---
title: Identify the phenomenon whereby a change in the population of a top… — Wolves in Yellowstone, beavers in Brit… · tree and pragmatics
description: Identify the phenomenon whereby a change in the population of a top predator affects successive levels of a food chain. Exam question 1 of lesson 283 «Wolves in Yellowstone, beavers in Britain and bringing nature back» of the biology course of Mova's primary school, with the dependency tree and prag
---

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# Exam question 1 · Wolves in Yellowstone, beavers in Britain and bringing nat…

<!-- .ven lang=en -->
Identify the phenomenon whereby a change in the population of a top predator affects successive levels of a food chain.

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**Mova's choice:** option 4 · **The right answer:** option 4 · right ✓ · **Who acts:** you, change · **What happens:** identify, affect · **To what, where:** phenomenon, successive levels

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This is exam question 1 of lesson 283 «Wolves in Yellowstone, beavers in Britain and bringing nature back» of the biology course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/biology/283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back/#e1).

## The question {#question}

```conllu
# sent_id = question:biology:283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back:e1:1
# text = Identify the phenomenon whereby a change in the population of a top predator affects successive levels of a food chain.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	3	det	_	_
3	phenomenon	phenomenon	NOUN	NN	Number=Sing	1	obj	_	_
4	whereby	whereby	ADV	WRB	PronType=Int	14	advmod	_	_
5	a	a	DET	DT	Definite=Ind|PronType=Art	6	det	_	_
6	change	change	NOUN	NN	Number=Sing	14	nsubj	_	_
7	in	in	ADP	IN	_	9	case	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
9	population	population	NOUN	NN	Number=Sing	6	nmod	_	_
10	of	of	ADP	IN	_	13	case	_	_
11	a	a	DET	DT	Definite=Ind|PronType=Art	13	det	_	_
12	top	top	ADJ	JJ	Degree=Pos	13	amod	_	_
13	predator	predator	NOUN	NN	Number=Sing	9	nmod	_	_
14	affects	affect	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	1	advcl	_	_
15	successive	successive	ADJ	JJ	Degree=Pos	16	amod	_	_
16	levels	level	NOUN	NNS	Number=Plur	14	obj	_	_
17	of	of	ADP	IN	_	20	case	_	_
18	a	a	DET	DT	Definite=Ind|PronType=Art	20	det	_	_
19	food	food	NOUN	NN	Number=Sing	20	compound	_	_
20	chain	chain	NOUN	NN	Number=Sing	16	nmod	_	SpaceAfter=No
21	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **identify** | imperative | you *not said here* | the phenomenon |  |  |  |  | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent phenomenon=Theme |
| 2 | **affect** | present | a change in the population of a top predator | successive levels of a food chain |  |  |  | whereby *property* | vn amuse-31.1 «NP V NP»: agent=Stimulus level=Experiencer |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 {#o1}

<!-- .ven lang=en -->
Metamorphosis

```conllu
# sent_id = question:biology:283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back:e1:o1:1
# text = Metamorphosis
1	Metamorphosis	metamorphosis	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 2 {#o2}

<!-- .ven lang=en -->
Natural selection

```conllu
# sent_id = question:biology:283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back:e1:o2:1
# text = Natural selection
1	Natural	natural	ADJ	JJ	Degree=Pos	2	amod	_	_
2	selection	selection	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 3 {#o3}

<!-- .ven lang=en -->
Hibernation

```conllu
# sent_id = question:biology:283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back:e1:o3:1
# text = Hibernation
1	Hibernation	hibernation	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 4 · ← Mova's choice · ✓ the right answer {#o4}

<!-- .ven lang=en -->
A trophic cascade

```conllu
# sent_id = question:biology:283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back:e1:o4:1
# text = A trophic cascade
1	A	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
2	trophic	trophic	ADJ	JJ	Degree=Pos	3	amod	_	_
3	cascade	cascade	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

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**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

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- next →: [Wolves in Yellowstone, beavers in Brit…, exam 2](https://md.mova.elamur.ai/free/en/corpora/questions/biology/283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back/e2/)
- ↑ back to [Wolves in Yellowstone, beavers in Britain and bringing nature back](https://md.mova.elamur.ai/free/en/corpora/questions/biology/283-wolves-in-yellowstone-beavers-in-britain-and-bringing-nature-back/)