TOEFL Reading Practice Online | Q&A 011

This is an original TOEFL-style academic reading passage with practice comprehension questions, not reproduced from any official test. Time yourself at roughly 1.5 minutes per question, and try the reading practice hub or browse more reading practice articles for additional sets.

Passage

Amber: A Window into Ancient Life

[1] Most fossils form when the hard parts of an organism, such as bone or shell, are gradually replaced by minerals after burial, leaving behind an impression or a mineralized copy of the original structure. Soft tissue, which decays quickly, is rarely preserved this way. Amber offers a striking exception. Because it can seal small organisms away from air and decay-causing bacteria soon after they are trapped, amber sometimes preserves insects, spiders, and even feathers in a condition close to how they appeared while alive.

[2] Amber begins as resin, a sticky substance produced by certain trees, most famously several groups of conifers, in response to injury or infection. When resin is exuded onto bark or exposed wood, insects and other small creatures occasionally become trapped in it, much as they might become stuck to any thick, slow-moving liquid. If the resin is then buried by falling leaves or sediment before it can be broken down by weathering, it is cut off from the atmosphere. Over long periods, chemical changes within the buried resin cause its molecules to link together into larger, more stable structures. Combined with the pressure and mild heat that come with deep burial over millions of years, this transformation gradually converts the original resin into the hard, glassy material known as amber.

[3] The organisms trapped inside amber are often preserved in remarkable detail because the resin excludes oxygen and blocks the bacteria and fungi that normally break down soft tissue. Researchers have recovered amber specimens showing the fine hairs on an insect's legs, the delicate veins of a wing, and in some cases traces of original color patterns. Pollen grains, tiny flowers, and fragments of feathers have also been found sealed inside amber, offering a level of detail that is rarely available from fossils preserved in rock.

[4] Because of this level of preservation, amber inclusions give researchers unusually direct evidence about ancient ecosystems. Specimens have captured insects in the middle of mating, an ant attacking another insect, or a spider spinning silk, offering glimpses of behavior rather than just anatomy. Claims that intact ancient DNA can be routinely recovered from amber-trapped organisms are not supported by careful chemical analysis, however; DNA breaks down steadily after death regardless of how well the surrounding tissue looks preserved, and most amber specimens are far too old for usable genetic material to survive.

[5] Amber preservation also has clear limits as a historical record. Because it depends on trees that produce large amounts of resin, amber deposits are concentrated in certain forest environments and time periods, and they are heavily biased toward small, land-dwelling organisms. Large animals, deep-sea creatures, and entire ecosystems that left no resin-producing trees behind are essentially invisible in the amber record, so amber complements rather than replaces other types of fossil evidence.

Questions

1. What does the passage mainly discuss?

• (A) The chemical composition of tree resin
• (B) The recovery of dinosaur DNA from amber
• (C) The market value of amber compared with bone fossils
• (D) How amber forms and why it preserves ancient organisms in unusual detail

2. The word "it" in the fourth sentence of paragraph 1 refers to

• (A) bone
• (B) an impression
• (C) amber
• (D) bacteria

3. The word "exuded" in paragraph 2 is closest in meaning to

• (A) released
• (B) absorbed
• (C) hardened
• (D) measured

4. According to paragraph 2, what must happen to resin before it can eventually become amber?

• (A) It must be exposed to sunlight for several years.
• (B) It must be buried and sealed off from the air, then changed chemically over a very long time under pressure and heat.
• (C) It must be mixed with volcanic ash.
• (D) It must be eaten and digested by insects.

5. According to paragraph 3, amber has been found to preserve all of the following EXCEPT

• (A) fine hairs on an insect's legs
• (B) traces of original color patterns
• (C) pollen grains and tiny flowers
• (D) complete skeletons of large land animals

6. Why does the author mention insects captured "in the middle of mating" and a spider "spinning silk" in paragraph 4?

• (A) To argue that amber specimens are more valuable than living insects
• (B) To explain how insects became trapped in resin
• (C) To illustrate that amber can preserve behavior, not just physical structure
• (D) To describe how spiders build webs

7. According to paragraph 4, why are claims about routinely recovering intact ancient DNA from amber not supported?

• (A) DNA breaks down after death, however well preserved the surrounding tissue looks.
• (B) Amber contains chemicals that destroy DNA immediately.
• (C) Researchers are not permitted to cut open amber specimens.
• (D) Insects in amber contain no DNA at all.

8. The word "concentrated" in paragraph 5 is closest in meaning to

• (A) spread evenly
• (B) grouped together
• (C) weakened
• (D) hidden

9. According to paragraph 5, why are large animals and deep-sea creatures poorly represented in the amber record?

• (A) They decay too quickly to be studied.
• (B) Researchers have not looked for them.
• (C) Amber preserves only organisms younger than a thousand years.
• (D) Amber forms from tree resin, which traps mainly small organisms living on land.

Answers and explanations

1. (D) Paragraph 2 explains how amber forms, and paragraphs 3–5 explain what it preserves, why, and where its record falls short. Option (B) contradicts paragraph 4.
2. (C) "Amber offers a striking exception. Because it can seal small organisms away from air…": "it" is amber.
3. (A) Resin "exuded onto bark" is resin released or given off by the tree.
4. (B) Paragraph 2 says the resin must be buried and "cut off from the atmosphere," after which chemical changes, pressure, and mild heat over millions of years turn it into amber.
5. (D) Paragraph 3 lists leg hairs, wing veins, color traces, pollen, flowers, and feathers. Paragraph 5 says large animals are "essentially invisible" in the amber record.
6. (C) These examples show behavior caught in action, "offering glimpses of behavior rather than just anatomy."
7. (A) Paragraph 4 states that "DNA breaks down steadily after death regardless of how well the surrounding tissue looks preserved."
8. (B) Amber deposits "concentrated in certain forest environments" are grouped in particular places rather than spread evenly.
9. (D) Paragraph 5 explains that amber depends on resin-producing trees and is "heavily biased toward small, land-dwelling organisms."