Class 12th

The passage below is accompanied by a set of questions. Choose the best answer to each question.

Tens of thousands of years ago, a huge horse species walked, trotted and galloped across the shifting sands of what is today South Africa's Cape south coast.

The Giant Cape Zebra (Equus capensis) weighed an estimated 450 kg. Its extant relatives in southern Africa are far smaller: the plains zebra weighs between 250 and 300 kg and the Cape mountain zebra is the smallest of all zebra species, with a mass of between 230 and 260 kg.

The Giant Cape Zebra became extinct just over 10,000 years ago. This may have been partly because of the loss of its preferred habitat of extensive grasslands, as rising sea levels flooded the vast Palaeo-Agulhas Plain. But until now it hasn't been clear how common the species was on the Cape south coast because its body fossils are predominantly from southern Africa's west coast.

That's where ichnology – the study of tracks and traces – comes in. Since 2007 our team has documented more than 350 fossil vertebrate tracksites along a 350 km stretch of the Cape south coast.

Now, by studying the tracks left by those galloping, walking and trotting zebra so long ago, we're able to say that they must have been a fairly regular sight on the landscape of the Cape south coast, and were more common than was suggested by the body fossil record in the area. This confirms the capacity of the body fossil record and ichnology to complement each other.

Being able to look back in time in this way doesn't just help scientists to better understand ancient landscapes. It's also an important part of understanding what's changed over time and the effects of climate change and humans.

In our recently published article, we described how we have identified 26 equid tracksites – including tracks belonging to Equus capensis – in aeolianites (cemented dunes) on South Africa's Cape south coast in the vicinity of towns like Still Bay and Plettenberg Bay.

This is especially exciting because equid tracks dating to the Pleistocene epoch, which started 2.6 million years ago and ended about 11,700 years ago, are rare. In fact, our finds mean that the Cape south coast accounts for the majority of the sites known globally from this time period (other sites are in Kenya, Ethiopia, Italy, the Arabian Peninsula, and the Americas).

Thirteen of the tracksites we found contain tracks 12 cm or greater in length, and eight contain tracks 10 cm or less in length (in the remaining five cases we could not access the tracks for measurement). Well preserved equid tracks are fairly distinctive: features include an unbroken hoof wall and what is known as a “frog” towards the centre of the track.

The given passage is mainly associated with

The passage below is accompanied by a set of questions. Choose the best answer to each question.
How we as human beings develop cognitively has been thoroughly researched. Theorists have suggested that children are incapable of understanding the world until they reach a particular stage of cognitive development. Cognitive development is the process whereby a child's understanding of the world changes as a function of age and experience.
No theory of cognitive development has had more impact than the cognitive stages presented by Jean Piaget. Piaget, a Swiss psychologist, suggested that children go through four separate stages in a fixed order that is universal in all children. Piaget declared that these stages differ not only in the quantity of information acquired at each, but also in the quality of knowledge and understanding at that stage Piaget's four stages are known as the sensorimotor, preoperational, concrete operational, and formal operational stages.
The sensor motor stage in a child is from birth to approximately two years. During this stage, a child has relatively little competence in representing the environment using images, language, or symbols. An infant has no awareness of objects or people that are not immediately present at a given moment. Piaget called this a lack of object permanence. Object permanence is the awareness that objects and people continue to exist even if they are out of sight.
The preoperational stage is from the age of two to seven years. The most important development at this time is language. Children develop an internal representation of the world that allows them to describe people, events, and feelings. Children at this time use symbols, they can pretend when driving their toy car across the couch that the couch is actually a bridge. Children in the preoperational stage are characterized by what Piaget called egocentric thoughts. The world at this stage is viewed entirely from the child's own perspective. Thus a child's explanation to an adult can be uninformative. Three-year-olds will generally hide their face when they are in trouble--even though they are in plain view, three-year-olds believe that their inability to see others also results in others' inability to see them. A child in the preoperational stage also lacks the principle of conservation. This is the knowledge that quantity is unrelated to the arrangement and physical appearance of objects. If you put two identical pieces of clay in front of a child, one rolled up in the shape of a ball, the other rolled into a snake, a child at this stage may say the snake piece is bigger because it is rolled out.
The concrete operational stage lasts from the age of seven to twelve years of age. The beginning of this stage is marked by the mastery of the principal of conservation. Children develop the ability to think in a more logical manner and they begin to overcome some of the egocentric characteristics of the preoperational period. One of the major ideas learned in this stage is the idea of reversibility. This is the idea that some changes can be undone by reversing an earlier action. An example is the ball of clay that is rolled out into a snake piece of clay. Children at this stage understand that you can regain the ball of clay formation by rolling the piece of clay the other way. Children can even conceptualize the stage in their heads without having to see the action performed. The formal operational stage begins in most people at age twelve and continues into adulthood. This stage produces a new kind of thinking that is abstract, formal, and logical. Thinking is no longer tied to events that can be observed. A child at this stage can think hypothetically and use logic to solve problems. It is thought that not all individuals reach this level of thinking.
Most developmental theorists have agreed that Piaget has provided us with an accurate account of age-related changes in cognitive development. Piaget's suggestion, that cognitive performance cannot be attained unless cognitive readiness is brought about by maturation and environmental stimuli, has been instrumental in determining the structure of educational curricula.

