TOEFL® Reading Practice with Question Types Answers
This blog is the last part in a two blog series for the TOEFL Reading Practice with Question Types. If you haven’t done so already, please read and complete the blog found here TOEFL Reading Practice with Question Types where we looked at some TOEFL reading question types after reading a university level passage.
Did you finish reading the previous blog? Great! let’s continue on.
Here is the example, but this time with answers from the previous blog. The questions also come with clear explanations, so you can figure out how to logically reason your ways to the correct answers. All our reading questions on our website include answer explanations. If you’re interested, please have a look at our TOEFL Reading Practices.
 It is believed that eyes evolved over a few million years during the Cambrian explosion, a rapid period of evolution. Prior to this era, there is no direct evidence of eyes. Eyes have a vast range of adaptations to meet the needs of the organism. They vary in visual acuity, the array of wavelength detected, sensitivity in low light, color discrimination and their capacity to identify motion.
 Charles Darwin, in On the Origin of Species, suggests that the eye evolved from "an optic nerve merely coated with pigment, and without any other mechanism" to "a moderately high stage of perfection". Darwin presented intermediate grades of evolution and made suggestions that were soon shown to be correct. Since this time, modern scientists have been putting forward work on the topic of eye evolution, suggesting that the eye developed from a vertebrate patch of photoreceptors. Current research validates the theory of Darwin.
 The first eye fossils date back to 540 million years ago. Prior to this time, organisms may have had use for light sensitivity, but not for fast locomotion and navigation by vision. However, it remains difficult to evaluate the rate of eye evolution because the fossil record of this period is weak. The development of the circular patch of photoreceptor cells into a fully functional vertebrate eye has been estimated on the rates of mutation, relative benefit to the organism and natural selection. Based on these estimations, it is suggested that it would take less than 364,000 years for the complete evolution of the eye.
 The fundamental light-processing unit of the eye is the photoreceptor cell, a specialized cell with two types of molecules in its membrane: the opsin, a light-sensitive protein, and the chromophore – a pigment that can distinguish colors – which it surrounds. This group of cells is called an ‘eyespot. These eyespots allow animals a basic sense of light direction and intensity. However, 96% of species have a more complex optical system that allows light discrimination within a few degrees. These optical systems began as multi cellular eye patches and gradually evolved into a cup which first allowed the capacity to discriminate brightness in directions, then in finer and finer directions as the pit became deeper. Whereas a flat shape of the eyes allowed limited directional differentiation, the cup shape of the pit eye allows for increasingly precise visual information. Pit eyes, which date back to Cambrian period, were detected in ancient snails, and are still found in snails today.
 When a photon is absorbed by the chromophore, a chemical reaction causes the photon's energy to be converted into electrical energy and relayed, in higher animals, to the nervous system. These photoreceptor cells form part of the retina, a thin layer of cells that relays visual information, including the light and day-length information needed by the circadian rhythm system, to the brain. However, some jellyfish, such as Cladonema, have elaborate eyes but no brain. Their eyes transmit a message directly to the muscles without the intermediate processing provided by a brain.
 During the Cambrian explosion, evolution of the eye was very fast, with dramatic developments in image-processing and light direction detection. As the photosensitive cell region developed, there came a point when the reduction of the width of the light opening became more efficient for visual resolution than the ongoing deepening of the cup. With a reduced size of the opening, organisms achieved true imaging, allowing for finer sensing of direction and shape. The nautilus, a marine mollusc, has this type of opening. Without a cornea or lens, the eye openings provide poor resolution and dim imaging. However, they are still a major evolution from the earlier eye patches.
 So, why is it that eyes specialize in detecting a specific, narrow range of wavelengths on the electromagnetic spectrum —the visible spectrum? It is probably because the earliest species to develop photosensitivity were aquatic (such as jellyfish), and only two specific wavelength ranges of electromagnetic radiation, blue and green visible light, can be transmitted through water. This same light-filtering property of water also influenced the photosensitivity of plants.
