---
title: The platypus and the echidna: mammals that lay eggs — how Mova does on the tests · Biology
description: Lesson 43 of the biology course of Mova's primary school: 6 of 11 tests right, exam 2 of 4, every question with the options, the student's choice, the right answer and why it chose.
---

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# The platypus and the echidna: mammals that lay eggs

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**Tests:** 6 of 11 right · **Exam:** 2 of 4 right · **Kind:** plain · **Understood:** 9 of 15 · **Run:** 2026-10-18, commit `f3c23ea72`

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Lesson 43 of the biology course of Mova's primary school, as Mova's small model took its tests: it had read this lesson and the ones before it and learned from their exercises. Each test shows the options in the order the student saw them, its choice, the right answer, the score of every option and why it chose. The lesson itself, sentence by sentence with trees and pragmatics: [the lesson in the corpora](https://md.mova.elamur.ai/free/en/corpora/school/biology/43-platypus-and-echidna/).

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Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: [the lesson's questions in the corpora](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/).

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### Test 1 · wrong ✗ {#t1}

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«all mammals have live babies, that's the whole point of mammals» What is right?

- **1.** Yes, the platypus is a kind of duck — **← Mova's choice** · no support
- **2.** No, the platypus and echidnas are mammals that lay eggs — **✓ the right answer** · no support
- **3.** No, all mammals lay eggs — no support
- **4.** Yes, any animal that lays eggs is a bird or a reptile, simple — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t1/)

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### Test 2 · right ✓ {#t2}

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In a cartoon, a platypus quacks and hunts with big open eyes. What would a real platypus do?

- **1.** Fly low over the water like a duck — no support
- **2.** Dive with its eyes shut and feel for food with its bill — **← Mova's choice** · **✓ the right answer** · score 12
- **3.** Quack loudly under the water to scare the fish out of the weeds — score 5
- **4.** Hunt only on land by sight — score 10

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**Why:** It took the question to ask what is done. It chose option 2 with score 12, against 10 for the next best. Its support: lesson 43, line 7: «A platypus dives with its eyes, ears and nostrils closed and finds shrimps, worms and insect larvae with tens of thousands of sensors in its soft bill that fee…», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same action «dive» (+4); the same circumstance (+4). Against it: a different doer (counts against) (-2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t2/)

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### Test 3 · wrong ✗ {#t3}

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«found a platypus on the creek bank, gonna pick it up for a pic» What is the best advice?

- **1.** Only pick up the ones that glow — **← Mova's choice** · no support
- **2.** Leave it: a male can stab with a venomous spur — **✓ the right answer** · no support
- **3.** Fine, platypuses are totally harmless little things — no support
- **4.** Fine, just hold its bill shut — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t3/)

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### Test 4 · wrong ✗ {#t4}

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A poster shows five animals, one platypus and four echidnas. What do all five share?

- **1.** They all have sharp teeth — **← Mova's choice** · no support
- **2.** They all live in South America — no support
- **3.** They are the only egg-laying mammals alive today — **✓ the right answer** · no support
- **4.** They are all marsupials that carry babies in pouches — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t4/)

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### Test 5 · wrong ✗ {#t5}

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«a duck bill + beaver tail?? that thing's fake mate» Why should a scientist be careful before deciding?

- **1.** Animals with bills are always birds — no support
- **2.** Scientists never doubt anything — no support
- **3.** Anything that looks that strange is always fake, so throw it straight out — **← Mova's choice** · score 3
- **4.** Strange things can be real, so check the evidence before deciding — **✓ the right answer** · no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 3 with score 3, the only option with support. Its support: lesson 43, line 3: «When the first platypus skin reached Britain around 1799, a scientist looked for stitches, sure that a joker had sewn a duck's bill onto a furry animal, like a…», reached through the option's own match among the sentences about the question's things. What matched: the same action «look» (+2); the same doer «scientist» (+1). The right option, 4, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t5/)

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### Test 6 · right ✓ {#t6}

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Why does a platypus fill its cheek pouches before coming up?

- **1.** It wants to feed its eggs on the surface — score 2
- **2.** It breathes only at the surface, so it saves trips by eating many mouthfuls at once — **← Mova's choice** · **✓ the right answer** · score 4
- **3.** It is hiding food from the other platypuses that share its stretch of the creek — score 4
- **4.** It cannot swallow under water at all — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 2 with score 4, tied with another option at 4 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 43, line 12: «A platypus stuffs food from the riverbed into its cheek pouches and chews it at the surface with hard horny pads, because adults have no teeth; it must come up…», reached through the same lesson line as the sentence the question matched. What matched: the same place «surface» (+3); the same doer «platypus» (+2). Against it: a different action (counts against) (-1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t6/)

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### Test 7 · wrong ✗ {#t7}

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«echidnas = hedgehogs, same thing» What is right?

- **1.** Yes, they are the same animal, just with different names in Australia — **← Mova's choice** · no support
- **2.** No, an echidna lays eggs; a hedgehog gives birth to live young — **✓ the right answer** · no support
- **3.** Yes, both lay eggs — no support
- **4.** No, an echidna is a kind of porcupine fish — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t7/)

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### Test 8 · right ✓ {#t8}

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What would happen if a mother echidna kept her puggle in the pouch after its spines grew?

- **1.** The spines would prick her, so she moves it to a burrow — **← Mova's choice** · **✓ the right answer** · score 6
- **2.** The pouch would grow spines too — no support
- **3.** The puggle would lay its own egg — score 3
- **4.** Nothing at all, because baby spines stay soft forever — no support

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**Why:** It took the question to ask what happens next. It chose option 1 with score 6, against 3 for the next best. Its support: lesson 43, line 15: «A mother echidna lays one soft egg straight into a pouch; after about 10 days a baby the size of a jellybean, called a puggle, hatches and drinks milk there; w…», reached through what followed the sentence the question matched. What matched: the same thing acted on «echidna» (+4); the same place «burrow» (+4). Against it: a different action (counts against) (-2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t8/)

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### Test 9 · right ✓ {#t9}

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In a game, a platypus hatches from an egg and its mother feeds it worms. What is wrong?

