Bihar Board Class 12 Biology Solutions Chapter 7 Evolution

Bihar Board Class 12 Biology Solutions Chapter 7 Evolution Textbook Questions and Answers, Additional Important Questions, Notes.

BSEB Bihar Board Class 12 Biology Solutions Chapter 7 Evolution

Bihar Board Class 12 Biology Evolution Text Book Questions and Answers

Question 1.
Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Answer:
The use of antibiotics or drugs against eukaryotic organisms has resulted in selection of resistant varieties in a much lesser time scale. There are examples of evolution by anthropogenic action. This tells us that evolution is a stochastic process based on chance events in nature and chance mutation in the organisms. This is the antibiotic resistance observed in micro-organisms (bacteria) in light of Darwinian selection theory.

Question 2.
Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Answer:
Is evolution a process or the result of a person? The answer to this questions is being studied by many scientists of the world. A French naturalist Lamarck has said that evolution of life forms had occurred but driven by one and desire of organs. For example, giraffes who is an attempt to forage leaves on tall trees had to adapt by elongation of their necks. With the passage of time this acquired character of elongated neck to succeedings generations, giraffes, slowly, came to acquire long necks. In 1938, a fish caught in South Africa, called Coelacanth was thought to be extinct. The lobefins evolved into the first amphibians that lived in both land and way.

There were the ancestors of modern-day frogs’ and salamanders. The amphibians evolved into reptiles and their modern descendants are turtles, tortoises and crocodiles.
Example I: Dual origin of tribosphenic mammals – Marsupials, placentals and their close therian relatives possess complex (tribosphenic) molars that are capable of versatile occlusal functions. This functional complex is widely thought to be a key to the early diversification and evolutionary success of extant therians and their close relatives (tribosphenidans).

Long thought to have arisen on northern continents, tribosphenic mammals have recently been reported from southern landmasses. The great age and advanced morphology of these new mammals has led to the alternative suggestion of a Gondwanan origin for the group. Implicit in both biogeographic hypotheses is the assumption that tribosphenic molars evolved only once in mammalian evolutionary history.

Phylogenetic and morphometric analyses including these newly discovered taxa suggest a different interpretation: that mammals with tribosphenic molars are not monophyletic. Tribosphenic molars evolved independently in two ancient (holotherian) mammalian groups with different geographic distributions during the Jurassic/ Early Cretaceous: an australosphenidan clade endemic to Gondwanan landmasses, survived by extant monotremes; and a boreosphenidan clade of Laurasian continents, including extant marsupials, placentals and their relavites.

Example II : A new specimen of Ankarapithecus meteal from the Sinap Formation of central Anatolia –
Paleoantropoloji, Ankara Universitesi, Ankara, Turkey. Hominoid fossils from the Middle and Late Miocene are exceedingly rare, yet such material is necessary for determining hominoid phylogeny. We report here the discovery of a fossil hominoid partial skull from the Upper Miocene Sinap Formation of central Turkey that is the most complete known from the period of 18 to 3 Myr.

Our fieldwork places the hominoid locality within a precisely dated geochronological and biostratigraphical framework that permits detailed comparisons with other fossil hominoids.
Earlier discoveries of more fragmentary remains of Ankarapithecus meteai suggested affinities with the Asian hominoids Sivapithecus and Pongo.

This new and nearly complete specimen reveals a combination of facial, mandibular, and dental features including a relatively narrow interorbital region, extensive frontal and maxillary sinuses, moderately developed supraorbital tone square orbits, robust mandibular corpus, and incisor heteromorphy that is not matched in any extent or fossil hominoid. This configuration of features seems to support its placement as a stem member of the great ape and human clade.

Question 3.
Attempt giving a clear definition of the term species.
Answer:
Species refers to different life forms existing on earth. It is the lowest category into which similar organisms are grouped.

Question 4.
Try to trace the various components of human evolution hint: brain size and function, skeletal structure, dietary preference etc.
Answer:
Around 15 mya, primates called Ramapithecus and Dryopithecus were existing. Ramapithecus were more man-like while Dryopithecus were more ape-like. In Ethiopia and Tanzania, few fossils of man like bones have been discovered. There revealed hominid features leading to the belief that about 3-4 mya, man like primates walked in eastern Africa. They were about 4 feet tall and walked upright. In about 2 mya Australopithecines lived in east African grasslands.

They ate fruits and hunted with stone weapons. This creature was called the first human-like being – the hominid and was called Homo habilis. The brain capacities of there creatures was probably between 650-800cc. In 1891, fossils discovered in Java revealed the next stage, i.e., Homo erectus about 1.5 mya. These had a large brain around 900cc. Between 1,00,000-40,000 years back lived the Neanderthal man with a brain size of 1400cc near east and central Asia. In Africa arose the Homo sapiens who moved across continents and developed into distinct races. Around 75,000-10,000 years ago modem Homo sapiens arose.

