---
title: "Exploring Our Environment"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 37
exercises: 12
source: https://one-course.com/books/biology/1/en/chapter/37-exploring-our-environment
---

# Chapter 37 — Exploring Our Environment

Cross the schoolyard on a July noon and the wall’s south face is hot under your hand, the air above the asphalt shimmers, and the only green thing in sight is a weed in a crack. Step behind the north wall: cool air, damp soil, moss, woodlice under a stone. Two worlds, three metres apart. This year begins by exploring [environments](#def-g6-exploring-our-environment-components) the way scientists do — measuring them, and asking why each [living thing](#def-g6-exploring-our-environment-components) lives exactly where it does.

## 37.1 What an environment is made of

**Definition 37.1 (The components of an environment).**

An *environment* — a yard, a wood, a pond bank — contains three kinds of components:

1. *living things* : the [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) , [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) , mushrooms and microscopic life present;
2. *mineral matter* , which was [never alive](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-nonliving) : rock, stone, soil’s mineral part, water, air;
3. *traces and remains* of living things: dead [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) , fallen wood, droppings, [feathers](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) , [shells](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) — the “was living” box of [Definition 1.5](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-nonliving) , now a clue kit for the explorer.

**Example 37.2 (Inventory behind the north wall).**

Ten minutes’ inventory in the cool corner: living — moss, [ferns](https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds#prop-g4-plants-without-seeds-damp), woodlice, a snail, a centipede, ivy; mineral — the stone of the wall, damp soil, a puddle; traces — dead [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), a snail [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering), bird droppings on the coping. Three lists, and the corner is described like a scientist’s site.

![The cool corner, mid-inventory: moss, ferns, a snail on the stone — and under the lifted slab, the woodlice’s microhabitat (put it back).](https://one-course.com/images/onecourse/chapters/biology-1/g6-exploring-our-environment/img-05e44d841d30.jpg)

*The cool corner, mid-inventory: moss, [ferns](https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds#prop-g4-plants-without-seeds-damp), a snail on the stone — and under the lifted slab, the woodlice’s [microhabitat](#def-g6-exploring-our-environment-microhabitat) (put it back).*

**Remark 37.3 (Traces count as data).**

Most [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) hide or flee, so the explorer often reads *traces* instead: a nibbled hazelnut names the wood mouse, a spider’s web names its owner, tracks in mud name the heron. An inventory that only lists what sat still enough to be seen misses half the inhabitants.

## 37.2 Measuring the conditions

**Definition 37.4 (Environmental conditions).**

The *conditions* of an [environment](#def-g6-exploring-our-environment-components) are its measurable physical characteristics:

- *temperature* , measured with a thermometer, in degrees Celsius;
- *humidity* — how damp the air or soil is;
- *light* — from full sun to deep shade.

Conditions change from spot to spot — often sharply within metres — and through the day and the year.

**Example 37.5 (The yard, measured).**

The July noon survey, with instruments: south wall foot — $38{}^{\circ}\mathrm{C}$, dry, full sun; north corner — $22{}^{\circ}\mathrm{C}$, damp soil, deep shade. Three metres of distance, sixteen degrees of difference. The two worlds of the opening paragraph are now two *rows in a table* — and that is progress, because tables can be compared.

**Proposition 37.6 (Conditions decide the inhabitants).**

The [living things](#def-g6-exploring-our-environment-components) of a spot match its [conditions](#def-g6-exploring-our-environment-conditions): each [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) thrives only within its own range of [temperature](#def-g6-exploring-our-environment-conditions), [humidity](#def-g6-exploring-our-environment-conditions) and [light](#def-g6-exploring-our-environment-conditions). Moss and woodlice need dampness (the woodlouse’s covering, unlike an insect’s, lets water escape — it dries out fatally in an hour of sun); the weed in the crack bears drought and glare. Where [conditions](#def-g6-exploring-our-environment-conditions) differ, inhabitants differ — the rule behind every [habitat](https://one-course.com/books/biology/1/en/chapter/11-where-animals-live#def-g2-where-animals-live-habitat) of [Chapter 11](https://one-course.com/books/biology/1/en/chapter/11-where-animals-live#ch-g2-where-animals-live).

**Proof.** *Admitted at this level.* ∎

**Example 37.7 (The woodlouse chooser).**

The classic experiment: a closed box, half lined with damp paper, half with dry, and a dozen woodlice released along the middle. Within minutes, nearly all are on the damp side. Run again with a shaded half against a lit half: they gather in the shade. No one herds them — each [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal), wandering and turning, ends where its body is comfortable. The map of woodlice *is* a map of dampness.

