Gills Reading Answers

Jul 15, 2024

Gills Reading Answers is an academic reading answers topic. Gills Reading Answers have a total of 6 IELTS questions in total. In the questions, you have to choose the correct heading for the statement.

Candidates should read the IELTS Reading passage thoroughly to recognize synonyms, identify keywords, and answer the questions below. IELTS Reading practice papers, which feature topics such as The Gills Reading Answers. Candidates can use IELTS reading practice questions and answers to enhance their performance in the reading section.

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Section 1

Read the Passage to Answer the Following Questions

Gills

Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers (operculum) on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids, and ammonia. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide.
Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen -poor water out through openings in the sides of the pharynx. Some fish, like sharks and lampreys, possess multiple gill openings. However, bony fish have a single gill opening on each side. This opening is hidden beneath a protective bony cover called the operculum. Juvenile bichirs have external gills, a very primitive feature that they share with larval amphibians.
Previously, the evolution of gills was thought to have occurred through two diverging lines: gills formed from the endoderm, as seen in jawless fish species, or those form by the ectoderm, as seen in jawed fish. However, recent studies on gill formation of the little skate (Leucoraja erinacea) have shown potential evidence supporting the claim that gills from all current fish species have in fact evolved from a common ancestor.
Air breathing fish can be divided into obligate air breathers and facultative air breathers. Obligate air breathers, such as the African lungfish, are obligated to breathe air periodically or they suffocate. Facultative air breathers, such as the catfish Hypostomus plecostomus, only breathe air if they need to and can otherwise rely on their gills for oxygen. Most air breathing fish are facultative air breathers that avoid the energetic cost of rising to the surface and the fitness cost of exposure to surface predators.
All basal vertebrates breathe with gills. The gills are carried right behind the head, bordering the posterior margins of a series of openings from the esophagus to the exterior. Each gill is supported by a cartilaginous or bony gill arch. The gills of vertebrates typically develop in the walls of the pharynx, along a series of gill slits opening to the exterior. Most species employ a counter-current exchange system to enhance the diffusion of substances in and out of the gill, with blood and water flowing in opposite directions to each other.
The gills are composed of comb-like filaments, the gill lamellae, which help increase their surface area for oxygen exchange. When a fish breathes, it draws in a mouthful of water at regular intervals. Then it draws the sides of its throat together, forcing the water through the gili openings, so that it passes over the gills to the outside. The bony fish have three pairs of arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven. The vertebrate antecedent no doubt had more arches, as some of their chordate relatives have more than fifty pairs of gills.

Section 2

Solution and Explanation

Questions 15-20

Choose the correct heading for the given sections from the list of headings below.

Write the correct number in the answer sheet.
LIST OF HEADINGS

Location of the organ that is responsible for fish breathing.
Increased external side of protein structures for swapping oxygen and carbon dioxide.
Gills are more robust than lungs in terms of breathing capacity.
Current studies clarifying the development of gills.
An ancestral specie having more gills.
Divergent air breathing fish compared.
Air breathing fish are faster in water than fish that breath through gills.
Some marine species have numerous gill slots.
The evolution of the gills has resulted in better reproduction.

Paragraph A

Answer: II
Supporting statement:“......Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide........”
Keywords: area, exchanging
Keyword Location: para A, line 5-6
Explanation: Paragraph A describes the structure and function of fish gills, particularly focusing on the capillary network within the filaments that increases the surface area for gas exchange. This matches with the ‘II’, which refers to the increased external side of protein structures for swapping oxygen and carbon dioxide.

Paragraph B

Answer: VIII
Supporting statement:“.......Some fish, like sharks and lampreys, possess multiple gill openings. However, bony fish have a single gill opening on each side........”
Keywords: openings, bony
Keyword Location: para B, line 4-6
Explanation: Para B discusses the differences in gill structures among different fish species, highlighting that some fish like sharks and lampreys have multiple gill openings. This directly corresponds to the heading VIII, which mentions that some marine species have numerous gill slots.

Paragraph C

Answer: IV
Supporting statement:“......Recent studies on gill formation of the little skate (Leucoraja erinacea) have shown potential evidence supporting the claim that gills from all current fish species have in fact evolved from a
common ancestor........”
Keywords: formation, common
Keyword Location: para C, line 3-4
Explanation: Para C presents findings from recent studies on gill evolution, suggesting a common ancestral origin for gills in all current fish species. This fits heading IV, which refers to current studies clarifying the development of gills.

Paragraph D

Answer: VI
Supporting statement:“......Obligate air breathers, such as the African lungfish, are obligated to breathe air periodically or they suffocate. Facultative air breathers, such as the catfish Hypostomus plecostomus, only breathe
air if they need to and can otherwise rely on their gills for oxygen........”
Keywords: breathers, facultative
Keyword Location: para D, line 1-3
Explanation: Para D differentiates between obligate and facultative air-breathing fish, describing their different breathing mechanisms. This aligns with heading VI, which addresses the comparison of divergent air-breathing fish.

Paragraph E

Answer: I
Supporting statement:“.......The gills are carried right behind the head, bordering the posterior margins of a series of openings from the esophagus to the exterior........”
Keywords: gills, right
Keyword Location: para E, line 2
Explanation: Para E specifies the anatomical location of gills in basal vertebrates, stating that they are located right behind the head. This corresponds to heading I, which is about the location of the organ responsible for
fish breathing.

Paragraph F

Answer: V
Supporting statement:“........The vertebrate antecedent no doubt had more arches, as some of their chordate relatives have more than fifty pairs of gills......”
Keywords: antecedent, more
Keyword Location: para F, line 5-6
Explanation: Para F mentions that the vertebrate ancestors had more gill arches than the current species, with some chordate relatives having over fifty pairs of gills. This matches heading V, which refers to an ancestral species having more gills

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