RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Rajasthan Board RBSE Class 7 Science Chapter 7 Organic Evolution

RBSE Solutions for Class 7 Science

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

RBSE Class 7 Science Organic Evolution Intext Questions and Answers

Page No 63.

Question 1.
When and how did life begin?
Answer:
The life on earth is considered to begin around 3.5 billion years ago. The origin of life on earth as a result of a very slow process occurred. As a result of chemical reactions first of all sonic amino acids were produced. Then by combination of amino acids a simple cell is formed and then virus like organism dc eloped. From this, then multicellular organisms. inevrtebrates. vertebrates are originated. Gene rally this gradual change move to wards the complex organisms from simpler one.

Question 2.
What were all the creatures from beginning same as they are today ?
Answer:
No. initially they were like a virus. Then microscopic organism, thereafter single-celled organism protozoan are developed, in this gradually present organisms were developed.

RBSE Class 7 Science Organic Evolution Text Book Questions and Answers

Choose the correct option:

Question 1.
Heart of fish has –
(a) One auricle one ventricle
(b) One auricle to ventricles
(c) Two auricles to ventricles
(d) two auricles two ventricles
Answer:
(a) One auricle one ventricle

Question 2.
Archaeopteryx is a connecting link between –
(a) Pisces and amphibian
(b) Reptiles and aves
(c) Aves and mammals
(d) Amphibians and reptiles
Answer:
(a) One auricle one ventricle

Question 3.
Which scientist gave a theory of mutation
(a) Lamarck
(b) Darwin
(c) Hugo de Vries
(d) Mendel
Answer:
(c) Hugo de Vries

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 4.
Fore limb of whale is called as –
(a) Flipper
(b) Arm
(c) Wing
(d) Leg
Answer:
(a) Flipper

Fill in the blanks:

  1. Wings of bird and bats are ………………….. organ.
  2. Vertebral column is consists of small …………………..
  3. Every organism, in its development, repeats its ………………….. History.
  4. Organic evolution is a ………………….. and ………………….. process.
  5. Darwin gives theory of …………………..

Answer:

  1. Analogous
  2. Vertebrec
  3. Racial development
  4. Gradual solution
  5. Natural selection.

Short Answer type Questions:

Question 1.
Write differences between homologous and analogous organs.
Answer:
1. Homologous organs –
Differences between functions and external structure of forclimbs of animals such as whale. bird. bat. human etc. basic structure of the skeleton and the origin of these animals is the same. Such organs arc called homologous organs.

2. Analogous organs –
Wings of insect. bird. bat help them in following. But there arc differences in the structure and origin of their wings. Though the functions are similar, the origin and structure arc different. Such organs arc called analogous organs.

Question 2.
Write a process of fossil formation.
Answer:
Many lakhs of ears ago. so many organisms got trapped below soil in the earth or below sedimentary rocks due to natural calamities on earth. After a long, period of time. they changed into fossils. They arc found in sedimentary rocks during digging the earth. It is a most concrete evidence of evolution. So. these remains of dead animals and plants or their impressions found in rocks arc called fossils.
These are of two types –

  1. Remains of whole body
  2. impressions of organisms, cg. Foot Print. Trails. Baroj.

Question 3.
Draw a structure of hearts of different animals to show sequence of organic evolution.
Answer:
Structure of hearts according to sequence of organic evolution –
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-1.1

Question 4.
Define Lamarck’s theory of evolution with examples.
Answer:
Lamarck’s theory – This theory as given Jean Baptiste Lamarck in 1809. This theory is known as Theory of acquired characters. According Lo Lamarck due to changes in environment, more frequently used organs strengthened and organ that was less frequently used. disappeared. cg. Giraffes arc found in Africa It has long legs and neck.

It hes by eating the leaves of tall trees. According of Lamarck giraffe was not as long as their ancestor. The could easy to eat weed. Gradually due to change in environment, deserts extended and grassland perished. To get the leaves of the trees which were at height. legs and neck had to use more that’s why his legs and neck became too long. These traits are inherited from generation to generation.
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-1.2

Question 5.
What is Mutation ?
Answer:
Hugo de vries gave the theory of the mutation. When he tested some plants. found that some of the plants produced are quite different from their species. These traits are inherited from generation to generation. These sudden variations in inherited characters are called mutation.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Long Answer Type Questions:

Question 1.
Explain evolution on the basis of evidences of embryology.
Answer:
Evidence from embryology – In multicellular animals a unicellular zygote is formed b sexual reproduction which creates embryo b the division. When We see fish, turtle, chicken, humans embryos. earl stages of them appears almost identical. This proves that the ancestor of all vertebrates resemble with fish and their development is certainly in order.
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-1.3
Even organism. in its development repeats its organic history called as theory Recapitulation. This theory was proposed by German scientist. Haeckel.

