Samacheer Kalvi 10th Science Solutions Chapter 19 Pdf
Tamilnadu Board Samacheer Kalvi 10th Science Solutions Chapter 19: Tamilnadu State Board Solution Class 10 Science Chapter 19 – ORIGIN AND EVOLUTION OF LIFE.
Samacheer Kalvi 10th Science Solutions Chapter 19: Overview
|ORIGIN AND EVOLUTION OF LIFE|
Samacheer Kalvi 10th Science Solutions Chapter 19 Pdf
I choose the correct answer
1> Biogenetic law states that ______________
- Ontogeny and phylogeny go together
- Ontogeny recapitulates phylogeny
- Phylogeny recapitulates ontogeny
- There is no relationship between phylogeny and ontogeny
Ans: b. Ontogeny recapitulates phylogeny
Because, Biogenetic law states that Ontogeny recapitulates phylogeny
2> The ‘use and disuse theory’ was proposed by ______________.
- Charles Darwin
- Ernst Haeckel
- Jean Baptiste Lamarck
- Gregor Mendel
Ans: c. Jean Baptiste Lamarck
Because, the use and disuse theory of organs was postulated by Jean Baptiste Lamarck.
3> Paleontologists deal with
- Embryological evidences
- Fossil evidences
- Vestigial organ evidences
- All the above
Ans: b. Fossil evidences
Because, Paleontologists deal with fossils evidences.
4> The best way of direct dating fossils of recent origin is by
- Radio-carbon method
- Uranium lead method
- Potassium-argon method
- Both (a) and (c)
Ans: a. Radio-carbon method
Because, the radioactive carbon C14 dating method is mainly used for determining age of fossils.
5> The term Ethnobotany was coined by
- J.W. Harsbberger
- Ronald Ross
- Hugo de Vries
Ans: b. J.W. Harsbberger
Because, Ethnobotany was coined by J.W. Harsbberger
II Fill in the blanks
1> The characters developed by the animals during their life time, in response to the environmental changes are called ______________.
Ans: The characters developed by the animals during their life time, in response to the environmental changes are called acquired characters.
2> The degenerated and non-functional organs found in an organism are called ______________.
Ans: The degenerated and non-functional organs found in an organism are called vestigial organ.
3> The forelimbs of bat and human are examples of ______________ organs.
Ans: The forelimbs of bat and human are examples of homologous organs.
4> The theory of natural selection for evolution was proposed by ____________.
Ans: The theory of natural selection for evolution was proposed by Charles Darwin,
III State true or false. Correct the false statements
1> The use and disuse theory of organs’ was postulated by Charles Darwin.
Correct statement: The use and disuse theory of organs was postulated by Jean Baptiste Lamarck.
2> The homologous organs look similar and perform similar functions but they have different origin and developmental pattern.
Correct statement: The homologous organs look dissimilar and perform dissimilar functions but they have the same origin and developmental pattern.
3> Birds have evolved from reptiles.
IV Match the following
- Atavism: rudimentary tail and thick hair on the body
- Vestigial organs: caudal vertebrae and vermiform appendix
- Analogous organs: a wing of bat and a wing of an insect
- Homologous organs: a forelimb of a cat and a bats wing
- Wood Park: Thruvakkarai
- F. Libby: radiocarbon dating
V Answer in a word or sentence
1> A human hand, a front leg of a cat, a front flipper of a whale and a bat’s wing look dissimilar and adapted for different functions. What is the name given to these organs ?
Ans: A human hand, a front leg of a cat, a front flipper of a whale and bat’s wing look dissimilar and adapted for different functions, these organs are called as homologous organs.
2> Which organism is considered to be the fossil bird?
Ans: Archaeopteryx is the oldest called as fossil bird.
3> What is the study of fossils called?
Ans: The study of fossils is called as palaeontology.
VI Short answers questions
1> The degenerated wing of a kiwi is an acquired character. Why is it an acquired character?
Ans: Kiwi do not have wings because kiwi does not have any need to fly. The characters which are developed by animals during their life time to response the environmental changes are called acquired characters.
The vestigial wings are very small. Hence the degenerated wings of kiwi is an acquired character.
2> Why is Archaeopteryx considered to be a connecting link?
