These questions are designed with the help of highly trained and technical team at cbseinsights.com. We have divided CBSE CLASS 8 MICRO-ORGANISMS QUESTIONS under various heads such as Very Short answers, Short answers , Long answers and Higher Order Thinking Skills .
CBSE CLASS 8 MICRO-ORGANISMS QUESTIONS Very short questions.
Q 1 – What are Micro-organisms?
Ans – Those organisms which are too small to be seen without a microscope are called micro-organisms.
Q 2 – What are the harmful effects of Micro-organism?
Ans –
- Bacteria: Causes various diseases such as typhoid, diarrhea, and cholera.
- Fungi: Causes a large number of diseases in plants and in animals such as rust diseases in plants, fruit rot in apple, red rot in sugar cane and ring worm disease in human beings.
- Algae: Algal boom in water (rapid growth of algae) causes poisonous effect after they die and results in the death of aquatic organisms.
- Protozoa: Causes Amoebic dysentery, pyorrhoea and sleeping sickness etc.
- Virus: Cause small pox, common cold, influenza, herpes, hepatitis, polio and rabies.
Q 3 – Define refrigeration.
Ans – The storing of food products at the temperature of 0°C to 5°C is known as refrigeration.
Q 4 – What is vaccine?
Ans – A vaccine is a special kind of preparation (or medicine ) and are useful in the production of immunity against various diseases in the living body .
Q 5 – What are the uses of Micro-organism?
Ans-
- They are used in winemaking, baking, pickling and other food-making processes.
- Alcoholic fermentation by yeast is widely used in the preparation of wine and bread.
- A bacterium Lactobacillus promotes the formation of curd.
- Microbes are used to reduce pollution.
- They are used to increase soil fertility by fixing atmospheric nitrogen. (Rhizobium Bacteria & Blue Green Algae)
- Microbes are also useful in preparing many medicines and antibiotics.
- Certain microbes are also used in the biological treatment of sewage and industrial effluents.
- Some microorganisms are taken as probiotics, that are believed to provide health benefits when consumed.
- Bacteria are also involved in making cheese.
- Acetobacter bacteria is used for producing acetic acid from alcohol.
Q 6 – What are Bacteria?
Ans –
- Bacteria are single celled microbes.
- The cell structure is simpler than that of other organisms as there is no nucleus or membrane bound organelles.
- The control centre containing the genetic information is contained in a single loop of DNA. (Deoxyribonucleic acid)
- Some bacteria have an extra circle of genetic material called a plasmid. The plasmid often contains genes that give the bacterium some advantage over other bacteria.
- For example it may contain a gene that makes the bacterium (singular of Bacteria) resistant to a certain antibiotic.
CBSE CLASS 8 MICRO-ORGANISMS QUESTIONS for easy grasping…..
Q 7 – What are the types of Bacteria as per shape?
Ans – There are mainly three groups of bacteria on the basis of their shape: Spherical bacteria, rod-Shaped bacteria and spiral bacteria.
Q 8 – What are various diseases caused by virus?
Ans –
- Viruses are also microscopic but are different from other microorganisms.
- They, however, reproduce only inside the cells of the host organism, which may be a bacterium, plant or animal.
- Some of the viruses are Common ailments like cold, influenza (flu) and most coughs are caused by viruses.
- Serious diseases like polio and chicken pox are also caused by viruses.
- Diseases like dysentery and malaria are caused by protozoa (protozoans) whereas typhoid and tuberculosis (TB) are bacterial diseases.
Q 9 – Why viruses are on the borderline between living and non-living?
Ans –
- Viruses are on the borderline between living and non-living because they show the body properties.
- when they inside the host body they show living properties and they considered as living because they have their own DNA and RNA.
- They have ability to reproduce when inside the host body.
- Viruses show genetic recombination.
- They are nonliving because they have non cellular structure , undergo crystalization and completely inactive outside the host cell.
Q 10 – Name any two human diseases caused by viruses.
Ans – Measles, Polio
Q 11 –Name any three common plant diseases.
