heredity and evolution exercise
heredity and evolution exercise answers
heredity and evolution class 10 exercise answers state board
1. Complete the following diagram.
2. Read the following statements and justify same in your own words with the help of suitable examples.
a. Human evolution began approximately 7 crore years ago.
Ans :
i) Although time of descent of man is controversial subject but fossil evidence indicates that time of evolution of man is approximately 7 crore years ago.
ii) Last dinosaurs disappeared approximately seven crore years ago. At that time, monkey-like animals are said to be evolved from some ancestors who were more or less similar to the modern lemurs.
iii) Tail of these monkey-like animals of Africa disappeared about 4 crores ago.
iv) Available fossils give the evidence that most of the fossils of pre-human ancestors including monkeys and apes have been recovered from Africa, Asia and Europe.
b. Geographical and reproductive isolation of organisms gradually leads to speciation.
Ans :
i) The process by which new species develop from the existing species known as speciation. In other words, formation of new species of plants and animals is the effect of evolution.
ii) Species is the group of organisms that can produce fertile individuals through natural reproduction.
iii) Each species grows in specific geographical conditions. Their food, habitat, reproductive ability and period is different.
iv) However, genetic variation is responsible for formation of new species from earlier one. Besides, geographical and reproductive changes are also responsible. Similarly, geographical and reproductive isolation also leads to speciation.
c. Study of fossils is an important aspect of study of evolution.
Ans :
i) Large number of organisms get buried due to disasters like flood, earthquake, volcano, etc. Remnants and impressions of such organisms remain preserved underground. These are called as fossils and the study of fossils is an important aspect of study of evolution.
ii) Once the age of fossil is been determined, it becomes easy to deduce the information about other erstwhile organisms.
d. There is evidences of fatal science among chordates.
Ans :
i) The chordates and the hemichordes had a common ancestor earlieas 500 mayor.
ii) There was also an extreme conservation of the phylotypic compartment map which could act as an evidence that development constrains future avenues. This is because after the compartments have been established whereby each compartment shows large flexibility.
iii) The structure of the fatal science among chordates mitigated the pleiotrophy problems/ conflating effects of those mutants whose actions could be beneficial.
3. Complete the statement by choosing correct options from bracket.
(Gene, Mutation, Translocation, Transcription, Gradual development, Appendix)
a. A causality behind the sudden changes was understand due to ........... principle of Hugo de Vries.
Ans :
A causality behind the sudden changes was understand due to Mutation principle of Hugo de Vries.
b. The proof for the fact that protein synthesis occurs through ............. was gives by George Beadle and Edward Tatum.
Ans :
The proof for the fact that protein synthesis occurs through Gene was gives by George Beadle and Edward Tatum.
c. Transfer of information from molecule of DNA to mRNA is called as .............. process.
Ans :
Transfer of information from molecule of DNA to mRNA is called as transcription process.
d. Evolution means ...................
Ans :
Evolution means Gradual development.
e. Vestigial organ ............. present in human body is proof of evolution.
Ans :
Vestigial organ Appendix present in human body is proof of evolution.
4. Write short note based upon the information known to you.
a. Lamarckism
Ans :
i) Lamarckism is the hypothesis that an organism can pass on characteristics that it has acquired during its lifetime to its offspring.
ii) It is also known as the inheritance of acquired characteristics or soft inheritance.
iii) Jean-Baptiste Lamarck proposed that morphological changes occurring in living organisms are responsible for evolution and the reason behind those morphological changes is activities or laziness of that organism.
iv) He called this concept as principle of 'use or disuse of organs'.
v) The neck of giraffe has become too long due to browsing o leaves of tall plants by extending their neck for several generations; similarly, shoulders of the ironsmith have become very strong due to frequent hammering movements.
vi) Wings of birds like ostrich and emu have become weak due to no use.
vii) Legs of the birds like swan and duck have become useful for swimming due to living in water and snake have lost their legs by modifications in their body for burrowing habit.
viii) All these examples are types of 'acquired characters' and are transferred from one to another generation. This is called as theory of inheritance of acquired characters or Lamarckism.
b. Darwin's theory of natural selection
Ans :
i) Charles Darwin had collected innumerable specimens of plant and animals and depending upon the observations of those specimens; he published the theory if natural selection which preaches the survival of fittest.
ii) For this purpose, Darwin had published a book titled 'Origin of Species'.
iii) While explaining the concept, Darwin said that al the organisms reproduce prolifically. All the organisms compete with each other in a life threatening manner.
iv) In this competition, only those organisms sustain which show the modifications essential for winning the competition.
v) However, besides this, natural selection also plays important role because nature selects only those organisms which are fit to live and the res perish.
vi) Sustaining and selected organisms can perform reproduction and thereby give rise to the new species with their own specific characters.
vii) Darwin's theory of natural selection was widely accepted for long duration. However, some objection were raised against the theory. Some of the main objections are -
1) Natural selection is not the only factor responsible for evolution.
2) Darwin did not mention any explanation about useful and useless modifications.
3) There is no explanation about slow changes and abrupt changes.
c. Embryology
Ans :
It is the study of prenatal development of gametes, fertilization and development of embryos and fetuses. The ball of dividing cells that results after fertilization is termed as an 'embryo' for eight weeks and from nine weeks after fertilization the term used is 'fetus'.
