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Synopsis – Grade 8 Science
Chapter 1: Crop Production And Management
 Crop: Same kinds of plants cultivated on a large scale
Types
Kharif
crops
Rabi crops

Season
Sown in rainy season (June to
September).
grown during winter season
(October to March)

Examples
soyabean, paddy, maize
wheat, gram, pea

 Basic crop production practices
Practices
Preparation
of soil
Sowing

Process
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
Adding nutrients to the soil
manure and
fertilizers

Irrigation

Supplying of water to plants at
various intervals is called
irrigation.

Tools


Plough
 Hoe
 Cultivator
 Funnel shaped traditional
tool driven by animals
 Seed Drills
Manures - Prepared from
decomposed animals and plant
waste.
Fertilizers
Commercially
available
inorganic salts rich in plant
nutrients
 Moat (pulley system)
 Chain pump
 Dhekli
 Rahat (chain system)
 Sprinkler system
 Drip system
 Manually by hands
 Seed drills
 Khurpi
 Weedicides like 2,4-D
 Sickle
 Combine

Protection
Removal of unwanted plants
from weeds from the field that compete with
(weeding)
crops for space, water and
nutrients
Harvesting The process of cutting of mature
crops from the field is called
harvesting
Threshing
The process of removing grains Combine

Storage

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
scale storage
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.
Microorganisms
Discripion
Bacteria
 Single-celled organisms
 Found in wide range of habitats ranging from glaciers to deserts and hot springs
 Example – curd bacteria (Lactobacillus)
Fungi
 Multicellular, heterotrophic organisms
 Lack chlorophyll and are generally found in colonies
 Example – Penicillium, Aspergillus
Protozoa
 Unicellular or multicellular microorganisms
 Usually found in water
 Example – Amoeba and Paramecium
Algae
 Unicellular or multicellular autotrophic organisms
 Contain chlorophyll pigment and carry out photosynthesis  Example – Chlamydomonas and Spirogyra
Viruses
 Ultramicroscopic organisms
 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.
o...
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