1. Complete the statements using the proper option from those given below. Explain the statements.
(mycotoxins, budding, rhizobium)
a. Yeast reproduces asexually by the …………. method.
Answer. Budding : Budding is the asexual method of reproduction in yeast. Upon getting favorable conditions yeast start growing rapidly with the process of budding.
b. Toxins of fungal origin are called …………. .
Answer. Mycotoxins : Different species of fungi can secrete mycotoxins which is a toxic and harmful substance. When fungal hyphae absorb the nutrients from the food materials, at the same time they release the mycotoxins into the food.
c. Leguminous plants can produce more proteins due to …………. .
Answer. Rhizobium : Rhizobium is beneficial symbiotic bacterium that lives in the root nodules of the leguminous plants. Plants are unable to take nitrogen from the air directly. But these bacteria convert nitrogen into compounds of nitrogen by a process of biological nitrogen fixation. Plants are able to produce food with high protein contents due to action of these bacteria.
2. Write the names of microbes found in following food materials.
yoghurt, bread, root nodules of leguminous plants, idli, dosa, spoiled potato curry.
Answer.
| Food materials | Microbes |
| Yogurt | Lactobacilli |
| Bread | Yeast |
| Root nodules of leguminous plants | Rhizobium |
| Idli | Yeast, bacteria |
| Dosa | Yeast, bacteria |
| Spoiled potato curry | Clostridium |
3. Identify the odd word out and say why it is the odd one ?
a. Pneumonia, diphtheria, chicken pox, cholera.
Answer. Chickenpox. It is caused by a virus, whereas others are caused by bacteria.
b. Lactobacilli, rhizobia, yeast, clostridia.
Answer. Yeast. It is a fungus, whereas the rest are bacteria.
c. Root rot, rust (tambera), rubella, mozaic.
Answer. Rubella. It is a disease of humans, whereas the rest are diseases of plants.
4. Give scientific reasons.
a. Foam accumulates on a the surface of ‘dal’ kept for a long time in summer.
Answer.
- Dal is rich in proteins.
- During summer, bacteria attack the dal and cause fermentation resulting in the production of carbon dioxide gas.
- Therefore, foam accumulates on the surface of the ‘dal’ kept for long time in summer.
b. Why are naphthalene balls kept with clothes to be put away.
Answer.
- Naphthalene balls are balls of chemical pesticide and deodorant.
- They help to kill or repel insects such as moths, cockroaches, mice etc.
- Therefore, naphthalene balls are kept with clothes to be put away to prevent clothes from getting damaged.
5. Write down the modes of infection and the preventive measures against fungal diseases.
Answer.
The fungal diseases such as ringworm and other skin diseases spread through contact of the patients. The clothes, bed linen, combs, etc. spread the fungal spores or hyphae and this infects other healthy persons. The preventive measures include maintaining personal hygiene and preventing the contact with infected persons.
6. Match the pairs
‘A’ group ‘B’ group
- Rhizobium a. Food poisoning
- Clostridium b. Nitrogen fixation
- Penicillium c. Bakery products
- Yeast d. Production of antibiotics
Answer.
(1) Rhizobium – Nitrogen fixation
(2) Clostridium – Food poisoning
(3) Penicillium – Production of antibiotics
(4) Yeast – Bakery products.
7. Answer the following questions.
a. Which vaccines are given to infants? Why?
Answer.
Infants have less resistance power to fight against diseases. They should be protected from infectious diseases. Therefore they are given following vaccinations :
(1) The BCG vaccine is given initially within first eight days after birth. B.C.G. vaccine protects infants against tuberculosis infections.
(2) In third, fourth and fifth months they are given triple vaccine or DPT which has vaccines against DPT – ( Diphtheria, Pertussis, Tetanus. )
(3) At the same time they are also given oral dose of polio vaccine.
(4) In ninth month babies are given combined MMR vaccine which is to get protection against Mumps, Measles, Rubella.
(5) School going children are given vaccines against typhoid and cholera. Sometimes vaccination for prevention of hepatitis is also done.
b. How is a vaccine produced?
Answer.
