Test: Class 8 General Science NCERT Based - 1

15 Questions MCQ Test Science & Technology for UPSC CSE | Test: Class 8 General Science NCERT Based - 1

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In India, crops are classified into two groups, on the basis of the season they grow-Rabi crops and Kharif crops. In the context of these crops, consider the following statements:

1. Kharif crops are sown in summer.

2. Rabi crops are grown in winter.

Which of the statements given above is/are correct?

  • Kharif crops are sown during the monsoon (June to September), and not in summer. Rice, corn, soybean, groundnut, cotton, etc. are Kharif crops.

  • Rabi crops are grown in winter. Wheat, chickpea, pea, mustard, flax are examples of Rabi crops.

  • Apart from this, several pulses and vegetables are grown in the summer season, in many places.


With regard to organic manure, consider the following statements:

1. It enhances the water holding capacity of the soil.

2. It makes the soil loose and porous.

3. It enhances the number of friendly microbes.

Which of the statements given above is/are correct?

  • Organic manure is better than chemical fertilizers. While organic manure enhances the water holding capacity of the soil, makes the soil porous and loose, and increases the number of friendly microbes; prolonged use of chemical fertilizers decline the soil fertility and also cause water pollution.

  • Chemicals are used as pesticides and weedicides as well. 2, 4 D is an example of weedicide. The chemicals present in these increase the chemical content of the soil.


Cod liver oil contains a high amount of vitamin D. From which of the following animals, is cod liver oil obtained?

Solution: Cod liver oil is obtained from fishes. It is abundant in vitamin A and D. It is also rich in other nutrients.


Which one of the following is a preservative used in preservation of fruits as jams and jellies?

  • SUGAR and Citric Acid (Lemon Juice) are the main preservatives The product is preserved by lowering the water activity by cooking the fruit (evaporating water) in a very high sugar concentration.

  • Acid helps by lowering the pH After the jam is ready it is hot-filled to a clean jar, which is sterilized by the heat from the jam. The inversion of the jars helps by sterilizing the lid. Vinegar contains acetic acid, it is perfectly suited to preserve foods. It works because most of the microorganisms responsible for destroying food cannot live in an acetic acid environment.

  • Preservation is probably the most common reason vinegar is used in food preparation.

  • The use of mustard oil or vinegar prevents the spoilage of fruits and vegetables because food-spoiling bacteria cannot live in such an environment.

  • They are used as preservatives for preserving fruits such as raw mango,amla and lemon in the form of their pickles.





Beans and peas are preferably grown in nitrogen deficient soil because:

1. They absorb most of the nitrogen from the soil.

2. They are leguminous plants.

3. They have rhizobium in root nodules which can fix atmospheric nitrogen.

4. They are green plants.

  • Bean and Peas are leguminous plants.

  • They fix nitrogen in the soil with the help of Rhizobium bacteria present in the root nodules of the plants.

  • Thus, they fix nitrogen and replenish the deficiency of nitrogen in the soil. Therefore, farmers prefer to grow beans and peas in nitrogen deficient soil.


Which one of the following crops does not require nitrogenous fertiliser?

Solution: Beans is legume crop.A legume crop does not require nitrogenous fertilizers because its roots have root nodules that have nitrogenous bacteria called Rhizobium. This bacteria fixes atmospheric nitrogen and the plants convert nitrogen into various nitrogenous compounds.


Which one of the following pairs is incorrect?

Aspergillosis - Fungi.


The process of loosening and turning the soil is called:

  • The processing of loosening and turning the soil is called 'tilling' or 'ploughing' of the soil. It is the most important task in the field of agriculture.

  • It is very important to loosen the soil because it allows the roots of the plants to penetrate deep into the soil. This provides roots the space to expand under the surface of the earth.

  • The loosened soil helps in the growth of earthworms and microbes which add humus to the soil and increase the fertility. Loosening and turning the soil brings the nutrients to the top so that the plants can use them.


