Synopsis – Grade 8 Science
Chapter 1: Crop Production And Management
Crop: Same kinds of plants cultivated on a large scale
Sown in rainy season (June to
grown during winter season
(October to March)
soyabean, paddy, maize
wheat, gram, pea
Basic crop production practices
Loosening and upturning of the
soil. This process is known as
tilling or ploughing.
Placing of seeds of a crop in the
soil is called sowing.
Adding nutrients to the soil
Supplying of water to plants at
various intervals is called
Funnel shaped traditional
tool driven by animals
Manures - Prepared from
decomposed animals and plant
inorganic salts rich in plant
Moat (pulley system)
Rahat (chain system)
Manually by hands
Weedicides like 2,4-D
Removal of unwanted plants
from weeds from the field that compete with
crops for space, water and
Harvesting The process of cutting of mature
crops from the field is called
The process of removing grains Combine
from chaff is called threshing.
The process of keeping seeds Jute bags and metallic bins safe from spoilage due to
for small scale storage
moisture, insects, rats, and Silos and granaries for large microorganisms for a long time
is called storage
Sources of irrigation: Wells, tube wells, ponds, lakes, canal, river, dams etc. The process of separating grains from the husk in the mixture of threshed chaff is called winnowing.
Small scale storage of grains: It is usually done in jute bags and metallic bins. Large scale storage of grains: It is done in.
Food from animals - Milk from cow, buffalo, goat, and camel; Meat from chicken, goat, and sheep; Eggs from chicken and ducks.
Animal husbandry - The rearing of animals, which includes feeding, breeding, and disease control on a large scale, is called animal husbandry.
Chapter 2: Microorganisms
Microorganisms: The living organisms that cannot be seen with unaided eye are called microorganisms.
Classification of microorganisms: There are five major groups of microorganisms.
Found in wide range of habitats ranging from glaciers to deserts and hot springs
Example – curd bacteria (Lactobacillus)
Multicellular, heterotrophic organisms
Lack chlorophyll and are generally found in colonies
Example – Penicillium, Aspergillus
Unicellular or multicellular microorganisms
Usually found in water
Example – Amoeba and Paramecium
Unicellular or multicellular autotrophic organisms
Contain chlorophyll pigment and carry out photosynthesis Example – Chlamydomonas and Spirogyra
Require cells of host organisms to reproduce
Example – Influenza virus, polio virus
Importance of microorganisms
In food industry
o Lactobacillus bacteria promote the conversion of milk into curd. o Yeast is used in preparation of breads, pastries, and cakes. In beverage industry
o Yeast acts on sugar and converts into alcohol by the process of fermentation.
o Louis Pasteur discovered fermentation.
o Yeast is used for commercial production of alcohol, wine and vinegar (acetic acid).
In medicine production
o Medicines produced by certain microorganisms to kill or stop the growth of other disease-causing microorganisms are called antibiotics. o Antibiotics are obtained from bacteria and fungi.
o Commonly used antibiotics are streptomycin, tetracycline, and erythromycin.
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