Question 5.
Find act through internet and popular science articles whether animals other than man has self-consciousness.
Answer:
Yes, according to many biologists animals like man also have self-consiousness.

Question 6.
List 10 modern-day animals and using internet resources link it to a corresponding ancient fossil. Name both.
Answer:
Modern Day Animal Ancestors

1. Frogs- Lobefins
2. Salamanders – Lobefins
3. Turtles – Pteridophytes
4. Tortoises – Pteridophytes
5. Crocodiles – Pteridophytes
6. Fish – Ichthyosaurs
7. Lizards – Dinosaurs
8. Birds – Archaeopteryx
9. Reptiles – Archaeopteryx
10. Monkey – Dryopithecus

Question 7.
Practise drawing various animals and plants.
Answer:

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

Question 9.
Can we call human evolution as adaptive radiation?
Answer:
Human evaluation is not adaptive radiation. But in humans, we find both herbivorous and omnivorous.

Question 10.
Using various resources such as school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.
Answer:
Evolutionary Stages of a Horse :
The very first horses evolved on the North American continent over 55 million years ago. Over millions of years they roamed the grasslands slowly extending their range to most of the continents on earth. Then horses migrated across the Bering land bridge from North America into what is now Siberia. From there, they spread across Asia into Europe and south to the Middle East and Northern Africa.

Our understanding of the evolution of the horse has evolved as well. Palaeontologist Kathleen Hunt has done a good job of outlining this evolution on her “Talks Origin” site. In the 1870s, the palaeontologist O.C. Marsh published a description of newly discovered North American horse fossils. At the time, very few transitional fossils were known.

The sequence of horse fossils that Marsh described (and that T.H. Huxley popularized) was a striking example of evolution taking place in a single lineage. Here, through a series of clear intermediates, one could see the fossil species Eophippus transforming into an almost totally different-looking (and very familiar) descendent, Equus. Biologists and interested laypeople alike were justifiably excited.

But horse evolution was not smooth and gradual. Different traits evolved at different rates didn’t always evolve together, and occasionally reversed ‘‘direction”. Also, horse species did not always come into being by gradual transformation (anagenesis) of their ancestors; instead, sometimes new species split off from ancestors (cladogenesis) and then coexisted with those ancestors for some time.

Some species arose gradually, others suddenly. Overall, the horse family demonstrates the diversity of evolutionary mechanisms. The most modern equids (descendants of Parahippus) are called equines. Strictly speaking, only the very modern genus Equus contains “horses”.

Then about 8,000 B.C. – succumbing to climate change and human hunters – the horses vanished from North America completely. Meanwhile, across the sea, horses were becoming a fixture of many ancient civilizations and establishing their place in human history. In 1,000 B.C. the first horses were domesticated and used for transportation of both humans and cargo. 500 years later, Persian officials began using mounted couriers for message relaying. Horses had become a part of human life.

It wasn’t until 1500 A.D. that the horse was reintroduced to North America when the Spanish came to conquer the New World in the 16th Century. Their small, sturdy mounts spread quickly, once again, throughout America.

Bihar Board Class 12 Biology Evolution Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
What do you mean by Evolutionary Biology?
Answer:
It is the study of history of life forms in earth.

Question 2.
Who concluded that existing life forms share similarities not only among themselves also with life forms that existed millions of years ago?
Answer:
Charles Darwin.

Question 3.
What does homology indicate?
Answer:
Homology indicates common ancestry.

Question 4.
Give one example of analogy.
Answer:
One example of analogy is the eye of octopus and of mammals.

Question 5.
Name an example of adaptive radiation.
Answer:
Australian Marsupials.

Question 6.
Name the two concepts of Darwinian Theory of Evolution.
Answer:
Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution.

Question 7.
Name the biologist who worked on populations that influenced Darwin.
Answer:
Thomas Matthus.

Question 8.
What is natural selection?
Answer:
Natural selection is a process in which heritable variations enabling better servival are enabled to reproduce and leave greater number of progeny.

Question 9.
What were the land reptiles of earlier period known as?
Answer:
Dinosaurs.

Question 10.
Name the biggest dinosaur.
Answer:
Tyrannosaurus.

Short Answer Type Questions

Question 1.
What does the Big Bang theory explain to us?
Answer:
The Big Bang theory attempts to explain to us the origin of universe. It tells us of a singular huge explosion. Hydrogen and Helium formed sometime later. The gases condensed under gravitation and formed the galaxies of the present-day universe.

Question 2.
When was the earth formed? What was its condition at that time?
Answer:
The earth was supposed to have been formed 4.5 billion years ago. At that time, there was no atmosphere on the earth. Water vapour, methane, carbon dioxide and ammonia released from molten mass covered the surface.

