Until recently, zoologists believed that all species of phocids (true seals), a pinniped family, use a different maternal strategy than...
GMAT Reading Comprehension : (RC) Questions
Until recently, zoologists believed that all species of phocids (true seals), a pinniped family, use a different maternal strategy than do otariids (fur seals and sea lions), another pinniped family. Mother otariids use a foraging strategy. They acquire moderate energy stores in the form of blubber before arriving at breeding sites and then fast for 5 to 11 days after birth. Throughout the rest of the lactation (milk production) period, which lasts from 4 months to 3 years depending on the species, mother otariids alternately forage at sea, where they replenish their fat stores, and nurse their young at breeding sites. Zoologists had assumed that females of all phocids species, by contrast, use a fasting strategy in which mother phocids, having accumulated large energy stores before they arrive at breeding sites, fast throughout the entire lactation period, which lasts from 4 to 50 days depending on the species. However, recent studies on harbor seals, a phocids species, found that lactating females commenced foraging approximately 6 days after giving birth and on average made 7 foraging trips during the remainder of their 24-day lactation period.
The maternal strategy evolved by harbor seals may have to do with their small size and the large proportion of their fat stores depleted in lactation. Harbor seals are small compared with other phocids species such as grey seals, northern elephant seals, and hooded seals, all of which are known to fast for the entire lactation period. Studies show that mother seals of these species use respectively 84 percent, 58 percent, and 33 percent of their fat stores during lactation. By comparison, harbor seals use 80 percent of their fat stores in just the first 19 days of lactation, even though they occasionally feed during this period. Since such a large proportion of their fat stores is exhausted despite feeding, mother harbor seals clearly cannot support all of lactation using only energy stored before giving birth. Though smaller than many other phocids, harbor seals are similar in size to most otariids. In addition, there is already some evidence suggesting that the ringed seal, a phocids species that is similar in size to the harbor seal, may also use a maternal foraging strategy.
It can be inferred from the passage that the females of all phocids species differ from the females of all otariid species in that the female phocids
1. Passage Analysis:
Progressive Passage Analysis
| Text from Passage | Analysis |
|---|---|
| Until recently, zoologists believed that all species of phocids (true seals), a pinniped family, use a different maternal strategy than do otariids (fur seals and sea lions), another pinniped family. | What it says: Scientists thought two types of seals had different ways of caring for babies. What it does: Sets up the main topic and establishes a contrast between two seal families. Source/Type: Statement about what scientists previously believed. Connection to Previous Sentences: This is the opening - establishes our foundation. Visualization: Seal Family 1: Phocids (true seals) → Strategy A Seal Family 2: Otariids (fur seals/sea lions) → Strategy B What We Know So Far: Two seal families exist with different maternal strategies What We Don't Know Yet: What these strategies actually are Reading Strategy Insight: Note "Until recently" - this signals the passage will challenge this belief! |
| Mother otariids use a foraging strategy. They acquire moderate energy stores in the form of blubber before arriving at breeding sites and then fast for 5 to 11 days after birth. Throughout the rest of the lactation (milk production) period, which lasts from 4 months to 3 years depending on the species, mother otariids alternately forage at sea, where they replenish their fat stores, and nurse their young at breeding sites. | What it says: Otariids (fur seals/sea lions) build up fat, fast briefly after birth, then alternate between finding food at sea and feeding babies on land. What it does: Explains Strategy B in detail. Source/Type: Factual description of otariid behavior. Connection to Previous Sentences: This builds on Sentence 1 by defining what "Strategy B" actually is - the otariid approach. Visualization: Otariid Timeline: Before birth: Build moderate fat stores Days 1-5 to 11: Fast (no eating) Months 1-36: Alternate sea (eating) ↔ land (nursing) What We Know So Far: Otariids use a "go back and forth" strategy What We Don't Know Yet: What phocids do differently Reading Strategy Insight: The author helpfully defines "foraging strategy" and "lactation" - this is support, not complexity! |