Question 2.
Clarify different steps of Darwin’s Theory.
Answer:
Darwin’s Theory –
Charles Darwin gave a theory of natural selection for organic evolution. Different phases of Darwin’s theory are as under –
1. Production of off springs in living organisms – Each organism does production of off springs to maintain their race.

2. The struggle for survival – Due to overproduction of off springs, the struggle for space and food for the growing number of off springs takes place. It is the struggle of survival. Which is capable of the same shall live. Destruction due to struggle. the number of organisms.will remain balanced and \ consistence in nature.

3. Natural selection – In struggle of survival only those animals live who adapt them according to nature.

4. Origin of the new species – Inheritance of useful traits will continue from generation to generation and harmful traits gradually become extinct or remain as a vestigeal organ. Sometimes variations increase so that after hundreds of millions of times new generation is more different from older generation and the development of a new race goes.

For example –
at the beginning dog. Jackals and Wolves, three were members of the same race but due to change in atmosphere to adapt themselves accordingly changes in their size and physical characteristics. After thousands of years. dog.
fox, and wolf three new species was developed.

5. Neo-Darwinism –
According to this, the new species are originated due to gene variation into the members of the particular species. Only genetic variations are inherited and environmental characteristics ends with animal die.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 3.
Explain a process of formation of fossils.
Answer:
Many lakhs of years ago. so many organisms got trapped below soil in the earth or below sedimentary rocks due to natural calamities on earth After a long period of time. they changed into fossils. They are found in Sedimentary rocks during digging the earth. It is a most concrete evidence of evolution. So. these remains of dead animals and plants or their impressions found in rocks arc called fossils.
These are of two types –

  1. Remains of whole body
  2. Impressions of organisms. cg. Trails, Baroj, foot prints, etc.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-1

RBSE Class 7 Science Organic Evolution Important Questions and Answers

Objective type Questions:

1. What is the number of races of Plants and animals on earth ?
(a) Two
(b) Five hundreds
(c) Infinite
(d) Five thousands
Answer:
(c) Infinite

Question 2.
How was all animals initially based on backbone –
(a) Invertebrates
(b) Vertebrates
(c) Both types
(d) None of above
Answer:
(a) Invertebrates

Question 3.
Which one of the following has one auricle and one ventricle –
(a) Frog
(b) Fish
(c) Snake
(d) Human
Answer:
(b) Fish

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 4.
Who gave the theory of Recapitulation-
(a) Haekel
(b) Hostin
(c) Hook
(d) Harvest
Answer:
(a) Haekel

Question 5.
Where among the following places, giraffe is found
(a) Asia
(b) Africa
(c) Europe
(d) At all places
Answer:
(b) Africa

Question 6.
Prof. Beerbal Sahni is considered founder of what researches in india?
(a) Mutation theory
(b)Theory of inheritance of acquired characters
(c) Theory of natural selection
(d) None of these
Answer:
(c) Theory of natural selection

Question 7.
Which one of the following is pair of analogous organs –
(a) Wing of bat – Wing of insects
(b) Flipper of Whale – Wings of fish
(c) Wings of insect – Wings of bird
(d) Wings of bird – Hands of human
Answer:
(b) Flipper of Whale – Wings of fish

Question 8.
Which one of the following is pair of homologous organs –
(a) Flipper of hale – Wings of Fish
(b) Insects wings – Birds Wings
(c) Wings of bat – Forelimbs of Horse
(d) Wings of bird – Hands of Human
Answer:
(c) Wings of bat – Forelimbs of Horse

Fill in the blanks:

  1. Remains of dead organisms found in rocks are called …………………… (Fossils / Skeleton)
  2. …………………… is found in vertebrate animals. (Fossil / Skeleton)
  3. Snakes are found in soil in …………………… (Holes / Houses)
  4. Even organism does …………………… to maintain their race. (Production of off springs / bread & butter)
  5. Process of sudden variations in inherited characters is called …………………… (Transformation / Mutation)

Answer:

  1. Fossil
  2. Skeleton
  3. Holes
  4. Production of off springs
  5. Mutation

Match the Column I with Column II –

Question 1.
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-2
Answer:

  1. (b)
  2. (d)
  3. (a)
  4. (e)
  5. (c)

Very short Answer type Questions:

Question 1.
What is organic evolution ?
Answer:
Origin and evolution of respective complex organisms from simpler ones by changes is called organic evolution.