An embryo is an immature organism contained within the coverings of an egg or within the body of the mother. Embryology considers the mechanisms of both sexual reproduction and regeneration.
d. Evolution
Ans :
i) Evolution is the gradual change occurring in living organisms over a long duration.
ii) This is a very slow going process through which development of organisms is achieved.
iii) All the stages in changes occurred in various components ranging from stars and planets in space to the biosphere present on the earth should be included in the study of evolution.
iv) Formation of new species due to changes in specific characters of several generations of living organisms as a response to natural selection, is called as evolution.
e. Connecting link
Ans :
i) Some plants and animals show some morphological characters by which they can be related to two different groups; hence they are called as 'connecting links'.
ii) Ex. In Peripatus, characters like segmented body, thin cuticle, and parapodia-like organs are present. Similarly, these animals show tracheal respiration and open circulatory system similar to arthropods. This indicates that Peripatus is connecting link between annelida and arthropoda.
iii) Similarly, duck billed platypus lays eggs like reptiles but shows relationship with mammals too due to presence of mammary glands and hairs. Lung fish performs respiration with lungs irrespective of being fish. These examples indicate that mammals are evolved from reptiles and amphibians from fishes.
5. Define Heredity. Explain the mechanism of hereditary changes
Ans :
i) Heredity is the transfer of biological characters from one generation to another via genes.
ii) It is also called mechanism of inheritance.
iii) Mechanisms that increase genetic variation include mutation, recombination and gene flow.
iv) Mutation generally occurs via chromosomal mutations, point mutation, frame shift and breakdown in DNA repair mechanisms. Ex. Mutation may cause the genetic disorders like sickle cell anemia.
v) Chromosomal mutation include translocation, inversion, deletions and chromosome non disjunction.
vi) Point mutation may be nonsense mutation leading to early termination of protein synthesis.
6. Define vestigial organs. Write names of some vestigial organs in human body and write the names of those animals in whom some organs are functional
Ans :
Definition : Degenerated or under developed useless organs of organisms are called as vestigial organs. In humans, Appendix is useless but it is useful and fully functional organ in ruminants. Similarly, muscles of ear pinna, are also useless in humans but are useful in monkeys for movement of ear pinna.
7. Answer the following questions.
a. How are the hereditary changes responsible for evolution ?
Ans :
Hereditary is the transfer of biological characters from one generation to another via genes. Formation if new species dur to changes in specific characters of several generations of living organisms as a response to natural selection is called as evolution. Evolution is the gradual change occurring in living organisms over a long duration. This is a very slow-going process through which development of organisms is achieved.
b. Explain the process of formation of complex proteins
Ans :
The amino acids brought in by tRNA are bonded together by peptide bonds with the help of rRNA. During this process, the ribosome keeps on moving from one end of mRNA to other end by the distance of one triplet codon. This is called as 'translocation'. Such many chains come together to form complex proteins. These proteins control various functions in the body of living organisms and their appearance too.
c. Explain the theory of evolution and mention the proof supporting it
Ans :
Progressive development of plants and animal from the ancestors having different structural and functional organization is called evolution. According to the theory of evolution, first living material (protoplasm) has been formed in ocean. In due course of time, unicellular organism was formed. Gradually, changes occurred in the unicellular organisms from which larger and more complex organisms were formed. All those changes were slow and gradual. Duration of all these changes is at the most 300 crore years. Changes and development in living organisms had been all round and multi-dimensional and this let to evolution of different types of organisms. Hence, this overall process is called as evolution which is organizational. Collective thinking on the theory of evolution implies that it is an everlasting process of changes.
Following are the various proofs available in support of the theories -
1) Morphological Evidences - Similarities in superficial characters.
2) Anatomical Evidences - Similarities in bone structures.
3) Vestigial Organs - Degenerated or underdeveloped useless organs of organisms. Example: Tail bone (coccyx), Appendix, Wisdom teeth and Body hairs.
4) Paleontological Evidences - Study of fossils.
5) Connecting links - Plants and animals show some morphological characters by which they can be related to two different groups.
6) Embryological Evidences - Comparative study of embryonic developmental stages of various vertebrates.
d. Explain with suitable examples importance of anatomical evidences in evolution
Ans :
i) Organisms with similar anatomical features are assumed to be relatively closely related evolutionarily and they are assumed to share a common ancestor.
ii) Some organisms have anatomical structure that are very similar in embryological development and form but very different in function.
iii) Since, these structure are so similar, they indicate an evolutionary relationship and a common ancestor of the species that possess them.
iv) If the pictures are carefully observed, it will be seen that there doesn't seem any superficial similarity between human hand, cat's fore leg, flipper of whale and patagium of bat.
v) Similarly, use of each of those structures is different in respective animals.
vi) However, there is similarity in structure of bones and bony joints in organs of each of these animals. This similarity indicates that these animals may have common ancestor.
e. Define fossil. Explain importance of fossils as proof of evolution
Ans:
Definition : The remains of dead plants and animals that lived in the remote past are known as fossils.
Fossils help in the study of evolution in following ways -
i) Fossils exhibit mode of preservation of ancient species.
ii) Fossils establish evolutionary relationship between organisms and their ancestors.
iii) Fossils establish the geological time period in which organisms existed.
f. Write evolutionary history of modern man
Ans :
i) Modern humans originated in Africa within the past 200,000 years and evolved from the upright man.
ii) Evolution of upright man continued in the direction of developing its brain for the period of about 1 lakh years and meanwhile it discovered fire.
iii) Brain of 50 thousand year old man had been sufficiently evolved to the extent that it could be considered as member of the class-wise man.
iv) A modern human (Homo sapiens), the species that we are, means 'wise man' in Latin.
v) Netherland man can be considered as the first example of wise-man. The Cro-Magnon man evolved about 50 thousand years ago and afterwards, this evolution had been faster than the earlier.