Category: CBSE Class 7

NCERT Solutions for Class 7 Science Chapter 13 Motion and Time are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 13 Motion and Time.

NCERT Solutions for Class 7 Science Chapter 13 Motion and Time

Question 1.
Classify the following as motion along a straight line, circular or oscillatory motion:

1. Motion of your hands while running.
2. Motion of a horse pulling a cart on a straight road.
3. Motion of a child in a merry-go-round.
4. Motion of a child on a see-saw.
5. Motion of the hammer of an electric bell.
6. Motion of a train on a straight bridge.

Answer:

1. Oscillatory
2. Straight line
3. Circular
4. Oscillatory
5. Oscillatory
6. Straight line

Question 2.
Which of the following are not correct?
(i) The basic unit of time is second.
(ii) Every object moves at a constant speed.
(iii) Distance between two cities is measured in kilometers.
(iv) The time period of a given pendulum is not constant.
(v) The speed of a train is expressed in m/h.
Answer:
(ii), (iv), (v).

Question 3.
A simple pendulum takes 32 sec. to complete 20 oscillations. What is the time period of the pendulum?
Answer:
Time taken for 20 oscillations = 32 s
Time taken for 1 oscillation = \(\frac { 32 s }{ 20 } \)
Hence, Time period = 1.6 s

Question 4.
The distance between the two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Answer:
Given, distance = 240 km
time = 4 h
speed = \(\frac { distance }{ time } \) = \(\frac { 240 km }{ 4 h } \) = 60 km/h.

Question 5.
The odometer of a car reads 57321.0 km when the clock shows the time 08: 30 AM. What is the distance moved by car, if at 08: 50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also.
Answer:
In this question, it is given that,
Initial reading of odometer = 57321.0 km
Final reading of odometer = 57336.0 km
Initial time = 08.30 AM
Final time = 08.50 AM
Now, total distance covered = Final reading of odometer – Initial reading of odometer
= 57336.0 km – 57321.0 km = 15.0 km
Total time taken = Final time – Initial time
= 08.50 AM – 08.30 AM
= 20 min
We know that,
speed = \(\frac { Distance\quad covered }{ Time\quad taken } =\frac { 15Km }{ 20min } =0.75Km/min\)
Speed in km/h = 0.75 x 60 (1 hr = 60 min) = 45 km/hr
Therefore, the distance moved by the car =15 km
and the speed of the car = 0.75 km/min and 45 km/h.

Question 6.
Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.
Answer:
Given, Speed = 2 m/s
Time =15 min = 15 x 60 s = 900 s
distance = speed x time = 2 m/s x 900 s = 1800 m
\(\frac { 1800 m }{ 1000 } \) km = 1.8 km

Question 7.
Show the shape of the distance-time graph for the motion in the following cases:
(i) A car moving at a constant speed.
(ii) A car parked on a side road.
Answer:

Question 8.
Which of the following relations is correct?
(i) Speed = Distance × Time
(ii) Speed = \(\frac { Distance }{ Time }\)
(iii) Speed = \(\frac { Time }{ Distance }\)
(iv) Speed = \(\frac { 1 }{ Distance\times Time } \)
Answer:
(ii) Speed = \(\frac { Distance }{ Time }\)

Question 9.
The basic unit of speed is:
(i) km/min
(ii) m/min
(iii) km/h
(iv) m/s
Answer:
(iv) m/s

Question 10.
A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:
(i) 100 km
(ii) 25 km
(iii) 15 km
(iv) 10 km
Answer:
(ii) 25 km

Question 11.
Suppose the two photographs shown in Figures A and B had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the red car.

Answer:
Do it yourself.

Question 12.
The figure shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Fig. Distance-time graph for the motion of two cars
Answer:
A is moving faster.

Question 13.
Which of the following distance-time graphs shows a truck moving with a speed which is not constant?


Answer:
(ii) and (iii).

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NCERT Solutions for Class 7 Hindi Bal Mahabharat Chapter 1 बाल महाभारत कथा are part of NCERT Solutions for Class 7 Hindi. Here we have given NCERT Solutions for Class 7 Hindi Bal Mahabharat Chapter 1 बाल महाभारत.

NCERT Solutions for Class 7 Hindi Bal Mahabharat Chapter 1 बाल महाभारत

पाठ्य-पुस्तक के प्रश्न-अभ्यास

प्रश्न 1.
गंगा ने शांतनु से कहा-“राजन्! क्या आप अपना वचन भूल गए?” तुम्हारे विचार से शांतनु ने गंगा को क्या वचन दिया होगा?
उत्तर
शांतनु ने गंगा की शर्त के अनुसार यह वचन दिया था कि उसके किसी भी कार्य में शांतनु को बोलने का अधिकार नहीं होगा। इसी वचन के आधार पर गंगा ने एक-एक करके सात पुत्र नदी में फेंक दिए किंतु शांतनु सदा चुप रहे। वचन बद्ध होने के कारण ही उन्होंने कभी कुछ न कहा।

