Table of Contents
BEST IELTS General Reading Test 481
IELTS GENERAL READING TEST 481 – PASSAGE – 2
IELTS GENERAL READING TEST – 481
READING PASSAGE – 2
The stars
A star is an astronomical object consisting of a glowing spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but due to their gigantic distance from Earth they appear as fixed points of light in the sky. The most prominent stars are grouped into constellations and asterisms, and many of the brightest stars have proper names.
Astronomers have assembled star collections that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 1022 to 1024 stars, but most are invisible to the naked eye from Earth, including all individual stars outside our galaxy, the Milky Way.
IELTS General Reading Test
A star’s life begins with the gravitational breakdown of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. The total mass of a star is the main factor that determines its evolution and eventual fate. For most of its active life, a star shines due to thermonuclear synthesis of hydrogen into helium in its core, releasing energy that traverses the star’s interior and then radiates into outer space. At the conclusion of a star’s lifetime, its centre becomes a stellar remnant: a white dwarf, a neutron star, or, if it is sufficiently massive, a black hole.
Almost all naturally occurring elements heavier than lithium are created by stellar nucleosynthesis in stars or their remnants. Chemically enriched material is returned to the interstellar medium by stellar mass loss or supernova explosions and then recycled into new stars. Astronomers can determine stellar properties including mass, age, metallicity (chemical composition), variability, distance, and motion through space by carrying out observations of a star’s apparent brightness, spectrum, and changes in its position on the sky over time.
IELTS General Reading Test
Stars can form orbital systems with other astronomical objects, as in the case of planetary systems and star systems with two or more stars. When two such stars have a relatively close orbit, their gravitational interface can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.
During their helium-burning phase, a star of more than nine solar masses expands to form first a blue and then a red supergiant. Particularly massive stars may evolve to a Wolf-Rayet star, characterised by spectra dominated by emission lines of elements heftier than hydrogen, which have reached the surface due to strong convection and intense mass loss, or from stripping of the outer layers.
IELTS General Reading Test
When helium is exhausted at the core of a massive star, the core contracts and the temperature and pressure rise enough to fuse carbon. This process continues, with the successive stages being fuelled by neon, oxygen, and silicon. Near the end of the star’s life, fusion continues along a series of onion-layer shells within a massive star. Each shell fuses a different element, with the farthest shell fusing hydrogen, the next shell fusing helium, and so forth. The final stage occurs when a massive star begins producing iron. Since iron nuclei are more tightly bound than any heavier nuclei, any fusion beyond iron does not produce a net release of energy.
Questions 15-20
Do the following statements agree with the information given in the Reading Passage?
TRUE – If the statement agrees with the information.
FALSE – If the statement contradicts the information.
NOT GIVEN – If there is no information on this.
IELTS General Reading Test
15. Numerous stars are noticeable to the nude eye as immovable points because they are in proximity to Earth.
16. The entire energy of a star determines its development and ultimate destiny.
17. At the culmination of a Star’s existence, its core develops into a small planet.
18. Astronomers can measure stellar properties of a star by witnessing its illumination, spectrum, and location in the sky.
19. If two stars come close to each other, they can impact the Earth’s gravitational properties.
20. The ultimate phase of a star’s life transpires when it starts churning out iron.
IELTS General Reading Test
Read the text below and answer questions 21-26.
History of Earth
The past of Earth concerns the development of planet Earth from its creation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth’s past, characterized by constant geological change and biological evolution. The geological time scale (GTS), as defined by international convention, depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula.
Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. While the Earth was in its earliest stage, a giant impact collision with a planet-sized body named Theia is thought to have created the Moon.
IELTS General Reading Test
Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water on the surface. The Hadean eon represents the time before a reliable (fossil) record of life; it began with the formation of the planet and ended 4.0 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution.
The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. Recognizable humans emerged at most 2 million years ago, a vanishingly small period on the geological scale. The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era, after a geological crust started to solidify following the earlier molten Hadean Eon.
IELTS General Reading Test
There are microbial mat fossils such as stromatolites found in 3.48-billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7-billion-year-old metasedimentary rocks discovered in southwestern Greenland as well as “remains of biotic life” found in 4.1-billion-year-old rocks in Western Australia. According to one of the researchers, “If life arose relatively quickly on Earth, then it could be common in the universe.”
Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose, developed over time, and culminated in the Cambrian Explosion about 541 million years ago. This sudden diversification of life forms produced most of the major phyla known today and divided the Proterozoic Eon from the Cambrian Period of the Paleozoic Era.
IELTS General Reading Test
It is estimated that 99 percent of all species that ever lived on Earth, over five billion, have gone extinct. Estimates on the number of Earth’s current species range from 10 million to 14 million, of which about 1.2 million are documented, but over 86 percent have not been described. However, it was recently maintained that one trillion species currently live on Earth, with only one-thousandth of one percent described.
The Earth’s crust has constantly changed since its formation, as has life since its first appearance. Species continue to evolve, taking on new forms, splitting into daughter species, or going extinct in the face of ever-changing physical environments. The process of plate tectonics continues to shape the Earth’s continents and oceans and the life they harbour.
IELTS General Reading Test
Questions 21-26
Write no more than TWO WORDS and/or numbers for each answer.
21. The GTS portrays the enormous ………………… of period from the commencement to the contemporary of Earth.
22. It is assumed that volcanic eruptions perhaps shaped the ………………… after forming atmosphere.
23. A crash of Earth with ………………… is alleged reason behind the formation of the moon.
24. Cenozoic age perceived the intensification of …………………
25. ………………… were responsible for elevating the levels of oxygen in the air about three billion years ago.
26. It was lately claimed that ………………… species presently prevail on Earth.
IELTS General Reading Test
IELTS General Reading Test
ANSWERS
15. FALSE
16. FALSE
17. FALSE
18. TRUE
19. NOT GIVEN
20. TRUE
21. SPANS
22. OCEAN
23. THEIA
24. MAMMALS
25. PHOTOSYNTHETIC ORGANISMS
26. ONE TRILLION
IELTS General Reading Test