---
title: Identify the principal reason for which predators are invariably few… — Balance in a food web · tree and pragmatics
description: Identify the principal reason for which predators are invariably fewer than plant-eaters. Exam question 2 of lesson 30 «Balance in a food web» of the world course of Mova's primary school, with the dependency tree and pragmatics of the question and of each option; Mova's choice was right.
---

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# Exam question 2 · Balance in a food web

<!-- .ven lang=en -->
Identify the principal reason for which predators are invariably fewer than plant-eaters.

<!-- .vintro -->
**Mova's choice:** option 3 · **The right answer:** option 3 · right ✓ · **Who acts:** you, predators · **What happens:** identify, be · **To what, where:** principal reason

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This is exam question 2 of lesson 30 «Balance in a food web» of the world 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/world/30-balance-in-food-webs/#e2).

## The question {#question}

```conllu
# sent_id = question:world:30-balance-in-food-webs:e2:1
# text = Identify the principal reason for which predators are invariably fewer than plant-eaters.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	4	det	_	_
3	principal	principal	ADJ	JJ	Degree=Pos	4	amod	_	_
4	reason	reason	NOUN	NN	Number=Sing	1	obj	_	_
5	for	for	ADP	IN	_	6	case	_	_
6	which	which	DET	WDT	PronType=Int	7	det	_	_
7	predators	predator	NOUN	NNS	Number=Plur	10	nsubj	_	_
8	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	10	cop	_	_
9	invariably	invariably	ADV	RB	_	10	advmod	_	_
10	fewer	few	ADJ	JJR	Degree=Cmp	4	nmod	_	_
11	than	than	ADP	IN	_	14	case	_	_
12	plant	plant	NOUN	NN	Number=Sing	14	compound	_	SpaceAfter=No
13	-	-	PUNCT	HYPH	_	12	punct	_	SpaceAfter=No
14	eaters	eater	NOUN	NNS	Number=Plur	10	obl	_	SpaceAfter=No
15	.	.	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 principal reason |  |  |  |  | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent reason=Theme |
| 2 | **is** | present | which predators |  |  |  |  | than plant eaters; few, invariably *property* | tree rules |

<!-- .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 -->
Plants are fewer than predators

```conllu
# sent_id = question:world:30-balance-in-food-webs:e2:o1:1
# text = Plants are fewer than predators
1	Plants	plant	NOUN	NNS	Number=Plur	3	nsubj	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	cop	_	_
3	fewer	few	ADJ	JJR	Degree=Cmp	0	root	_	_
4	than	than	ADP	IN	_	5	case	_	_
5	predators	predator	NOUN	NNS	Number=Plur	3	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is** | present | Plants |  |  |  |  | than predators; few *property* | tree rules |

### Option 2 {#o2}

<!-- .ven lang=en -->
Predators are hunted by plant-eaters

```conllu
# sent_id = question:world:30-balance-in-food-webs:e2:o2:1
# text = Predators are hunted by plant-eaters
1	Predators	predator	NOUN	NNS	Number=Plur	3	nsubj	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	aux:pass	_	_
3	hunted	hunt	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
4	by	by	ADP	IN	_	7	case	_	_
5	plant	plant	NOUN	NN	Number=Sing	7	compound	_	SpaceAfter=No
6	-	-	PUNCT	HYPH	_	5	punct	_	SpaceAfter=No
7	eaters	eater	NOUN	NNS	Number=Plur	3	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **hunt** | present · passive | plant eaters | Predators |  |  |  |  | vn hunt-35.1 «NP V NP»: agent=Agent subject=Theme |

### Option 3 · ← Mova's choice · ✓ the right answer {#o3}

<!-- .ven lang=en -->
Energy is lost at each step of the food chain

```conllu
# sent_id = question:world:30-balance-in-food-webs:e2:o3:1
# text = Energy is lost at each step of the food chain
1	Energy	energy	NOUN	NN	Number=Sing	3	nsubj:pass	_	_
2	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	aux:pass	_	_
3	lost	lose	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
4	at	at	ADP	IN	_	6	case	_	_
5	each	each	DET	DT	PronType=Tot	6	det	_	_
6	step	step	NOUN	NN	Number=Sing	3	obl	_	_
7	of	of	ADP	IN	_	10	case	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
9	food	food	NOUN	NN	Number=Sing	10	compound	_	_
10	chain	chain	NOUN	NN	Number=Sing	6	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **lose** | present · passive |  | Energy |  |  |  | at each step of the food chain | vn succeed-74-3-1 «NP V NP»: subject=Eventuality |
| 2 | **step** |  |  | the food chain |  |  |  |  | nom step «act transitive»: of=patient |

### Option 4 {#o4}

<!-- .ven lang=en -->
Predators reproduce more slowly from choice

```conllu
# sent_id = question:world:30-balance-in-food-webs:e2:o4:1
# text = Predators reproduce more slowly from choice
1	Predators	predator	NOUN	NNS	Number=Plur	2	nsubj	_	_
2	reproduce	reproduce	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	more	more	ADV	RBR	Degree=Cmp	4	advmod	_	_
4	slowly	slowly	ADV	RB	_	2	advmod	_	_
5	from	from	ADP	IN	_	6	case	_	_
6	choice	choice	NOUN	NN	Number=Sing	2	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **reproduce** | present | Predators |  |  | choice |  | slowly *property* | vn birth-28.2-2 «NP V»: agent=Agent |

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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.

<!-- /div -->

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- ← previous: [Balance in a food web, exam 1](https://md.mova.elamur.ai/free/en/corpora/questions/world/30-balance-in-food-webs/e1/)
- next →: [Balance in a food web, exam 3](https://md.mova.elamur.ai/free/en/corpora/questions/world/30-balance-in-food-webs/e3/)
- ↑ back to [Balance in a food web](https://md.mova.elamur.ai/free/en/corpora/questions/world/30-balance-in-food-webs/)