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Balance in a food web

Tests: 4 of 14 right · Exam: 1 of 4 right · Kind: ★★★ · Understood: 7 of 18 · Run: 2026-10-18, commit f3c23ea72

Lesson 30 of the world 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 island has grass, rabbits and foxes. A disease kills most of the rabbits. What happens to the grass and the foxes?

  • 1. Both the grass and the foxes grow more — ← Mova's choice · no support
  • 2. The grass dies and the foxes grow fat — no support
  • 3. Nothing happens to either of them — no support
  • 4. The grass grows more and the foxes go hungry — ✓ 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

Test 2 · ★★★ · wrong ✗

A meadow has 1000 kilograms of grass a year. Roughly how many kilograms of grasshoppers can it feed?

  • 1. About 1000 — ← Mova's choice · no support
  • 2. About 100 — ✓ the right answer · no support
  • 3. About 2000 — no support
  • 4. About 500 — 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 3 · ★★★ · wrong ✗

A farmer kills all the owls on his farm because they scare his chickens. What is likely to happen next?

  • 1. Mice decrease because owls protected them — ← Mova's choice · no support
  • 2. The grain grows better without the owls — no support
  • 3. His chickens start to catch the mice — no support
  • 4. Mice increase and eat more of his grain — ✓ 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

Test 4 · ★★★ · wrong ✗

Why is it impossible to have a habitat with more lions than zebras for long?

  • 1. Zebras would eat all the lions — ← Mova's choice · no support
  • 2. Zebras would run away to other lands — no support
  • 3. The lions would not get enough food energy — ✓ the right answer · no support
  • 4. Lions eat only grass in winter — 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 pond food web has algae, water fleas, small fish and a pike. Someone adds many more pike. What happens first?

  • 1. Water fleas become fewer — ← Mova's choice · no support
  • 2. The pike all become thin at once — no support
  • 3. Small fish become fewer — ✓ the right answer · no support
  • 4. Algae become fewer — 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 · ★★★ · right ✓

Bees pollinate a meadow's flowers, birds eat the seeds, and foxes hunt the birds. Bees vanish. Who may suffer, even though they never eat bees?

  • 1. Only the bees' nests — no support
  • 2. Nobody, because foxes eat birds — no support
  • 3. Only the flowers, nobody else — no support
  • 4. The birds and then the foxes — ← Mova's choice · ✓ the right answer · score 4

Why: It took the question to ask who or what does it. It chose option 4 with score 4, the only option with support. Its support: lesson 23, line 4: «Seeds must travel away from their parent, so the young plants do not compete with it for light and water: dandelion seeds fly on little parachutes, burdock bur…», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «birds» (+2). Against it: a different action (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 7 · ★★★ · right ✓

A koala eats only eucalyptus leaves; a fox eats mice, berries and insects. Which is in more danger if one of its foods disappears?

  • 1. The koala — ← Mova's choice · ✓ the right answer · no support
  • 2. The fox — no support
  • 3. Both the same — no support
  • 4. Neither of them — 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 8 · ★★★ · right ✓

Why is a tiger much rarer than a deer in the same forest?

  • 1. Each step up the food chain has much less energy — ← Mova's choice · ✓ the right answer · no support
  • 2. Tigers need much more water than deer — no support
  • 3. Deer have more stripes for hiding — no support
  • 4. Tigers have far more enemies than deer — 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 9 · ★★★ · wrong ✗

A town removes all fallen leaves and dead logs from a park every week for years. What slowly happens?

  • 1. The plants grow faster and greener than ever — ← Mova's choice · no support
  • 2. Nothing, because dead things are useless — no support
  • 3. The predators get much more prey to eat — no support
  • 4. The soil gets poorer for the plants — ✓ 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

Test 10 · ★★★ · wrong ✗

Sea otters return to a coast. What happens to the kelp forest over the years?