प्रश्न 2.
महाभारत के समय में बड़े पुत्र को अगला राजा बनाने की परंपरा को ध्यान में रखते हुए बताओ कि तुम्हारे अनुसार किसे राजा बनाया जाना चाहिए था— युधिष्ठिर या दुर्योधन को? अपने उत्तर का कारण भी बताओ।
उत्तर-
महाभारत के समय में राजा के बड़े पुत्र को अगला राजा बनाने की परंपरा थी। इस परंपरा को ध्यान में रखते हुए हमारे अनुसार युधिष्ठिर को ही रोजा बनाया जाना चाहिए था, क्योंकि हस्तिनापुर की गद्दी के उत्तराधिकारी पांडु थे। अतः उनके बड़े पुत्र को ही गद्दी मिली चाहिए थी। यदि हम यह भी मान लेते हैं कि धृतराष्ट्र भी राजा थे, तो भी युधिष्ठिर गद्दी के दावेदार थे, क्योंकि वे दुर्योधन से बड़े थे।

प्रश्न 3.
महाभारत के युद्ध को जीतने के लिए कौरवों और पांडवों ने अनेक प्रयास किए। तुम्हें दोनों के प्रयासों में जो उपयुक्त लगे हों, उनके कुछ उदाहरण दो।
उत्तर
महाभारत युद्ध के कुछ अनुचित प्रयासों को छोड़ दिया जाए तो दोनों पक्षों के प्रयास उपयुक्त लगे। कुछ उदाहरण इस प्रकार हैं

1. अपने मित्रों की सहायता लेना।
2. युधिष्ठिर का भीष्म, द्रोण, कृप, शल्य से युद्ध करने की आज्ञा लेना।
3. पांडवों द्वारा श्रीकृष्ण को अपने साथ लेना।
4. पांडवों द्वारा कौरव-पक्ष के लोगों की सहानुभूति पा लेना।

प्रश्न 4.
तुम्हारे विचार से महाभारत के युद्ध को कौन रुकवा सकता था? कैसे?
उत्तर
हमारे विचार से महाभारत युद्ध को रोकने का सामर्थ्य पितामह भीष्म और आचार्य द्रोण में था क्योंकि यदि ये दोनों यह निर्णय कर लेते कि हम अन्याय का साथ नहीं देंगे, तो कृपाचार्य व अश्वत्थामा भी इनके साथ ही रहते। इनके अभाव में दुर्योधन लड़ने की हिम्मत न करता।
एक और शक्ति थी, जो महाभारत की नौबत ही नहीं आने देती और वह शक्ति थी, कुंती। शस्त्र-अभ्यास के दिन जब कर्ण अर्जुन को चुनौती दे रहा था, तब कुंती यदि साहस करके यह घोषणा कर देती कि कर्ण उसका पुत्र है, तो अर्जुन तो कर्ण के पैर पकड़ लेता। कर्ण की दोस्ती के बल पर ही दुर्योधन इतना आक्रामक हुआ।

प्रश्न 5.
इस पुस्तक में से कोई पाँच मुहावरे चुनकर उनका वाक्यों में प्रयोग करो।
उत्तर

1. नीचा दिखाना-दुर्योधन का प्रयास सदैव पांडवों को नीचा दिखाने का रहता था।
2. काम तमाम करना-महाभारत युद्ध के दूसरे दिन भीमसेन ने दुर्योधन के चार भाइयों का काम तमाम कर दिया था।
3. व्यर्थ डींग मारना-पितामह भीष्म ने धृतराष्ट्र से कहा था-महाराज! यह राधापुत्र कर्ण व्यर्थ की डींग मारता है।
4. दंग रहना-अभिमन्यु के युद्ध कौशल को देखकर कौरव-सेना दंग रह गई।
5. नाक में दम करना-घटोत्कच ने अपने प्रहारों से कर्ण की नाक में दम कर दिया था।

प्रश्न 6.
महाभारत में एक ही व्यक्ति के एक से अधिक नाम दिए गए हैं। बताओ, नीचे लिखे हुए नाम किसके हैं?
पृथा राधेय वासुदेव गांगेय सैरंध्री कंक
उत्तर
पृथा        –    कुंती
राधेय      –    कर्ण
वासुदेव   –    श्रीकृष्ण
गांगेय     –    देवव्रत, भीष्म
सैरंध्री     –    द्रौपदी
कंक      –    युधिष्ठिर।

प्रश्न 7.
इस पुस्तक में भरतवंश की वंशावली दी गई है। तुम भी अपने परिवार की ऐसी ही एक वंशावली तैयार करो। इस कार्य के लिए तुम अपने माता-पिता या अन्य बड़े लोगों से मदद ले सकते हो।
उत्तर
छात्र यह कार्य स्वयं करेंगे।

प्रश्न 8.
तुम्हारे अनुसार महाभारत कथा में किस पात्र के साथ सबसे अधिक अन्याय हुआ और क्यों?
उत्तर-
हमारे अनुसार महाभारत कथा में सबसे अधिक अन्याय कर्ण के साथ हुआ है- मसलन वह एक ऐसा पात्र था जो जन्म के समय से ही उसे अपनी माता के द्वारा त्याग दिया गया। उत्तम कुल में जन्म लेकर भी वह सूत-पुत्र कहलाया। शस्त्र परीक्षण के दिन पहचान लेने के बाद भी कुंती ने उसे नहीं अपनाया। इंद्र ने उसके साथ छल किया। परशुराम ने उसे शाप दिया। अर्जुन ने उसे छल से मारा। इस तरह हम देखते हैं कि महाभारत कथा में सबसे अधिक अन्याय कर्ण पर ही हुआ था।