Ans – Rust of wheat, citrus canker and wilt
Q 12 – Define Protozoa?
Ans –
- Protozoa are a group of single-celled micro-organisms which are classified as animals.
- Protozoa are animal like just as algae are plant like.
For examples of protozoa are: Amoeba, Paramecium, Entamoeba and Plasmodium.
Q 13 – Name a microorganism which helps in nitrogen fixation.
Ans – Rhizobium
Q 14 – Name a disease caused by food poisoning.
Ans – Botulism
Q 15 – Define Algae and its causes.
Ans –
- Algae is a large group of simple, plant-like organisms.
- They contain chlorophyll and produce food by photosynthesis just like plants.
- Algae, however differ from plants because they do not have proper roots, stems and leaves. Some of the examples of algae are: Chlamydomonas, Spirogyra, Blue-green algae; Diatoms and Seaweeds.
Q 16 – What is the difference between refrigeration and freezing?
Ans – In refrigeration, the storing of the food is done at a temperature of 0°C to 5°C, whereas freezing is used to store food at -18°C of temperature.
Q 17 – What is decomposition?
Ans – Decomposition is the process in which organic materials are broken down into simple inorganic substances by the microorganisms.
Q 18 – Name the two microbes that are involved in the process of decomposition.
Ans – Bacteria and fungi
Q 19 – Name the first antibiotic discovered.
Ans – Penicillin
Q 20 – Name the type of microorganism that is smaller than bacteria.
Ans – Virus
Q 21 – Write a use of yeast.
Ans – Yeast is used in the production of alcohol, wine, beer and other beverages.
Q 22 – What does yeast produce during respiration?
Ans – Yeast produces carbon dioxide gas during respiration.
Q 23 – What are pathogens? Write another name of pathogens.
Ans – Disease-causing microorganisms are known as pathogens. They are also called germs.
Q 24 – Define food preservation.
Ans – Food preservation is the method of preserving food from being spoiled by the microbes.
Q 25 – Write the names of any two antibiotics.
Ans – Streptomycin, Erythromycin
Q 26 – Who discovered the vaccine for small pox?
Ans – Edward Jenner
Q 27 – What is fermentation?
Ans – Fermentation is the process of conversion of food into alcohol.
Short Answer Type Questions for Class 8
Q 28 – What are microorganisms? Give four examples.
Ans – Small organisms that cannot be seen through the naked eyes and can only be seen under a microscope are called microorganisms or microbes; e.g., Amoeba, Paramecium, Volvox, Spirogyra, etc.
Q 29 – Classify bacteria on the basis of their shapes.
Ans – On the basis of their shapes, bacteria are classified into four categories:
rod-shaped bacteria (bacilli)
spherical-shaped bacteria (cocci)
curved-shaped bacteria (vibrios)
spiral-shaped bacteria (spirilla)
Q 30 – Define communicable diseases. Give some examples.
Ans – Communicable diseases are microbial diseases that can spread from an infected person to a healthy person through air, water, or other physical contacts; e.g., cholera, chicken pox, tuberculosis, common cold, etc.
Q 31 – Differentiate between viruses and other microorganisms.
Ans –
| Viruses | Other microbes |
(i) They show the characteristics of living organisms or reproduce only by entering the host organisms. (ii) They are non-cellular microbes. | (i) They do not need to enter any host organism to reproduce or show any characteristics of life. (ii) They are cellular microbes. |
Q 32 – What do you mean by food spoilage?
Ans – The process in which food is deteriorated to such extent that it does not remain fit for human consumption is known as food spoilage.
Q 33 – What role does sugar play in the preservation of food?
Ans – The role of sugar in food preservation is significant. By adding sugar in the food item, we reduce its moisture content and hence, it stops the growth of the microorganisms.
Q 34 – How are carriers harmful to us?
Ans – Carriers take with them many harmful microorganisms or pathogens. They play a great role in transferring these pathogens to a healthy person, by sitting on the food items, or directly transferring the pathogens inside the body of a person. Hence they are harmful to us.
Q 35 – What do you mean by immunity?
