2nd PUC Biology Question Bank Chapter 7 Evolution

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Karnataka 2nd PUC Biology Question Bank Chapter 7 Evolution

2nd PUC Biology Evolution  NCERT Text Book Questions and Answers

Question 1.
Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Answer:
When a bacterial population encounters a particular antibiotic, those sensitive to it, die. Sometimes a bacterial population happens to contain a few bacteria having mutations which make them resistant to the antibiotic. Such resistant bacteria survive and multiply quickly. Soon the resistance providing genes become widespread and entire bacterial population becomes resistant. This type of sorting out of the organisms with useful variations has been called as ‘natural selection’ by Darwin.

Question 2.
Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Answer:

• Fossil of small terrestrial dinosaur with feathers covering limbs and body. (Archaeopteryx lithographic)
• Mesohippus – intermediate horse size of goat with 3 toes on each foot and molar teeth had serration.

Question 3.
Attempt giving a clear definition of the term species.
Answer:
Species (used both as singular and plural) is a natural population of individuals or group of populations which resemble one another in all essential morphological and reproductive characters so that they are able to interbreed freely and produce fertile offspring.

Question 4.
Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
Answer:

Question 5.
Find out through the internet and popular science articles whether animals other than man have self-consciousness.
Answer:
Yes, chimpanzees are most near to man than any other living animal and have self-consciousness.

Question 6.
List 10 modern-day animals and using the internet resources link it to a corresponding
ancient fossil. Name both.
Answer:
Please do survey in internet.

Question 7.
Practice drawing various animals and plants.
Answer:
Please practice drawing.

Question 8.
Describe one example of adaptive radiation.
Answer:
The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation. Adaptive radiation gave rise to Australian marsupials. A number of marsupials, each different from the other evolved from an ancestral stock, but all within the Australian island continent.

Question 9.
Can we call human evolution adaptive radiation?
Answer:
No, we cannot call human evolution adaptive radiation

Question 10.
Using various resources such as your school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.
Answer:
E.g.: Horse – See textbook diagram

2nd PUC Biology Evolution Additional Questions and Answers

2nd PUC Biology Evolution One Mark Questions 

Question 1.
Name the non-cellular organism.
Answer:
Virus.

Question 2.
It is said the earth has formed about 4.5 billion years back. How did the earth crust and atmosphere formed according to Big Bang theory?
Answer:
It is said there was no atmosphere on early earth and the earth was a hot ball of gases. With the passage of years, the gases condensed into a molten core and different elements got stratified according to their density. Heavy elements such as iron, nickel etc. sank deep into centre and formed the core. Lighter elements like silicon, aluminum etc. formed the middle layer, while the lighter elements like hydrogen, helium, nitrogen etc. formed the gaseous part.

Question 3.
Releasing of 02 by the evolution of photosynthesis an ancient time is called?
Answer:
Oxygen revolution.

Question 4.
Define analogous organs. (CBSE 93,94,2007)
Answer:
The organs which perform the same function but differ in their origin and structures are called analogous organs.

Question 5.
Where did life originate?
Answer:
In water.

Question 6.
What is paleontology?
Answer:
It is the branch of science that deals with fossils.

Question 7.
Name the method of the changing of the structure of a gene resulting in a variant form that may be transmitted to.
Answer:
Mutation.

Question 8.
Name any two vertebrate body parts that are homologous to human forelimbs.
(CBSE 2008)
Answer:
Wings of birds, flippers of whale forelimbs of cheetah, wings of bats.

Question 9.
Who wrote the origin of species?
Answer:
Charles Darwin.

Question 10.
Mention the type of evolution that has brought similarity as seen in potato tuber and sweet potato.
Answer:
Convergent evolution.

Question 11.
Who proposed the Recapitulation theory or Biogenetic law?
Answer:
Haeckel.

Question 12.
Thorns of Bougainvillea and tendrils of cucurbit are analogous or homologous.
Or
Wings of bird and forelimbs of horse are homologons or analogous
Or
Flippers of penguin and dolphin are analogous or Homologies.
What type of evolution has brought similarity in these cases? (CBSE 1992, Delhi 2009, Foreign 2009)
Answer:

• All these are homologous.
• Divergent type evolution has brought this similarity.

Question 13.
Name the theory by which earth is said to originate.
Answer:
The big bang theory.

Question 14.
What kind of evidence is afforded by Darwin’s finches in support of organic evolution? (CBSE 1991)
Answer:
Adaptive radiation i.e. All these finches evolved from a common ancestor but they diverge in various directions.

Question 15.
What is a mutation?
Answer:
New species originate due to changes of hereditary characters is called a mutation.

Question 16.
Define ontogenetic law.
Answer:
Ontogeny recapitulates phytogeny.

Question 17.
Which era is called the golden period of Dinosaurs?
Answer:
Mesozoic period is called the golden period of Dinosaurs.

