Directions : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as :
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If assertion is true but reason is false.
(d) If assertion is false but reason is true.
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Assertion : Azolla pinnata is used as a biofertiliser in rice fields.
Reason : Azolla pinnata is a nitrogen fixing cyanobacteria and can coexist with rice plants.
(a)
Assertion : Streptococcus thermophilus increases nutritional value of milk.
Reason : Curd and yogurt have higher vitamin content than milk.
(a) : Microbes have been used for long time in production of dairy products like curd, yogurt, cheese, etc. Yogurt is produced by curdling of milk with the help of Streptococcus thermophilus and Lactobacillus bulgaricus. Yogurt has higher nutritional value than milk thus, it can be said that Streptococcus thermophilus increases nutritional value of milk.
Assertion : Toddy becomes unpalatable after 24 hours.
Reason : The fermentation of toddy is continued by naturally occurring yeasts.
(a) : Toddy is a traditional drink of some parts of South India which is made by fermentation of sap of palms. Toddy left for few hours undergoes fermentation with the help of naturally occurring yeast to form beverage containing about \(6 \%\) alcohol. But after about 24 hours toddy becomes unpalatable because fermentation is carried on. Now, it can be used for production of vinegar.
Assertion : Beer and wine are called soft liquors while gin, rum, etc., are hard liquors.
Reason: Beer and wine are made without distillation.
(b)
Assertion : Griseofulvin extracted from P. griseofulvum is used for ringworm treatment.
Reason : Trichophyton, Epidermophyton, etc., cannot grow well in presence of Penicillium griseofulvum.
(a) : Antibiotics are chemical substances produced by some microbes which, in small concentration, can kill or retard the growth of harmful microbes without adversely affecting the host. Griseofulvin is an antibiotic produced by Penicillium griseofulvum and is antifungal in nature, especially effective against ringworm. Ringworm is caused by dermatophyti fungi like Epidermophyton, Trichophyton, Microsporium which cannot grow in presence of P. griseofulvum because of the antagonistic effect of antibiotic griseofulvin secreted by the Penicillium sp.
Assertion : Acetic acid production involves both aerobic and anaerobic processes.
Reason : Production of alcohol from glucose is an aerobic process and production of acetic acid from alcohol is an anaerobic process.
(c) : Acetic acid is prepared from fermented alcohols with the help of acetic acid bacteria, Acetobacter aceti. Alcoholic fermentation of sugars is an anaerobic process but the conversion of alcohol to acetic acid is an aerobic process.
Assertion : An organ transplant patient if not provided with cyclosporin A may reject the transplanted organ.
Reason : Cyclosporin A inhibits activation of T-cells and interferes with destruction of non-self cells.
(a) : Cyclosporin A is cyclic oligopeptide obtained through fermentative activity of fungus Trichoderma polysporum. It has immunosuppressive properties and inhibits activation of J-cells. T- cells of immune system mainly function to kill non-self cells. Because cyclosporin A inhibits T-cell function, it causes immunosuppression and chances of rejection of transplanted organ are reduced. Thus, organ transplant patients are provided with cyclosporin A.
Assertion : Rennet and fruit extract of Withania somnifera have antagonistic functions.
Reason : Rennet is obtained from calf’s stomach and is used for curdling of milk.
(d) : Rennet is obtained from calf’s stomach and is a commercially available form of enzyme rennin. Rennet is used for curdling of milk to initiate the process of cheese formation. The same function can be carried out with the help of fruit extract of Withania somnifera. Thus, rennet and fruit extract of Withania somnifera have similar functions and are not antagonistic.
Assertion : Secondary treatment of sewage is also called biological treatment.
Reason : During secondary sewage treatment, microbes are involved.
(a) : Sewage treatment is divided into primary treatment and secondary treatment. Primary treatment involves filtration of the sewage and then sedimentation of the debris present on filtrate. No microbes are used. The sediment of primary treatment, called primary sludge, is treated by aerobic microbes and then by anaerobic microbes to reduce its organic components during secondary treatment. A secondary treatment involves microbes, thus it is also called biological treatment.
Assertion: Energy value of biogas is lower than that of organic matter.
Reason : Biogas minimises the chances of spread of fecal pathogens.
(b)
Assertion : Antibiotics are effective against all pathogens.
Reason : Antibiotics inhibit ribosome functions and disrupt cell wall synthesis.
(d) : Antibiotics are not effective against all pathogens. Most antibiotics are useful against one or a few diseases. Mode of action of antibiotics includes disruption of wall synthesis, inhibition of ribosome function and disruption of plasmalemma repair.
Assertion : Integrated pest management (IPM) programme at the same time deals with conservation of insects and destruction of insects.
Reason : IPM programmes are specially used in dealing with ecologically sensitive areas.
(b)
Assertion: Biofertilisers are preferred to chemical fertilisers.
Reason : Chemical fertilisers are generally more expensive and hazardous to environment.
(a) : Biofertilisers are microorganisms that are used for increasing fertility of soil. For example, free-living bacteria and cyanobacteria that fix nitrogen increase soil productivity. Biofertilisers are preferred over chemical fertilisers because chemical fertilisers are more expensive, disturb soil fauna and flora and affect soil pH. Although chemical fertilisers initially show better response than biofertilisers but they decrease soil fertility in the long run.
Assertion: Amylases are used for clearing turbidity in juices caused by starch.
Reason : Amylases degrade starches.
(a)
Assertion : Frankia is symbiotically associated with the root nodules of several non-legume plants.
Reason : Frankia releases phosphate from bound and insoluble state.
(c): Microphos biofertilizers release phosphate from bound and insoluble states. Frankia is symbiotic nitrogen fixing bacteria.
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