Ans – Immunity is the ability of a body to develop resistance against diseases.
Q 36 – Give two examples of each of the following types of microorganisms:
(a) Algae
(b) Fungi
(c) Protozoa
Ans –
(a) Algae – Spirogyra, Chlamydomonas
(b) Fungi – Aspergillus, yeast
(c) Protozoa – Paramecium, Amoeba
Q 37 – What are antibodies?
Ans – Whenever any harmful disease-causing microorganism enters the human body, the body produces substances to fight with the entered microbe. These substances are called antibodies.
Q 38 – What is the role of bacteria in increasing the soil fertility?
Ans –
Some bacteria, which are present in the root nodules of leguminous plants or free-living fix the atmospheric nitrogen in the soil which is ultimately used up by the plants. Hence they increase the fertility of the soil. For example, Rhizobium, Azotobacter, Azospirillum, etc.
Q 39 – Define Ohmic heating.
Ans –
Ohmic heating is the process in which electric current of high voltage is passed through the food items to kill the microbes that cause the spoilage of food.
Class 8 Questions for gaining edge in EXAMS…….
Q 40 – What is sterilisation?
Ans –
The process of killing all the microorganisms above the temperature of 100°C is known as sterilisation. It is one of the widely used methods to preserve
food, and is often used for various food items.
Q 41 – What is pasteurisation?
Ans –
Pasteurisation can be defined as the partial sterilisation of foods at a temperature that destroys harmful microorganisms without major changes in the
chemical property of the food.
Q 42 – How is pasteurised milk obtained ?
Ans –
In pasteurisation, the milk is heated to 62.5°C for 30 minutes or to 71.5°C for 15 seconds. It is then rapidly cooled to 10°C and packed in airtight containers.
Q 43 – How can we control the spread of malaria or dengue ?
Ans –
All mosquitoes breed in water. Hence, by keeping the surroundings clean and dry, we can prevent mosquitoes from breeding. We should not allow water to collect in coolers, flower pots, etc and should wear full sleeves shirts in the evenings and at night. We can also use mosquito repellant creams and mosquito nets.
Q 44 – Name the microorganisms which can fix atmospheric nitrogen in the soil.
Ans – Bacteria such as Rhizobium and certain blue-green algae present in the soil can fix atmospheric nitrogen and convert it into usable nitrogenous compounds. These nitrogenous compounds can be easily utilized by plants for the synthesis of plant proteins and other compounds.
Q 45 – Name of Algae which helps in nitrogen fixing?
Ans –Anabaena is a Blue-Green algae. It is a unicellular prokaryotic organism so does not have membrane-bound organelles or true nucleus. Anabaena is used as nitrogen-fixing bacteria. It fixes atmospheric nitrogen into ammonia and makes it available to the plants.
Q 46 – How to convert the lactose sugar into lactic acid?
Ans –These bacteria contain an enzyme called lactase which attack lactose, splitting its molecules into glucose and galactose. Other enzymes from the lactic acid bacteria then attack the glucose and galatose, converting them into various acids of which lactic acid is the most important.
Long Questions and Answers
Q 47 – Explain why antibiotics do not work against flu or any infection caused by viruses.
Ans –
- Viruses cannot be killed by using antibiotics as their cell pathways are different from that of bacteria.
- It means taking antibiotics to get rid of flu or any other viral infection is useless, because it does not re-duce the strength of the virus, nor does it reduce the duration of the infection.
- Antibiotic will work if we get attacks of viral infection and bacterial disease at the same time. Even then, it will cure bacterial disease only but not the viral infection.
Q 48 – Mention any three ways through which pathogens are transmitted.
Ans – Three ways because of which pathogens are transmitted are as follows:
1. When a person sneezes or coughs, tiny droplets containing a number of disease-causing microorganisms come out of the mouth, and are released in the air. They are transmitted to a healthy person while breathing.
2. By making direct contacts with an infected person, pathogens are transferred to a healthy person. Carriers of pathogens also help in their transmission. For instance, when a fly sits on animal excreta or garbage, harmful disease-causing microbes stick to its legs.
