Morphological characteristics

For explanation I WOULD say: ARISTOTLE classified the organisms BASED on their morphological characteristics. His classification neglected characteristics like nature of the cell wall, evolutionary relationships and METHOD of reproduction.

Right answer is (b) ALEXANDER Flemming in 1928

To elaborate: Penicillin was the first anti-biotic to be discovered by Alexander Flemming on September 28 1928. This discovery is a MILESTONE in the history of science and changed the lives of MANY SOLDIERS.

The correct answer is (c) Penicillium camemberti is used in the MANUFACTURING of penicillin

The explanation: P.Notatum and P.chrysogenum are used in the MANUFACTURE of Penicillin. Fungi are used in the manufacture of PROTEINS, beer and bread. Fungi are the natural scavengers on the Earth. Fungi grow in DAMP and dark AREAS.

Correct choice is (c) Aplanospores

Explanation: Non-MOTILE spores in Phycomycetes are called as Aplanospores and motile spores are known as ZOOSPORES. FUSION of similar or DISSIMILAR gametes through SEXUAL mode results in Zygospores.

Right option is (c) cillia

For explanation I would SAY: Movement in paramecium is due to HAIR like structures called cilia that grows on its body.Paramoecium can MOVE actively due to the presence of thousands of cilia. Cilia performs rhythmic movement in order to steer FOOD CONTAINING water into the gullet.

Correct answer is (c) These are parasites

Best explanation: Lacto bacilli, as the NAME says, are rod shaped BACTERIA that are responsible for turning milk into curd. They adopt heterotrophic MODE of nutrition. These are ALSO useful in fermentation of WINE.

Right choice is (a) HALOPHILES

To elaborate: DUNALIELLA salina belongs to the category of Halophiles. Halophiles can SURVIVE in areas which are highly concentrated in salt. THERMOPHILES can survive in conditions with HIGH temperature. Methanogens are responsible for production of methane.

Correct choice is (b) False

To explain I would say: VIRUSES are non-LIVING ORGANISMS. They don’t have cell. They don’t REPRODUCE or perform any metabolic activities when they are outside a living host. When they are inside a living host they do reproduce and MULTIPLY in numbers.

Right choice is (b) SCABIES

Explanation: Mycosis is the scientific terminology for FUNGAL infection. Scabies is not a fungal infection. It is CAUSED due to an ARTHROPOD CALLED mite. Candidiasis, Tinea versicolor and cryptococcosis are different mycoses.

The correct OPTION is (b) Cortex

Easiest explanation: Dianoflagellates have a complex CELL wall made up of cortex. They also possess LIGHT sensitive organelle in their cell. Eye spot is found in some of them. Erythropsidium is known to have SMALLEST eye.

The correct choice is (B) False

The explanation: CHRYSOPHYTES contain chlorophyll or carotene or xanthophyll in them. Chrysophytes attain color DUE to these pigments present in them. Their cell wall is RIGID and is made up of Cellulose/ Pectin/ Silica.

The correct choice is (C) it snatches out LIPIDS from the outermost waxy layer of PESTS called cuticle and makes them DRY which RESULTS in their death

To elaborate: Diatomaceous earth is used in pest control and grain storage. This is because they are abrasive in nature which snatches out lipids from the outermost layer of pests called cuticle and makes them dry which results in their death.

The CORRECT ANSWER is (b) Bracket fungi are an EXAMPLE of ascomycetes

For explanation I would say: Bracket fungi are an example of Basidiomycetes. Asexual spores are formed due to mitosis. Basidiomycetes produce sexual spores CALLED BASIDIOSPORES exogenously in Basidium. Sexual spores are absent in Deuteromycetes but reproduce asexually through Conidia.

The correct choice is (c) Lice in humans are EXAMPLE for endo-symbiosis

The best EXPLANATION: Lice in humans are example of exo-symbiosis. FUNGI are heterotrophic and can be either SAPROPHYTIC or parasitic. Some of the parasitic fungi can cause diseases in humans. Lichens are an example of obligative symbiosis. Cell wall of fungi is made of CHITIN and polysaccharides.

The CORRECT option is (C) Fungi prefer cold-dry conditions to grow

To explain: Fungi prefer warm and moist conditions to grow. All the fungi are multi-cellular eukaryotic organisms EXCEPT yeast. Fungi are heterotrophic and are either PARASITIC or saprophytic. Parasitic fungi sometimes cause diseases. Fungi are IMMOBILE and this is the major difference between slime molds and that of fungi.

Correct choice is (a) Trypanosoma

For explanation I WOULD say: Trypanosoma is a flagellated PROTOZOAN that is PARASITIC and CAUSES sleeping sickness. Sleeping sickness causes joint and muscle PAINS. It results in behavioural changes, confusion and poor coordination.

Right ANSWER is (b) Under favourable CONDITIONS, slime moulds form fruiting bodies bearing spores at their TIPS which then get dispersed through air currents

The BEST I can explain: Slime moulds can reproduce either sexually or asexually. During favourable conditions they form an aggregation called plasmodium which may GROW and spread over several feet.Under unfavourable conditions, plasmodium differentiates to form fruiting bodies bearing spores at their tips which then get dispersed through air currents. Slime moulds reproduce either sexually or asexually.

Correct answer is (c) locomotion and INGESTION of food

For explanation I WOULD say: PSEUDOPODIA help amoeboids in both locomotion and ingestion of food. Pseudopodia are temporary extensions in amoeba that help them to move to as well as intake food by SURROUNDING it with temporary extensions.

Right choice is (d) All the other PROTISTS except Slime moulds have cell wall

Explanation: Like Slime moulds, Protozoans also don’t contain cell wall. Slime moulds feed on bacteria, yeast and fungi and have AMOEBA like food INGESTION. The pigments in Euglena are identical to that of higher plants. Slime moulds reproduce either by FORMING an aggregate called PLASMODIUM or by spore formation.

Right ANSWER is (a) 2 × 10^29

To ELABORATE: n = N×e^kt = N×10^kt/2.303

Where, n = current population

N = initial population

k = RATE constant

t = TIME taken

n = 2000×10^2×30/2.303 = 2×10^29.

The correct OPTION is (a) DAMP and dark conditions

For explanation I would say: Yeast grows in damp and dark conditions. It doesn’t need sunlight to GROW. Refrigerators PROVIDE cold and dry conditions that prevent growth of yeast. Yeast preferably grows well in warm conditions than that of cold conditions.

Correct option is (b) ANIMALIA

The best I can explain: Linnaeus classified AMOEBA under Animalia. His classification didn’t consider cell STRUCTURE, NATURE of the cell wall, mode of REPRODUCTION, evolutionary relationships which resulted amoeba in Animalia.

Correct OPTION is (b) False

Best explanation: Linnaeus didn’t consider the cell structure of ORGANISMS (prokaryotes and eukaryotes) in order to classify them. Linnaeus classification is based on the MORPHOLOGICAL CHARACTERISTICS of organisms.