**Method 37.8 (Surveying a site).**

To survey a small site like a field scientist:

1. choose and mark a small area — a square metre tells more, well searched, than a hectare glanced at;
2. measure the [conditions](#def-g6-exploring-our-environment-conditions) : [temperature](#def-g6-exploring-our-environment-conditions) , dampness, [light](#def-g6-exploring-our-environment-conditions) — same instruments, same way, at each site ( [Method 22.1](https://one-course.com/books/biology/1/en/chapter/22-what-plants-need#met-g4-what-plants-need-fairtest) ’s fairness rule);
3. inventory the three component kinds — [living things](#def-g6-exploring-our-environment-components) , [mineral matter](#def-g6-exploring-our-environment-components) , traces — searching properly: under stones (put them back: [Method 13.6](https://one-course.com/books/biology/1/en/chapter/13-caring-for-nature#met-g2-caring-for-nature-rules) ), in crevices, on [leaf](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) undersides;
4. record everything on the spot — lists, sketches, counts; memory is not a recording instrument;
5. compare sites: pair each difference of inhabitants with a difference of [conditions](#def-g6-exploring-our-environment-conditions) .

**Remark 37.9 (Why records beat memories).**

Back indoors, two surveyors who trusted memory will argue about whether the snails numbered three or five. The notebook settles it — or admits honestly that snails were not counted. Written records, made at the site, are what turn a walk into data; every science of this book runs on them.

## 37.3 One environment, many micro-worlds

**Definition 37.10 (Microhabitat).**

Within one [environment](#def-g6-exploring-our-environment-components), each small spot with its own [conditions](#def-g6-exploring-our-environment-conditions) and its own inhabitants — the underside of a stone, a crack in the wall, the shaded foot of the hedge — is a *microhabitat*. [Remark 11.3](https://one-course.com/books/biology/1/en/chapter/11-where-animals-live#rem-g2-where-animals-live-layers)’s forest floors were microhabitats; the surveyor’s square metre usually holds several.

**Example 37.11 (The stone, above and below).**

One stone in the cool corner: on top, lichen and a sunning fly — lit, dry, warm. Beneath, woodlice, a centipede, pale rootlets — dark, damp, cool. Two complete [microhabitats](#def-g6-exploring-our-environment-microhabitat) separated by five centimetres of rock, each inhabited by exactly those [living things](#def-g6-exploring-our-environment-components) whose ranges its [conditions](#def-g6-exploring-our-environment-conditions) match.

## 37.4 Exercises

**Exercise 37.1 ★.**

Name the three kinds of components of an [environment](#def-g6-exploring-our-environment-components), with two examples of each from the north-corner inventory.

**Solution of Exercise 37.1.**

[Living things](#def-g6-exploring-our-environment-components) (moss, woodlice); [mineral matter](#def-g6-exploring-our-environment-components) (the wall’s stone, the puddle); traces and remains of [living things](#def-g6-exploring-our-environment-components) (dead [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), the snail [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering)).

**Exercise 37.2 ★.**

Which [conditions](#def-g6-exploring-our-environment-conditions) does a field scientist measure at a site, and with what (where an instrument was named)?

**Solution of Exercise 37.2.**

[Temperature](#def-g6-exploring-our-environment-conditions), with a thermometer (in degrees Celsius); [humidity](#def-g6-exploring-our-environment-conditions) of air and soil; [light](#def-g6-exploring-our-environment-conditions), from full sun to deep shade.

**Exercise 37.3 ★.**

Sort into the three component kinds: a fern, a snail [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering), a puddle, bird droppings, a centipede, the wall’s stone.

**Solution of Exercise 37.3.**

Living: the fern, the centipede. Mineral: the puddle, the wall’s stone. Traces: the snail [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering), the bird droppings.

**Exercise 37.4 ★.**

From [Example 37.5](#ex-g6-exploring-our-environment-measured): what are the [temperature](#def-g6-exploring-our-environment-conditions) and [light](#def-g6-exploring-our-environment-conditions) differences between the two spots? Which inhabitants match each?

**Solution of Exercise 37.4.**

Sixteen degrees ($38{}^{\circ}\mathrm{C}$ against $22{}^{\circ}\mathrm{C}$) and full sun against deep shade (dry against damp, too). The drought-and-glare weed matches the south foot; moss, [ferns](https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds#prop-g4-plants-without-seeds-damp) and woodlice match the cool damp corner.

**Exercise 37.5 ★.**

Why does the woodlouse die in an hour of sun, and what does that explain about where woodlice are found?

**Solution of Exercise 37.5.**

Its covering lets water escape, so in dry sun its body loses its water fatally fast. That is why woodlice are found in damp, dark [microhabitats](#def-g6-exploring-our-environment-microhabitat) — under stones, under dead wood.