| Zoologists had assumed that females of all phocids species, by contrast, use a fasting strategy in which mother phocids, having accumulated large energy stores before they arrive at breeding sites, fast throughout the entire lactation period, which lasts from 4 to 50 days depending on the species. | What it says: Scientists thought phocids (true seals) build up lots of fat, then don't eat at all during the entire nursing period. What it does: Explains Strategy A and contrasts it with Strategy B. Source/Type: What zoologists assumed to be true. Connection to Previous Sentences: This completes the contrast setup from Sentence 1. Now we understand both strategies! Visualization: STRATEGY COMPARISON: Otariids: Moderate fat → Brief fast → Alternate eating/nursing (4mo-3yr) Phocids: Large fat stores → Fast entire time (4-50 days) What We Know So Far: Complete picture of the supposed difference What We Don't Know Yet: Why the passage said "until recently" Reading Strategy Insight: Feel confident here! The author just gave us a clear comparison. Also note "had assumed" - this belief is about to be challenged. |
| However, recent studies on harbor seals, a phocids species, found that lactating females commenced foraging approximately 6 days after giving birth and on average made 7 foraging trips during the remainder of their 24-day lactation period. | What it says: New research shows harbor seals (a type of phocid) actually DO go out to find food - starting 6 days after birth and making 7 trips total. What it does: Introduces the challenge to the old belief with specific evidence. Source/Type: Recent research findings. Connection to Previous Sentences: This directly contradicts Sentence 3! Harbor seals are phocids but they're NOT using the "fast throughout" strategy. Visualization: What Scientists Thought All Phocids Did: Fast for entire 4-50 days What Harbor Seals Actually Do: Days 1-6: Fast Days 7-24: Make 7 foraging trips (like otariids!) What We Know So Far: The old theory is wrong - at least some phocids act like otariids What We Don't Know Yet: Why harbor seals are different Reading Strategy Insight: This is the "However" moment! The passage is now explaining why the old belief was wrong. |
| The maternal strategy evolved by harbor seals may have to do with their small size and the large proportion of their fat stores depleted in lactation. | What it says: Harbor seals might act differently because they're small and use up most of their fat while nursing. What it does: Proposes an explanation for why harbor seals are exceptional. Source/Type: Author's hypothesis/reasoning. Connection to Previous Sentences: This builds on Sentence 4 by offering a theory for WHY harbor seals don't follow the expected phocid pattern. Visualization: Harbor Seal Problem: Small size → Less total fat storage capacity High fat depletion → Must eat during nursing or run out What We Know So Far: Harbor seals break the rule, possibly due to size constraints What We Don't Know Yet: How their size compares to other seals specifically Reading Strategy Insight: The author is being logical and helpful - giving us a reasonable explanation rather than just stating facts. |
| Harbor seals are small compared with other phocids species such as grey seals, northern elephant seals, and hooded seals, all of which are known to fast for the entire lactation period. | What it says: Harbor seals are smaller than other phocids (grey seals, elephant seals, hooded seals), and those bigger ones DO fast the whole time. What it does: Provides supporting evidence for the size theory. Source/Type: Factual comparison. Connection to Previous Sentences: This supports Sentence 5's size hypothesis and confirms that most other phocids still follow the original pattern. Visualization: PHOCID SIZE COMPARISON: Small: Harbor seals → Break the fasting rule Large: Grey seals, elephant seals, hooded seals → Follow fasting rule What We Know So Far: Size seems to determine strategy within phocids What We Don't Know Yet: Specific numbers proving this theory Reading Strategy Insight: This reinforces rather than complicates! The author is building a clear size-based argument. |
| Studies show that mother seals of these species use respectively 84 percent, 58 percent, and 33 percent of their fat stores during lactation. | What it says: The bigger phocids (grey, elephant, hooded seals) use 84%, 58%, and 33% of their fat respectively. What it does: Provides concrete data supporting the theory. Source/Type: Research data/statistics. Connection to Previous Sentences: This builds on Sentence 6 by giving specific numbers for the larger phocids mentioned. Visualization: LARGE PHOCIDS' FAT USAGE: Grey seals: 84% of fat stores Elephant seals: 58% of fat stores Hooded seals: 33% of fat stores (All can survive on stored fat alone) What We Know So Far: Large phocids don't exhaust their fat stores What We Don't Know Yet: Harbor seal numbers for comparison Reading Strategy Insight: These are setup numbers - expect harbor seal data next to complete the comparison! |
