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Karnataka 2nd PUC Biology Question Bank Chapter 7 Evolution
2nd PUC Biology Evolution One Mark Questions and Answers
Question 1.
What is a abiogenesis?
Answer:
It is the process of the appearance of first form of life slowly from non living molecules.
Question 2.
Define Analogous organs.
Answer:
The organs which perform the same function but differ in their origin and structures are called. analogous organs.
Question 3.
Define homologous organs.
Answer:
The organs which have similar embryonic orgin but they perform the different functions.
Question 4.
What is paleontology?
Answer:
It is the branch of science that deals with fossils.
Question 5.
Define evolution as per Hardy Weinberg.
Answer:
As per Hardy weinberg, change of frequency of alleles in a population would be considered as evolution i.e., disturbance in the genetic equilibrium.
Question 6.
What is meant by gene flow?
Answer:
Changes in the gene pool of population when there is continuous migration of organisms between them i.e., it refers to the additon or loss of genes.
Question 7.
Define genetic drift/Sewall Wright effects.
Answer:
Random changes in the allelic frequencies of a population, occuring only by chance events, r constitute genetic drift.
Question 8.
Name the modern Darwinism theory that incorporates DNA and the concept of molecular biology?
Answer:
Neo-Darwinism or synthetic theory of evolution.
Question 9.
DDT was known to be a highly effective insecticide in the past. Why did it not wipe out all mosquito population?
Answer:
Some of the mosquitoes had developed a mutant gene for DDT resistance.
Question 10.
Name the phenomenon by which rapid speciation takes place?
Answer:
Genetic Drift.
Question 11.
Name the two scientists who set up a special experiment to prove Oparin’s theory of 1 origin of life?
Answer:
Urey and Miller.
Question 12.
What provided energy for a biotic synthesis on primitive earth?
Answer:
Very-high temperatures due to lightening or uv – rays provided energy for biotic synthesis.
Question 13.
Who showed that life comes from pre-existing life?
Answer:
Louis Pasteur.
Question 14.
What is meant by Gene pool?
Answer:
Gene pool refers to sum total, of different kinds of genes pooled by all the members of a population.
Question 15.
State Hardy-Weinberg principle.
Answer:
It states that the allele frequencies in a population are stable and constant from generation to ’
generation.
Question 16.
Write the scientific name of man who lived about 1.5 million years ago and probably ate meat.
Answer:
Homo erectus.
2nd PUC Biology Evolution Two Marks Questions and Answers
Question 1.
What is the significance of archaeopteryx in the study of organic evolution?
Answer:
Archaeopteryx is a connecting link fossil between reptiles and birds. It shows features of both the birds and the reptiles, giving an evidence that birds have evolved from reptiles.
Question 2.
Differentiate between Homo habilis and Homo erectus.
Answer:
Homo habilis:
(a) They were the first human-like beings, the hominids.
(b) They had a brain capacity of 650-800 cc.
(c) They probably did not eat meat.
Homo erectus:
(a) Their fossils were found in Java (Java man) in 1981. They probably lived about 1.5 million years ago.)
(b) They had a brain capacity of about 900cc.
(c) They probably ate meat.
Question 3.
What are coacervates? Give their importance in the origin of life.
Answer:
Coacervate is defined as colloidal droplet in which the suspended particles like protein and negative electrical charges are present. This phenomenon is called coacevation. They exhibited properties of life like growth and the surface layer of the coacevate had the ability to absorb substances from the medium.
The protoplasm in the cells is similar to a coacervate.
Question 4.
What is convergent evolution? Give an example.
Answer:
The evolutionary process in which anatomically different structures in different groups of organisms evolve towards the same function,
e.g : eyes of Octopus and mammals
Wings of butterflies and birds.
Flippers of whales and penguins.
Tubers of sweet potato and potato.
Question 5.
What is adaptive radiation? Give an example.
Answer:
Adaptive radiation is an evolutionary process in which an ancestral stock gives rise to new species in a given geographical area, starting from a point and literally radiating to other geographical areas or habitats.
e.g., I. Darwin’s finches.
Question 6.
Define the terms :
(a) Gene Flow
(b) Genetic drift.
Answer:
(a) Gene flow is defined as the transfer of genes between two interbreeding populations which differ genetically. Migration and hybridization are the chief sources of gene flow. The gene flow pattern decides the gene frequency of a population
(b) Genetic drift or Sewall Wright effect is defined as “Random changes in gene frequency in a small interbreeding population happen purely by change”. As a result of genetic drift, some genes may be reduced or increased in frequency. Some of them may even be lost by chance. This genetic drift leads to the fixation or loss of certain genes irrespective of their adaptive value.
Question 7.
What are analogous organs? Give examples.