Question 3.
What changes took place on the earth when life appeared on earth?
Answer:
The UV rays from the sun broke up water into hydrogen and oxygen and the lighter H, escaped. Oxygen combined with ammonia and methane to from water, CO, and others. The ozone layer was formed. As it cooled, the water vapour fell as rain, to fill all the depressions and forms oceans. Life appeared 500 million years after the formation of earth.

Question 4.
Write in brief about Louis Pasteur’s experiments about evolution.
Answer:
Louis Pasteur experiments demonstrated that life comes only from pre-existing life. He showed that in pre-sterilised flasks life did not come from killed yeast while in flask open to air, new living organisms arose from killed yeast:

5. What was the contribution of Oparin of Russia and Haldane of England regarding evolution?
Answer:
Both Oparin of Russia and Haldane of England proposed that the first form of life could have come from pre-existing nonliving organic molecules (e.g.: RNA, protein etc.) and that formation of life was preceded by chemical evolution i.e. formation of diverse organic molecules from inorganic constituents.

Question 6.
Explain homology and analogy will examples.
Answer:
Homology is based on divergent evolution whereas analogy refers to a situation exactly opposite. For example, wings of butterfly and of birds look alike. They are not anatomically similar structures though perform similar functions. Analogous structures are a result of convergent evolution – different structures evolving for the same function and thus, having similarity.

Question 7.
What do you mean by evolution by anthropogenic action?
Answer:
Anthropogenic action tells us that evolution is not a direct process in the sence of determinism. It is a stochastic process based on chance events in nature and chance mutation in the organisms. For example, excess use of herbicides, pesticides etc. has only resulted in selection of resistant varieties in a much lesser tonic scale.

Question 8.
What is the essence of Darwinian theory about evolution?
Answer:
The essence of Darwinian theory about evolution is national selection. The rate of appearance of new forms is linked to life cycle or life span. Microbes that divide fast have the ability to multiply and become millions of individuals within hours.

Question 9.
What was Darwin view on his visit to Galapagos Islands.
Answer:
In Galapagos Islands, Darwin observed amazing diversity of creatures. A small black bird called finches amazed him. He realised that there were many varieties of finches within the same island. All the varieties, he conjectured, evolved on the island itself. From the original seed-eating features, many other forms with altered beaks arose, enabling then to become insectivorous and vegetarian finches. This process of revolution is regarded as adaptive radiation.

Question 10.
What was the contribution of Lamarche for the evolution of life forms?
Answer:
Lamarch a French naturalist has said that evolution of life forms had occurred but driven by use and disuse of organs. For example, giraffes who in an attempt to forage leaves on tall trees had to adopt by elongation of their necks. As time passed, this acquired character of elongated neck passed to succeeding generations. Giraffes slowly, over the years, came to acquire long necks.

Long Answer Type Questions

Question 1.
What are the evidences for evolution?
Answer:
Following are the evidences for evolution :

• Some fossils appear similar to modem organism. They represent extinct organisms.
• Study of fossils in different sedimentary layers indicates the geological period in which they existed.
• The studies showed that the life froms varied our time and certain life forms are restricted to certain geological time-spans. Then, new forms have arisen at different times in the history of earth.

Question 2.
Explain with an example evolution by natural selection.
Answer:
In 1850s in England, in a collection of moths, before industrialisation was sent in, it was observed that there were more white-winged moths on trees than dark-winged or melanised moths. However, after industrialisation, there were more dark-winged moths in the same area i.e, the proportion was reversed. The reason for this was, during post-industrialisation period the tree trunks became dark due to industrial smoke and soots. Under this condition the white-winged moth did not survive due to predators, dark-winged or melanised moth survived.

Before industrialisation, thick growth- of white-coloured lichen covered the trees – in that background the white-winged moth surveyed but the dark-coloured moth were picked out by predators. Hence, moths that were able to camouflage themselves i.e.: hide in the background, survived.

One Word Type Questions

Question 1.
Name the scientist who demonstrated experiments that life comes only from pre-existing life forms.
Answer:
Louis Pasteur.

Question 2.
Name the Russian scientist who contributed towards the theory of evolution.
Answer:
Oparin.

Question 3.
Name the naturalist who worked in Malay Archipelago regarding evolution.
Answer:
Alfred Wallace.

Question 4.
What is the study of history of life forms on earth called?
Answer:
Evolutionary Biology.

Question 5.
Name the theory which explains the origin of universe.
Answer:
Big Bang Theory.

Question 6.
Name the English scientist who proposed that the first form of life came from pre-existing non-living organic molecules.
Answer:
Haldane.

Question 7.
How many connotations are there in the conventional religious literature of special creation?
Answer:
Three.

Question 8.
Can the ages of the fossils be calculated?
Answer:
Yes.

Question 9.
By what name was the first human known as?
Answer:
Homo habilis.

Question 10.
…………………….. lived in East African grasslands.
Answer:
Australopithecines.