- **1.** Nothing is wrong — no support
- **2.** Platypuses do not hatch from eggs — score 3
- **3.** Platypus mothers feed their babies fish bones — score 2
- **4.** Platypus babies drink their mother's milk — **← Mova's choice** · **✓ the right answer** · score 11

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**Why:** It took the question to ask which statement is true. It chose option 4 with score 11, against 3 for the next best. Its support: lesson 43, line 15: «A mother echidna lays one soft egg straight into a pouch; after about 10 days a baby the size of a jellybean, called a puggle, hatches and drinks milk there; w…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «baby» (+5); the same action «drink» (+4); the same thing acted on «milk» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t9/)

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### Test 10 · right ✓ {#t10}

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Why does a cooler echidna body need less food?

- **1.** Keeping warm burns food, so a cooler body burns less — **← Mova's choice** · **✓ the right answer** · score 11
- **2.** Cold bodies can make their own food out of air and sunlight — score 5
- **3.** Food freezes inside a cool body — no support
- **4.** Cool animals never move at all — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 1 with score 11, against 5 for the next best. Its support: lesson 43, line 16: «Echidnas can survive bushfires by hiding in burrows or logs and lowering their body temperature and heartbeat, a state called torpor; their normal body tempera…», reached through the cause of the sentence the question matched. What matched: the same action «keep» (+5); the same thing acted on «burns food» (+4); the same doer «cooler body» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t10/)

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### Test 11 · right ✓ {#t11}

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A kangaroo and a platypus are both mammals. How are their babies different?

- **1.** A kangaroo lays eggs in a pouch, and a platypus has live babies in a burrow — score 8
- **2.** Both give birth to big live babies — score 7
- **3.** Both lay eggs in a pouch — score 8
- **4.** A kangaroo gives birth to a tiny live baby, a platypus lays eggs — **← Mova's choice** · **✓ the right answer** · score 10

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**Why:** It took the question to ask what something is like. It chose option 4 with score 10, against 8 for the next best. Its support: lesson 43, line 17: «Other mammals give birth: a hedgehog looks a bit like an echidna but has live babies, and a kangaroo gives birth to a tiny live baby that grows in its pouch.», reached through the option's own match among the sentences about the question's things. What matched: the same action «give» (+4); the same doer «kangaroo» (+3); the same receiver «tiny live baby» (+2); the same thing acted on «birth» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/t11/)

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### Exam question 1 · formal language · wrong ✗ {#e1}

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Which of the following statements most accurately characterises the monotremes?

- **1.** They are mammals which give birth to young of exceptional size and strength — **← Mova's choice** · score 8
- **2.** They are reptiles which have acquired fur and the capacity to produce milk — score 8
- **3.** They are birds which have lost the capacity for flight — score 8
- **4.** They are mammals bearing fur and nourishing their young with milk, yet laying eggs — **✓ the right answer** · score 8

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**Why:** It took the question to ask who or what does it. It chose option 1 with score 8, tied with another option at 8 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 43, line 9: «A male platypus has a hollow spur on each back ankle that injects venom, very painful to people and able to kill a dog; males use it mostly against other males…», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+5); the same doer «male platypus» (+3). The right option, 4, scored 8. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/e1/)

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### Exam question 2 · formal language · right ✓ {#e2}

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Identify the principal means whereby the platypus locates its prey beneath the water.

- **1.** Sensors within the bill which detect movement and faint electrical activity — **← Mova's choice** · **✓ the right answer** · no support
- **2.** Hearing, the ears remaining open throughout the entire course of the dive — no support
- **3.** Acute vision, the eyes remaining open throughout the dive — no support
- **4.** Echolocation in the manner of the bat — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/e2/)

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### Exam question 3 · formal language · right ✓ {#e3}

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Select the response consistent with the established facts concerning the spines of the echidna.

- **1.** The spines are shed and regrown on a daily basis — no support
- **2.** The spines are feathers of an unusual form, inherited from the ancestral birds — no support
- **3.** The spines are modified hairs, protecting an animal unable to flee rapidly — **← Mova's choice** · **✓ the right answer** · score 9
- **4.** The spines are hollow and inject a venom sufficient to disable a dingo — no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 9, the only option with support. Its support: lesson 43, line 13: «An echidna is covered in spines that are thick hairs; it walks slowly and cannot run from danger, so when frightened it curls into a ball or digs straight down…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «spines» (+5); the same thing acted on «thick hairs» (+2); the same light verb (be, have, do, get, go) (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/e3/)

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### Exam question 4 · formal language · wrong ✗ {#e4}

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Ascertain the number of species of egg-laying mammals presently extant.

- **1.** Precisely two — **← Mova's choice** · no support
- **2.** Twelve — no support
- **3.** Five — **✓ the right answer** · no support
- **4.** A single species — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/biology/43-platypus-and-echidna/e4/)

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- ← previous: [42. The capybara: the calmest animal, friend of croc…](https://md.mova.elamur.ai/free/en/school-run/biology/42-the-capybara/)
- next →: [44. The axolotl, the tardigrade and the mantis shrimp](https://md.mova.elamur.ai/free/en/school-run/biology/44-axolotl-tardigrade-mantis-shrimp/)
- ↑ back to [Biology](https://md.mova.elamur.ai/free/en/school-run/biology/)