Question 18.
As per Hugo deVries, what is the cause of speciation? (Delhi 2008, CBSE 1995)
Answer:
Mutation. (Single-step large mutation)

Question 19.
What is meant by genetic equilibrium?
Answer:
When allele frequencies in a population are stable, the allele frequency of a population remains constant. It is called as genetic equilibrium, i.e. the sum total of all the allelic frequency is one.

Question 20.
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 21.
Who is the early man of the modern human?
Answer:
Cro-Magnon peoples are early human of modern human.

Question 22.
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 addition or loss of genes.

Question 23.
Which human form first started to walk on two legs?
Answer:
Australopithecus form first started to walk on two legs.

Question 24.
Define natural selection?
Answer:
Natural selection is the process in which heritable variations that enable better survival, are enabled to produce and leave behind a greater number of progeny.

Question 25.
On the basis of evolution which human had a brain size of 1400cc?
Answer:
Neanderthal.

Question 26.
Define the term “reproductive isolation”.
Answer:
If the population of 2 different species whether they are isolated or not, cannot enter bread to produce offspring.

Question 27.
Differentiate between Dryopithecus and Ramapithecus.
Answer:
Dryopithecus was apelike but Ramapithecus was mostly human-like.

Question 28.
Name the group of animals that evolved into amphibians.
Answer:
Lobe-fins evolved into amphibians.

Question 29.
Mention the key concepts about the mechanism of biological evolution/ speciation according to
(a) Devries and
(b) Darwin (Delhi 2008)
Answer:
(a) De Vries – Mutation
(b) Darwin – Natural selection and branching descent.

2nd PUC Biology Evolution Two Marks Questions

Question 1.
What is a virus? Why is it treated as a link between living and non-living?
Answer:
Viruses are the simplest organisms of the earth, which consists of nucleic acid (DNA or RNA) surrounded by protein cover. It shows characteristics of living as well as non-living organisms.
(A) Living characters of virus:

• The virus shows structural differentiations.
• They contain hereditary material.
• They exhibit mutation.
• They spread plant and animal diseases.
• Growth and development present.
• They exhibit adaptation.
• They possess sensitivity.

(B) Non-living characters of virus:

• Lack protoplasm and cell organelles.
• Can be crystallized.
• No metabolic activities are seen.
• Cannot reproduce outside living cells.
• They lack enzymes.

Due to the above reason, viruses are considered as a link between the living and non-living organisms, thus, it is the first life that originated on the earth.

Question 2.
Life has originated in seawater. Justify the statement.
Answer:
According to Oparin and Haldane, the first cell protobionts arose in the broth (not dilute soup). So it is considered that life has originated in water.

Question 3.
Explain the origin of the earth.
Answer:
Origin of the earth:

• Earth was formed 4-5 billion years back.
• Initially, die surface was covered with water vapOur, methane, C02 and NH3.
• The UV rays of the sun broke water into hydrogen and oxygen.
• Hydrogen escaped and oxygen combined with NH3 and CH4 to form water, C02 and other gases, also forming die ozone layer.
• Cooling of water vapour led to rain which filled the depressions on earth’s surface, forming water bodies.

Question 4.
Ontogeny recapitulates phylogeny. Discuss.
Answer:
In the higher animals their development passes through stages which are similar to adult stages of lower animals which were their ancestors. For e.g. The tadpole larva of frog represents its fish like ancestors.

Question 5.
Given below are the names of 2 pairs of limbs. Categorize them into homologous and analogous organs, give reason.
(i) Human arm and fore leg of cow
(ii) Bat’s wing and Grass hopper’s wing. (CBSE 1999)
Answer:
(i) Human arm and foreleg of cow are homologous organs because they are built upon the same fundamental plan (pentadactyl pattern) but they perform different functions as grasping in man and locomotion in cow.

(ii) Bat’s wing and grass hopper’s wing are analogous organs because they perform the same function bat differ in their origin and structure. Wings of bats are modified forelimbs whereas grasshoppers wings are modified outgrowth of the body wall.

Question 6.
Give 2 examples each of analogy and homology in plants. (Hots)
Answer:
Analogy:

• Tubers of sweet potato and potato
• Tendrils of pea and cucurbits.

Homology:

• Tendrils of cucurbit and lemon thorn
• Tendrils of Pea and Spines of opuntia

Question 7.
What do you mean by analogous?
Answer:
Analogous organs: Organs which are different in origin and structure but per¬forming similar functions are known as analogous organs and the phenomenon is called an analogy. Analogous organs do not indicate phylogeny.
Examples: Wings of butterflies are made up of chitin, wings of birds made by production of feathers on forelimbs, and skin present between the fingers of bat are the examples of analogous organs.

Question 8.
Define adaptive radiation with 2 eggs. (Hots)
Answer:
Adaptive radiation is defined as the process of evolution of different species in a given geographical area starting from single species and radiated to other habitats.
Example:

• Australian marsupials, each different from the other, have evolved from ancestral stock.
• Darwin’s finches – from the original seed-eating stock insectivores and vegetarian birds have evolved.

