Explanation:
The first human fossil probably belonged to Zinjanthropus. It is an extinct hominin postulated from a skull found in Olduvai Gorge, Tanzania, in 1959 and originally designated Zinjanthropus boisei by Louis S.B. Leakey.
It was later renamed Paranthropus boisei. It lived in Eastern Africa during the Pleistocene epoch from about 2.3 until about 1.2 million years ago. The brain had a small capacity of 500-550cc.
Most of the primitive organisms live in water, while most of the complex organisms live on land. This shows that evolution of life progressed from water to land.
Explanation:
The sun is a huge sphere of glowing gases that produce energy and light, which make life on Earth possible. The temperature of the sun varies tremendously. At the core of the sun, gravitational attraction produces immense pressure and temperature can reach upto 20 million degrees centigrade.
Hydrogen atoms get compressed and fuse together, creating Helium. This process is called nuclear fusion, and it causes the sun's interior to be extremely hot. Nuclear fusion produces huge amount of energy. The energy radiates outward to the sun's surface, atmosphere and beyond.
The nuclear burning is almost completely shut off beyond the outer edge of the core. At that point the temperature is only half its central value.
Explanation:
Hardy-Weinberg law represents the equilibrium of gene frequencies.
According to the Hardy Weinberg law, the allele and genotype frequencies in a population remain constant in the absence of factors responsible for evolution. It states that the sum of all genotype frequencies can be represented as the binomial expansion of the square of the sum of p and q.
This sum is equal to one : ( p + q )2 = p2 × 2pq × q2 = 1.
"p" is the frequency of the dominant allele, and "q" is the frequency of the recessive allele. The "2pq" in the equation shows the frequency of heterozygotes in the population.
Explanation:
Plate tectonics is the theory that states that Earth's outer shell is divided into several plates that glide over the mantle. The plates act like a hard and rigid shell compared to Earth's mantle. This strong outer layer is called the lithosphere. Plate tectonics is the modern version of continental drift.
The plates consist of two principal types of material, oceanic crust, and continental crust. The earth is considered to have 15 major tectonic plates. Seven of which are primary plates and the rest are secondary plates.
The primary plates are the African plate, the Antarctic plate, the Eurasian plate, the Indo-Australian plate, the North American plate, the Pacific plate, and the South American plate. The secondary plates are the Arabian plate, the Caribbean plate, the Cocos plate, the Juan de Fuca plate, the Indian plate, the Nazca plate, the Philippine Sea plate and the Scotia plate.
Explanation:
The Mesozoic era is the age of the dinosaurs and lasted almost 180 million years from approximately 250 to 65 million years ago. This era includes 3 well known periods, called the Triassic, Jurassic, and Cretaceous periods. A mass-extinction marked the beginning and end of the Mesozoic era.
The event that caused the transition from the Paleozoic era to the Mesozoic era was the greatest extinction this earth has seen. This extinction wiped out about 95% of all marine life and 70% of land-life. This allowed the dinosaurs to step in and settle into their role as the lords of the earth.
The era ended with "The Great Extinction", which marked the end of the dinosaurs as the Cenozoic era began. So, mesozoic era is associated with the mass extinction of dinosaurs.
Explanation:
The geological time scale of life on earth is divided into four major units: Eons, Eras, Periods, and Epochs. The first three Eons are collectively called Precambrian. It is the stretch of time that involves the formation of the earth and the appearance of life on earth.
Precambrian is divided into Hadean eon (formation of the earth), Archaean eon (appearance of prokaryotes), Proterozoic eon (stable continents with eukaryotes). The final eon is Phanerozoic, which means revealed or visible life and constitutes the age of multicellular organisms.
Explanation:
Tail in present day man is a vestigial organ. All chordates including man have a well developed post anal tail. Change in diet brought about changes in dental and facial make up and other anatomical changes and development of voice were important events during evolution of man.
Disappearance of tail was a minor anatomical improvement that finally lead to bipedal locomotion and upright posture.
Explanation:
In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
Hence, Adaptation is a type of Adaptive radiation.
Explanation:
Triassic period, in geologic time, the first period of the Mesozoic era. It began 252 million years ago.
Reptiles increased in diversity and number, and the first dinosaurs appeared during this period along with the appearance of first mammals.
Explanation:
The primitive reducing atmosphere of earth was rich in water vapour, carbon monoxide, carbon dioxide and hydrogen. Absorption of infrared radiation by green house gases (CO2 and CH4) imparted high temperature to primitive earth.
The high temperature, UV light and lightening facilitated reaction between above-mentioned elements. Oxygen did not occur in the free state as the prevailing reduced substances immediately combined with it to form oxides (iron oxides, silicon oxides).
Abundant hydrogen combined with free oxygen, nitrogen and carbon to form water, ammonia, methane and cyanides.
Explanation:
In 1948, Leakey reported skull of Proconsul africanus.
Explanation:
Moving from centre to surface, earth can be divided into three major layers namely; the core, the mantle and the crust. Core is the deepest and hottest layer of earth; the outer core consists of iron-nickel alloy along which small amount of heavy metals while the inner core is made up mostly of iron.