Answer:
Analogy is the relationship among organs of different groups of organisms performing the same function, irrespective of structural or anatomical differences.
Some examples of organs showing analogy are ;
- Eyes of octopus and those of mammals.
- Wings of a butterfly (insect) and those of birds.
- Flippers of whales or dolphins and those of penguins.
- Tubers of sweet potato (root modified) and those of potato (stem modified).
Analogy is the result of convergent evolution, i.e., the evolutionary process, where anatomically different structures in different groups of organisms evolve towards the same function. It is the similar habitat conditions that have selected similar adaptive features in different groups of organisms, towards the same function;
Question 8.
‘Darwin’s finches represent one of the best examples for adaptive radiation”. Comment.
Answer:
Adaptive radiation is an evolutionary process in which an ancestral stock gives rise to new species in a given geographical area, starting from a point and literally radiating to other geographical areas or habitats.
e.g. I. Darwin’s finches.
These were small black birds which Darwin observed in Galapagos island
There were many varieties in the same island.
2nd PUC Biology Evolution Three Marks Questions and Answers
Question 1.
Write a short note on analogous and homologous organs?
Answer:
1. Homology: Homology is the relationship among organs of different groups of organisms, that show similarity in their basic structure and embryonic development, but perform different functions.
Homology of organs of different organisms indicates their common ancestry.
Homology is found in the bones of forelimbs of whales, cheetah, birds, amphibians and humans; they have similar basic anatomical structure with the bones humerus, radius, ulna, carpals, metacarpals and phalanges.
Other examples are the hearts and brains of vertebrates.
Among plants, the thorns of Bougainvillea and tendrils of Cucurbita represent homology.
Homology or homologous organs is/are the result of divergent evolutions, i.e., the evolutionary process where the same structure develops along different directions due to adaptations for different needs.
2. Analogy: Analogy is the relationship among organs of different groups of organisms performing the same function, irrespective of structural or anatomical differences.
Some examples of $rgans showing analogy are :
- Eyes of octopus and those of mammals.
- Wings of a butterfly (insect) and those of birds.
- Flippers of whales or dolphins and those of penguins.
- Tubers of sweet potato (root modified) and those of potato (stem modified).
Analogy is the result of convergent evolution, i.e., the evolutionary process, where anatomically different structures in different groups of Organisms evolve towards the same function. It is the similar habitat conditions that have selected similar adaptive features in different groups of organisms, towards the same function.
Question 2.
Name the following
(a) This man like primate walked in eastern Africa.
(b) This primate lived in east African grassland;
(c) The primate which lived in east and central Asia between 1,00,000 to 40,000 years back.
Answer:
(a) Rampithecus
(b) Australopithecus
(c) Neanderthal man.
Question 3.
State Hardy-Weinberg equilibrium and mention the factors affecting the equilibrium of a population.
Answer:
Hardy Weinberg Law or Hardy Weinberg Equilibrium: This law was proposed by British Mathematician Hardy and German Physicist E. Weinberg. The Law states that “Gene frequency of a Mendelian population remains constant through generations unless there are chromosomal aberrations, mutation etc to alter the genetic equilibrium”.
This law describes that when the population is in equilibrium there is no evolution. Evolution occurs only when the equilibrium is altered. Mendelian population is a closely interbreeding group of organisms sharing a common gene pool.
Evolutionary factors like mutation, migration, genetic drift, gene flow, and sexual reproduction are factors affecting the equilibrium of a population.
Question 4.
a) Write a note on homologous organs.
b) Write the scientific name of man like primate who lived in East African grasslands about 3- 4 million years ago.
Answer:
(a) Homology is the relationship among organs of different groups of organisms, that show similarity in the basic structure and embryonic development, but perform different functions.
Homology of organs of different organisms indicates their common ancestry.
Homology is found in the bones of forelimbs of whales, cheetah, birds, amphibians and humans; they have similar basic anatomical structure with the bones humerus, radius, ulna, carpals, metacarpals and phalanges.
Other examples are the hearts and brains of vertebrates.
Among plants, the thorns of Bougainvillea and tendrils of Cucurbita represent homology.
Homology or homologous organs is/are the result of divergent evolution, i.e., the evolutionary process where the same structure develops along different directions due to adaptations for different needs.
(b) Australiopithecines.
Question 5.
Define homology. Mention any four evidences in support of evolution;
Answer:
Homology: Homology is the relationship among organs of different groups of organisms, that show similarity in their basic structure and embryonic development, but perform different functions.
Evolution: There are plenty of evidences in support of organic evolution but the mechanism of evolution has been interpreted in different ways by different scientists. As a result of this, there are many theories to explain the mechanism of evolution like
- Use and Disuse theory of Lamarck (Lamarckism)
- Theory of natural selection by Darwin (Darwinism)
- Mutation theory by Hugo De varies
- Neo Darwinism
- Neo Lamarckism
2nd PUC Biology Evolution Five Marks Questions and Answers
Question 1.