| By comparison, harbor seals use 80 percent of their fat stores in just the first 19 days of lactation, even though they occasionally feed during this period. | What it says: Harbor seals burn through 80% of their fat in only 19 days, despite already eating some food. What it does: Completes the comparison and proves the theory. Source/Type: Research data. Connection to Previous Sentences: This is the smoking gun! Compares directly to Sentence 7's data and proves harbor seals are different. Visualization: FAT DEPLETION COMPARISON: Large Phocids: 33-84% over ENTIRE lactation (fasting works) Harbor Seals: 80% in just 19 days (fasting impossible!) What We Know So Far: Harbor seals burn fat much faster What We Don't Know Yet: The final conclusion Reading Strategy Insight: Feel confident! This data clearly supports everything built up so far. |
| Since such a large proportion of their fat stores is exhausted despite feeding, mother harbor seals clearly cannot support all of lactation using only energy stored before giving birth. | What it says: Because harbor seals use up almost all their fat even while eating, they obviously can't rely only on stored energy. What it does: States the logical conclusion from all the evidence. Source/Type: Author's logical deduction. Connection to Previous Sentences: This is pure restatement and conclusion! Takes all the data from Sentences 7-8 and explains what it means. Visualization: HARBOR SEAL REALITY: Fat stores alone = Not enough energy Must forage during lactation = Survival necessity Reading Strategy Insight: Feel relieved here! This is simplification, not new complexity. The author is helping us understand what all those numbers mean. |
| Though smaller than many other phocids, harbor seals are similar in size to most otariids. | What it says: Harbor seals are small for phocids but about the same size as otariids. What it does: Makes a connection between harbor seal behavior and otariid behavior. Source/Type: Factual comparison. Connection to Previous Sentences: This connects back to Sentences 2-3, suggesting that similar size leads to similar strategy (harbor seals act like otariids because they're the same size). Visualization: SIZE & STRATEGY CONNECTION: Large phocids → Can fast (like expected) Small harbor seals ≈ Otariids → Must forage (same strategy!) Reading Strategy Insight: This is pattern recognition! Size determines strategy across both seal families. |
| In addition, there is already some evidence suggesting that the ringed seal, a phocids species that is similar in size to the harbor seal, may also use a maternal foraging strategy. | What it says: Ringed seals (also small phocids like harbor seals) might also forage during nursing. What it does: Provides additional support that this is a pattern, not just one exception. Source/Type: Preliminary research evidence. Connection to Previous Sentences: This reinforces the size-strategy pattern established throughout. Another small phocid acting like otariids. Visualization: EMERGING PATTERN: Small Phocids: Harbor seals + Ringed seals → Forage (like otariids) Large Phocids: Grey, elephant, hooded seals → Fast (original theory) What We Now Know: Size, not family, determines maternal strategy! Reading Strategy Insight: Perfect ending! This generalizes the lesson and shows the new understanding replaces the old belief from Sentence 1. |
2. Passage Summary:
Author's Purpose:
To explain how new research has challenged and changed scientists' understanding of maternal strategies in seals, showing that size rather than family type determines how mother seals feed their babies.
Summary of Passage Structure:
In this passage, the author walks us through a scientific discovery that overturned old beliefs about seal behavior:
- First, the author explains what scientists used to believe - that two different seal families had completely different ways of caring for their babies during nursing
- Next, the author describes both strategies in detail: one family alternates between finding food and nursing, while the other was thought to fast completely during nursing
- Then, the author presents new research showing that some seals from the "fasting" family actually do forage for food, contradicting the old theory
- Finally, the author provides evidence that size, not family type, explains the difference - smaller seals must forage because they burn through fat stores too quickly, while larger seals can survive by fasting
Main Point:
Scientists were wrong to think that all seals in the same family use the same nursing strategy. Instead, seal size determines behavior - small seals must find food during nursing regardless of which family they belong to, while large seals can survive by fasting on stored fat alone.
