**MICROORGANISM** Class 8 Q1.WHAT ARE MICROORGANISM? A1. THEY ARE VERY TINY ORGANISMS THAT CAN NOT BE SEEN THROUGH OUR NAKED EYE.WE NEED A MICROSCOPE TO SEE THEM. Eg .BACTERIA,ALGAE,FUNGI E. Coli bacteria in our intestine Q2.WHAT IS THE STUDY OF MICROBES CALLED?
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**MICROORGANISM**
Class 8
Q1.WHAT ARE MICROORGANISM?
A1. THEY ARE VERY TINY ORGANISMS THAT CAN NOT BE SEEN THROUGH OUR NAKED EYE.WE NEED A MICROSCOPE TO SEE THEM.
Eg .BACTERIA,ALGAE,FUNGI
E. Coli bacteria in our intestine
Q2.WHAT IS THE STUDY OF MICROBES CALLED?
A2. THE SCIENCE THAT DEALS WITH THE STUDY OF MICROORGANISMS IS CALLED MICROBIOLOGY.
Q3.A MICROBE CAN EVEN SURVIVE IN EXTREME UNFAVOURABLE CONDITIONS.HOW?
A3.THEY SURVIVE IN UNFAVOURABLE CONDITIONS BY FORMING SPORES AND CYSTS.
-SPORE IS A PROTECTIVE LAYER,THEY REMAIN INACTIVE INSIDE THE CYST AND SPRING BACK TO LIFE AGAIN WHEN CONDITIONS (FOOD,TEMPERATURE,MOISTURE) ARE FAVOURABLE.
Q4.WHAT ARE DIATOMS?HOW ARE THEY USEFUL TO US?
A4. DIATOMS ARE A GROUP OF ALGAE ,WHICH ARE MOSTLY UNICELLULAR.
-THEY ARE FOUND IN FRESHWATER AND MARINE HABITATS.
THEIR CELL WALL IS COMPOSED OF SILICA,WHEN THEY DIE, THE SILICA ACCUMULATES AT THE BOTTOM OF LAKES,RIVERS,AND SEAS TO FORM SILICEOUS EARTH.
-THEY ARE USED TO MAKE GLASS,PORCELAIN AND CERAMICS.
Q5.WRITE ANY THREE USES OF ALGAE.
1.ALGIN,OBTAINED FROM BROWN ALGAE ,IS USED TO THICKEN ICECREAMS AND COSMETICS.
2.AGAR,OBTAINED FROM RED ALGAE,IS USED IN THE LABORATORIES TO CULTURE TISSUE AND MICROBES
3.CERTAIN RED ALGAE ARE EATEN IN CHINA AND JAPAN AS VEGETABLES OR TAKEN AS SOUPS.
Q6.HOW DOES THE GROWTH OF ALGAE LEAD TO DEATH OF MARINE LIFE ?
A5.THE EXCESSIVE USE OF FERTILISERS,THAT DRAIN INTO THE WATERBODIES ,LEADS TO AN UNNATURAL AND RAPID GROWTH OF ALGAE.(KNOWN AS ALGAL BLOOM).
2.THE ALGAE KEEP ON MULTIPLYING FORMING A DENSE LAYER ON THE SURFACE OF THE WATER BODY.
THIS DEPRIVES THE MARINE LIFE BELOW,OF LIGHT AND OXYGEN,LEADING TO THEIR DEATH .
3. THIS IS KNOWN AS EUTROPHICATION.
Q7.WHAT ARE THE GROUPS INTO WHICH BACTERIA ARE DIVIDED, ON THE BASIS OF THEIR SHAPES.NAME THESE WITH EXAMPLES.
A6.1.ROD SHAPED BACTERIA,BACILLI.
Eg. BACILLUS ANTHRACIS ,WHICH CAUSES ANTHRAX.
2.SPHERICAL BACTERIA,COCCI
.Eg.STREPTOCOCCUS PNEUMONIAE ,WHICH CAUSE PNEUMONIA
3.SPIRALBACTERIA
SPIRILLUM. EG.CAMPYLOBACTER JUJUNI ,A FOOD BORNE PATHOGEN THAT CAUSES CAMPYLOBACTERIOSIS.
4.COMMA-SHAPED BACTERIA,VIBRIOS Eg.VIBRIO CHOLERAE WHICH CAUSES CHOLERA.
Q7.ARE BACTERIA PROKARYOTIC OR EUKARYOTIC?EXPLAIN.
A7.BACTERIA ARE PROKARYOTIC AS THEY DO NOT HAVE A WELL DEFINED NUCLEUS.
-THE NUCLEAR MATERIAL LIES UNBOUND IN THE CYTOPLASM OF THE BACTERIAL CELL.
Q9.HOW DO BACTERIA REPRODUCE?
A8.BACTERIA REPRODUCE SEXUALLY AS WELL AS ASEXUALLY.
ASEXUALLY : BY BINARY FISSION,A MODE OF ASEXUAL REPRODUCTION IN WHICH ONE CELL DIVIDES INTO TWO.