प्रश्न 9.
महाभारत के युद्ध में किसकी जीत हुई? (याद रखो कि इस युद्ध में दोनों पक्षों के लाखों लोग मारे गए थे।)
उत्तर
युद्ध में कितने ही लोग मारे जाएँ, अंत में जीत तो एक पक्ष की होती ही है। महाभारत युद्ध में अठारह अक्षौहिणी सेना कट गई थी किंतु राज्य तो पांडवों को मिला। अतः जीत पांडवों की हुई, न्याय की हुई।

प्रश्न 10.
तुम्हारे विचार से महाभारत की कथा में सबसे अधिक वीर कौन था/थी? अपने उत्तर का कारण भी बताओ।
उत्तर-
महाभारत के युद्ध में एक से बढ़कर एक महारथियों ने भाग लिया था लेकिन सबसे अधिक कौन वीर था, इस पर निष्कर्ष निकाल पाना कठिन था। इसमे तुलनामक दृष्टि से देखते है तो पितामह, भीष्म, भीम, आचार्य द्रोण, कर्ण व अर्जुन एक से बढ़कर एक महारथी इस युद्ध में भाग लिए थे। अर्जुन की वीरता महाभारत कथा में कई जगहों पर देखने को मिलती है। उसने अपनी वीरता के बल पर राजा द्रुपद को बंदी बनाकर आचार्य द्रोणाचार्य के सामने ला खड़ा किया था। गंधर्वराज से कर्ण पराजित हुआ जबकि अर्जुन विजयी हुए। विराट के पास रहकर अर्जुन ने कर्ण को हराया। उसने द्रौपदी के स्वयंवर में रखे गए शर्त को पूरा कर स्वयंवर को जीता। अर्जुन ने कर्ण, द्रोणाचार्य, अश्वत्थामा और कृपाचार्य जैसे महारथियों को परास्त कर दिया। पितामह भीष्म को पृथ्वी छेद कर उनकी अंतिम समय में इच्छा पूरी की। इस प्रकार तुलनात्मक दृष्टि से देखा जाए तो पांडु पुत्र अर्जुन को सबसे अधिक वीर माना जा सकता है, क्योंकि उसकी वीरता की प्रशंसा स्वयं पितामह भीष्म और द्रोणाचार्य भी कर चुके हैं।

प्रश्न 11.
यदि तुम युधिष्ठिर की जगह होते, तो यक्ष के प्रश्नों के क्या उत्तर देते?
उत्तर
यदि मैं युधिष्ठिर की जगह होता तो मैं भी यक्ष के प्रश्नों के उत्तर इस प्रकार देने का प्रयास करता कि यक्ष प्रसन्न होकर मेरे मृत भाइयों को जीवित कर देते।

प्रश्न 12.
महाभारत के कुछ पात्रों द्वारा कही गई बातें नीचे दी गई हैं। इन बातों को पढ़कर उन पात्रों के बारे में तुम्हारे मन में क्या विचार आते हैं
(क)शांतनु ने केवटराज से कहा-“जो माँगोगे दूंगा, यदि वह मेरे लिए अनुचित न हो।”
(ख)दुर्योधन ने कहा-“अगर बराबरी की बात है, तो मैं आज ही कर्ण को अंगदेश का राजा बनाता हूँ।”
(ग)धृतराष्ट्र ने दुर्योधन से कहा-”बेटा, मैं तुम्हारी भलाई के लिए कहता हूँ कि पांडवों से वैर न करो। वैर दुख और मृत्यु का कारण होता है।”
(घ)द्रौपदी ने सारथी प्रातिकामी से कहा-”रथवान! जाकर उन हारनेवाले जुए के खिलाड़ी से पूछो कि पहले वह अपने को हारे थे या मुझे?”
उत्तर

1. हमारे मन में यह विचार आता है कि उस काल के शासक ऐसा कोई कार्य करने के लिए तैयार नहीं होते थे जिससे उनके राज्य या स्वयं उनको किसी प्रकार की हानि उठानी पड़े।
2. हमें दुर्योधन अशिष्ट लगता है। उसका व्यवहार आतंकवादियों जैसा है। वह राजा नहीं है। राजा तो धृतराष्ट्र हैं किंतु उसके सामने कोई बोल नहीं पाता। कर्ण को अंगदेश का राजा बनाने में भी उसका स्वार्थ झलकता है।
3. धृतराष्ट्र लाचार पिता के समान दिखाई देते हैं जो संतान को उचित सलाह दे रहे हैं किंतु जानते भी हैं कि उनकी बात नहीं मानी जाएगी। अतः दुख और मृत्यु का भय भी दिखाते हैं। हमारे मन में यह भाव आता है कि बड़ों की बात न मानने का परिणाम महाभारत है।
4. द्रौपदी तेजस्वी नारी है। उस तेज के कारण ही वह युधिष्ठिर को ‘हारने वाले जुए के खिलाड़ी’ कहती है। उसे नीति का ज्ञान है। विचार आता है कि काश! सभी भारतीय नारियों में इतना तेज होता, तो समाज का बहुत बड़ा हित होता।।