**Exercise 37.6 ★.**

Name three traces and the [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) each one names, as in [Remark 37.3](#rem-g6-exploring-our-environment-traces).

**Solution of Exercise 37.6.**

For example: a nibbled hazelnut — the wood mouse; a spider’s web — its spider; tracks in the mud — the heron (droppings, [feathers](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering), [shells](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) serve the same way).

**Exercise 37.7 ★★.**

Describe the woodlouse chooser experiment: setup, result, and what it shows — without anyone herding the [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal).

**Solution of Exercise 37.7.**

A closed box, half damp paper and half dry, woodlice released along the middle line; minutes later nearly all sit on the damp side (likewise shade against [light](#def-g6-exploring-our-environment-conditions)). It shows each [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) settles where [conditions](#def-g6-exploring-our-environment-conditions) suit its body — the group’s map draws itself with no herding.

**Exercise 37.8 ★★.**

Why must [conditions](#def-g6-exploring-our-environment-conditions) be measured the same way at each site? Which earlier method is this the field version of?

**Solution of Exercise 37.8.**

Because only measurements made the same way can be compared: a difference must come from the sites, not from the measuring. It is the field version of the fair test — one thing varies (the site), everything else is kept equal.

**Exercise 37.9 ★★.**

Give the two [microhabitats](#def-g6-exploring-our-environment-microhabitat) of the stone of [Example 37.11](#ex-g6-exploring-our-environment-stone), with their [conditions](#def-g6-exploring-our-environment-conditions) and one inhabitant each.

**Solution of Exercise 37.9.**

Stone top: lit, dry, warm — lichen (with the sunning fly as a visitor). Stone underside: dark, damp, cool — woodlice (or the centipede). Five centimetres apart, two matched sets of inhabitants.

**Exercise 37.10 ★★.**

A survey lists “some bugs, it was warmish”. Rewrite the surveyor’s instructions using [Method 37.8](#met-g6-exploring-our-environment-survey) — what should have been done at each step?

**Solution of Exercise 37.10.**

Step 1: mark a definite square metre. Step 2: measure — thermometer reading written down, soil dampness felt and noted, [light](#def-g6-exploring-our-environment-conditions) class noted. Step 3: search properly, stones lifted and replaced, all three component kinds listed. Step 4: record on the spot — counts, not “some”. Step 5: no comparison was even possible with one site; survey a second site the same way.

**Exercise 37.11 ★★.**

Ivy grows up the north wall but not the south. Propose an explanation in the form of [Proposition 37.6](#prop-g6-exploring-our-environment-decide), and an observation or measurement that would test it.

**Solution of Exercise 37.11.**

Explanation: ivy thrives in the north wall’s range of [conditions](#def-g6-exploring-our-environment-conditions) (shade, dampness) and not in the south wall’s (glare, drought). Test: measure both wall feet — [temperature](#def-g6-exploring-our-environment-conditions), dampness, [light](#def-g6-exploring-our-environment-conditions) — and check ivy’s known preferences; or find ivy on other walls and record which orientation its walls share.

**Exercise 37.12 ★★★.**

In the woodlouse box, a student objects: “maybe they just gathered near the wall, and the damp side happened to have more wall.” Design an improved version of the experiment that answers the objection. (Think fair test.)

**Solution of Exercise 37.12.**

Remove the wall difference: run the choice in a round box (wall everywhere the same), with the damp and dry halves swapped between runs — damp east in run 1, damp west in run 2. If the woodlice follow the dampness wherever it is put, walls are ruled out; only the tested condition changed between runs, everything else held equal.

## 37.5 Problem: The Two Ditches

**Problem 37.1.**

Weekend problem — the naturalist club surveys two roadside ditches and finds two different worlds

The naturalist club surveys two ditches along the same lane, $50$ metres apart. Ditch N runs along the north side of a tall hedge; ditch S runs in the open, facing south. The club works by the book: same instruments, same square metre per site, same search time.

**Part I — The measurements.**

1. The thermometers read $19{}^{\circ}\mathrm{C}$ in ditch N and $31{}^{\circ}\mathrm{C}$ in ditch S at the same hour. Which single feature of the sites best explains the difference?
2. Ditch N’s soil sticks to the fingers; ditch S’s crumbles to dust. Translate both observations into the vocabulary of [Definition 37.4](#def-g6-exploring-our-environment-conditions) .
3. The club measures at noon. Give one reason the comparison would be less fair if ditch N were measured at noon and ditch S at 6 p.m.
4. Why does the club use the *same* square-metre frame and the same search time at both sites?