3. When this fly sits on the food items, pathogens get transferred to them. This contaminated food items cause serious diseases when it is eaten by a healthy person.
Q 49 – Explain canning.
Ans – Canning is a process used for food preservation. Heat, at a certain temperature and for a limited period of time, is used to kill the harmful microorganisms as well as enzymes. This method also involves the removal of oxygen gas, and to avoid post-process contamination by airtight sealing of food items.
Q 50 – Explain how malaria is transmitted to humans.
Ans –
- A protozoan called Plasmodium is responsible for malaria.
- It lives in the liver and blood of the person who has been infected by this disease.
- A female Anopheles mosquito when sucks blood from the infected person, Plasmodium along with blood, is taken into its stomach.
- The Plasmodium, here, multiplies itself and reaches the salivary gland of the mosquito.
- This mosquito bites a healthy person, it injects Plasmodium along with saliva to him. The healthy person then gets an attack of malaria. In this way, malaria is transmitted to humans.
Q 51 – Explain various types of bacteria.
Ans – Bacteria are classified on the basis of their shapes into the following categories:
1. Rod-shaped bacteria (bacilli):
These are aerobic rod-shaped, spore-producing bacteria. They are often occurring in chain-like formations, and they are found primarily in soil; e.g., Lactobacillus.
2. Spherical-shaped bacteria (cocci):
They are spherical or nearly spherical bacteria; e.g., Streptococcus.
3. Curved-shaped bacteria (vibrios):
They are curved-shaped bacteria; e.g., Vibrio.
4. Spiral-shaped bacteria (spirilla):
They are flagellated, aerobic bacteria, having a spirally twisted rod-like form; e.g., Treponema.
Q 52 – What are the various diseases caused by Protozoa?
Ans – Protozoan infections are responsible for diseases that affect many different types of organisms, including plants, animals, and some marine life. Many of the most prevalent and deadly human diseases are caused by a protozoan infection, including African sleeping sickness, amoebic dysentery, and malaria.
Q 53 – Define Algae
Ans –
- Algae is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. They contain chlorophyll and produce food by Photosynthesis.
- It is a polyphyletic( different organisms originating from same Ancestor) grouping that includes species from multiple distinct clades .
- It Includes organisms ranging from unicellular microalgae, such as Chlorella, Prototheca and the diatoms to multicellular forms such as the giant kelp ( a large brown alga ) which may grow up to 50 metres (160 ft) in length.
- Most are aquatic and autotrophic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem, which are found in land plants.
- The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and stoneworts.
Analytical and Reasoning Questions for Class 8
A variety of microscopic unicellular and colonial freshwater algae
Q 54 – Define Fungi.
Ans –
- Fungi are a kingdom of usually multicellular eukaryotic organisms that are heterotrophs (cannot make their own food) and have important roles in nutrient cycling in an ecosystem.
- Fungi reproduce both sexually and asexually, and they also have symbiotic associations with plants and bacteria. However, they are also responsible for some diseases in plants and animals. The study of fungi is known as mycology.
- Hyphae which are branching filaments have a tubular shape and are split into cell-like compartments by walls that are known as septa.
- These cells can have more than one nucleus, and nuclei and other organelles can move in between them.
Q 55 – What are the saprophytes and parasites?
Ans – i) Saprophyte – The organisms which obtain their food from dead plants (like rotten leaves), dead and decaying animal bodies, and other decaying organic matters (like rotten bread) are known as saprophytes.
Example: Fungi and some bacteria.
ii) Parasite: The organisms which feed on another living organism called its host are known as parasites.
Example: Plasmodium and roundworm.
Parasites are those organisms which obtain their nutrition from other living organisms, whereas saprophytes obtain their nutrition from the dead decaying organic matter.
Q 56 – Name any two human disease caused by Fungi?
Ans – Disease caused by fungi
Explanation:
Fungi cause three different types of human illness: poisonings, parasitic infections, and allergies. Many poisonous mushrooms are eaten by mistake because they look like edible mushrooms. Parasitic yeasts cause candidiasis, ringworm, and athlete’s foot. Mold allergies are very common.