The vocabulary question
The word ‘evolution’ in paragraph 1 is closest in meaning to:
- Change in habits and behavior
- Change in heritable traits
- Development of the human species
Correct answer: C
The key to answering this question is to highlight the word in the sentence and clarify its meaning and part of speech. It is believed that eyes evolved over a few million years during the Cambrian explosion, a rapid period of evolution. Evolution is the noun form of evolve, which means change and develop. Eyes changes and developed over millions of years. Therefore the correct answer is C.
The inference question
Which of the following can be inferred from paragraph 1 about eyes before the Cambrian Explosion?
- We can safely assume eyes existed prior to the Cambrian Explosion
- We can safely assume eyes did not exist prior to the Cambrian Explosion
- We can assume that prior to the Cambrian Explosion, eyes varied in visual acuity
- Prior to the Cambrian Explosion, eyes had not ability to identify motion, color or light.
Correct answer: B
It is the correct answer because there is evidence to support this statement in paragraph 1. The key to answering this question correctly is to find the general meaning of the text that refers to the Cambrian Explosion. Find the referral in the text and underline key ideas around it. Eyes seem to have evolved over a few million years during the Cambrian explosion, a rapid period of evolution. Prior to this time, there is no direct evidence of eyes.
We can safely conclude that before (prior to) the Cambrian Explosion, eyes did not exists – Answer B
The Negative Factual question
According to paragraph 4, all of the following statements are true about the light processing unit of the eye, EXCEPT:
- The photoreceptor cell contains two molecules: the opsin and the chromophore
- The group of cells is called an ‘eyespot’
- 96% of species have a light processing unit that allows a basic light sensitivity and direction
- Complex optical systems permit light discrimination within a few degrees
Correct answer: C
It is correct because this sentence changes the statement, 96% of species have a more complex optical system that allows light discrimination within a few degrees.
To answer the question successfully, read the answers carefully and remember that you are looking for the false statement. Then, scan paragraph 4 and highlight the matching information that correspond to the true answers. Answer C is the only false statement.
A, B and D are all found in the text.
The Paraphase question
Which of the sentence below best expresses the essential information in the following sentence?
These optical systems began as multi cellular eye patches and gradually evolved into a cup
- These optical systems started out as cells grouped into eye patches and then developed over time into a cup
- These multi cellular systems were cups that gradually evolved into optical systems
- These optical systems started out as eye patches grouped into cells and gradually became cups
- These eye patches were cups that gradually evolved into multiple cells
Correct answer: A
A is the correct answer because it follows what the passage states that the optical system started out as cells grouped into eye patches and then developed into cups.
The strategy in answering this question accurately is to highlight the key words in the sentences, clarify the general meaning and then match both to the correct answer.
Let’s look at the synonyms between the statement from the text and the first answer:
Began = started out
Multi cellular eye patches = cells grouped into eye patches
Gradually evolved = developed over time
Therefore, (A) is the right answer.
The Insert Text question
Examine the four spaces in the selection below and indicate at which block the following sentence could be inserted into the passage:
This is proposed in the research paper of modern scientists, Nilsson and S. Pelger.
□[A] Darwin presented intermediate grades of evolution and made suggestions that were soon shown to be correct. □ [B] Modern scientists have been putting forward work on the topic of eye evolution, suggesting that the eye developed from a vertebrate patch of photoreceptors. □ [C] Current research validates the theory of Darwin. □ [D]
Correct answer: D
D is correct because the sample sentence should following the preceding sentence describing the theory of Darwin.
The technique in answering the question is to identify the part of speech of the word ‘This’. A demonstrative adjective. This is replacing the subject noun. From the sentence, we know it is something proposed by modern scientists. As we read through the paragraph, we understand ‘This’ is referring to the idea that current research validates Darwin’s theory. Hence, the sentence must be placed at [D].
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