Question 2.
In the sequence of organic evolution, initially which type of organisms originated?
Answer:
First of all unicellular organisms originated which were invertebrates.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 3.
What are the divisions of Chordate?
Answer:
Following divisions come under chordate –

  1. Pisces
  2. Amphibia
  3. Reptilia
  4. Aves
  5. Mammalia

Question 4.
What are the similarities among the various animals of chordate group?
Answer:
All chordate animals contain hollow vertebral column.

Question 5.
Pisces division is developed from?
Answer:
Pisces division animals are developed from non-chordate.

Question 6.
Name the animals which are similar based on blood protein ?
Answer:
Human, Monkey, Fish, Frog, etc.

Question 7.
Which organisms come under connecting link series ?
Answer:
In the classification of organisms. there are some animals which have properties of the to classes. These organisms arc called as connecting link organisms.

Question 8.
How much time is taken in development of animals of one class from another one ?
Answer:
It takes approx. thousands of years.

Question 9.
What is the sequence of organic evolution ?
Answer:
In the sequence of organic evolution. earlier animals ere simpler but gradually they become complex.

Question 10.
State the connecting link between reptilian and mammalia class of animals.
Answer:
Playtypus and cchidna serves as connecting link between reptilian and mammalia classes.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 11.
What are fossils ?
Answer:
Remains of dead animals and plants or their impressions found in rocks are called fossils.

Question 12.
What are vertebree ?
Answer:
Generally chordata animals contains backbone which is made up of small bones. These are called vertebree.

Question 13.
What ¡s the importance of production of off springs in living organisms ?
Answer:
Production of off springs is important in maintaining their race for living organisms.

Question 14.
What is natural selection ?
Answer:
In struggle ofsurvival only those animals live who adapt them according to nature. It is natural selection.

Question 15.
What is theory of Recapitulation?
Answer:
Ever organism. in its development. repeats its organic history called as theory of Recapitulation.

Question 16.
Who gave the theory of Recapitulation ?
Answer:
Theory of Recapitulation was proposed by German Scientist Haekel.

Question 17.
What is neo-darvinism ?
Answer:
According to this theory. the new species are originated due to gene variation into the members of the particular species. Only genetic variations arc inherited and environmental characteristics ends with animal die.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Short Answer Type Questions:

Question 1.
What is the sequence of animals development. Explain.
Answer:
Firstly single-celled organisms were formed. Then multi cellular organisms were originated from them. Earlier, these are simple. but in gradual development became complicated. All animals are initially without a backbone. Fishes grew front them. by which amphibians are developed. From these evolved reptiles. Thereafter sonic reptiles developed into birds and other in mammals. Animals from one class to another takes thousands of wears to develop.

Question 2.
What is organic evolution ? Give names of evidences of organic evolution?
Answer:
Origin and evolution of respective complex organisms from simpler ones by changes is called organic evolution. Following are the evidences of organic evolution –

  1. Evidences from classification
  2. Structural evidences
  3. Fossils evidences
  4. Vestigeal organ evidence
  5. Embryological evidence
  6. Connecting link evidence
  7. Evidences from geographical distribution etc.

Question 3.
How many types are of structural evidences among organic evolution evidences ?
Answer:
Among evidences of organic evolution. structural evidences are of two types –

  1. Homologous organ – Basic structure of the skeleton and the origin of these forelimbs in whale. bird. bat, human is same but differ in functions.
  2. Analogous organs Wings of insect, bird & bat are differ in Structure but same in function.

Question 4.
Which are the evidences of physiology of organic evolution ?
Answer:
Out of organic evolution evidences. following are the evidences of physiology –

  1. Similarity in digestive system
  2. Evidence of the complexity of the heart.
  3. Similarities in blood protein

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 5.
how does skeleton in animals prove their organic evolution ? Explain with diagram.
Answer:
Generally a skeleton is found in chordata animals. The have backbone which is made.up of small bones called vertebrae. The similarity in their bones of hand and leg and skeletal systems. shows that their ancestors would have been similar. Over the time some differences appear due to change in conditions
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-3

Question 6.
What is Haekel’s theory ? Explain with example and diagram.
Answer:
According to Hackel even organism. in its development. repeats its organic history called as theory of Recapitulation when we sec fish, turtle, chicken, humans cmbryos. early stages of them appears almost identical. This proves that the ancestor of all vertebrates resembles with fish and their development is certainly in order,
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-4

Question 7.
Tell about reptiles.
Answer:
Reptiles are evolved from amphibians. They ruled on the earth millions of years, Thereafter, some reptiles developed into birds and other in mammals. eg. Dinosaur (Extinct animal).

