The formation of polymers, long-chain molecules made of repeating units of monomers, is a far more difficult experimental problem than the formation of monomers. Polymerization reactions tend to be dehydration. A molecule of water is lost in the formation of a peptide from two amino acids or of a disaccharide sugar from two monomers. Dehydrating agents are used to initiate polymerization. The polymerization of amino acids to form long protein-like molecules (“proteinoids”) was accomplished through dry heating by American biochemist Sidney Fox and his colleagues. The polyamine acids that he formed are not random molecules unrelated to life. They have distinct catalytic activities. Long polymers of amino acids were also produced from hydrogen cyanide and anhydrous liquid ammonia by American chemist Clifford Matthews in simulations of the early upper atmosphere.

Some evidence exists that ultraviolet irradiation induces combinations of nucleotide bases and sugars in the presence of phosphates or cyanides. Some condensing agents such as cyanamide are efficiently made under simulated primitive conditions. Despite the breakdown by the water of molecular intermediates, condensing agents may quite effectively induce polymerization, and polymers of amino acids, sugars, and nucleotides have all been made this way.

That adsorption of relevant small carbon compounds on clays or other minerals may have concentrated these intermediates was suggested by the British scientist John Desmond Bernal. The concentration of some kind is required to offset the tendency for water to break down polymers of biological significance. Phosphorus, with which Deoxyribose sugar forms the “backbone” of DNA and is integrally involved in cell energy transformation and membrane formation, is preferentially incorporated into pre-biological organic molecules. It is hard to explain how such a preference could have happened without the concentration of organic molecules.

What is the structure of the passage?

Four jumbled up sentences, related to a topic, are given below. Three of them can be put together to form a coherent paragraph. Identify the odd one out.

1. Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation.

2. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby.

3. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion.

4. When a star burns through the last of its fuel, the object may collapse, or fall into itself.

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.

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

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 study of tracks and traces is called

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