प्रश्न 13.
युधिष्ठिर ने आचार्य द्रोण से कहा- “अश्वत्थामा मारा गया, मनुष्य नहीं, हाथी।” युधिष्ठिर सच बोलने के लिए प्रसिद्ध थे। तुम्हारे विचार से उन्होंने द्रोण से सच कहा था या झूठ? अपने उत्तर का कारण भी बताओ?
उत्तर-
मेरे विचार से युधिष्ठिर ने द्रोणाचार्य से झूठ कहा था कि अश्वत्थामा मारा गया क्योंकि कथन था- ‘अश्वत्थामाः मृतो नरो या कुंजरो या”। इस वाक्य से स्पष्ट हो जाता है कि अश्वत्थामा हाथी मर गया लेकिन एक तो युधिष्ठिर ने जान बूझकर ऐसा कहा, दूसरी बात नरो पहले कहा है, अंतिम अंश धीमी आवाज़ में था। ऐसा युधिष्ठिर ने इसलिए कहा था क्योंकि वे जानते थे कि द्रोण के लिए यह असहनीय सदमा होगा, जिससे वे विचलित हो जाएँगे फिर उनको मारना आसान हो जाएगा।

प्रश्न 14.
महाभारत के युद्ध में दोनों पक्षों को बहुत हानि पहुँची। इस युद्ध को ध्यान में रखते हुए युद्धों के कारणों और परिणामों के बारे में कुछ पंक्तियाँ लिखो। शुरुआत हम कर देते हैं-

1. युद्ध में दोनों पक्षों के असंख्य सैनिक मारे जाते हैं।
2. …………………………………………………..
3. …………………………………………………..
4. …………………………………………………..
5. …………………………………………………..
6. …………………………………………………..

उत्तर
(2)जन-धन की अपार हानि होती है।
(3)युद्ध का दंड हमारी अनेक पीढ़ियों को सहना पड़ता है।
(4)नारियों व बच्चों को अपार कष्ट सहने पड़ते हैं।
(5)वैज्ञानिक उन्नति रुक जाती है।
(6)सांस्कृतिक पतन प्रारंभ हो जाता है।

प्रश्न 15.
मान लो तुम भीष्म पितामह हो। अब महाभारत की कहानी अपने शब्दों में लिखो। जो घटनाएँ तुम्हें ज़रूरी न लगें, उन्हें तुम छोड़ सकते हो।
उत्तर
पूरी कहानी के सार को पढे व अपने शब्दों में लिखने का प्रयास करें।

प्रश्न 16.
(क)द्रौपदी के पास एक ‘अक्षयपात्र’ था, जिसका भोजन समाप्त नहीं होता था। अगर तुम्हारे पास ऐसा ही एक पात्र हो, तो तुम क्या करोगे?
(ख)यदि ऐसा कोई पात्र तुम्हारे स्थान पर तुम्हारे मित्र के पास हो, तो तुम क्या करोगे?
उत्तर

1. यदि मेरे पास एक अक्षयपात्र हो तो मैं अपनी पहुँच के किसी भी निर्धन को भूख से तड़प कर मरने नहीं दूंगा।
2. यदि अक्षयपात्र मेरे मित्र के पास हो, तो उसे सलाह दूंगा कि इससे निर्धन व जरूरतमंद की सहायता करो।

प्रश्न 17.
नीचे लिखे वाक्यों को पढ़ो। सोचकर लिखो कि जिन शब्दों के नीचे रेखा खींची गई है, उनके अर्थ क्या हो सकते हैं?
(क) गंगा के चले जाने से शांतनु का मन विरक्त हो गया।
(ख) द्रोणाचार्य ने द्रुपद से कहा-“जब तुम राजा बन गए, तो ऐश्वर्य के मद में आकर तुम मुझे भूल गए।”
(ग) दुर्योधन ने धृतराष्ट्र से कहा-“पिता जी, पुरवासी तरह-तरह की बातें करते हैं।
(ध) स्वयंवर मंडप में एक वृहदाकार धनुष रखा हुआ था।
(ङ) चौसर का खेल हमने तो ईजाद किया नहीं।
उत्तर-
(क) विरक्त – उदासीन
(ख) मद – अहंकार, सत्ता का नशा ।
(ग) पुरवासी। – नगरवासी
(घ) वृहदाकार – बहुत बड़े आकार का
(ङ) ईजाद – खोज, आविष्कार

प्रश्न 18.
लाख के भवन से बचने के लिए विदुर ने युधिष्ठिर को सांकेतिक भाषा में सीख दी थी। आजकल गुप्त भाषा का इस्तेमाल कहाँ-कहाँ होता होगा? तुम भी अपने दोस्तों के साथ मिलकर अपनी गुप्त भाषा बना सकते हो। इस भाषा को केवल वही समझ सकेगा, जिसे तुम यह भाषा सिखाओगे। ऐसी ही एक भाषा बनाकर अपने दोस्त को एक संदेश लिखो।
उत्तर
आजकल गुप्तचर विभाग गंभीर अवसरों पर सांकेतिक भाषा का प्रयोग करता है। सेना के भी अपने सांकेतिक शब्द होते हैं। आतंकवादी भी ऐसी ही भाषा बना लेते हैं। आप भी अपने मित्रों के साथ मिलकर किसी भी प्रकार की सांकेतिक भाषा बना सकते हैं। इस भाषा के आधार पर आप बातचीत भी कर सकते हैं और एक दूसरे को संदेश भी भेज सकते हैं।