3. Question Analysis:
This question asks us to identify a difference that applies to ALL females of phocids species compared to ALL females of otariid species. The key word "all" means we need to find a characteristic that's universally true for one group versus the other, not just for some species within each group.
Connecting to Our Passage Analysis:
From our passage analysis, we know that:
- The passage initially described two different maternal strategies - otariids use a foraging strategy while phocids were thought to use a fasting strategy
- New research showed this distinction isn't absolute - some small phocids (like harbor seals) actually forage like otariids
- However, one clear difference remains consistent throughout: lactation periods differ significantly between the families
- From the passage: otariid lactation lasts "from 4 months to 3 years depending on the species" while phocid lactation lasts "from 4 to 50 days depending on the species"
- Even harbor seals, which break the fasting rule, still have only a 24-day lactation period
Prethinking:
While the passage shows that maternal strategies (foraging vs. fasting) aren't universally different between the families due to size factors, the lactation period lengths remain consistently different. All phocids mentioned have lactation periods measured in days (4-50 days), while all otariids have lactation periods measured in months to years (4 months to 3 years). This represents a fundamental biological difference that applies universally to both families.
Why It's Right:
• The passage clearly states otariid lactation lasts "from 4 months to 3 years" while phocid lactation lasts "from 4 to 50 days"
• This difference holds true for ALL species mentioned in both families
• Even harbor seals, which break other rules, still have only a 24-day lactation period
• This is a universal biological difference that applies regardless of size or behavioral strategy
Key Evidence: "Throughout the rest of the lactation (milk production) period, which lasts from 4 months to 3 years depending on the species, mother otariids alternately forage" vs. "fast throughout the entire lactation period, which lasts from 4 to 50 days depending on the species"
Why It's Wrong:
• The passage shows that some phocids (harbor seals, possibly ringed seals) actually DO forage during lactation
• This contradicts the idea that phocids consume less food than otariids
• Harbor seals make an average of 7 foraging trips during their lactation period
Common Student Mistakes:
1. Didn't the passage say most phocids fast while otariids forage?
→ Remember that "all phocids" must include harbor seals, which do forage
1. But larger phocids don't eat during lactation, so don't they consume less overall?
→ The question asks about all females of each species, not average consumption patterns
Why It's Wrong:
• This reverses what the passage actually shows about fat store usage
• Harbor seals use 80% of their fat stores despite being phocids
• Some large phocids use only 33% of their fat stores
• The passage doesn't provide comprehensive data comparing all phocids to all otariids
Common Student Mistakes:
1. Don't the numbers show phocids use more fat (33-84% vs otariids)?
→ The passage only gives fat usage data for some phocids, not otariids
1. Since harbor seals use 80%, doesn't that mean phocids generally use more?
→ Harbor seals are exceptional; we can't generalize from one species to all phocids
Why It's Wrong:
• This contradicts the established pattern where otariids consistently forage throughout lactation
• The passage shows otariids "alternately forage at sea" throughout their entire lactation period
• Only some phocids forage occasionally, and this is presented as exceptional behavior
• This choice reverses the actual foraging patterns described
Common Student Mistakes:
1. Since harbor seals forage and they're phocids, don't all phocids forage occasionally?
→ Harbor seals are exceptions; most phocids still fast completely
1. The passage mentions otariids alternating between foraging and nursing - isn't that occasional?
→ "Alternately" means regularly throughout lactation, not occasionally
Why It's Wrong:
• Harbor seals use 80% of their fat stores, which is higher than some other phocids
• The passage doesn't provide fat store depletion data for otariids for comparison
• Grey seals (phocids) use 84% of their stores, showing high depletion within phocids
• We cannot make universal claims about fat store usage without complete comparative data
Common Student Mistakes:
1. Don't the percentages (33-84%) show that phocids deplete less than the 80% harbor seals use?
→ Those percentages ARE from phocids - they show variation within phocids, not comparison to otariids
1. Since otariids keep foraging, don't they must deplete less fat?
→ The passage doesn't provide otariid fat depletion data to support this assumption