Amazon giants and tall tales: anacondas, caimans, electric eels and the candiru

Tests: 2 of 11 right · Exam: 1 of 4 right · Kind: ★★ · Understood: 9 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 158 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.

Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: the lesson's questions in the corpora.

Test 1 · ★★ · wrong ✗

An old story tells of a hunter who found an anaconda as long as a bus, about 12 metres. What would a scientist say?

1. No anaconda over about seven metres has been well measured, so the tale is doubtful — ✓ the right answer · score 6
2. Too short, because they are often found reaching a hundred metres in the jungle — ← Mova's choice · score 7
3. Snakes cannot grow longer than a metre — score 7
4. Totally true, they are often that long — no support

Why: It took the question to ask what it is done to. It chose option 2 with score 7, tied with another option at 7 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 54, line 4: «Cartoons show birds flying south with suitcases and a map, and the old story said swallows slept at the bottom of ponds; scientists put tiny rings and trackers…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «scientists» (+4); the same action «find out» (+3). The right option, 1, scored 6. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★ · wrong ✗

In a cartoon a snake wraps a hero and you hear his bones crack like twigs. What is true for anacondas?

1. Anacondas never squeeze; they swallow animals while they are still kicking — ← Mova's choice · score 3
2. Exactly what anacondas do — no support
3. Anacondas only bite — score 2
4. They squeeze until blood stops flowing, not by cracking bones — ✓ the right answer · score 3

Why: It took the question to ask which statement is true. It chose option 1 with score 3, tied with another option at 3 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 158, line 4: «Cartoons show snakes crushing bones like a garden hose tied in knots; a real anaconda squeezes until the prey's blood stops flowing, and it is a shy animal tha…», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «shy animal» (+3). The right option, 4, scored 3. · the question and its options parsed, with trees and pragmatics

Test 3 · ★★ · wrong ✗

«they say a tiny fish swims up into you if you wee in the Amazon» What is right?

1. It only happens to adults — no support
2. It is proved and happens daily — no support
3. The candiru story rests on very few unclear reports, and scientists doubt most of them — ✓ the right answer · no support
4. The fish is as big as a dolphin and chases people who swim in the river every day — ← Mova's choice · score 5

Why: It took the question to ask which statement is true. It chose option 4 with score 5, the only option with support. Its support: lesson 132, line 13: «In a clownfish group the biggest fish is the female and the next biggest is the male; if the female is lost, the male becomes a female and the next fish become…», reached through the option's own match among the sentences about the question's things. What matched: the same property (+3); the same light verb (be, have, do, get, go) (+2). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · wrong ✗

A guide's torch shows 7 pairs of glowing red eyes, sorry, 8 pairs. How many caimans probably?

1. 16 — ← Mova's choice · no support
2. 14 — no support
3. 8 — ✓ the right answer · no support
4. 7 — no support

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

Test 5 · ★★ · wrong ✗

A capybara family of 5 grazes while one caiman lies on the same bank. How many legs on the bank altogether?

1. 28 — ← Mova's choice · no support
2. 24 — ✓ the right answer · no support
3. 20 — no support
4. 22 — no support

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

Test 6 · ★★ · wrong ✗

What would happen if the black caimans came back to a river where they had been hunted?

1. Piranhas would all grow huge and fat — no support
2. Piranha numbers would go down again — ✓ the right answer · no support
3. Capybaras would come back and start eating the fish — ← Mova's choice · score 7
4. All the other fish would vanish at once — no support

Why: It took the question to ask what happens next. It chose option 3 with score 7, the only option with support. Its support: lesson 100, line 16: «Otters keep in touch with squeaks, chirps and whistles, and they came back to many British rivers after harmful farm chemicals, which had poisoned otters and t…», reached through the same lesson line as the sentence the question matched. What matched: the same action «eat» (+4); the same thing acted on «fish» (+3). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 7 · ★★ · wrong ✗

«red touches yellow, that snake's harmless, I'll pick it up» What is the best answer?

1. Fine, pick it up — no support
2. Fine, if you are quick — no support
3. Fine, because coral snakes are harmless and only look scary to keep birds away — ← Mova's choice · score 3
4. Don't; harmless snakes copy coral snakes, and you cannot be sure, so leave it — ✓ the right answer · score 3

Why: It took the question to ask which statement is true. It chose option 3 with score 3, tied with another option at 3 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 158, line 15: «Some harmless snakes copy the red, black and yellow bands of the deadly coral snake, so predators avoid both, and it is not safe to guess which is which.», reached through the option's own match among the sentences about the question's things. What matched: the same property (+3). The right option, 4, scored 3. · the question and its options parsed, with trees and pragmatics

Test 8 · ★★ · right ✓

An electric eel leaps out at a hand. Why jump instead of staying in the water?