Which one among the following is a useful microorganism?

1. Salmonella typhi

2. Rhizobium

3. Lactobacillus

4. Rhinovirus

  • Rhizobium are a group of Gram-negative soil bacteria that are well known for their symbiotic relationship with various leguminous (soybeans, alfalfa etc). Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae).

  • To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In general, they are gram negative, motile, non-sporulating rods.

  • Lactobacillus is a type of bacteria. There are lots of different species of lactobacillus bacteria. These are "friendly" bacteria that normally live in our digestive, urinary, and genital systems without causing disease.

  • Lactobacillus is also in some fermented foods like yogurt and in dietary supplements.Lactobacillus is most commonly taken by mouth to treat and prevent diarrhea, including infectious diarrhea and diarrhea linked with using antibiotics.

  • Some people also take lactobacillus by mouth for general digestion problems, irritable bowel syndrome (IBS), colic in babies, inflammatory bowel disease (IBD), inflammation of the colon, stomach pain, constipation, and many other conditions but there is no good scientific evidence to support many of these uses.


Which leaves are used to protect stored grains from insects and microorganisms?

Solution: Neem tree is native of India. Its leaves contain chemicals such as Nimbin which have antifungal, antibacterial properties. Hence, dried neem leaves are used for storing food grains at home. Neem leaves are kept in stored grain, protecting from pests and microorganisms.


Consider the following statements in the context of microorganisms and diseases caused by them:

1. Chicken pox and Hepatitis A are caused by viruses.

2. Typhoid and Measles are caused by bacteria.

3. Diarrhoea and Malaria are caused by protozoa.

Which of the statements given above is/are correct?

  • Measles is not caused by bacteria, but by viruses. Common cold, influenza and most coughs are caused by viruses. In animals, foot and mouth disease of cattle is also caused by viruses.
  • Some microorganisms, disease caused by them and the mode of transmission:


Consider the following:

1. Algae: Spirogyra

2. Protozoa: Chlamydomonas

3. Fungi: Rhizopus (bread mould)

Which of the pairs given above is/are correctly matched?

  • Of the given microorganisms, Spirogyra and Chlamydomonas are examples of algae. Common examples of protozoa are amoeba and paramecium.

  • Rhizopus (bread mould), Penicillium and Aspergillus are examples of fungi. Microorganisms can be unicellular, like bacteria; some are multicellular, like algae and fungi.

  • Some microorganisms are dependent on other microorganisms (parasitic), while some are not (free living). Microorganisms like amoeba live alone (solitary) while fungi live in groups (colonial).


Which of the following microorganisms is required to turn milk into curd?

Solution: Bacteria is required to turn milk into curd. Many microorganisms are found in curd, of which a microorganism called Lactobacillus plays a primary role. It multiplies in milk and converts it into curd. Microorganisms are helpful in the production of many food Items like cheese, bread etc.


Which of the following is produced by yeast through respiration, when it is mixed with food items?

Solution: Once mixed with food items, yeast multiplies quickly to give out carbon dioxide through respiration. Carbon dioxide bubbles enhance the volume of the food item. Yeast is used in the baking industry, to make bread, pastry, cake, etc.


Match the items in Column 1 with those in Column 2, and choose the correct option.

  • The process of conversion of sugar into alcohol is called fermentation. Louis Pasteur discovered fermentation in 1857.

  • Penicillin was discovered by Alexander Fleming in 1929. It is an antibiotic which destroys the disease causing organisms.

  • Streptomycin, terramycin and erythromycin are some of the commonly used antibiotics; which are produced from fungi and bacteria.

  • Vaccine for measles was invented by Edward Jenner in 1798. If dead or inactive microorganisms are injected into the body, then the cells of the body release antibodies according to the microorganisms. This concept is the basis for the production of vaccines. Robert Koch discovered Bacillus anthracis in the year 1876, which is the causative organism of anthrax. Anthrax is a dangerous disease affecting humans and animals.