Ans: Fossils are the impressions or remains of animals and plants preserved in the rocks over a million years ago.
2. What is anthracite?
Ans: Anthracite is the hardest coal having highest amount of carbon.
3. When did the evolution of development of fish take place?
Ans: The evolution and development of fish took place in the period of Silurian of Paleozoic era.
4. How is the information about the ancient living beings taken?
Ans: The information about the ancient living beings is taken from their fossils found in sedimentary rocks or hard parts of soil.
5. Write any three information obtained by the study of fossil.
Ans: The following information is obtained by the study of fossil:
a. It provides the information about the structure of the animals and the plants.
b. The condition of a fossil indicates the type of the environment existed at the time.
c. Similar fossils in different areas indicate the patterns in the movement of the earth’s crust.
6. Mention any three importance of fossil.
Ans: The importance of the fossil is given below:
a. They provide evidence of the evolution of living beings.
b. They help to know about the extinct animals and plants.
c. They help to make geological timescale.
7. Write any three ways of identification of fossil.
Ans: The ways of identification of fossil are given below:
a. Traces of dead bodies are formed on sedimentary rocks which can be identified as fossils.
b. A part of the skeletal system or the whole skeleton preserved in sedimentary rocks is a fossil.
c. They are also identified by tallying the fossils with the photos of fossils that were already identified.
8. Describe the process of formation of fossil.
Ans: Fossils are formed in different ways. Most of the fossils are formed when plants or animals die in or near water and is buried in mud, dirt, gravel and hard rock. Soft tissues quickly decompose leaving the hard bones or shells. These hard bones or shells are preserved in their original form in the rock. Some fossils are formed when animals are frozen in ice and preserved to the core. Organisms are also fossilized in the form of casts in sediments. The fossils are exposed at the surface by geographical activities like faulting and surface erosion.
9. What is mineral oil?
Ans: Mineral oil is a liquid mixture of hydrocarbons obtained from petroleum.
10. Write any three importance of mineral oil.
Ans: The importance of mineral oil are:
a. It is used as a lubricant.
b. It is used as fuel for cooking food.
c. It is used in the manufacturing of plastics, chemical fertilizers, pesticides, paints, explosives, medicines, etc.
11. Describe the process of formation of mineral oil.
Ans: Mineral oils are formed by the remains of phytoplankton and zooplankton that are buried under the ocean bed by natural disasters such as earthquakes and volcanic eruption. The drastic change in climate, huge volcanic eruption and massive earthquakes cause micro-organisms of the ocean to get buried under the earth crust where they are compressed under high temperature and pressure in the absence of oxygen. They finally formed mineral oil after the millions of years.
12. What are the two conditions required to form mineral oil inside the earth crust?
Ans: The following conditions are required to form mineral oil:
a. Mineral oils are formed by the remains of phytoplankton and zooplankton that are buried under the ocean bed by natural disasters such as earthquakes and volcanic eruption.
b. When micro-organisms are buried under the earth crust and compressed under high temperature and pressure in the absence of oxygen.
13. What is geological era?
Ans: A very long duration of time which helps to study the geological history of the earth is called a geological era.
14. What are the three periods of the Mesozoic era?
Ans: The three periods of the Mesozoic era are Triassic, Jurassic and Cretaceous.
15. When did the evolution of insects with wings take place?
Ans: The evolution of insects with wings took place in Devonian of Paleozoic era.
16. Define Mesozoic era.
Ans: Mesozoic era is the geological division from 250 million years ago to 65.5 million years ago.
17. Define Cenozoic era.
Ans: Cenozoic era is the geological division from 65.5 million years ago to recent.
18. Which era is called the era of creepers and why?
Ans: Mesozoic era is called the era of creepers because different types of creeping animals like dinosaurs, reptiles, tortoise, etc. were evolved and developed in this era.
19. Why did the life evolve after a long time from the birth of the earth?
Ans: The life evolves after a long time from the birth of the earth because the earth was very hot at the time of its birth and the condition of the environment was not suitable for the evolution of life.
20. Write any three events which occurred in the mesozoic era.
Ans: The important events which occurred in mesozoic era are:
a. The giant reptiles like dinosaurs evolved, flourished and were extinct.
b. Climate became suitable for aquatic, terrestrial and aerial animals.
c. Mammals and birds began to evolve at the end of this era.
21. Write down the duration of Paleozoic era and enlist the major events of this era.
Ans: Paleozoic era began about 570 million years ago and ended about 250 million years ago.
The major events of this era are:
a. Sedimentary rocks were formed.
b. Aquatic and terrestrial vertebrates and invertebrates were evolved.
c. Climatic change and change in atmosphere took place.
22. Mention the major events in Mesozoic era regarding evolution of living beings.
Ans: The major events in mesozoic era regarding evolution of living beings are:
a. Mammals and birds began to evolve at the end of this era.
b. Flowering plants were developed.
c. The giant reptiles like dinosaurs evolved, flourished and were extinct.