The concrete operational stage lasts from the age of

The passage below is accompanied by a set of questions. Choose the best answer to each question.
How we as human beings develop cognitively has been thoroughly researched. Theorists have suggested that children are incapable of understanding the world until they reach a particular stage of cognitive development. Cognitive development is the process whereby a child's understanding of the world changes as a function of age and experience.
No theory of cognitive development has had more impact than the cognitive stages presented by Jean Piaget. Piaget, a Swiss psychologist, suggested that children go through four separate stages in a fixed order that is universal in all children. Piaget declared that these stages differ not only in the quantity of information acquired at each, but also in the quality of knowledge and understanding at that stage Piaget's four stages are known as the sensorimotor, preoperational, concrete operational, and formal operational stages.
The sensor motor stage in a child is from birth to approximately two years. During this stage, a child has relatively little competence in representing the environment using images, language, or symbols. An infant has no awareness of objects or people that are not immediately present at a given moment. Piaget called this a lack of object permanence. Object permanence is the awareness that objects and people continue to exist even if they are out of sight.
The preoperational stage is from the age of two to seven years. The most important development at this time is language. Children develop an internal representation of the world that allows them to describe people, events, and feelings. Children at this time use symbols, they can pretend when driving their toy car across the couch that the couch is actually a bridge. Children in the preoperational stage are characterized by what Piaget called egocentric thoughts. The world at this stage is viewed entirely from the child's own perspective. Thus a child's explanation to an adult can be uninformative. Three-year-olds will generally hide their face when they are in trouble--even though they are in plain view, three-year-olds believe that their inability to see others also results in others' inability to see them. A child in the preoperational stage also lacks the principle of conservation. This is the knowledge that quantity is unrelated to the arrangement and physical appearance of objects. If you put two identical pieces of clay in front of a child, one rolled up in the shape of a ball, the other rolled into a snake, a child at this stage may say the snake piece is bigger because it is rolled out.
The concrete operational stage lasts from the age of seven to twelve years of age. The beginning of this stage is marked by the mastery of the principal of conservation. Children develop the ability to think in a more logical manner and they begin to overcome some of the egocentric characteristics of the preoperational period. One of the major ideas learned in this stage is the idea of reversibility. This is the idea that some changes can be undone by reversing an earlier action. An example is the ball of clay that is rolled out into a snake piece of clay. Children at this stage understand that you can regain the ball of clay formation by rolling the piece of clay the other way. Children can even conceptualize the stage in their heads without having to see the action performed. The formal operational stage begins in most people at age twelve and continues into adulthood. This stage produces a new kind of thinking that is abstract, formal, and logical. Thinking is no longer tied to events that can be observed. A child at this stage can think hypothetically and use logic to solve problems. It is thought that not all individuals reach this level of thinking.
Most developmental theorists have agreed that Piaget has provided us with an accurate account of age-related changes in cognitive development. Piaget's suggestion, that cognitive performance cannot be attained unless cognitive readiness is brought about by maturation and environmental stimuli, has been instrumental in determining the structure of educational curricula.

