Project Work of Science

8/4/2019 Project Work of Science

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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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