1. It needs to dry its skin — no support
2. Out of water the shock goes straight into the hand instead of spreading out — ← Mova's choice · ✓ the right answer · score 0
3. It wants to bite the hand, because electric eels attack anything that lifts them out of the water — no support
4. It is trying to fly — no support

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 0, the only option with support. Its support: lesson 45, line 14: «Electric eels breathe air and must gulp at the surface every few minutes, and they send out weak electric pulses to sense things in murky water.», reached through the option's own match among the sentences about the question's things. · the question and its options parsed, with trees and pragmatics

Test 9 · ★★ · right ✓

«why's that big frog eating a mouse, frogs eat flies» What is right?

1. That is not a frog — no support
2. Frogs only ever eat flies and worms, so the picture must be a trick made with a computer — score -1
3. The horned frog grabs anything that fits in its huge mouth, even mice — ← Mova's choice · ✓ the right answer · score 0
4. It is just holding the mouse — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 0, against -1 for the next best. Its support: lesson 158, line 14: «The horned frog has a mouth nearly as wide as its body, grabs anything that fits, even mice, and is nicknamed the Pac-Man frog.», reached through the option's own match among the sentences about the question's things. · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · wrong ✗

Smoke rises where forest is being cleared. Which is a likely result?

1. The river becomes deeper — ← Mova's choice · no support
2. More rain would fall everywhere, because the open ground would be cooler — no support
3. Less rain, because the trees help make the Amazon's rain — ✓ the right answer · no support
4. Animals get bigger homes — no support

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

Test 11 · ★★ · wrong ✗

A giant armadillo moves out of its burrow. Who might move in?

1. Nobody, burrows collapse at once — ← Mova's choice · no support
2. A lizard, an ocelot or birds — ✓ the right answer · no support
3. A fish washed in from a nearby stream — no support
4. A young caiman from the river — no support

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

Exam question 1 · formal language · wrong ✗

Select the response consistent with the established facts concerning the maximum length of the green anaconda.

1. Specimens of thirty metres are frequently recorded — ← Mova's choice · no support
2. No specimen exceeding approximately seven metres has been reliably measured — ✓ the right answer · no support
3. The species does not exceed one metre in length — no support
4. The length of the species has never been measured at all, so no figure can be given — no support

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

Exam question 2 · formal language · wrong ✗

Identify the principal reason for which the electric eel may leap from the water against a threatening animal.

1. The eel thereby obtains a breath of air — no support
2. The eel thereby bites the animal with its teeth and holds it fast until it ceases entirely to struggle — ← Mova's choice · score 5
3. The discharge thereby passes directly into the animal rather than dispersing through the water — ✓ the right answer · score 4
4. The eel thereby escapes into the forest — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, against 4 for the next best. Its support: lesson 75, line 2: «Stand under the open jaws of a T. rex skull in the museum and you see a bone-crusher: teeth like bananas and one of the strongest bites of any land animal that…», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «land animal» (+3); the same action «bite» (+2). The right option, 3, scored 4. · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · right ✓

Which of the following statements most accurately characterises the reports of the candiru attacking human beings?

1. They concern a fish of the dimensions of a dolphin — no support
2. They rest upon very few unclear reports, most of which scientists regard with doubt — ← Mova's choice · ✓ the right answer · score 5
3. They are reported exclusively in respect of adults bathing in the sea — no support
4. They are confirmed by numerous experiments — no support

Why: It took the question to ask who or what does it. It chose option 2 with score 5, the only option with support. Its support: lesson 158, line 11: «The candiru is a tiny, thin catfish that feeds on the blood of bigger fish by entering their gills; the story of it attacking people rests on very few unclear…», reached through the same lesson line as the sentence the question matched. What matched: the same action «rest» (+3); the same place «few unclear reports» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Ascertain the consequence observed upon the killing by hunters of the majority of black caimans.

1. The drying of the river channel — ← Mova's choice · no support
2. The disappearance of capybaras from the river, the caimans having driven them away — no support
3. A decline in the number of piranhas — no support
4. An increase in the number of piranhas, upon which the caimans had preyed — ✓ the right answer · no support

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

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/biology/158-amazon-giants-and-tall-tales/