23. Write the name of era and its duration for each of the following incidents.
a. Invertebrates originated in sea
b. Evolution of human beings
c. Evolution and extinction of dinosaurs
Ans: a. Invertebrates originated in seab. Evolution of human beings
c. Evolution and extinction of dinosaurs
Era: Proterozoic era
Duration: 2500 -542 million years ago
b. Evolution of human beings
Era: Cenozoic
Duration: 65 million years ago to till now
c. Evolution and extinction of the dinosaur
Evolution of dinosaur: the Mesozoic era
Extinction of dinosaur: Mesozoic era
Duration: 252-65 million years ago
24. Write down the duration of mesozoic era and describe the origin of organisms in this era.
Ans: The Mesozoic era began about 250 million years ago and ended 65 million years ago. Mammals and birds began to evolve at the end of this era. The giant reptiles like dinosaurs evolved, flourished and were extinct. Turtles, crocodile-like species and frogs made their first appearances in this era. Flowering plants were developed. Coniferous plants were developed. Gymnosperms were dominating plants of this era.
25. Mention the duration of paleozoic era. Explain about the origin of organisms in paleozoic era.
Ans: The Palaeozoic era began 570 million years ago and ended about 250 million years ago. Aquatic and terrestrial vertebrates and invertebrates evolved in this era. The first vertebrate appeared in the form of primitive fish, some fish had lungs and powerful bony fins. The bones in their fins eventually evolved into legs and became the first tetrapods. Macroscopic plant life appeared in the early Palaeozoic era.
Different bryophytes and pteridophytes were evolved.
Fern plant up to 25 ft and club moss up to 100 ft were evolved in this era.
26. Write down the duration of cenozoic era. Describe in brief about the origin of organisms in cenozoic era.
Ans: Cenozoic era began 65 years ago and still going on. The first primates and horses were evolved in this era. Mammals, birds and insects were spread. Rhinoceros, camels, elephants, first modern mammals were evolved during this era. Angiosperm spread rapidly. This era is also known as the era of human beings. Earliest man, a man in Stone age and human cultures were developed during this era.
27. Write short notes on:
a. Pre Cambrian era
b. Mesozoic era
Ans: a. Pre Cambrian erab. Mesozoic era
Pre Cambrian era started about 4.6 billion years ago and ended 570 million years ago. It is the combination of the archeozoic, Proterozoic and Cenozoic era. The early part of this era is the beginning of the earth. Formation of atmosphere, hydrosphere and lithosphere took place. Unicellular and multicellular organisms were evolved in a shallow sea. Very primitive bacteria were evolved during this era.
b. Mesozoic era
The Mesozoic era began about 250 million years ago and ended 65 million years ago. Mammals and birds began to evolve at the end of this era. The giant reptiles like dinosaurs evolved, flourished and were extinct. Turtles, crocodile-like species and frogs made their first appearances in this era. Flowering plants were developed. Coniferous plants were developed. Gymnosperms were dominating plants of this era. Hill and mountains were formed. The climate became suitable for aquatic, terrestrial and aerial life.
28. What is earth science?
Ans: Earth science is the study of nature, distribution, behaviour and origin of the materials of the earth and its atmosphere.
29. What is geology?
Ans: The study of earth science is known as geology.
30. State Nubular theory.
Ans: The nebular theory states that the whole of our solar system was formed from a very big mass of the dust and gases called nebula which was whirling on its own axis.
31. How is it known that there were dinosaurs on the earth in the ancient time? In which era were they dominant? What is the time duration of that era?
Ans: It is known that there were dinosaurs on the earth in the ancient time by the study of fossils.
They were dominant in the Mesozoic era.
The Mesozoic era began about 250 million years ago and ended about 65 million years ago.
32. Write short notes on:
a. Nebular hypothesis
b. Tidal hypothesis
Ans: a. Nebular hypothesisb. Tidal hypothesis
According to Nebular hypothesis, the sun and the planets were formed from a large whirling cloud of hot gases and dust. When the cloud cooled and grew smaller, it began to spin faster. As the surface of the cloud cooled by radiation, a ring of matter was formed at the equatorial region of it. The ring escaped out from the surface of the main mass and the first planet was formed. The process was repeated till the entire solar system was formed. The remaining mass formed the sun.
b. Tidal hypothesis
According to this hypothesis, the sun was a very big and extensive mass of gas which was moving in space. A big comet came closer to the sun and gravitational force of the comet attracted the sun, then the molten mass of the sun was elongated toward the comet forming tides. As the star moved away from the sun, some parts of the tide broke down into number of pieces, which became planet and satellite. Finally they began to revolve around the sun.
33. What is carbon dating?
Ans: The process of recognizing the age of the organism is called carbon dating.
34. What is coal?
Ans: Coal is a fossil fuel which is obtained from plants buried under the earth as thick layers, millions of years ago.
35. What is refining?
Ans: The process of purifying crude oil is known as refining.
36. What are fossil fuels?
Ans: Fossil fuels are the buried combustible geologic deposits of organic materials, formed from decayed plants and animals after millions of years.
37. How is coal formed?
Ans: Coal is formed by the decomposition of large plants and trees buried under the earth crust for millions of years.
38. Describe the method of coal formation.
Ans: Coal is formed when the remains of trees, fern and other plants are buried under the soil by a natural disaster such as earthquakes and volcanic eruptions. As more soil deposited on them, they are compressed. When the temperature rises they sink deeper. As the process continues, they are protected from biodegradation and oxidation. This trapped carbon slowly converts into coal under high pressure and temperature in the absence of oxygen.