- Ringworm is caused by a type of fungus that eats keratin. These are called dermatophytes. The scientific names for the types of fungi that cause ringworm are Trichophyton, Microsporum, and Epidermophyton.
- Candidacies is a fungal infection typically on the skin or mucous membranes caused by candida.
Q 57 – Where do microorganism live?
Ans –
Microorganisms may be single-celled like bacteria, some algae and protozoa, or multicellular such as algae and fungi. They can survive under all types of environment, ranging from ice cold climate to hot springs and deserts to marshy lands. They are also found inside the bodies of animals including humans.
Some microorganisms grow on other organisms while others exist freely. Microorganisms like amoeba can live alone, while fungi and bacteria may live in colonies.
Microorganisms have a ubiquitous presence. They are present everywhere in land, water and air . Besides,they have a high degree of adaptability and can survive in all kinds of environments, like hot springs, ice cold water etc..
Microorganisms are also present in our body and in dead and decomposed organic matter. Some of them may be parasitic.
Microorganisms are omnipresent, they are found everywhere. They live in every nook and corner you could possibly imagine.
On your seat, under the table, over the roof, even on your body parts, your palms, literally everywhere. They also dwell in extreme weather conditions like the equator, poles, deserts, ice-cold water bodies, hot boilers etc and adapt accordingly.
CBSE Class 8 Very Imp questions……
Q 58 – What are the uses of microorganism?
Ans – Micro-organisms are too small to be seen through naked eyes. However, they are vital to plants and the environment. Given below are the few uses of microorganisms:
- Lactobacillus is used to form curd from milk.
- Rhizobium present in pulse plants’ roots fix nitrogen from the air and supply nitrogen compounds to the pulse plants.
- Micro-organisms are also used in winemaking, baking, pickling, and other food-making processes.
- Alcoholic fermentation by yeast is widely used in the preparation of wine and bread.
- Microbes are used to reduce pollution. For example, decomposers such as bacteria and fungi break down dead bodies and excreta to form inorganic compounds, which plants can absorb.
- Microbes also play an important role in the preparation of medicines. Antibiotics are chemicals produced by microorganisms to kill bacteria. Penicillin is an antibiotic made from Penicillium.
- Bacteria in our intestine helps in proper digestion and release vitamin B, absorbed by the intestine.
- Many vaccines are prepared from micro-organisms. These vaccines are given to children to protect them from the disease.
- Certain microbes are also used in the biological treatment of sewage and industrial effluents.
- Yeast is used in making idli, bhaturas, bread, pastries, and cakes.
Microbes as our Friends in daily life
Q 59 – How milk is convert into curd?
Ans – When a little of Pre-made curd is added to warm milk, then Lactobacilli bacteria present in curd multiply in milk and convert it into curd.
- Milk contains a sugar called Lactose .
- Lactobacilli Bacteria converts the Lactose sugar into Lactic Acid.
- The Lactic acid converts the milk into Curd.
Q 60 – How yeast is used for making bread?
Ans –
- Yeast is used for the leavening (expansion) of bread. In baking process , Yeast uses the sugars and oxygen in dough to produce more yeast cells and carbon dioxide gas.
- Yeast uses sugars by breaking them down into carbon dioxide and water. The yeast needs lots of oxygen in order to complete this type of fermentation..
- Baker’s yeast is the common name for the strains of yeast commonly used in baking bread and bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable sugars present in the dough into carbon dioxide and ethanol.
- The bubbles of Carbon dioxide gas fill the dough and increase the volume of the Bread .
- The holes in the bread are due to the bubbles of Carbon dioxide given off during the Baking process which in turn make the bread light, soft and spongy.
Q 61 – Define fermentation?
Ans – Fermentation is the process of food processing in which sugar is converted into alcohol by the action of microorganisms. This process is used to produce alcoholic beverages such as wine, beer, and cider.