Question 8.
What is Archaeopteryx ? Draw its diagram.
Answer:
Archaeopteryx serves as connecting link between reptiles and bird because this animal had some features beak wings. structure of legs etc. ere similar to aves (bird) and sonic characteristics beak. tail, scales. on body etc. ere similar to reptiles.
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-5

Question 9.
hat are vestigeal organs ? Explain with diagram.
Answer:
Some organs are found in animals today. which are present in the form of remains. But they ere highly developed and functional in their ancestors. Over time. as their utility decreases. they remained as a vestigeal
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-6

Question 10.
Write the names of transformations of for limbs and their functions in following animals –

  1. hale
  2. Bird
  3. Bat
  4. Human.

Answer:
Modifications and functions of forelimbs of Animals –
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-7

Question 11.
Name the main vestigial organs in following animals –

  1. Human
  2. Marine bottom fish
  3. Pythons
  4. Kiwi / Ostrich.

Answer:
Vestigial organs of Animals –
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-8

Question 12.
State about the structure of hearts in tabular form of following animals –

  1. Fish
  2. Frog
  3. Snake
  4. Human.

Answer:
Structure of heart of animals –
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-9

Question 13.
What are the evidences related to geographical distribution evidences?
Answer:
Now a day variations are found in the geographical distribution of plants and animals. For example – Platypus. Kangaroo and eucalyptus plant is found in Australia only. Similarly Giraffe is found only in Africa. According to scientists at a time the continents were connected to each other. Later on they ere separated by the sea, That is animals and plants found in one continent could not reach to another continent Due to different circumstances structures of them are changed according to different places.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 14.
Why there is struggle for survival in living organisms ?
Answer:
Due to over production of off springs. the struggle for space and food for the growing number of off springs takes place. It is the struggle of survival. Which is capable of the same shall Live. Destruction due to struggle. the number of organisms will remain balanced and consistence in nature.

Question 15.
Explain about evolution of new species with example.
Answer:
At the beginning dog. Jackals and Wolves. three were members of the same race but due to change in atmosphere to adapt themselves accordingly changes in their size and physical characteristics. After thousands of ‘ears dog. fox and wolf, three new species was developed.

Question 16.
Indicate homologous organs with a diagram.
Answer:
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-10

Question 17.
Write short notes on neo-Darwinism.
Answer:
Darwin added new. approaches to his old doctrine and gave a new doctrine of neo Darwinism. According to this, the new species are originated due to gene variation into the members of the particular species Only genetic variations are inherited and environmental characteristics ends with animal die.

Question 18.
Which theories are given for organic evolution?
Answer:
Due to the development in the living world. new species arc discovered and is going on till to day. To plain the order of organic evolution scientists gave different theories. Following are the theory of organic evolution –

  1. Lamarck’s theory (theory of inheritance of acquired characters)
  2. Darwin’s theory
  3. Mutation theory.

Essay Type Questions:

Question 1.
Write a note on origin of life.
Answer:
The origin of life on earth as a result of a very slow process occurred. initially, nitrogen and water vapour was in the Earth’s atmosphere. From the reaction of extreme hot vapour and carbon build-up a hydrocarbons, By the action of nitrogen and metals, nitrite was formed. Reaction beteen newly formed nitrite and hot vapour produced ammonia gas. Chemical combination between hydrocarbons and ammonia.

sugars and organic acids are formed. As a result of chemical reactions between amino acids and organic acids. build proteins. Three billion years ago a virus like organism developed from these early proteins. The first creatures were extremely small and like a blue-green algae. Thereafter, single-celled organism protozoan were originated. Generally. this gradual change move towards the complex organisms from simpler one.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 2.
Describe in short the evidences of organic evolution with diagrams.
Answer:
Evidences of organic evolution are following –
1. Evidences from classification –
Classification of animals. from protozoa to echinodermata is the gradual evolution of all animals. Similarly all classes of chordate have many similarities. Animals of class pisces developed b non-chordates. It is proven that all organisms evolved from a common ancestor like many branches originated from the main stern of a tree.
RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution-11

2. Structural evidences – There are Two evidences:

  1. Homologous organs – The origin and basic structure of skeleton in whale. bird. bat and human, is same but functions are different.
  2. Analogous organs – wing of insects, birds. bat have same functions but different structures.