प्रश्न 19.
महाभारत कथा में तुम्हें जो कोई प्रसंग बहुत अच्छा लगा हो, उसके बारे में लिखो। यह भी बताओ । कि वह प्रसंग तुम्हें अच्छा क्यों लगा?
उत्तर
महाभारत एक ऐसा विशाल ग्रंथ है जिसकी समता संसार की किसी भी भाषा का कोई भी ग्रंथ नहीं कर सकता। अतः उसमें अनेक प्रसंग ऐसे हैं जो बहुत अच्छे लगते हैं। यदि एक का ही चयन करना है, तो महाभारत युद्ध प्रारंभ होने से पूर्व अर्जुन का मोह और श्रीकृष्ण का उपदेश ऐसा प्रसंग है जिसकी प्रशंसा सारा संसार करता है। वह प्रसंग ही ‘श्रीमद्भगवतगीता’ के नाम से जाना जाता है। | यह प्रसंग हमें इसलिए अच्छा लगता है क्योंकि इसमें श्रीकृष्ण ने अर्जुन को यही संदेश दिया है कि मनुष्य को कर्म करने में विश्वास करना चाहिए, फल की इच्छा की चाह नहीं करनी चाहिए। वर्तमान में भी यह कथन सत्य प्रतीत होता है।

प्रश्न 20.
तुमने पुस्तक में पढ़ा कि महाभारत कथा कंठस्थ करके सुनाई जाती रही है। कंठस्थ कराने की क्रिया उस समय इतनी महत्त्वपूर्ण’ क्यों रही होगी? तुम्हारी समझ में आज के ज़माने में कंठस्थ करने की आदत कितनी उचित है?
उत्तर-
उस जमाने में आज के समान पुस्तक की छपाई नहीं होती थी। अतः शिक्षा गुरु मुख से सुनकर कंठस्थ की जाती थी। आज उतना कंठस्थ करने की आवश्यकता नहीं है। आज के ज़माने में कागज़ और प्रैस की तकनीक उपलब्ध है। अतः अब इसकी उतनी आवश्यकता नहीं है, फिर भी विद्या को कंठस्थ कर लेने से ज्ञान का विकास होता है और वक्त पर काम आता है।

We hope the NCERT Solutions for Class 7 Hindi Bal Mahabharat Chapter 1 बाल महाभारत कथा help you. If you have any query regarding NCERT Solutions for Class 7 Hindi Bal Mahabharat Chapter 1 बाल महाभारत कथा, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants.

NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants

Question 1.
Fill in the blanks:
(a) Production of new individuals from the vegetative part of the parent is called ……..
(b) A flower may have either male or female reproductive parts. Such a flower is called ………
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as ………
(d) The fusion of male and female gametes is termed as ……………..
(e) Seed dispersal takes place by means of …….., ………. and ………..
Answer:
(a) vegetative propagation
(b) unisexual flower
(c) pollination
(d) fertilisation
(e) wind, water, animals.

Question 2.
Describe the different methods of asexual reproduction. Give examples.
Answer:
Various methods of asexual reproduction are:
(i) Vegetative propagation:
It is a type of asexual reproduction in which new plants are produced from roots, stems, leaves, and buds. Since reproduction takes place through the vegetative parts of the plant, it is known as vegetative propagation.

(ii) Budding:
Here, the small bulb-like projection coming out from, the yeast cell is called a bud, gradually grows and gets detached from the parent cell and forms an organism, e.g., yeast. The new yeast grows, matures, and produces more yeasts. If this process continues, a large number of yeasts are produced in a short time.

(iii) Fragmentation:
This type of reproduction is common in algae. These are slimy green patches in ponds, or in other stagnant water bodies. When water and nutrients are available algae grow and multiply rapidly by fragmentation An algae breaks up into two or more fragments. These fragments or pieces grow into new individuals. This process continues and they cover a large area in a short period of time.

(iv) Spore formation:
The fungi on a bread piece grow due to spores which are present in the air. When spores are released, they keep floating in the air. As they are very light, they can travel over long distances. The spores are asexual reproductive bodies. Each spore is covered by a hard protective coat to withstand unfavourable conditions such as high temperature and low humidity. So, they can survive for a long time. Under favourable conditions, a spore germinates and develops into a new individual. Plants such as moss and ferns also reproduce by means of spores.
Fig. Vegetative propagation in (a) bryophyllum (by leaf) (b) potato (by the stem)

Question 3.
Explain what do you understand by sexual reproduction?
Answer:
In sexual reproduction, the male and the female gametes fuse to form a zygote. For sexual reproduction, one or two parents are required to produce two different gametes and ultimately after zygote formation, new individual forms.

Question 4.
State the main difference between sexual and asexual reproduction.
Answer:

Question 5.
Sketch the reproductive parts of a flower.
Answer:

Fig. Reproductive parts of a flower

Question 6.
Explain the difference between self-pollination and cross-pollination.
Answer:

Question 7.
How does the process of fertilization take place in flowers?
Answer:
When the pollen grain reaches the stigma of the same species flower, it starts growing out into the pollen tube of the stigma. This tube continues to grow inside the style till it reaches the ovule. Male cells are released into the ovule for fertilization with the female egg cell and thus the zygote is formed. After this process of fertilization, the ovary develops into fruit and ovule into seeds.