It can be inferred from the passage that –

The passage below is accompanied by a set of questions. Choose the best answer to each question.
How we as human beings develop cognitively has been thoroughly researched. Theorists have suggested that children are incapable of understanding the world until they reach a particular stage of cognitive development. Cognitive development is the process whereby a child's understanding of the world changes as a function of age and experience.
No theory of cognitive development has had more impact than the cognitive stages presented by Jean Piaget. Piaget, a Swiss psychologist, suggested that children go through four separate stages in a fixed order that is universal in all children. Piaget declared that these stages differ not only in the quantity of information acquired at each, but also in the quality of knowledge and understanding at that stage Piaget's four stages are known as the sensorimotor, preoperational, concrete operational, and formal operational stages.
The sensor motor stage in a child is from birth to approximately two years. During this stage, a child has relatively little competence in representing the environment using images, language, or symbols. An infant has no awareness of objects or people that are not immediately present at a given moment. Piaget called this a lack of object permanence. Object permanence is the awareness that objects and people continue to exist even if they are out of sight.
The preoperational stage is from the age of two to seven years. The most important development at this time is language. Children develop an internal representation of the world that allows them to describe people, events, and feelings. Children at this time use symbols, they can pretend when driving their toy car across the couch that the couch is actually a bridge. Children in the preoperational stage are characterized by what Piaget called egocentric thoughts. The world at this stage is viewed entirely from the child's own perspective. Thus a child's explanation to an adult can be uninformative. Three-year-olds will generally hide their face when they are in trouble--even though they are in plain view, three-year-olds believe that their inability to see others also results in others' inability to see them. A child in the preoperational stage also lacks the principle of conservation. This is the knowledge that quantity is unrelated to the arrangement and physical appearance of objects. If you put two identical pieces of clay in front of a child, one rolled up in the shape of a ball, the other rolled into a snake, a child at this stage may say the snake piece is bigger because it is rolled out.
The concrete operational stage lasts from the age of seven to twelve years of age. The beginning of this stage is marked by the mastery of the principal of conservation. Children develop the ability to think in a more logical manner and they begin to overcome some of the egocentric characteristics of the preoperational period. One of the major ideas learned in this stage is the idea of reversibility. This is the idea that some changes can be undone by reversing an earlier action. An example is the ball of clay that is rolled out into a snake piece of clay. Children at this stage understand that you can regain the ball of clay formation by rolling the piece of clay the other way. Children can even conceptualize the stage in their heads without having to see the action performed. The formal operational stage begins in most people at age twelve and continues into adulthood. This stage produces a new kind of thinking that is abstract, formal, and logical. Thinking is no longer tied to events that can be observed. A child at this stage can think hypothetically and use logic to solve problems. It is thought that not all individuals reach this level of thinking.
Most developmental theorists have agreed that Piaget has provided us with an accurate account of age-related changes in cognitive development. Piaget's suggestion, that cognitive performance cannot be attained unless cognitive readiness is brought about by maturation and environmental stimuli, has been instrumental in determining the structure of educational curricula.

Which of the following statements is NOT true according to the passage?