- THEY ALSO FORM A CYST AND REMAIN INACTIVE INSIDE THIS PROTECTIVE COVERING.WHEN THE CONDITIONS BECOME FAVOURABLE,THE SPORES BURST AND MANY BACTERIA ARE FORMED.
Q10..WHAT HAPPENS IF YOU EAT BADLY PRESERVED CANNED CHIPS OR MUSHROOM?
A9.A HARMFUL PATHOGEN,KNOWN AS CLOSTRIDIUM BOTULINUM ,TENDS TO GROW IN PRESERVED CANNED FOOD AND MAKES IT POISONOUS.
-HENCE,IF WE CONSUME SUCH FOOD, WE ARE BOUND TO GET INFECTED BY FOOD POISONING CALLED AS BOTULISM.
-IN SEVERE CONDITIONS,A PERSON CAN EVEN DIE OF THIS.
Q11.MENTION TWO WAYS IN WHICH BACTERIA ARE HELPFUL TO US.
A10.ANAEROBIC BACTERIA ARE OFTEN USED TO MAKE ALCOHOL AND VINEGAR ,THROUGH THE PROCESS OF FERMENTATION.
2.BACTERIA LIVING IN OUR INTESTINES AS E.COLI ,HELP IN THE ABSORPTION OF FOOD AND PROTECT US FROM MANY DISEASES.
Q12. BACTERIA ARE ALSO KNOWN TO BE NATURE'S FRIEND.HOW?
A11.THEY ARE NATURAL DECOMPOSERS LIKE PSEUDOMONAS, WHICH HELP IN THE BREAKDOWN OF COMPLEX ORGANIC MATTER(ANIMAL EXCRETA OR REMAINS OF PLANTS AND ANIMALS) INTO SIMPLER ONE.
-THUS,THEY RECYCLE THE NUTRIENTS BACK INTO THE SOIL AND ALSO CLEAN THE ENVIRONMENT
-ALSO THERE ARE MANY NITROGEN FIXING BACTERIA AS AZOTOBACTER OR RHIZOBIUM WHICH CONVERT ATMOSPHERIC NITROGEN INTO NITRATES AND THUS MAKE THE SOIL FERTILE.
Q12.EXPLAIN THE PROCESS OF LOCOMOTION AND NUTRITION IN PARAMOECIUM.
A12.PARAMOECIUM IS A FRESHWATER PROTOZOAN,FOUND IN PONDS AND DITCHES.
-THE LOCOMOTRY ORGAN THAT THEY POSSESS ARE CALLED CILLIA,A HAIRLIKE STRUCTURE, WHICH HELP THEM TO SWIM AND MOVE.
-NUTRITION IN PARAMOECIUM TAKES PLACE THROUGH ORAL GROVE INTO WHICH FOOD AND WATER IS DIRECTED BY THE CILIA.
Q14.HOW CAN PROTOZOANS BE HELPFUL TO OTHER ORGANISMS?
A14.PROTOZOANS CAN BE HELPFUL AS,THEY LIVE IN THE BODY OF TERMITES,DIGEST THE CELLULOSE PRESENT IN THE WOOD THAT IS EATEN BY THESE TERMITES AND CONVERT IT INTO CARBOHYDRATES WHICH CAN BE USED UP BY THE TERMITES.
Q15.EXPLAIN THE STRUCTURE OF MOULDS THAT IS VEIWED UNDER MICROSCOPE.
A15.MOULDS ARE A GROUP OF MULTICELLULAR FUNGI.
-THEY CONSIST OF TANGLED MASS OF THREADLIKE STRUCTURES.
-THE TANGLED MASS IS CALLED MYCELIUM WHILE THE THREADLIKE STRUCTURES ARE CALLED HYPHAE.
-THERE ARE ROUND STRUCTURE AT THE TOP OF HYPHAE CALLED SPORANGIA,WHICH CONTAIN SPORES(A METHOD OF REPRODUCING ASEXUALLY).
-THESE SPORES BURST DURING THE ARRIVAL OF FAVOURABLE CONDITIONS TO RELEASE THE SPORES INTO THE AIR ,WHICH FURTHER GROW INTO NEW INDIVIDUAL.
Eg.MOULDS GROWING ON A SLICE OF STALE BREAD.
Q16.WHAT ARE YEAST?HOW ARE THEY A HELPING HAND IN THE WINE AND FOOD INDUSTRY?
A16.-YEAST ARE A TYPE OF FUNGI.
-THEY ARE UNICELLULAR
-THEY HELP IN THE PROCESS OF FERMENTATION,TO FERMENT FRUIT JUICES OR MOLASSES FOR THE PRODUCTION OF WINE ,BEER AND OTHER ALCOHOLIC DRINKS.
-THEY ARE ALSO USED IN THE PREPARATION. OF B-COMPLEX VITAMINS.
-WHEN ADDED TO THE BATTER,THEY RELEASE CO2,WHICH MAKES THE BAKERY PRODUCT FLUFFY AND SPONGY.
Yeast cell under microscope.
