Comprehension

The levels of dissolved oxygen in the world's ocean waters are declining precipitously. Just like humans, fish need oxygen to survive, and so in ocean areas experiencing significant levels of oxygen scarcity, or hypoxia, fish populations are plummeting. Although some hypoxic areas, called "dead zones," occur naturally, hypoxia in coastal areas and inland waters is caused mainly by agricultural run-off and by discharge of industrial wastewater. More than one hundred permanent dead zones, many covering thousands of square miles, exist worldwide today.
Since reproductive success is the most critical factor in the sustainability of any species, the extent of this threat to marine life and genetic diversity can hardly be overstated. After several months in hypoxic waters, female fish produce fewer eggs. Moreover, hypoxic conditions serve to alter the normal ratio between two particular hormones manufactured during the embryonic stage when a fish's gender is determined. During gestation and under these conditions, the mother produces more testosterone (and less estradiol), which inhibits the development of female reproductive organs and other female characteristics in the embryo, while promoting the development of male traits.
The implications of declining oxygen levels extend beyond individual species to entire ecosystems. Marine biodiversity is at risk as species that cannot adapt to hypoxic conditions may face extinction, leading to a cascade of effects throughout the food web. Predators may struggle to find adequate prey, while other marine organisms, such as coral reefs, which rely on healthy fish populations for symbiotic relationships, may also deteriorate. The loss of biodiversity can disrupt ecosystem services that are essential for human communities, including fisheries, tourism, and coastal protection.

Question: 1

How does hypoxia affect female fish reproduction?

  • It increases egg production
  • It has no effect on reproduction
  • It decreases egg production
  • It improves the survival rate of embryos
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The Correct Option is C

Solution and Explanation

The passage states that after several months in hypoxic waters, female fish produce fewer eggs, which directly implies that hypoxia negatively affects egg production.
Thus, the correct answer is Option (C).
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Question: 2

What term is used in the passage to describe areas with significantly low levels of oxygen?

  • Oxygen-rich zones
  • Dead zones
  • Marine reserves
  • Hypoxic waters
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The Correct Option is B

Solution and Explanation

The term ”dead zones” is used in the passage to describe areas with significantly low levels of oxygen, where marine life struggles to survive.
Thus, the correct answer is Option (B).
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Question: 3

What effect do altered hormone levels during gestation have on fish embryos in hypoxic conditions?

  • They promote the development of female traits
  • They cause all embryos to become hermaphrodites
  • They have no impact on gender determination
  • They inhibit female trait and promote male traits
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The Correct Option is D

Solution and Explanation

The passage explains that under hypoxic conditions, the mother fish produces more testosterone, which inhibits the development of female traits and promotes male traits in the embryo.
Thus, the correct answer is Option (D).
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Question: 4

What broader ecological impact does declining oxygen levels have, as mentioned in the passage?

  • Increase in hypoxic fish populations
  • Enrichment of coral reefs
  • Disruption of entire ecosystems
  • Degradation of marine biodiversity
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The Correct Option is C

Solution and Explanation

The passage explains that declining oxygen levels lead to a disruption of entire ecosystems, affecting species’ survival, food webs, and biodiversity.
Thus, the correct answer is Option (C).
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Question: 5

Why is reproductive success critical for any species, according to the passage?

  • It ensures the continuation of genetic diversity
  • It determines the physical traits of the species
  • It affects the feeding habits of the species
  • It influences the increase in habitat size
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The Correct Option is A

Solution and Explanation

Reproductive success is critical for ensuring the continuation of genetic diversity, which is necessary for the long-term survival of species.
Thus, the correct answer is Option (A).
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Question: 6

Which of the following implications of hypoxia is not mentioned in the passage?

  • Permanent loss of fish populations in affected areas
  • Changes in the gender ratio of fish populations
  • Increased competition among fish species
  • Decline in ecosystem services such as fisheries and tourism
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The Correct Option is C

Solution and Explanation

The passage mentions the loss of biodiversity, gender ratio changes, and the decline in ecosystem services, but it does not mention increased competition among fish species.
Thus, the correct answer is Option (C).
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Question: 7

In the context of the passage, which of the following best characterizes the term ‘sustainability’?

  • Maintaining current fish populations at all costs including government initiatives
  • Ensuring the reproductive success of marine species for future generations
  • Focusing solely on economic benefits derived from marine resources
  • Prioritizing industrial growth over environmental health
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The Correct Option is B

Solution and Explanation

The passage emphasizes that sustainability is about ensuring the reproductive success of marine species, which is necessary for the survival of species and the preservation of marine ecosystems.
Thus, the correct answer is Option (B).
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