3. Palaentological evidences –
Remains of dead animals and plants or their impressions found in rocks are called fossils. These are found in sedimentary rocks. It is a most concrete evidence of evolution.

4. Evidences from vestigial organs –
Some organs are found in animals, today which are present in the form of remains. But the were highly developed and functional in their ancestors. These vestigial organs certify that in their ancestors, these organs were functional and ell developed. But overtime, as their utility decreases they remained as a vestigial. eg. caudal vertebrae in human.

5. Evidences from Physiology –
Based on this following evidences are –

  1. Similarities in digestive system.
  2. Similarity in skeleton.
  3. Evidence of the complexity of the heart.
  4. Similarities in blood protein.

6. Evidences from Embryology –
In multicellular animals, a unicellular zygote is formed by sexual reproduction which creates embryo by the division. When w.e sec fish. turtle. chicken. human’s embryos. early stages of them appears almost identical. This proves that the ancestor of all vertebrates resembles with fish and their development is certain b in order.

7. Evidences from connecting Link – eg. Archaeopteryx. It serves as connecting link between reptiles and birds, This animal had some features beak. wings. structure of legs etc. were similar to aves (bird) and some characteristics beak, tail, scales on body etc. were similar to reptiles.

8. Evidences from geographical distribution –
Now a day variations arc found in the geographical distribution of plants and animals.
For example – Platypus, Kangaroo, and eucalyptus plant is found in Australia only Similarly. Giraffe is found only in Africa. The geographic distribution is therefore also certifies organic evolution.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 3.
Explain the theory of mutation with factors.
Answer:
Theory of Mutation – Hugo de Vries gave the theory of mutation. When he tested some plants. found that some of the plants produced are quite different from their species. These traits arc inherited from generation to generation. These sudden variations in inherited characters are called mutation, Causes of Mutations – Mutations in animals can be caused b the following –

  1. change in number of genes
  2. change in gene arrangement
  3. change in gene structure

Means of Mutations –
Mustard gas. Nitrous acid, phenol. x-rays. Beta rays. etc.

Question 4.
What is Darwin’s theory or theory of natural selection ? Explain.
Answer:
Darwin’s theory – Charles Darwin gave a theory of natural selection for organic evolution. Different phases of Darw in’s theory are as under –
1. Production of off springs in living organisms –
Earth organism does production of off springs to maintain their race. Example elephant produces 8 off springs in her life span. It is a slow breeder. A pair of elephants began to breed regularly and engender that all off springs are regularly breeding in the 750 ears a pair will generate approximately. 1 .9 million elements and number of elephants will be very high. But this does not happen.

2. The struggle for survival –
Due to over production of off springs the struggle for space and food for the growing number of off springs take place. It is the struggle of survival. This struggle occurs in between animals of own species and with other species also which is capable of the same shall live Destruction due to struggle. the number of organisms will remains balanced and consistence in nature,

3. Natural selection –
In struggle of survival only those animals live who adapt them according to nature. If the are not able to do it. they arc destroyed.

4. Origin of the new species –
Inheritance of useful traits will continue from generation to generation and harmful traits gradually become extinct or remain as a vestigial organ. Sometimes variations increase so that after hundreds of millions of times new generation is more different from older generation and the development of a new race goes.

For example –
at the beginning dog. Jackals. and wolves, three were members of the same race but due to change in atmosphere to adapt themselves accordingly changes in their size and physical characteristics. After thousands of years dog. fox and wolf three new species was developed. Thereafter Darwin added new approaches to his old doctrine and gas a new doctrine of neo-Darwinism. According to this. the new species are originated due to gene variation into the members of the particular species. Only genetic variations are inherited and environmental characteristics ends with animal die.

RBSE Solutions for Class 7 Science Chapter 7 Organic Evolution

Question 5.
Give information’s about palaeob-anical scientist Prof. Birbal Sahni.
Answer:
Palacobotanist who enchanted the word with interesting tidbits. Birbal Sahni was born on November 14, 1891 at Bhcra village: in the Shalpur district. He is the founder of palaeobotanical research in India. Amongst a large number of fossil plants described by him from Rajmahal Hills of Bihar.

was his most remarkable discovery of a new group of fossil gvmnospcrnl. to which he gave the name Pentoxylae. His works on the Technique of casting coins in ancient lndïa” set a new standard in archaeological research in India. He founded the institute of Palaeobotanv at Lucknow. which was later renamed as Birbal Sahni Institute of palaeobotan’ after his death.

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