Q17.WRITE A NOTE ON VIRUSES.
A17.VIRUSES ARE SAID TO BE SOMETHING BETWEEN LIVING AND NON LIVING.
- THEY ARE ACELLULAR,WHICH MEANS THAT THEY DO NOT HAVE ANY CELLULAR STRUCTURE.
-THEY CONSIST OF A BIT OF NUCLEAR MATERIAL WRAPPED IN A PROTEIN COAT.
-THEY CAN NOT REPRODUCE UNLESS THEY ENTER THE CELL OF A LIVING ORGANISM.
-THEY CAN EITHER CONTAIN DNA OR RNA AS THEIR GENETIC MATERIAL.
FOR Eg. HIV VIRUS THAT CAUSES A.I.D.S.,HAS RNA AND IS KNOWN AS RETROVIRUS.
-A VIRUS TAKES OVER THE HOST CELL AND GRADUALLY DESTROYS IT.
Q18.WHAT HAPPENS TO THE HOST CELL OF AN AIDS PATIENT,AFTER BEING ATTACKED BY HIV VIRUS.
A18.-WHEN A VIRUS ENTERS THE CELL OF A LIVING ORGANISM i.e. THE HOST CELL, THE NUCLEAR MATERIAL OF THE VIRUS TAKES OVER THE NUCLEAR MATERIAL OF THE HOST CELL,DESTROYING IT AND DIRECTING IT TO PRODUCE COPIES OF VIRUS CELLS.
-THE HOST CELL FINALLY BURSTS TO RELEASE THE VIRUSES,WHICH INFECT OTHER CELLS .
-THIS WAY MORE AND MORE HEALTHY CELLS ARE TAKEN OVER AND DESTROYED BY VIRUSES,MAKING THE PATIENT WEAK AND MORE PRONE TO OTHER DISEASES.HIS IMMUNITY GETS DESTROYED.
Q19.NAME AN ANCIENT METHOD OF PRESERVING FOOD.
A19.DRYING, MAINLY SUNDRYING, IS AN ANCIENT METHOD OF PRESERVING FOOD.
-WHEAT,RICE ,PULSES ALONG WITH POTATO WAFERS,AND SOME LEAFY VEGETABLES LIKE METHI ARE WASHED AND SUN DRIED.
-THIS WAY THE CEREALS AND EATABLES CAN BE STORED FOR A LONGER PERIOD OF TIME.
- THIS REDUCES THE MOISTURE CONTENT AND SO THE FOOD CAN LAST LONGER.
Q20.HOW DOES ADDING PRESERVATIVES LIKE SALT OR OIL,HELP IN PRESERVING FOOD?
A20 .MICROBES THRIVE WELL IN PRODUCTS CONTAING HIGH MOISTURE CONTENT.
-RUBBING SALT OVER FISH OR MEAT OR PICKLES OF MANGO, GIVES RISE TO EXOSMOSIS.
-EXCESS WATER MOVES FROM HIGH CONCENTRATION TO LOW CONCENTRATION ,AND THUS THE GROWTH OF MICROBES IN THESE PRODUCTS IS INHIBITED.
Q21. WHO INVENTED THE METHOD OF PASTEURISATION?HOW WAS IT HELPFUL?
A21.LOUIS PASTEUR CAME UP WITH THE TECHNIQUE OF PATEURISATION,WHICH HE FIRST USED TO PASTEURISE WINE.
-THIS METHOD IS NOW USED TO PASTEURISE MILK,WHERE MILK IS FIRST HEATED TO A TEMPERATURE OF 62°C FOR 30 MINUTES AND THEN COOLED AND STORED IN STERILED BOTTLES.
-THIS PREVENTS THE GROWTH OF MICROBES.
**DO IT YOUSELF**
Q1.DO RED AND BROWN ALGAE HAVE CHLOROPHYLL?
2.NAME A PROTOZOAN THAT CAN PHOTOSYNTHESISE.
3.YOUR COKE AND FRUIT JUICES CAN GET SPOILED AFTER SOMETIME IF THE PRESERVATIVE IS NOT ADDED TO THEM.NAME 2 OF THESE PRESERVATIVES.
4.WHY ARE YOU ADVISED NOT TO CONSUME CHIPS THAT WERE LEFT OPEN?
5.YOU ARE GIVEN TWO GLASSES OF MILK,ONE WAS PRESERVED AND REFRIGERATED OVERNIGHT WHILE THE OTHER WAS KEPT IN THE KITCHEN.WHICH ONE OF THE TWO WOULD YOU PREFER TO MAKE TEA WITH AND WHY?
5.WHY IS IT THAT A COOKED POTATO GETS SPOILT EASILY BUT NOT THE RAW ONE?
6.WHAT WOULD YOUR MOTHER ADD TO YOUR CAKE,TO MAKE IT FLUFFY?
7.GIVE AN INSTANCE FROM THE NATURE,WHERE YOU CAN SPOT THE GROWTH OF ALGAE.
8.WHAT IS THE MOST INTERESTING FACT ABOUT SPIROGYRA?
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