(1) For preparing vaccines, in olden days, microbes were injected in the bodies of horses or monkeys. These laboratory animals used to make antibodies to defend these microbes. Antibodies are proteins which can act against the disease-causing germs. These antibodies were extracted from the blood of these animals and were used as vaccines.
(2) Now-a-days with the advent of biotechnology, the vaccines are manufactured in laboratories with the help of bacteria. For this purpose, a detailed study of the disease-causing germ is undertaken. The genes and the DNA of such microbes are thoroughly explored. Then based on this information, proteins which can act against such microbes are synthetically prepared in the laboratories. The safe vaccine is produced in such a way which can defend the body against infections.
(3) Some types of vaccines are prepared from the extracts of germs. These germs or microbes are deactivated and made dormant. When they are
injected in the body of a person, they initiate the defending action. The body of such vaccinated person, already develops the antibodies in his or
her body. When in future, this person is again attacked by similar germs the defence starts immediately and the person does not become sick.
c. How do antibiotics cure disease?
Answer.
- Targeting Biochemical Pathways: Antibiotics work by blocking specific biochemical life processes that are essential for the survival of bacteria.
- Preventing Cell Wall Synthesis: Medicines like Penicillin stop bacteria from building their protective cell walls, causing the bacterial cells to burst and die.
- Blocking Protein Production: Some antibiotics interfere with the bacteria’s ability to create proteins, which stops them from growing and repairing themselves.
- Selective Toxicity: They are designed to attack structures found only in bacterial cells, meaning they do not harm human cells (which have different structures).
- Stopping Multiplication: By stopping bacteria from reproducing or killing them directly, antibiotics allow the body’s natural immune system to clear the remaining infection.
d. Are the antibiotics given to humans and animals the same? Why?
Answer.
Animals are also affected by different kinds of diseases. They also catch infections from bacteria, virus and fungi. Therefore, they are also given antibiotics by veterinary doctor during their treatment. The bacteria infecting humans are of different species than the pathogens infecting animals, hence some of the antibiotics are different. Few, however, are similar to human antibiotics.
e. Why is it necessary to safely store the pathogens of a disease against which vaccines are to be produced?
Answer.
- Pathogens are microbes which can cause diseases in us.
- For the preparation of a vaccine, a particular pathogen is cultured and grown in a laboratory.
- If these pathogens are not safely stored, they many get modified due to environmental factors, resulting in decrease in the efficiency of the vaccine.
- Also, the live pathogens may escape and cause diseases in us.
8. Answer the following questions in brief.
a. What are ‘broad spectrum antibiotics’?
Answer.
The antibiotics that are useful against a wide variety of bacteria are called broad-spectrum antibiotics. Sometimes there are visible symptoms of the disease but the pathogen causing the disease cannot be identified. In such condition, broad spectrum antibiotics are used. E.g. ampicillin, amoxicillin, tetracycline, etc.
b. What is fermentation?
Answer.
- Yeast uses sugar for food.
- Yeast grows and multiplies rapidly due to the carbon compounds in the sugar solution.
- In the process of obtaining nutrition, yeast cells convert the carbohydrates in the food into alcohol and carbon dioxide.
- Also, the bacteria Lactobacilli convert lactose, the sugar in milk into lactic acid.
- This process is called fermentation.
c. Define ‘Antibiotic’.
Answer.
- Carbon compounds obtained from some bacteria and fungi for destroying or preventing the growth of harmful micro -organisms are called antibiotics.
- Antibiotics, a discovery of the 20th century, have brought a revolution in the field of medicine.
- Antibiotics mainly act against bacteria. Some antibiotics can destroy protozoa.
- Some antibiotics are useful against a wide variety of bacteria they are called broad-spectrum antibiotics. Examples – Ampicillin, amoxicillin, tetracycline, etc.
- When the pathogen cannot be identified even though the symptoms of the disease are visible, broad-spectrum antibiotics are used.
- Whenever a pathogenic micro-organism is definitely known, then narrow-spectrum antibiotics are used. Examples: Penicillin, gentamycin, erythromycin, etc.