Question 8.
Describe the various ways by which the seeds are dispersed.
Answer:
Seeds and fruits of plants are carried away in the following ways:
(i) Dispersion by the wind:
Winged seeds such as those of drumstick and maple, light seeds of grasses, or hairy seeds of aak CMadar) and hairy fruit of sunflower gets blown off with the wind to faraway places.

(ii) Dispersion by water:
Some seeds are dispersed by water. These fruits or seeds usually develop floating ability in the form of the spongy or fibrous outer coat as in coconut.

(iii) Dispersion by animals:
Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places. Examples are Xanthium and Urena.

(iv) Dispersion by explosion:
Some seeds are dispersed when the fruits burst with sudden jerks. The seeds are scattered far from the parent plant. This happens in the case of castor and balsam.

Question 9.
Match items in Column I with those in Column II:

Answer:

Question 10.
Tick (√) the correct answer :
(а) The reproductive part of a plant is the
(i) leaf
(ii) stem
(iii) root
(iv) flower

(b) The process of fusion of the male and the female gametes is called
(i) fertilisation
(ii) pollination
(iii) reproduction
(iv) seed formation

(c) Mature ovary forms the
(i) seed
(ii) stamen
(iii) pistil
(iv) fruit

(d) A spore producing plant is
(i) rose
(ii) bread mould
(iii) potato
(iv) ginger

(e) Bryophyllum can reproduce by its
(i) stem
(ii) leaves
(iii) roots
(iv) flower
Answer:
(a) (iv) flower
(b) (i) fertilisation
(c) (iv) fruit
(d) (ii) bread mould
(e) (ii) leaves

We hope the NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story.

NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 1.
Fill in the blanks:

1. Cleaning of water is a process of removing ……….
2. Wastewater released by houses is called ……….
3. Dried …….. is used as manure.
4. Drains get blocked by …….. and ……

Answer:

1. pollutants
2. sewage
3. sludge
4. cooking oils and fats

Question 2.
What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas?
Answer:
Sewage is wastewater released by homes, industries, hospitals, offices, and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste. Mostly, sewage contains water, which has dissolved and suspended impurities which are called contaminants. That is why it is harmful to discharge untreated sewage into rivers or seas.

Question 3.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oils and fats should not be thrown down the drain. They get hard and block the pipes. In an open drain, the fats clog the soil pores reducing their effectiveness in filtering water.

Question 4.
Describe the steps involved in getting clarified water from wastewater.
Answer:
Following steps are involved in getting clarified water from wastewater:
(i) Firstly, wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.

(ii) Water then, goes to a grit and sand removal tank. The speed of the incoming wastewater is decreased to allow sand, grit, and pebbles to settle down

(iii) The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the floatable solids like oil and grease. Water so cleared is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.

(iv) Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps, and other unwanted matter still remaining in clarified water. After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top. The activated sludge is about 97% water. The water is removed by sand drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to the soil.

The treated water has a very low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Nature cleans it up further. Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

Question 5.
What is sludge? Explain how it is treated.
Answer:
Solids like faeces which settle at the bottom of the tank and are removed with a scraper are called sludge. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.

Question 6.
Untreated human excreta is a health hazard. Explain.
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tube-wells, springs, and many rivers. Thus, it becomes the most common route for water-borne diseases. They include cholera, typhoid, polio, hepatitis, and dysentery.

Question 7.
Name two chemicals used to disinfect water.
Answer:

• Chlorine
• Ozone

Question 8.
Explain the function of bar screens in a wastewater treatment plant.
Answer:
Wastewater is passed through bar screens for removal of large objects such as rags, sticks, cans, plastic packets, napkins, etc.

Question 9.
Explain the relationship between sanitation and disease.
Answer:
Sanitation is the hygienic means of promoting health through the prevention of hazards of wastes as well as the treatment and proper disposal of sewage wastewater.
Poor sanitation is a major cause of diseases worldwide and improving sanitation is known to have a significant beneficial impact on households and across communities. So poor sanitation and contaminated water is the cause of a large number of diseases.

Question 10.
Outline your role as an active citizen in relation to sanitation.
Answer:
We all have a role to play in keeping our environment clean and healthy. We must realize our responsibility in maintaining the water sources in a healthy state. Through good sanitation practices, we keep our environment clean and healthy. We should make people aware of the benefits of sanitation and help municipal corporations to cover all the open drains and remove disease-causing substances thrown in open.

Question 11.
Here is a crossword puzzle. Good luck!
Across:
3. Liquid waste products
4. Solid waste extracted in sewage treatment fi. A word related to hygiene
8. Waste matter discharged from the human body.
Down:
1. Used water
2. A pipe carrying sewage
5. Microorganisms which cause cholera
7. A chemical to disinfect water

Answer:
Across:
3. Sewage
4. Sludge
6. Sanitation
8. Excreta
Down:
1. Wastewater
2. Sewer
5. Bacteria
7. Ozone

Question 12.
Study the following statements about ozone:
(a) It is essential for the breathing of living organisms.
(b) It is used to disinfect water.
(c) It absorbs ultraviolet rays.
(d) Its proportion in the air is about 3%.
Which of these statements are correct?
(i) (a), (b) and (c)
(ii) (b) and (c)
(iii) (a) and (d)
(iv) All four
Answer:
(ii) (b) and (c)

We hope the NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 18 Wastewater Story, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline.