Fermentation is the breakdown of organic substances by organisms to release energy in the absence of oxygen. For example – The anaerobic (Absence of air) breakdown of carbohydrates by yeasts to produce alcohol and carbon dioxide, and the bacterial breakdown of milk sugar to give lactic acid.
Types of Fermentation
There are three different types of fermentation:
Lactic Acid Fermentation
In this, starch or sugar is converted into lactic acid by yeast strains and bacteria. During exercise, energy expenditure is faster than the oxygen supplied to the muscle cells. This results in the formation of lactic acid and painful muscles.
Alcohol Fermentation
Pyruvate, the end product of glycolysis is broken down into alcohol and carbon dioxide. Wine and beer are produced by alcoholic fermentation.
Acetic Acid Fermentation
Starch and sugar present in grains and fruits ferment into vinegar and condiments. E.g. apple cider vinegar.
Q 62 – How vinegar is converted into alcohol?
Ans – Vinegar is made from a two-step fermentation process. First, alcohol is formed from yeast consuming sugars within fruits and grains. The yeast consumes the natural sugars in the produce and excretes alcohol. This is what we refer to as Alcoholic fermentation.
Vinegar is nothing but acetic acid. Alcohol can be converted into Acetic Acid by oxidation.This oxidation is done by various type of microorganism mostly fungus. This process is known as fermentation.
When fungus or anaerobic bacteria respires anaerobically then sugar is converted into to alcohol.This alcohol upon exposure to air gets oxidized to form Acetic Acid.This acetic acid can be used in industrial purposes.
To transform alcohol into vinegar, oxygen and a bacteria of the genus Acetobacter must be present for the second step to take place, acetic fermentation.
These bacteria are found in all organic produce that contains sugar, such as fruits and plant roots. A combination of these bacteria and an aerobic environment causes acetification and thus, vinegar.
Antibiotics and Alexander Fleming
Q 63 – What are antibiotics?
Ans – Any substance that inhibits the growth and replication of a bacterium or kills it outright can be called an antibiotic.
Antibiotics are a type of antimicrobial designed to target bacterial infections within (or on) the body. This makes antibiotics indirectly different from the other main kinds of antimicrobials widely used today:
- Antiseptics are used to sterilise surfaces of living tissue when the risk of infection is high, such as during surgery.
- Disinfectants are non-selective antimicrobials, killing a wide range of micro-organisms including bacteria. They are used on non-living surfaces, for example in hospitals.
Of course, bacteria are not the only microbes that can be harmful to us. Fungi and viruses can also be a danger to humans, and they are targeted by antifungals and antivirals, respectively. Only substances that target bacteria are called antibiotics, while the name antimicrobial is an umbrella term for anything that inhibits or kills microbial cells including antibiotics, antifungals, antivirals and chemicals such as antiseptics.
Most antibiotics used today are produced in laboratories, but they are often based on compounds scientists have found in nature. Some microbes, for example, produce substances specifically to kill other nearby bacteria in order to gain an advantage when competing for food, water or other limited resources. However, some microbes only produce antibiotics in the laboratory
Q 64 – How Alexander Discovered first antibiotic penicillin?
Ans –
- In 1929, Alexander Fleming was cultivating a culture of disease causing bacteria. Suddenly he found the spore of a green fungus in one his culture plates.
- He noticed that the presence of tiny green fungus stopped the growth of disease causing bacteria. In fact it also killed many of the disease causing bacteria.
- From the fungus called Penicillium the medicine which is made from the fungus penicillium. Penicillin controls bacterial and fungal infection.
Q 65 – How vaccine help person to fight disease?
Ans –
- A vaccine contains the dead or weakened but alive microorganism of a disease.
- When the vaccine containing dead or alive microorganism is introduced into the body of a health person orally or by injection, the body of the person respond by production some substances called antibodies in the blood.
- These antibodies kill any alive disease causing microorganism presence in the vaccine.
- Some of the antibodies remain in the blood of the person for a very long time and fight against the same microorganism and killed them if they happen to enter the body naturally at a later date.
- So due to presence of antibodies in the blood, a person remain protected from that particular disease. Thus a vaccine develops the immunity from a disease.