Question 9.
What do you mean by vestigial organs?
Or
Write the two names of vestigial organs of man.
Or
What are vestigial organs? Explain. Write four vestigial organs of the human body.
Answer:
Vestigial organs: Organs that are reduced and have become functionless in an organism but were functional in their ancestors are called vestigial organs:
Examples:

• Vermiform appendix
• Coccygeal vertebrae
• The nictitating membrane in the eyes of human
• Muscles of external ear (Pinna).

2nd PUC Biology Evolution Three Marks Questions

Question 1.
Whose theory was put to test by Miller Urey and what was the theory? How did their experiment prove the abiotic origin of life on earth?
Answer:
Oparin and Haldane proposed that the first life form could have come from the „ nonliving organic molecules like RNA, protein etc.

• The orgaine molecules must have been produced by chemical evolution, i.e. formation of divers organic molecules from inorganic constituents.
• The condition, of the earth that favoured chemical origin were

(i) very high temperature
(ii) volcanic storms
(iii) Reducing atmosphere that contained methane, ammonia and water vapour.

• Energy must have been produced by U-V radiation and lightning.
• Analysis of the products of their experiment showed the presence of amino acids which help to form proteins.

Question 2.
Give a brief account as how evolution has taken pleace from the time the non-cellular aggregate of giant molecules turned into cells.
Answer:
The first formed cells were anaerobic heterotrophs. But slowly some of these cells developed coloured proteins, that could release oxygen, in a process that could have been similar to the light reactions of photosynthesis. As oxygen started coming into the atmospheres is as the atmosphere started becoming an oxidising one, new formes of life could not arise from nonliving organic molecules.

The organisms started becoming aerobic and autotrophic. The single celled organism slowly became multicellular form, where some became autotrophic while many remained heterotrophic. Plants like bryophytes were the first to invade land, followed by reptiles among animals.

Question 3.
Differentiate between natural selection and artificial selection.
Answer:

Natural selection	Artificial selection
(a) It is the process occurring in nature over a number of generations to increase the number of fit individuals in a population. (b) The characters/ adaptations are advantageous to the organism.	(a)  It is the process practised by man over a number of generations, to select organisms with better qualities. (b) The characters are advantageous human.

Question 4.
Fossils are the written documents of evolution. Comment on it.
Answer:
Palaeontological evidence:
The direct and concrete evidence of the process of evolution can be obtained from the study of fossils. The word fossil is derived from the Latin word fossilium meaning something dugout. The term fossil refers to the remnants of the previously existed animals and plants preserved in the earth’s crust. In other words, the fossil is the dead remains of the past. The remnants include bones, teeth, shells, and other hard parts and also the impressions or imprints left by some previous organisms.

The process of preservation of organisms or their parts in the form of fossils is known as fossilization. The fossils are regarded as the written documents of evolution. The study of fossils is called paleontology. It includes paleozoology (fossil animals) and paleobotany (fossil plants). Leonardo da Vinci is considered the Father of Palaeontology.

Question 5.
How is genetic drift differ from gene migration?
Answer:

Genetic drift	Gene migration
Random changes in the allele frequencies of a population occurring only by chance events constitute genetic drift.	It refers to the change in allele frequencies of a given population when individuals ‘ migrate into the population or leave the population.

Question 6
(a) Name the largest dinosaurs and mention any two characteristic features.
(b) How did Darwin explain the existence of different varieties of finches on the Galapagos Islands?
Answer:
(a) Tyrannosaurus rex was the largest dinosaur it was about 20 feet in height. It had huge fearsome dagger-like teeth

(b) Darwin explained that all the verities evolved on the island itself from the original seed-eating birds, many other forms with altered beaks arose some others became insectivorous while remained the vegetarian flinches. Such process of evolution of different species in a given geographical area, starting from a point and literally radiating to other habitats, is called adaptive radiation.

Question 7.
Explain Landmark’s theory of evolution with an example.
Answer:
According to Lamarck, the evolution of life forms had occurred, drives by the use and disease of organs. This theory is as known as the theory of inheritance of acquired characters. He gave the examples of giraffes, who in an attempt to forage leaves on tall trees had to stretch their neck. As they passed this acquired character to the next generations giraffe slowly over the years, came to acquire tons of necks.

Question 8.
Stanley Miller and Harold C Urey performed an experiment by recreating in the laboratory the probable condition of the atmosphere of the primitive earth.
i. What was the purpose of the experiment?
ii. In what forms was the energy supplied for the chemical reactions to occur?
Answer:
i. Stanley Miller gave an experiment based on the theory of the origin of life on earth.
ii. In primitive times at the time of formation of the earth, there was a non-oxygenated atmosphere of CH₄, NH₃, CO₂, CO, NO₂, H₂O (water vapours), etc. Due to cooling and compression caused by increased pressure, the chemicals reacted, compressed against each other, and cooled (liquefied) to form the first life on earth in water.