Ans: Archaeopteryx is called as link between reptiles and birds because it has wings with feathers, like a bird. And also it has long tail, clawed digits and conical teeth like a reptiles.
3> Define Ethnobotany and write its importance.
Ans: Ethnobotany is the study of a region’s plants and their practical uses through the traditional knowledge of the local culture of the people.
The importance of ethnobotany is as follows.
- The traditional uses of plant is provided by ethnobotany.
- The information about certain known and unknown plants will be given by ethnobotany.
- The ethnomedicinal data will serve as a useful source of information for the chemists, pharmacologists and practitioners of herbal medicine.
- The ethnomedicinal plants part like bark, stem, leaves, flower buds, flowers, fruits, seeds, oils, resins, dyes, gum are utilized by tribal communities for the treatment of diseases like diarrhoea, fever, headache diabetes, jaundice, snakebites, leprosy etc.
4> How can you determine the age of the fossils?
- The age of fossils is determined by radioactive elements present in it. These radioactive elements may be carbon, uranium, lead or potassium.
- The radioactive carbon C14 dating method is mainly used for determining age of fossils. The decaying process of C14 occurs only when the consumption of carbon stops.
- After the death of animals and plants, carbon consumption stops. Hence, by measuring the amount of carbon C14 in the body of dead animal or plants, the age will be determined from the time of their death.
VII Long answer questions
1> Natural selection is a driving force for evolution-How?
- Survival for the fittest or natural selection is explained as follows.
- The organisms which overcome the challenging situations, survive and adapt to the surrounding environment during their struggle for existence. The organisms unfit to survive and disappear who are unable to face the challenges.
- The process of selection of organisms on the basis of adoptable variations is called as natural selection.
2> How do you differentiate homologous organs from analogous organs?
- The homologous organs are those which are having inherited from common ancestors with similar developmental pattern in embryo.
- Their basic structure of bone are similar.
- For example: A human hand, flipper of a whale and bat’s wing.
- The analogous organs are similar in looking and functions also but they are having different origin and developmental pattern.
- Analogous organs are having different basic structures.
- For example: wings of bat, wings of bird and wings of insects etc.
3> How does fossilization occur in plants ?
The process of formation of fossils in the rocks is called as fossilization.
There are different methods of fossilization which are discussed as follows.
- Silica slowly penetrate in and by replacing the original organic tissue it forms the rock like fossils. By this method of fossilisation hard and soft parts can be preserved.
- Mainly wood fossils and bones are petrified.
2.) Mold and cast:
- In sedimentary rocks the replica of plants or animals is preserved
- When the organisms get buried in then they get dissolved by underground water by leaving a hollow depression called as mold. This hollow depression is filled by minerals or sediment and forms the cast.
- The original remains are preserved in ice or amber which protects the organisms from decay so that the entire animal and plant will be preserved.
- When organisms dies their hard part will be settled down at the bottom of sea bed which covered by sediment. This process of sedimentation continues to form the fossils.
5.) Infiltration or replacement:
- After precipitation of minerals, the cell wall get unfiltered later and this process occurs through the elements like silica, calcium carbonate and magnesium carbonate which replace and dissolve the hard parts.
IX Higher Order Thinking Skills (HOTS)
1> Arun was playing in the garden. Suddenly he saw a dragon fly sitting on a plant. He observed the wings of it. He thought it looked similar to a wing of a crow. Is he correct? Give reason for your answer.
Ans: Arun’s observation is not correct because both the crow and dragonfly has same function of wings as flying but their basic structures are different.
Since, dragonfly’s wings are extended from membranous while in crow’s wings are modification in forelimbs.
2> Imprints of fossils tell us about evolution how?
Ans: Because, the study of fossils helps to us to understand the line of evolution of many invertebrates and vertebrates. The records of fossils shows evolution is a gradual process from simple to complex organisms. The origin of modern birds is given by the evidences from palaeontology.
3> Octopus, cockroach and frog all have eyes. Can we group these animals together to establish a common evolutionary origin? Justify your answer.
Ans: Convergent evolution is the process by using it we can evolved independent features which may be similar to each other but originated from different developmental pathways. Similar things happens in case of eyes of octopus, frog and cockroach. These eyes may similar with each other but they are originated from different developmental pathways.
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