Q 66 – What is vaccination?
Ans –
- A vaccine is a biological substance designed to protect humans from infections caused by bacteria and viruses.
- Vaccines are also called immunizations because they take advantage of our natural immune system’s ability to prevent infectious illness.
- To understand how vaccines work, we need to consider how our immune system protects us from infections.
- Vaccination is a simple, safe, and effective way of protecting people against harmful diseases, before they come into contact with them.
- It uses your body’s natural defenses to build resistance to specific infections and makes your immune system stronger.
- Vaccines train your immune system to create antibodies, just as it does when it’s exposed to a disease.
- However, because vaccines contain only killed or weakened forms of germs like viruses or bacteria, they do not cause the disease or put you at risk of its complications.
- Most vaccines are given by an injection, but some are given orally (by mouth) or sprayed into the nose.
Q 67 – Who discovered vaccination?
Ans –
The history of smallpox holds a unique place in medicine. It was one of the deadliest diseases known to humans, and to date (2016) the only human disease to have been eradicated by vaccination. The smallpox vaccine, introduced by Edward Jenner in 1796, was the first successful vaccine to be developed. He observed that milkmaids who previously had caught cowpox did not catch smallpox and showed that inoculated vaccine protected against inoculated variola virus.
CBSE
Q 68 – What is recycling the nutrients?
Ans –
- The recycling of various nutrients takes place in the form of nutrient cycles.
- A nutrient cycle is a cyclic movement of nutrients from its major reservoir through different organisms back into the same reservoir.
- These cycles indicate the flow of nutrients in an ecosystem. A nutrient cycle (or ecological recycling) is the movement and exchange of organic and inorganic matter back into the production of matter.
- Energy flow is a unidirectional and non-cyclic pathway, whereas the movement of mineral nutrients is cyclic.
- Mineral cycles include the carbon cycle, sulfur cycle, nitrogen cycle, water cycle, phosphorus cycle, oxygen cycle, among others that continually recycle along with other mineral nutrients into productive ecological nutrition.
Components
Each nutrient cycle comprises of three components;
- Reservoirs: These are the major storage sites of a nutrient. Different organisms consume a nutrient from these reservoirs.
- Sources: These are the ways by which a nutrient is regenerated and added to its reservoirs.
- Sinks: They are the major consumption sites of a nutrient.
Q 69 – What are pathogens?
Ans – A pathogen is simply defined as an organism that has the potential to cause infectious diseases in its host. Most pathogens are able to avoid the immune responses of the host, triggering associated illnesses. The pathogen then utilizes the host body’s resources to replicate before exiting and spreading to a new host (like a virus).
Pathogens are of different types and can spread through various means – usually skin contact, body fluids, or contact with contaminated surfaces. Some pathogens exist as airborne particles. The most common types of pathogens are viruses, bacteria, and fungi.
Diseases caused by pathogens are many. Common examples of viral pathogens include common cold, yellow fever, flu, dengue fever etc.
Similarly, the diseases caused by bacterial pathogens are Urinary Tract Infection (UTI), tuberculosis, gonorrhoea etc. The diseases caused by fungal pathogens are thrush, ringworm etc.
Q 70 – What are communicable diseases?
Ans – A communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.
Reporting of cases of communicable disease is important in the planning and evaluation of disease prevention and control programs, in the assurance of appropriate medical therapy, and in the detection of common-source outbreaks. California law mandates healthcare providers and laboratories to report over 80 diseases or conditions to their local health department.
Some examples of the reportable communicable diseases include Hepatitis A, B & C, influenza, measles, and salmonella and other food borne illnesses. communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.
Q 71 – Name some of the examples of the communicable diseases?
Ans – Some of the example of communicable diseases are: Common cold, Cholera, Chickenpox, Tuberculosis (TB), Malaria and AIDS.
CBSE Important Questions for class 8 Long Answer Type…..
Q 72 – What are the various way in which communicable disease can occur the spread?
Ans – A communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.
