Question 1

Question 1(x)A preparation consisting of weakened or dead germ substances is:ToxinsAntitoxinsToxoidsVaccines

Accepted Answer

VaccinesReason — Vaccine consists of weakened or dead germ substances. Administration of vaccine results in resistance in body against the particular disease.

Question 2

Question 4Define the terms :(a) Antibiotics(b) Antitoxins(c) Serum(d) Botulism(e) Pasteurization

Accepted Answer

(a) Antibiotics — An antibiotic is a chemical substance produced by a living microorganism which can stop the growth of or kill some disease-producing bacteria and fungi.(b) Antitoxins — Antitoxin is a substance produced in animal bodies which reacts with the poison (toxin) produced by the invading germs.(c) Serum — Serum actually means blood plasma from which fibrinogen has been removed. It may contain numerous chemical substances including anti-bodies and antitoxins.(d) Botulism — Botulism is a very serious food poisoning due to a special bacterium sometimes found in tinned or sealed foods.(e) Pasteurization — Pasteurization is the process of food preservation, applied usually to milk. In this process, the milk is heated at 60°C for 30 minutes and then chilled quickly. It kills majority of bacteria.

Question 3

Question 5Give two examples of each :(a) Bacterial diseases of cattle(b) Bacterial diseases in plants(c) Bacterial diseases in humans(d) Nitrifying bacteria(e) Free living nitrogen-fixing bacteria found in soil

Accepted Answer

(a) Anthrax and Bovine tuberculosis(b) Bacterial blight of cowpea and Black rot of mustard(c) Cholera and Tuberculosis(d) Nitrosomonas and Nitrobacter(e) Azotobacter and Clostridium

Question 4

Question 6Write the full forms of the following abbreviations:(a) TAB(b) BCG(c) DNA(d) GMO

Accepted Answer

(a) TAB — Typhoid-paratyphoid A and B(b) BCG — Bacille Calmette-Guerin(c) DNA — Deoxyribonucleic Acid(d) GMO — Genetically Modified Organism

Question 5

Question 7Give reasons :(a) Every room in the house should get direct sunlight at least for a short time.(b) Tinned and sealed food is not always safe to eat.

Accepted Answer

(a) Direct sunlight contains ultraviolet radiations of the Sun, which help in killing of mould spores present in air. Hence, it is advised that every living room in the house should get direct sunlight at least for a short time.(b) No, tinned and sealed food are not always safe to eat as it may contain harmful bacteria like Clostridium botulinum that causes food poisoning. Clostridium botulinum releases toxins under low-oxygen conditions. These toxins are very lethal and can block nerve functions leading to muscular and respiratory paralysis.Moreover, the chemicals used in the inner coating of the container can be harmful for humans.

Question 6

Question 8State the differences between:(a) Decay and putrefaction.(b) Pasteurization and sterilization of food/objects/equipments.

Accepted Answer

(a) Difference between Decay and Putrefaction:DecayPutrefaction.Complete breakdown of organic matter by bacteria.Incomplete breakdown of organic matter by bacteria.Does not emit a foul smell.Emits a foul smell.(b) Difference between Pasteurization and Sterilization:PasteurizationSterilizationTemperature - 60°CTemperature - 110°CDoes not kill sporesKills even sporesPartial sterilizationComplete sterilizationExample – Milk sterilizationExample – Canned food sterilization.

Question 7

Question 9Would there be any bacteria in an aquarium?

Accepted Answer

Yes, bacteria can exist in aquarium. Bacteria can exist practically everywhere, as they can withstand any climatic condition.

Question 8

Question 1Draw a diagram showing the Nitrogen cycle and answer the following questions.(a) Define the terms:NitrificationDenitrification(b) Distinguish between biological nitrogen fixation and industrial nitrogen fixation.(c) Name the kind of relationship that exists between Rhizobium and leguminous plants.

Accepted Answer

(a) Below diagram shows the Nitrogen cycle:Nitrification — The conversion of atmospheric nitrogen to nitrates is called nitrification.Denitrification — The conversion of nitrates into atmospheric nitrogen is called Denitrification.(b) Difference between biological nitrogen fixation and industrial nitrogen fixation are:S.No.Biological NitrogenFixationIndustrial NitrogenFixation1.Biological nitrogen fixation is carried out primarily by bacteria known as nitrogen-fixing bacteria.Industrial nitrogen fixation involves a series of controlled chemical reactions.2.Biological nitrogen fixation occurs in natural ecosystems such as soil, aquatic environments and symbiotic associations with plants.Industrial nitrogen fixation occurs in controlled industrial settings, such as chemical plants or fertilizer production facilities.3.Nitrogen-fixing bacteria possess the enzyme nitrogenase, which converts atmospheric nitrogen (N2) into ammonia (NH3) through a series of biochemical reactions.The Haber-Bosch process uses high pressure and temperature, along with a catalyst, to convert atmospheric nitrogen (N2) and hydrogen (H2) into ammonia (NH3).(c) Symbiotic relationship.

Question 9

Question 2Would there be any bacteria in an aquarium ?(a) A balanced aquarium contains certain animals as well as some plants. How many kinds of animals can you make out in the aquarium shown here. Name any two such animals.(b) Do you think there would be some bacteria in it? If so in which part of the aquarium would they be occurring in abundance and what for?

Accepted Answer

(a) Fishes and snails are present in the aquarium shown here.(b) Yes, aquariums contain bacteria. A balanced aquarium contains some nitrifying bacteria like Nitrosomonas and Nitrobacter which converts the ammoniacal waste released by fish to nitrates. The filter media and various solid surfaces in the aquarium, such as gravel, rocks, plants, and decorations, harbor these bacteria in abundance.

Question 10

Question 3Fill in the blanks:(a) The first antibiotic penicillin was discovered by ............... .(b) ............... bacteria is found living in the nodules on the roots of leguminous plants.(c) The hormone ............... was the first substance produced by Escherichia coli.(d) ............... is an example of denitrifying bacteria.(e) ............... and ............... are the two heterotrophic modes of nutrition in bacteria.

Accepted Answer

(a) The first antibiotic penicillin was discovered by Alexander Fleming.(b) Rhizobium bacteria is found living in the nodules on the roots of leguminous plants.(c) The hormone insulin was the first substance produced by Escherichia coli.(d) Pseudomonas is an example of denitrifying bacteria.(e) Saprotrophic and parasitic are the two heterotrophic modes of nutrition in bacteria.

Economic Importance of Bacteria

Multiple Choice Type

Short Answer Type

Structured Application Skill Type

Very Short Answer Type