Biology 2 Marks Questions

We use microbes. Our products are derived from them everyday.
(1) Curd: LABs are lactic acid bacteria.
→ They grow in milk and convert it to curd.
→ During growth, the LAB produce acids that coagulate and partially digest the milk proteins.
→ A small amount of a curd added to the fresh milk as inoculum or starter contain millions of LAB, which at suitable temperatures multiply, thus converting milk to curd.
→ LAB improves milk quality by increasing vitamin B12.
→ In our stomach too, the LAB play very beneficial role in checking diseases causing microbes.
2. Cheese:
→ Cheese is an edible substance. Microbes are used at different stages of cheese. making.
→ Different varieties of cheese are known by their characteristic texture, flavour and taste which is given by specific microbes used in the cheese production.
→ The large holes in "swiss cheese" are due to production of a large amount of carbon dioxide by a bacterium named Propionibacterium sharmanii.
→ The "Roquefort cheese" are ripened by growing a specific fungi on them, which gives them a particular flavour.

→ Yes, microbes are used as a source of energy.
→ For example microbes are used to produce biogas or gobar gas from dung and bio waste.
→ Biogas-gobar gas is a product of anaerobic respiration of which main component is methane gas.
→ The spent slurry from the biogas plant is used as fertiliser.

(1) Cyclosporin A: 
→ It is derived from Trichoderma polysporium fungi.
→ This bioactive molecule is used as immunosuppressive drug in organ transplant patients.
(2) Statins:
→ It is derived from Monascus purpurus a yeast.
→ This drug is used as blood cholesterol lowering agent.
(3) Streptokinase:
→ This enzyme is derived from streptococcus bacterium.
→ This bacterium is modified by using genetic engineering.
→ It is used as "clot bluster" for removing clots from the blood vessels of patients. This drug is used for those patients who have undergone myocardial infraction leading to heart attack.

→ Primary treatment steps basically involve physical removal of particles- large and small from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration.
→ Then the grit soil and small pebbles are removed by sedimentation.
→ All solids that settle form the primary sludge and the supernatant form the effluent. The effluent from the primary settling tank is taken for secondary treatment.

→ Sewage treatment plant contains mainly two steps:
(1) Primary treatment:
→ Primary treatment steps basically involve physical process during which removal of particles- large and small is done from the sewage.
→ For this process, filtration and sedimentation is done repeatedly.
→ This treatment is less expensive and comparatively simple process.
(2) Secondary treatment (biological treatment): (
→ This is a biological process in which organic matter is decomposed by microbes.
→ Here, by using aerobic and anaerobic microbes, organic matter is decomposed. This process is complex and expensive.

→ We know that large quantities of waste water are generated everyday in cities and towns. A major component of this waste water is human excreta. This municipal waste water is also called sewage.
→ It contains large amounts of organic matter and microbes, many of which are pathogenic.
→ This cannot be discharged into natural water bodies like rivers and streams directly.
→ Before disposal, hence, sewage is treated in Sewage Treatment Plant (STPs) to make it less polluting.
→ The pollutants and pathogens in sewage cause water-borne animal disease like typhoid, cholera etc.

→ Some microbes are used to prepare drugs.
→ Antibiotics which is produced by the use of microbes, inhibits the growth of pathogens or kill them.
→ This drugs commonly derived from fungi and bacteria.
→ Penicillium notatum (fungi) secrete penicillin antibiotic which inhibits or slow down the growth of staphylococci bacterium.
→ Antibiotics weaken the cell wall of bacteria. Such weak bacteria are destroyed by immune cells that is WBC. → Streptomysin, tetracyclin, penicilin etc. Are common antibiotics.

→ Recipe:
Wheat: bread, cake etc
Rice: Dosa, Idli etc.
Chickpeas: dhokala, khandavi, gatta etc.
→ Microbes:
Bacteria: Lactobacillus
Yeast-fungi: Saccharomyses cerevisiae

→ LABs are lactic acid bacteria.
→ They grow in milk and convert it to curd.
→ During growth, the LAB produce acids that coagulate and partially digest the milk proteins.
→ A small amount of a curd added to the fresh milk as inoculum or starter contain millions of LAB, which at suitable temperatures multiply, thus converting milk to curd.
→ LAB improves milk quality by increasing vitamin B12.
→ In our stomach too, the LAB play very beneficial role in checking diseases causing microbes.

→ BOD refers to the amount of the oxygen that would be consumed if all the organic matter in one liter of water were oxidised by bacteria.
→ The greater the BOD of waste water, more is its polluting potential
→ Water having least BOD is less polluted or river water.
→ For sample A (20 mg/L) is effluent which came out after the secondary sewage Treatment.
→ For sample B (8mg/L) is a river water.
→ For sample C (400mg/L) is not treated in sewage Treatment plant.
→ Sample C is the highly polluted water.
→ BOD of a river water is least among three. So, we can say that river water is clean as compared to other two samples.

→ The given microbes give useful products to humans.
→ Lactobacillus: curd
→ Saccharomyses cerevisiae: To prepare bread and alcoholic beverages.
→ Propionibacterium sharmanii: swiss cheese
→ Penicillium Roquefortii: roquefort cheese
→ Aspergillus niger fungi: citric acid
→ Acetobacter aceti: acitic acid
→ Clostridium butyricum: butyric acid
→ Penicillium notatum: penicillin
→ Streptococcus: streptokinase enzyme which used as a clot bluster
→ Trichoderma polysporium: cyclosporin-A which uses as immunosuppressive drug to organ transplant patients.
→ Monascus purpurus (yeast): statins which lowers down blood cholesterol level

→ Many useful products for mankind are produced or synthesized by using microbes at industrial level
→ Beverages and antibiotics are some examples of this.
→ For industrial production, useful microbes are grown in to a big vessel which is called fermentors.
→ Microbes have been used from time immemorial for the production of beverages like wine, beer, whiskey brandy or rum.
→ Saccharomyses cerevisiae(brewer's) yeast is used to produce ethanol from cereals and fruit juices.
→ Yeast produces ethanol by an anaerobic respiration pathway.
→ Depending on the type of the raw material used for fermentation and the type of processing (with or without distillation) different types of alcoholic drinks are obtained.
→ Wine and beer are produced without distillation.
→ By distillation whisky, brandy and rum are produced.

→ Saccharomyses cerevisiae is a fungi (yeast).
→ The dough, which is used for making bread, is fermented using saccharomyses cerevisiae- baker's yeast.
→ This yeast is also used for production of ethanol from the fermentation of cereals and fruit juices, so called brewer's yeast.

→ Cheese is an edible substance. Microbes are used at different stages of cheese making.
→ Different varieties of cheese are known by their characteristic texture, flavour and taste which is given by specific microbes used in the cheese production.
→ The large holes in "swiss cheese" are due to production of a large amount of carbon dioxide by a bacterium named Propionibacterium sharmanii.
→ The "Roquefort cheese" are ripened by growing a specific fungi on them, which gives them a particular flavour.