Some ways in which communicable diseases spread are by:
- Physical contact with an infected person, such as through touch (staphylococcus), sexual intercourse (gonorrhea, HIV), fecal/oral transmission (hepatitis A), or droplets (influenza, TB)
- Contact with a contaminated surface or object (Norwalk virus), food (salmonella, E. coli), blood (HIV, hepatitis B), or water (cholera);
- Bites from insects or animals capable of transmitting the disease (mosquito: malaria and yellow fever; flea: plague); and
- Travel through the air, such as tuberculosis or measles.
Q 73 – What is carrier?
Ans – The insects ( or other animals) which transmits disease causing microorganism to humans (without itself suffering from them) is called Carrier. There are two main carriers namely
- Mosquitoes.
- Houseflies .
Q 74 – Define food poisoning?
Ans –
- Food poisoning is a very common illness. For most people it is usually mild, but food poisoning can be severe and even deadly for some individuals.
- Most cases of food poisoning occur when people eat food or drink water containing bacteria, bacterial toxins (substances produced by bacteria), parasites, or viruses.
- Food poisoning can also occur when non-infectious poisons (such as poisonous mushrooms) or heavy metals (such as lead or mercury) find their way into people’s stomachs.
- It is estimated that about 11 million Canadians experience food poisoning each year. People at greatest risk for food poisoning are seniors, pregnant women, young children and babies, and people with chronic medical conditions (e.g., diabetes, AIDS, liver disease).
Q 75 – Name of bacteria and fungus causing food poisoning?
Ans – Mouldy food can be dangerous to eat if the fungi growing on it are the kind that produce mycotoxins. These are formed as the branching network of fungal filaments (hyphae) spread through the food and break it down.
Moulds can grow in drier environments than other microbes and mycotoxins are a problem in products such as nuts and cereals which have been stored in damp conditions. It is easy to mistakenly process and eat contaminated food because it does not look spoilt.
Aflatoxins – carcinogens – Cancer producing substances found in mouldy nuts.
Ochratoxins – cause kidney disease and are produced in cereals such as maize and barley.
Patulin – associated with mouldy apples and poisoning has arisen from drinking contaminated fresh apple juice.
Whilst some mushrooms are safe to eat and tasty, others, like the Death Angel can be deadly.
Mushrooms and toadstools – These fruiting bodies of certain fungi have been part of the human diet for centuries. However, not all of them are edible. Some, such as the aptly named Death Angel (Amanita bisporigera), contain poisonous compounds which can be lethal.
Other species cause unpleasant effects: sickness, diarrhoea, kidney and liver damage. Before you eat wild mushrooms you should have them checked for safety by an expert.
Important Questions for class 8 Long Answer Type…..
Q 76 – What is food preservation and hour it can use done?
Ans – The process in which the food material are given a suitable physical or chemical treatment to prevent their spoilage is called food preservation.
- Sun drying( or Dehydration
- Heating
- Cooling (or Refrigeration)
- Deep freezing
- Addition of common salt
- sugar addition
- Addition of mustard oil and vinegar
- Use of special Chemical preservatives
- Pasteurization
- Packing food in air tight packets.
Q 77 – What is the nitrogen cycle?
Ans –
- Nitrogen Cycle is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere.
- It involves several processes such as nitrogen fixation, nitrification, denitrification, decay and putrefaction.
- The nitrogen gas exists in both organic and inorganic forms. Organic nitrogen exists in living organisms, and they get passed through the food chain by the consumption of other living organisms.
- Inorganic forms of nitrogen are found in abundance in the atmosphere. This nitrogen is made available to plants by symbiotic bacteria which can convert the inert nitrogen into a usable form – such as nitrites and nitrates.
- Nitrogen undergoes various types of transformation to maintain a balance in the ecosystem. Furthermore, this process extends to various biomes, with the marine nitrogen cycle being one of the most complicated biogeochemical cycles.
Stages of Nitrogen Cycle
Process of Nitrogen Cycle consists of the following steps –
- Nitrogen fixation
- Nitrification
- Assimilation
- Ammonification
- Denitrification.
These processes take place in several stages and are explained below:
