project work of science
TRANSCRIPT
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Project work of science3
Chapter-1crop production4
and management5
Q1-what is a crop?6
Ans-when plants of the same kind are grown7
and cultivated8
At one place on a large scale it is called a9
crop.1011
Q2-what are rabbi and kharif crops?12
Ans-kharif crops-The crops which are sown in13
rainy season are called14
Kharif crops eq, maize, paddy, soybeans,15
cotton.16
Rabi crops-the crops grown in the winter17
season are called rabbi18
Crops. eq, wheat, gram, pea, mustard.19
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Q3-define irrigation?21
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Ans-the supply of water to crops at different22
intervals is called23
Irrigation.24
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Q4-differences between fertilizers and manure?27
S.NO FERTILIZER MANURE
a fertilizer is an organic salt. manure can be prepared
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. chapter-236
microorganisms;friend and foe37
a fertilizer is prepared in
factories.
manure provides a lot of
to the soil.
a fertilizer does not provide
any humus to the soil.
manure is relatively less
plant nutrients.
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Q5- What are weeds ? how can we41
control them?42
Ans-weeds are unwanted plants that grow along43
the crops weeds can be controlled44
By using certain chemicals called45
weedicides.eq,2,4-d etc.46
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Q6-what is fermentation?48
Ans-The process of conversation of sugar into49
alcohol is called fermentation.50
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Q7-What is antibiotics? what precautions must be52
taken while taking antibiotics?53
Ans-These medicines kill or stop the growth of the54
disease causing micro organisms. such medicines are55
antibiotics.56
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Q8-what are the major groups of microorganisms?58
Ans-bacteria, fungi, protozon, algae, viruses.59
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Q9-tick the correct answer?61
(a)yeast is used in the production of.62
1.sugar 2. alcohol. 3.hydrocholric 4.oxygen63
(b)The following is an antibiotic.64
1.sodium bicarbonate 2.streptmycin 3.alcohol65
4.yeast66
(c)carrier of malaria causing protozon is.67
1.female anopheles mosquito 2.cockroach68
3.housefly 4.butterfly69
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(d)the most common carrier of communicable70
diseases is.71
1.ant 2.housefly 3.dragonfly 4.spider72
(e)the bread or idli dough rises because of.73
1.heat 2.grinding 3.growth of yeast cells74
4.kneading75
(f)the process of conversion of sugar into alcohol is76
called.77
1.nitrogen cycle 2.moulding 3.fermentation78
4.infection79
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Q10-name the microorganisms which can fix81
atmospheric nitrogen cycle.?82
Ans- rhzobiam.83
Q11-write a short paragraph on the harms caused by84
micro organisms.?85
Ans-microbes cause disease in human beings, plants86
and animals like common cold in human,87
Anthrox both in human and animals and rust of88
wheat in plants. Microbes may cause food poising by89
Producing toxic substances.90
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Chapter-3 synthetic fibers92
and plastics93
Q12-what are thermoplastics?94
Ans-such plastics which gets deformed easily on95
heating and can be bent easily are known as96
thermoplastics.97
Q13-what are thermosetting?98
Ans-There are some plastics which when moulded99
once, cannot be softened by heating .these are100
thermosetting plastics.101
Q14-give examples which indicate that nylon fibres are102
very strong?103
Ans-nylon is used in making ropes and bra cutes.104
Q15-Explain why why plastic containers are favoured105
for storing food?106
Ans-Because plastic do not react with water and air and107
they are light in weight, low price, good strength and108
easy to handle.109
Q16-Explain why the following are made of110
thermosetting plastics?111
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Ans-saucepan handles-because it cannot be bent easily.114
electric plugs/switches/plug boards-because plastic115
is a poor conductor of heat and electricity.116
Q17-Give examples to show that plastics are non117
corrosive in nature?118
Ans-plastics dont react with air and water so they are119
not corrote, so we keep-120
1.chemicals in plastic bottles.121
2.pickels in plastic bottles.122
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Q18-should handle and bristles of a tooth be made of123
the same material? Explain your answer?124
Ans-No, the handles and bristles of tooth brushes not be125
of same materials. The handles should be made of hard126
material and bristles127
Should be made by soft material because our germs128
are soft and due to hard material our germs should129
started bleeding.130
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Name->Vishnu Nair133
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Class->VIIIthb135
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Roll.no->38137
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