**Part II — The inventories.**

5. Ditch N’s list: moss, [ferns](https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds#prop-g4-plants-without-seeds-damp) , woodlice, snails, a toad. Ditch S’s list: dry grasses, a large weed with waxy [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) , ants, a basking lizard, grasshoppers. Sort each list’s members into the three component kinds — and note what the lists are missing (check [Definition 37.1](#def-g6-exploring-our-environment-components) ).
6. For each of woodlice, toad and lizard, say which ditch’s [conditions](#def-g6-exploring-our-environment-conditions) match its needs, and why (use [Proposition 37.6](#prop-g6-exploring-our-environment-decide) and what you know of each [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) ).
7. In ditch S the club finds a snail [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) , but no snail, and asks whether snails live there. What are the two honest possibilities a trace like this [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) open?
8. Under a flat stone in ditch N: eight woodlice, a centipede, white rootlets. Name the [microhabitat](#def-g6-exploring-our-environment-microhabitat) ’s [conditions](#def-g6-exploring-our-environment-conditions) , and state the rule that put those inhabitants there.

**Part III — The explanation.**

9. Pair each difference of inhabitants with a difference of [conditions](#def-g6-exploring-our-environment-conditions) : complete “N has moss and toads because …; S has lizards and waxy-leaved weeds because …”.
10. The hedge is scheduled to be grubbed out. Predict ditch N’s [conditions](#def-g6-exploring-our-environment-conditions) two summers later — and its inhabitants, using the pairing of question 9.
11. A member proposes checking the prediction properly: survey both ditches again after the hedge is gone. Why must the *same* sites, instruments and season be used for the re-survey to count?
12. The club’s report ends: “the inhabitants map the [conditions](#def-g6-exploring-our-environment-conditions) .” Explain the sentence with the woodlouse chooser ( [Example 37.7](#ex-g6-exploring-our-environment-chooser) ), and say why no herding is needed for a map like that to draw itself.

**Solution of Problem 37.1.**

**1.** The tall hedge: it shades ditch N (and shelters it), while ditch S faces the sun all day.

**2.** [Temperature](#def-g6-exploring-our-environment-conditions): $19{}^{\circ}\mathrm{C}$ against $31{}^{\circ}\mathrm{C}$. [Humidity](#def-g6-exploring-our-environment-conditions): ditch N’s soil is damp (sticks), ditch S’s is dry (dust). [Light](#def-g6-exploring-our-environment-conditions) completes the trio: shade against full sun.

**3.** [Conditions](#def-g6-exploring-our-environment-conditions) change through the day: by 6 p.m. any site is cooler and its [light](#def-g6-exploring-our-environment-conditions) lower, so the difference measured would mix site with hour. Same hour keeps the comparison fair.

**4.** So that the search effort is equal: more area or more time at one site would find more inhabitants there — an unfair test of which ditch is richer.

**5.** Both lists name only [living things](#def-g6-exploring-our-environment-components). Missing: the mineral components (soil, stones, water) and the traces — which parts I of a proper inventory must also record.

**6.** Woodlice: ditch N — they need dampness and shade or they dry out. The toad: ditch N — moist [skin](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense), needing damp shelter. The lizard: ditch S — it warms its body in the sun, hunting where it can bask.

**7.** Either snails live there hidden (perhaps active only in damp night hours), or the [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) is a remain from elsewhere or another season — a trace proves presence *at some time*, not residence now.

**8.** Dark, damp, cool. The rule of [Proposition 37.6](#prop-g6-exploring-our-environment-decide): each spot is inhabited by the [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) whose ranges its [conditions](#def-g6-exploring-our-environment-conditions) match.

**9.** N has moss and toads because its shade keeps it cool and damp, which their bodies require; S has lizards and waxy-leaved weeds because its full sun makes it hot and dry, which suits a basking hunter and a drought-proof [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant).

**10.** Without the hedge, ditch N gets full sun: hotter, drier — [conditions](#def-g6-exploring-our-environment-conditions) drifting toward today’s ditch S. Expect the damp-lovers (moss, [ferns](https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds#prop-g4-plants-without-seeds-damp), woodlice, the toad) to dwindle and sun-lovers (dry grasses, grasshoppers, perhaps the lizard) to move in.

**11.** Because the re-survey must differ from the first in one thing only — the hedge’s absence. New sites, instruments or season would add differences of their own, and the change could no longer be pinned on the hedge: the fair-test rule at the scale of a landscape.

**12.** Each woodlouse wanders and turns until its body is comfortable, so the group ends gathered where dampness is — the [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal)’ positions record the [conditions](#def-g6-exploring-our-environment-conditions), as surely as thermometer readings. Nobody herds them; each individual’s own comfort does the map-drawing, which is exactly why inhabitants can be read as measurements.