NCERT Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline

Question 1.
Explain how animals dwelling in the forest help it grow and regenerate.
Answer:
Animals help in dispersing seeds of certain plants. The decaying animal dung also provides nutrients to the seedling to grow. This is how animals help the forest to grow and regenerate.

Question 2.
Explain how forests prevent floods.
Answer:
Raindrops in a forest do not hit the ground directly. The uppermost layer of the forest canopy intercepts the raindrops, and most of the water comes down up to soil through the branches and the stems of the trees. From the leaves, it drops slowly over the branches of the shrubs and herbs. Thus forests act as a natural absorber of rainwater and allow it to seep and therefore help in controlling floods.

Question 3.
What are decomposers? Name any two of them. What do they do in the forest?
Answer:
The micro-organisms which convert the dead plants and animals to humus are known as decomposers. Bacteria, mushrooms, etc. are decomposers. They decompose dead organisms and provide nutrients to trees.

Question 4.
Explain the role of forests in maintaining the balance between oxygen and carbon dioxide in the atmosphere.
Answer:
Plants release oxygen as a byproduct during the process of photosynthesis. This oxygen is inhaled by animals for respiration. This respiration process releases carbon dioxide which is used again by plants during photosynthesis. In this way, use and consumption of oxygen and carbon dioxide go on. Thus, they maintain the balance of oxygen and carbon dioxide in the atmosphere.

Question 5.
Explain why there is no waste in a forest.
Answer:
The decomposers decompose the dead organisms. The decomposed matter is absorbed by plants as nutrients. So, there is no waste in a forest.

Question 6.
List five products we get from forests.
Answer:

• Honey
• Wax
• Gum
• Herbs
• Wood.

Question 7.
Fill in the blanks:

1. The insects, butterflies, honeybees, and birds help flowering plants in ……..
2. A forest is a purifier of …….. and ………
3. Herbs form the ………. layer in the forest.
4. The decaying leaves and animal droppings in a forest enrich the ………..

Answer:

1. pollination
2. air, water
3. lowest
4. soil

Question 8.
Why should we worry about the conditions and issues related to forests far from us?
Answer:
Forests are very helpful for us. They clean air, play a vital role in the water cycle, provide various items, and so on. So, we should worry about the conditions and issues related to forests far from us.

Question 9.
Explain why there is a need for a variety of animals and plants in a forest.
Answer:
A variety of animals and plants are necessary for their survival and maintenance of the food chain. For example, the grass is eaten by insects, which in turn, are eaten by the frog. The frog is consumed by a snake which is eaten by an eagle. Thus it forms a food chain.
Grass ➜ insects ➜ frog ➜ snake ➜ eagle.
Many food chains can be found in the forest. All food chains are linked together. If anyone’s food chain is disturbed, it affects other food chains. Every part of the forest is dependent on the other parts. If we remove one component, say trees, all other commonest would be affected.

Question 10.
In Fig., the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels: clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
Answer:

Question 11.
Which of the following is not a forest product?
(i) Gum
(ii) Plywood
(iii) Sealing wax
(iv) Kerosene
Answer:
(iv) Kerosene.

Question 12.
Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not dependent on one another.
(iii) Forests influence the climate and water cycle.
(iv) Soil helps forests to grow and regenerate.
Answer:
(ii) Plants and animals in a forest are not dependent on one another.

Question 13.
Microorganisms act upon the dead plants to produce
(i) sand
(ii) mushrooms
(iii) humus
(iv) wood
Answer:
(iii) Humus.

We hope the NCERT Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 17 Forests: Our Lifeline, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 11 Transportation in Animals and Plants are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 11 Transportation in Animals and Plants.

NCERT Solutions for Class 7 Science Chapter 11 Transportation in Animals and Plants

Question 1.
Match structures given in Column I with functions given in Column II:

Answer:

 Question 2.
Fill in the blanks:

1. The blood from the heart is transported to all parts of the body by the ………..
2. Hemoglobin is present in cells.
3. Arteries and veins are joined by a network of ……….
4. The rhythmic expansion and contraction of the heart is called …………
5. The main excretory product in human beings is ………..
6. Sweat contains water and ……….
7. Kidneys eliminate the waste materials in the liquid form called ………..
8. Water reaches great heights in the trees because of suction pull caused by ………..

Answer:

1. arteries
2. red blood
3. capillaries
4. heartbeat
5. urea
6. salts
7. urine
8. transpiration

Question 3.
Choose the correct option:
(a) In plants, water is transported through
(i) xylem
(ii) phloem
(iii) stomata
(iv) root hair

(b) Water absorption through roots can be increased by keeping the plants
(i) in the shade
(ii) in dim light
(iii) under the fan
(iv) covered with a polythene bag
Answer:
(a) (i) xylem
(b) (iii) under the fan.

Question 4.
Why is the transport of materials necessary in a plant or in an animal? Explain.
Answer:
Transport of materials is essential for plants or animals because nutrients and oxygen are made available to all the parts of the body through transpiration. If the transport of necessary nutrients and oxygen does not take place in the body, the body will not be able to survive.