Piaget did not suggest that

The passage below is accompanied by a set of questions. Choose the best answer to each question.
How we as human beings develop cognitively has been thoroughly researched. Theorists have suggested that children are incapable of understanding the world until they reach a particular stage of cognitive development. Cognitive development is the process whereby a child's understanding of the world changes as a function of age and experience.
No theory of cognitive development has had more impact than the cognitive stages presented by Jean Piaget. Piaget, a Swiss psychologist, suggested that children go through four separate stages in a fixed order that is universal in all children. Piaget declared that these stages differ not only in the quantity of information acquired at each, but also in the quality of knowledge and understanding at that stage Piaget's four stages are known as the sensorimotor, preoperational, concrete operational, and formal operational stages.
The sensor motor stage in a child is from birth to approximately two years. During this stage, a child has relatively little competence in representing the environment using images, language, or symbols. An infant has no awareness of objects or people that are not immediately present at a given moment. Piaget called this a lack of object permanence. Object permanence is the awareness that objects and people continue to exist even if they are out of sight.
The preoperational stage is from the age of two to seven years. The most important development at this time is language. Children develop an internal representation of the world that allows them to describe people, events, and feelings. Children at this time use symbols, they can pretend when driving their toy car across the couch that the couch is actually a bridge. Children in the preoperational stage are characterized by what Piaget called egocentric thoughts. The world at this stage is viewed entirely from the child's own perspective. Thus a child's explanation to an adult can be uninformative. Three-year-olds will generally hide their face when they are in trouble--even though they are in plain view, three-year-olds believe that their inability to see others also results in others' inability to see them. A child in the preoperational stage also lacks the principle of conservation. This is the knowledge that quantity is unrelated to the arrangement and physical appearance of objects. If you put two identical pieces of clay in front of a child, one rolled up in the shape of a ball, the other rolled into a snake, a child at this stage may say the snake piece is bigger because it is rolled out.
The concrete operational stage lasts from the age of seven to twelve years of age. The beginning of this stage is marked by the mastery of the principal of conservation. Children develop the ability to think in a more logical manner and they begin to overcome some of the egocentric characteristics of the preoperational period. One of the major ideas learned in this stage is the idea of reversibility. This is the idea that some changes can be undone by reversing an earlier action. An example is the ball of clay that is rolled out into a snake piece of clay. Children at this stage understand that you can regain the ball of clay formation by rolling the piece of clay the other way. Children can even conceptualize the stage in their heads without having to see the action performed. The formal operational stage begins in most people at age twelve and continues into adulthood. This stage produces a new kind of thinking that is abstract, formal, and logical. Thinking is no longer tied to events that can be observed. A child at this stage can think hypothetically and use logic to solve problems. It is thought that not all individuals reach this level of thinking.
Most developmental theorists have agreed that Piaget has provided us with an accurate account of age-related changes in cognitive development. Piaget's suggestion, that cognitive performance cannot be attained unless cognitive readiness is brought about by maturation and environmental stimuli, has been instrumental in determining the structure of educational curricula.

Which of the following statements is NOT true according to the passage?

The passage below is accompanied by a set of questions. Choose the best answer to each question.

How we as human beings develop cognitively has been thoroughly researched. Theorists have suggested that children are incapable of understanding the world until they reach a particular stage of cognitive development. Cognitive development is the process whereby a child's understanding of the world changes as a function of age and experience.

No theory of cognitive development has had more impact than the cognitive stages presented by Jean Piaget. Piaget, a Swiss psychologist, suggested that children go through four separate stages in a fixed order that is universal in all children. Piaget declared that these stages differ not only in the quantity of information acquired at each, but also in the quality of knowledge and understanding at that stage Piaget's four stages are known as the sensorimotor, preoperational, concrete operational, and formal operational stages.

The sensor motor stage in a child is from birth to approximately two years. During this stage, a child has relatively little competence in representing the environment using images, language, or symbols. An infant has no awareness of objects or people that are not immediately present at a given moment. Piaget called this a lack of object permanence. Object permanence is the awareness that objects and people continue to exist even if they are out of sight.

