Question 1

Question 2(v)Assertion (A): Pasteurization is a technique of complete sterilization applied usually to milk, meat, fish, etc.Reason (R): Pasteurization kills a majority of the bacteria usually present in milk.A is True and R is False.A is False and R is True.Both A and R are True.Both A and R are False.

Accepted Answer

A is False and R is True.Reason — Pasteurization is a method of partial sterilization, typically used for milk. It is not generally used for meat or fish—those typically require different preservation or sterilization methods (like canning or freezing).Pasteurization kills most of the bacteria, especially pathogenic bacteria, making milk safe for consumption while maintaining its nutritional value.

Question 2

Question 1Discuss the role of yeasts in bakeries and breweries.

Accepted Answer

During the baking process, yeast added to the dough ferments sugar and produces carbon dioxide. This causes the dough to rise and when it is baked, the gas bubbles expand causing the bread to be spongy and light. Hence yeast is used in bakeries.The greatest importance of yeast to us is through their property of alcoholic fermentation. Fermentation is the process in which the micro-organisms like yeast break down the carbohydrates into simpler products like ethanol and lactic acid. This alcohol is of great commercial importance. Hence, yeast is used in breweries to produce beer and wine from barley maltose and grapes, respectively.

Question 3

Question 2Write in proper sequence the five major steps in the cultivation of the common edible mushroom.

Accepted Answer

Five major steps in the cultivation of common edible mushrooms are:Composting — Composting involves mixing of various components such asPaddy straw or WheatOrganic and Inorganic fertilizerChicken manureThe temperature of the compost is kept for about one week under 50°C.Spawning — 'Mushroom seed' in the form of mycelium of mushroom to be grown is introduced into the heap of compost and left for spreading for around two days.Casing — It is an important step wherein a thin layer of soil is spread over the compost. It:Gives support to the mushroomPrevents quick drying of the compostProvides humidityAssists to check temperatureCropping & Harvesting — The growth occurs in three principal stages:Mycelium grows within 2-6 weeksTiny pin headsButton stage grows bigger attaining marketable sizeFully grown mushrooms are taken out.Preservation — Shelf life of mushroom can be increased by the following processes:Vacuum coolingStoring at 15 degree Celsius and giving gamma radiationFreeze drying in a solution of ascorbic acid, citric acid, and brine etc.

Question 4

Question 4Both bacteria and yeast reproduce by asexual method, but how does this method differ in them ?

Accepted Answer

Bacteria reproduces by cell division or binary fission. The circular DNA duplicates. The cell expands and the two DNA are pulled apart. The cell constricts at the middle separating the two cells.Fungi like yeast reproduce by budding. In budding, a small bud or daughter cell is formed on the parent cell. The bud continues to grow until it separates from the parent cell, forming a new cell.

Question 5

Question 1(vii)The heterotrophic mode of nutrition in fungi is:SymbioticSaprophyticParasiticHeterozoic

Accepted Answer

SaprophyticReason — Most of the fungi show saprophytic mode of nutrition. Some may also show parasitic mode of nutrition.

Question 6

Question 1(viii)The stored food material in Yeast is in the form of :Glycogen and fatStarch and CelluloseGlycogen and ProteinNone of these

Accepted Answer

Glycogen and fatReason — Yeast stores food material in the form of Glycogen and fat in fat vacuoles.

Question 7

Question 1(ix)Which of the following properties of fungi separates them from plants ?Absence of chlorophyllAutotrophic mode of nutritionLack of a stemPoisonous and non-edible

Accepted Answer

Absence of chlorophyllReason — Fungi are differentiated from the plants as they don't have chlorophyll and their body is not differentiated into roots, stems and leaves.

Question 8

Question 1(x)The main products produced by microorganisms during fermentation are:Ethanol or lactic acidEthanol and uric acidAmino acid and lactic acidEthanol or uric acid

Accepted Answer

Ethanol or lactic acidReason — The main products produced by microorganisms during fermentation are ethanol or lactic acid and also acetic acid in some cases.

Question 9

Question 1(xi)Certain free living bacteria in the soil like (P) ............... and (Q) ............... use the free nitrogen of the soil and convert it to ammonia with hydrogen. P and Q are :P — Rhizobium, Q — AzobacterP — Azobacter, Q — ClostridiumP — Clostridium, Q — RhizobiumP — Nitrosomonas, Q — Nitrobacter

Accepted Answer

P — Azobacter, Q — ClostridiumReason — Azobacter and Clostridium convert atmospheric nitrogen (N2) into ammonia (NH3) using hydrogen. This process is known as biological nitrogen fixation.

Question 10

Question 3Write the chemical equation of fermentation.

Accepted Answer

The chemical equation of fermentation is:C6H12O6Glucose⟶2C2H5OHEthanol+2CO2\underset{	ext{Glucose}}{	ext{C}_6	ext{H}_{12}	ext{O}_6} \longrightarrow \underset{	ext{Ethanol}}{2	ext{C}_2	ext{H}_5	ext{OH}} + 2	ext{CO}_2GlucoseC6​H12​O6​​⟶Ethanol2C2​H5​OH​+2CO2​

Question 11

Question 6Differentiate between:(a) Saprophyte and Parasite(b) Aerobic and anaerobic respiration with regard to the products formed.

Accepted Answer

(a) Differences between Saprophyte and Parasite:CharacteristicsParasiteSaprophyteDefinitionIndividuals of one species that live at the expense of individuals from another species, called hosts.Organisms that feed on decaying dead organic matter and break it down into simple molecules that can be used by the autotrophs.Food sourceObtained from host without killing it.Obtained from decaying entities.FeedingFeeds with vital products from the host or parts of its body.Feeds with decaying dead organic matter.(b) Differences between aerobic and anaerobic respiration with regard to the products formed:Aerobic respirationAnaerobic respirationIt occurs in presence of oxygen. The products formed are water and carbon dioxide.It occurs in absence of oxygen. The end products are ethanol or lactic acid and carbon dioxide.

Economic Importance of Fungi

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