The higher temperature, 7000-9000°F keeps the outer core in liquid state while higher pressure on inner core keeps it in solid state despite the high temperature conditions. Thickness of outer and inner core is 2259km and 1221km respectively.
Mantle is 2900km thick layer wherein most of the earth’s internal heat is located. The outer most layer of earth is crust; it is 22.4km thick and forms the only habitable part of earth. It comprises continents (lithosphere) and ocean basin (hydrosphere) that support life.
Explanation:
The first small dinosaurs appeared during Triassic period (225 million years ago) of Mesozoic era. This makes option D incorrect as dinosaurs did not appear 500 million years ago.
Jurassic period (180 million years ago) is marked by diversification of dinosaurs; large dinosaurs dominated the earth. This makes option C correct.
The asteroid impact at the end of Cretaceous period around 60 million years ago caused mass extinction of dinosaurs thereby eliminating them. Asteroid hit increased the metal iridium concentration on earth. This makes options A and B incorrect as dinosaurs were extinct by 50 and 10 million years ago.
Explanation:
Java man (Homo erectus erectus or Pithecanthropus erectus), was a sub species of Homo erectus, that lived around 0.6 million years ago. His fossils have been discovered in Java. He lived in caves and used fire.
Explanation:
Convergent evolution describes the independent evolution of similar features in species of different lineages.
Explanation:
Speciation that occurs when one population becomes geographically separated from the rest of the species and subsequently evolves by natural selection and /or genetic drift is known as allopatric speciation.
Allopatric speciation is the most common method of speciation and accounts for almost all evolution of new animal species.
Differentiation of species is a wrong option because individuals show differentiation not species. Isolation is not related to maintenance or extermination of species.
Explanation:
Convergent evolution creates "analogous structures" that have similar from or function but were not present in the last common ancestor.
eg:- eye of octopus & mammals.
Divergent evolution is accumulation of differences between closely related populations within a species, adding to specification.
It creates homologous structure that have similar structure different function.
eg :- bones of forelimb of vertebrates.
Explanation:
Flowering plants (angiosperms) arose close to the beginning of the Cretaceous and became more abundant as the period progressed. The Late Cretaceous was a time of great productivity in the worlds oceans, as borne out by the deposition of thick beds of chalk in western Europe, eastern Russia, southern Scandinavia, the Gulf Coast of North America, and western Australia.
The Cretaceous ended with one of the greatest mass extinctions in the history of Earth, exterminating the dinosaurs, marine and flying reptiles, and many marine invertebrates. Thus, option B is correct. Angiosperm were not arose in carboniferous period, triassic period and tertiary period.
Explanation:
Approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula. Gravity collapsed the material in itself as it began to spin, forming the sun in the center of the nebula.
With the rise of the sun, the remaining material began to clump up. Small particles drew together, bound by the force of gravity, into larger particles. The solar wind swept away lighter elements, such as hydrogen and helium, from the closer regions, leaving only heavy, rocky materials to create smaller terrestrial worlds like Earth.
So, earth like other planets formed from cloud of gas and dust.
Explanation:
The cultural evolution of man is described in following stages – Palaeolithic, Mesolithic, Neolithic. Neolithic age is the most recent in which man developed agriculture, manufactured pottery and clothes.
Explanation:
Australopithecus ramidus is the most ape like hominid ancestor, who walked upright and is considered to be missing link between hominids and apes. It is the oldest and most primitive of hominin fossil dating back to 4.4 million years.
Explanation:
Homology refers to evolution of organisms in different directions from a common ancestry i.e., divergence. It leads to development of homologous organs that are adapted to perform different functions and have different appearance but share common basic structural plan and origin.
Divergent evolution is the accumulation of differences between groups, which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments.
Adaptive radiation is related to evolution of different designs for a single organ according to varied needs of different groups. Transduction is related to transfer of viral or bacterial genetic material. Divergent evolution is related to homologous organs.
Hence, option ‘c’ is correct.
Explanation:
The Cro-Magnon man was considered as carnivorous. The fossil evidences in the form of skull and other bones indicate that the early humans were hunters and gatherers who relied on what was available in their immediate environment. So, they made use of the animals for food, clothing and the bones were used for making ornaments, weapons, tools, etc.
Explanation:
Wings of pigeon, mosquito, and bat perform the same function (flying) but have evolved from separate ancestral populations.
This similarity developed in distantly related groups as an adaptation for the same function is called convergent evolution.
Explanation:
Geological Time scale is the vast expanse of geological time has been separated into eras, periods, and epochs.
All geologic time before the beginning of the Paleozoic era is known as Precambrian era. This includes about 90% of all geologic time and spans the time from the beginning of the earth, about 4.5 billion years ago, to 544 million years ago. It is the largest span of time in Earth's history.
Explanation:
Scientists have developed a theory that describes how the very first microscopic life on primitive Earth could have evolved as a result of a series of chemical reactions. This theory is called chemosynthesis, and it describes the chemical evolution of cellular life.
Chemosynthesis, process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source, rather than the sunlight. It starts when random molecules in the atmosphere of primitive earth form simple organic molecules with energy provided by ultra violet light, radiation and other energy sources.
The chemosynthesis theory implies that the development of life is probable wherever the proper physical and chemical conditions are in place.