The preoperational stage is from the age of two to seven years. The most important development at this time is language. Children develop an internal representation of the world that allows them to describe people, events, and feelings. Children at this time use symbols, they can pretend when driving their toy car across the couch that the couch is actually a bridge. Children in the preoperational stage are characterized by what Piaget called egocentric thoughts. The world at this stage is viewed entirely from the child's own perspective. Thus a child's explanation to an adult can be uninformative. Three-year-olds will generally hide their face when they are in trouble--even though they are in plain view, three-year-olds believe that their inability to see others also results in others' inability to see them. A child in the preoperational stage also lacks the principle of conservation. This is the knowledge that quantity is unrelated to the arrangement and physical appearance of objects. If you put two identical pieces of clay in front of a child, one rolled up in the shape of a ball, the other rolled into a snake, a child at this stage may say the snake piece is bigger because it is rolled out.

The concrete operational stage lasts from the age of seven to twelve years of age. The beginning of this stage is marked by the mastery of the principal of conservation. Children develop the ability to think in a more logical manner and they begin to overcome some of the egocentric characteristics of the preoperational period. One of the major ideas learned in this stage is the idea of reversibility. This is the idea that some changes can be undone by reversing an earlier action. An example is the ball of clay that is rolled out into a snake piece of clay. Children at this stage understand that you can regain the ball of clay formation by rolling the piece of clay the other way. Children can even conceptualize the stage in their heads without having to see the action performed. The formal operational stage begins in most people at age twelve and continues into adulthood. This stage produces a new kind of thinking that is abstract, formal, and logical. Thinking is no longer tied to events that can be observed. A child at this stage can think hypothetically and use logic to solve problems. It is thought that not all individuals reach this level of thinking.

Most developmental theorists have agreed that Piaget has provided us with an accurate account of age-related changes in cognitive development. Piaget's suggestion, that cognitive performance cannot be attained unless cognitive readiness is brought about by maturation and environmental stimuli, has been instrumental in determining the structure of educational curricula.

Which statement best captures the essence of the passage?

The majority of the time fossils are dated using relative dating techniques. Using relative dating the fossil is compared to something for which an age is already known.
For example, if you have a fossil trilobite and it was found in the Wheeler Formation. The Wheeler Formation has been previously dated to approximately 507-million-year-old, so we know the trilobite is also about 507 million years old.
Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation. Index fossils are fossils that are known to only occur within a very specific age range. Typically, commonly occurring fossils that had a widespread geographic distribution such as brachiopods, trilobites, and ammonites work best as index fossils. If the fossil you are trying to date occurs alongside one of these index fossils, then the fossil you are dating must fall into the age range of the index fossil.
Sometimes multiple index fossils can be used. In a hypothetical example, a rock formation contains fossils of a type of brachiopod known to occur between 410 and 420 million years. The same rock formation also contains a type of trilobite that was known to live 415 to 425 million years ago. Since the rock formation contains both types of fossils the age of the rock formation must be in the overlapping date range of 415 to 420 million years.
Studying the layers of rock or strata can also be useful. Layers of rock are deposited sequentially. If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age. If it is lower in sequence it's of a younger age. This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.
Unlike relative dating method absolute dating which is used to determine a precise age of a rock or fossil through radiometric dating methods. This uses radioactive minerals that occur in rocks and fossils almost like a geological clock. It's often much easier to date volcanic rocks than the fossils themselves or the sedimentary rocks they are found in. So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks.
The atoms in some chemical elements have different forms, called isotopes. These isotopes break down at a constant rate over time through radioactive decay. By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined.
We define the rate of this radioactive decay in half-lives. If a radioactive isotope is said to have a half-life of 5,000 years that means after 5,000 years exactly half of it will have decayed from the parent isotope into the daughter isotopes. Then after another 5,000 years half of the remaining parent isotope will have decayed.
While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils. Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast. It can only be used to date fossils younger than about 75,000 years. Potassium-40 on the other hand has a half like of 1.25 billion years and is common in rocks and minerals. This makes it ideal for dating much older rocks and fossils.

All of the following can be inferred abouAbsolute dating is used to determine a precise age of a fossil.
B. It uses radiometric dating to measure the decay of isotopes.
C. It compares similar rocks and fossils of known ages.
D. Volcanic rocks are much easily dated by this method.

t absolute dating EXCEPT