What was the experiment of Stanley Miller (1953) on the origin of life?
Answer:
Stanley Miller’s Experiment / Harold Urey – Miller’s experiment :
In 1953, Stanley Miller under the guidance of his professor Harold Urey conducted an experiment ‘ to investigate the conditions under which the simplest organic compounds were formed from the gases of the primitive earth. Miller designed a glass apparatus called “Spark-discharge apparatus” to conduct the experiment: Spark discharge apparatus is roughly rectangular in shape with a Spark discharge chamber, water boiler, U-trap condensers all of which were connected by a rectangular side tube as shown in the diagram.
The side tube is connected to the vacuum pump or stop cock, water was taken in the round bottom flask and the entire apparatus was evacuated to remove the free molecular oxygen. A mixture of gases like methane, hydrogen, and ammonia in the ratio of 2 : 1 : 2 by volume were passed into the apparatus. The water in the round bottom flask was boiled to produce steam which was circulated clockwise in the apparatus.
The spark discharge chamber contained two tungsten electrodes which were connected to a sparking coil that produced continuous discharge of sparks which served as sources of energy similar to lighting of the primitive Earth. The convectional current created by the circulation of the steam, carried the gases across the electrodes.
The cooling jacket or condenser present below the sparking chamber, condensed the steam and the contents were collected in the U-trap. When the products were analyzed it was found that there were a number of simpler organic compounds such as amino acids, acetic acid, propionic acid etc. The acids formed were alanine, glycine, aspartic acid, glutamic acids etc.
Formation of amino acid is an important step in the origin of life. This Miller’s experiment provided the vital proof that organic compoundecfcan be formed form simple inorganic molecules under the conditions that existed on the primitive earth. This proves the origin of life from chemical substances.
Question 2.
How did industrial revolution in England offer an example to natural selection? ,
Answer:
Industrial melanism in peppered moths : Beforel840 ie., before the industrial revolution in England there was the British peppered moth, Bistort betularia in abundance. This moth was speckled i.e., grey With dark pepper like spots on the wings. There were also dark or melanic forms of Bistort carbonaria but they were extremely rare.
Before industrialization the tree trunks were all covered with grey speckled lichens. This provided good camouflage or matching background for the peppered moths from predatory birds like robbins. Peppered variety formed 99% and the melanic variety formed 1% of the moth population.
In the late 1850s, due to industrialization, the pollutants released from the industries killed or dried the lichens and darkened the tree trunks by black soot emitted by factories. As a result the peppered moths fell prey to predators because they could be easily seen than the black mutant moths (melanic forms) which began surviving better than the grey-coloured moths.
Due to industrial smoke now 99% of moths are of the black variety, proving the point of natural selection and survival of the Attests. This indicates the natural selection eliminated the gene for light colour (harmful or favourable variation). The phenomenon was observed by a group of scientists led by Dr. H.B.D Kettlewell of Britain* R.A.Fischer, E.B Ford etc.
Question 3.
What is Neo-Darwinism? What are its advantages over Darwinism?
Answer:
This is also called as modern concept of organic evolution. The concept of Neo-Darwinism is a view of evolutionary theory arising out of a combination of Mendelian genetics, mutation theory by De Vries with Darwinism a group of eminent scientists lie Dobzhansky, De Vries, Weismaa, Fischer, J.B.S Haldane, H.J. Mulles, simpson, Gold Schmidt, Sewall Wright, Huxlay etc., constituted a group called Neo-Darwinism school of thought.
According to Neo-Darwinism, the gene pool in sexually reproducing organisms is the focal point to interpret evolutionary changes brought about by mutation, gene flow, genetic drift, genetic recombination, chromosomal aberrations, natural selection and isolation.
1. According to Darwinism, rapid rate of reproduction leads to struggle for existence during which useful variations help in the survival of an organism picked up by natural selection. The accumulation of such variations from generation to generation is responsible for the origin of a new species while according to Neo-Darwinism change in the gene frequency is evolution.
2. According to Darwinism, source of variation was not explained. The somatic and germinal variations were not differentiated and were considered as heritable while Neo-Darwinism differentiates somatic and germinal variations and has understood the principle of inheritance.
3. According to Darwinism, evolution operates on an organism while Neo-Darwinism believes that evolution operates on a gene pool.
4. According to Darwinism, natural selection operates through survival of the fittest, while in Neo-Darwinism natural selection operates the differential reproduction and comparative reproductive success.
5. According to Darwinism, the survival of the fittest was explained-but not the arrival of the fittest while Neo-Darwinism explains the arrival of the fittest.