Question 5.
What will happen if there are no platelets in the blood?
Answer:
Whenever we get injured, blood comes out from the cut. The function of platelets is to make a clot which plugs the cut to stop bleedings. If there are no platelets in the blood, no clot will be formed and as a result, bleeding will not stop and leads to a disease: haemophilia. This may lead to fatal consequences.

Question 6.
What are stomata? Give two functions of stomata.
Answer:
Stomata are the tiny pores present on the surface of the leaves. These are surrounded by two bean shaped cells called guard cells.

Functions of stomata :
(i) The exchange of gases in plants occurs through stomata.
(ii) The excess water in plants evaporates through stomata by a process called transpiration.

Question 7.
Does transpiration serve any useful function in the plants? Explain.
Answer:
Due to transpiration, a suction pressure develops which helps in the transportation of water.

Question 8.
What are the components of blood?
Answer:
Blood has two components: (a) Plasma and (b) Corpuscles, suspended in the plasma, with three kinds of blood cells.
(а) Plasma: It is the fluid part of blood.
(b) Corpuscles: It is of three types:
(i) Red Blood Cells (RBCs): Contain hemoglobin and impart a red color to the blood. Haemoglobin also carries oxygen from the lungs to all other body parts.
(ii) White Blood Cells (WBCs): Fight against the germs.
(iii) Platelets: Help in the clotting of blood.

Question 9.
Why is blood needed by all the parts of a body?
Answer:
Blood carries digested food and oxygen to all parts of the body. It also carries away the waste products.

Question 10.
What makes the blood look red?
Answer:
Blood contains three kinds of blood cells. Out of which Red Blood Cells contain an iron pigment called haemoglobin. Hemoglobin imparts red colour to the blood.

Question 11.
Describe the function of the heart.
Answer:
The heart collects and distributes purified blood to all parts of the body through arteries.

Question 12.
Why is it necessary to excrete waste products?
Answer:
Waste products are harmful to the body.

Question 13.
Draw a diagram of the human excretory system and label the various parts.
Answer:

We hope the NCERT Solutions for Class 7 Science Chapter 11 Transportation in Animals and Plants help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 11 Transportation in Animals and Plants, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 16 Water: A Precious Resource are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 15 Light.

NCERT Solutions for Class 7 Science Chapter 16 Water: A Precious Resource

Question 1.
Mark ‘T if the statement is true and F’ if it is false:
(а) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (T/F)
(b) Water shortage is a problem faced only by people living in rural areas. (T/F)
(c) Water from rivers is the only source for irrigation in the fields. (T/F)
(d) Rain is the ultimate source of water. (T/F)
Answer:
(a) T
(b) F
(c) F
(d) T

Question 2.
Explain how groundwater is recharged?
Answer:
The rainwater and water from other sources such as rivers and ponds seeps through the soil and fills the empty spaces and cracks deep below the ground. The process of seeping water into the ground is called infiltration. The groundwater thus gets recharged by this process.

Question 3.
There are ten tube wells in a lane of fifty houses. What could be the long-term impact on the water table?
Answer:
A huge amount of water will be pumped out from these ten tube wells and it will result in the depletion of the groundwater. Consequently, the water table will go deeper and deeper with time and in the longer-term, it will affect the availability of water in that area.

Question 4.
You have been asked to maintain a garden. How will you minimize the use of water?
Answer:
The use of water can be minimized by:

• using drip irrigation.
• preventing the leakage in the drains in the delivery pipes.
• filling the burrows of snakes and rats.
• protecting the boundaries of the field from breakage.

Question 5.
Explain the factors responsible for the depletion of the water table.
Answer:
There are three main causes of depletion of the water table.
(i) Increasing population:
The increasing population creates demand for the construction of houses, shops, offices, roads, and pavements. This decreases the open areas like parks and playgrounds. This, in turn, decreases the seepage of rainwater into the ground. Moreover, a huge amount of water is required for construction work. Often groundwater is used for this purpose. So, on the one hand, we are consuming more groundwater whereas, on the other hand, we are allowing lesser water to seep into the ground. This results in depletion of the water table.

(ii) Increasing industries:
Water is used by all industries. Almost everything that we use needs water somewhere in its production process. The number of industries is increasing continuously. Water used by most industries is drawn from the ground.

(iii) Agricultural activities:
A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems jUcîi Cl’îs equals are there only in a few places. Even these systems may suffer from a lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation. The increased use of groundwater day by day results in depletion of the water table.

Question 6.
Fill in the blanks with the appropriate answers:

1. People obtain groundwater through ……. and ……….
2. Three forms of water are …….,……. and ……….
3. The water-bearing layer of the earth is ………..
4. The process of water seepage into the ground is called ………..

Answer:

1. tubewells, hand pumps
2. solid, liquid, gas
3. aquifer
4. infiltration

Question 7.
Which one of the following is not responsible for water shortage?
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
Answer:
(iii) Heavy rainfall.

Question 8.
Choose the correct option.
The total water
(i) in the lakes and rivers of the world remains constant
(ii) under the ground remains constant
(iii) in the seas and the oceans of the world remains constant
(iv) of the world remains constant.
Answer:
(iv) of the world remains constant.

Question 9.
Make a sketch showing the groundwater and water table. Label it.
Answer:

We hope the NCERT Solutions for Class 7 Science Chapter 16 Water: A Precious Resource help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 16 Water: A Precious Resource, drop a comment below and we will get back to you at the earliest.