  • 1. It is replaced by bare sand and stones — no support
  • 2. It grows back as urchins become fewer — ✓ the right answer · no support
  • 3. It disappears completely as the otters eat the kelp — ← Mova's choice · score 5
  • 4. It stays exactly the same as it was before — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 5, the only option with support. Its support: lesson 30, line 16: «Sea otters protect kelp forests by eating the sea urchins that eat kelp.», reached through the same lesson line as the sentence the question matched. What matched: the same action «eat» (+4); the same thing acted on «kelp» (+2). Against it: a different doer (counts against) (-1). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 11 · ★★★ · wrong ✗

why r there way fewer foxes than rabbits

  • 1. Rabbits eat the foxes' food — ← Mova's choice · no support
  • 2. Foxes just have fewer babies than rabbits, by pure chance — no support
  • 3. Foxes live only in the winter — no support
  • 4. Only a little energy passes up each step of the chain — ✓ the right answer · no support

Why: Nothing it remembers matched the question, so it guessed: it took the first option shown. · the question and its options parsed, with trees and pragmatics

Test 12 · ★★★ · right ✓

if the wolves all go wot happens to the deer

  • 1. They usually increase and can eat too many plants — ← Mova's choice · ✓ the right answer · score 4
  • 2. They usually decrease straight away — no support
  • 3. They start eating other animals — score 4
  • 4. Nothing at all changes for them — no support

Why: It took the question to ask which statement is true. It chose option 1 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 30, line 3: «In a food web everything is connected, so a change to one living thing spreads: when wolves disappeared from Yellowstone Park, deer grew so many that they ate…», reached through the remembered sentence the question matched. What matched: the same action «eat» (+4); the same doer «wolves» (+2). Against it: a different thing acted on (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 13 · ★★★ · wrong ✗

my sister says predators are bad for a habitat and we should get rid of them. true?

  • 1. No, but only because they eat the plants — ← Mova's choice · score 10
  • 2. Yes, without them all animals live in peace — score 3
  • 3. No, they keep plant-eaters from growing too many — ✓ the right answer · score 10
  • 4. Yes, a habitat is healthier with no predators — score 4

Why: It took the question to ask which statement is true. It chose option 1 with score 10, tied with another option at 10 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 30, line 11: «If prey animals increase too much, they can eat too many plants and harm the whole habitat.», reached through the same lesson line as the sentence the question matched. What matched: the same action «eat» (+4); the same doer «predators» (+4); the same thing acted on «many plants» (+2). The right option, 3, scored 10. · the question and its options parsed, with trees and pragmatics

Test 14 · ★★★ · wrong ✗

Tom reckons almost all the energy an animal eats goes into the next animal. right?

  • 1. Yes, nearly all of it passes right on — ← Mova's choice · no support
  • 2. No, none of it ever passes on at all — no support
  • 3. Yes, about half of it gets passed on — no support
  • 4. No, only about a tenth passes on — ✓ 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

Exam question 1 · formal language · wrong ✗

State the approximate proportion of energy transferred from one step of a food chain to the next.

  • 1. Nine tenths — ← Mova's choice · no support
  • 2. One tenth — ✓ the right answer · no support
  • 3. One half — no support
  • 4. The whole — 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 · right ✓

Identify the principal reason for which predators are invariably fewer than plant-eaters.

  • 1. Plants are fewer than predators — score 4
  • 2. Predators are hunted by plant-eaters — no support
  • 3. Energy is lost at each step of the food chain — ← Mova's choice · ✓ the right answer · score 7
  • 4. Predators reproduce more slowly from choice — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 7, against 4 for the next best. Its support: lesson 30, line 8: «Because energy is lost at each step, there are always far fewer predators than plant-eaters.», reached through a sentence linked to the one the question matched. What matched: the same action «lose» (+3); the same thing acted on «energy» (+2); the same circumstance (+2). · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · wrong ✗

Whereas a predator disappears from a habitat, determine the usual consequence for its prey.

  • 1. The prey usually declines in number — ← Mova's choice · score 4
  • 2. The prey usually increases in number — ✓ the right answer · score 4
  • 3. The prey usually departs the habitat — score 4
  • 4. The prey usually remains unaltered — score 4

Why: It took the question to ask which statement is true. It chose option 1 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 30, line 10: «If a predator disappears, its prey usually increases in number.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «prey» (+4); the same property (+1). Against it: a different action (counts against) (-1). The right option, 2, scored 4. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · wrong ✗

Select the response that is consistent with the established facts concerning the return of wolves to Yellowstone Park.

  • 1. The wolves consumed the trees — ← Mova's choice · score 5
  • 2. The deer increased and the trees perished along the riverbanks — no support
  • 3. The deer were reduced and the riverside trees recovered — ✓ the right answer · no support
  • 4. The rivers dried up entirely — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, the only option with support. Its support: lesson 30, line 3: «In a food web everything is connected, so a change to one living thing spreads: when wolves disappeared from Yellowstone Park, deer grew so many that they ate…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «wolves» (+4); the same thing acted on «young trees» (+2). Against it: a different action (counts against) (-1). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/world/30-balance-in-food-webs/