The microscopic world: bacteria, good and bad

Tests: 6 of 11 right · Exam: 3 of 4 right · Kind: plain · Understood: 12 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 257 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 ✗

In a cartoon, a germ with angry eyes and sharp teeth attacks a boy. What is true of real bacteria?

1. They all have little faces, but they are far too small for us to see them — ← Mova's choice · score 5
2. They only attack children who are naughty — no support
3. They have no faces, eyes or brains, and most are harmless or helpful — ✓ the right answer · no support
4. They are all dangerous monsters — score 3

Why: It took the question to ask which statement is true. It chose option 1 with score 5, against 3 for the next best. Its support: lesson 257, line 1: «Bacteria are living things made of just one tiny cell, so small that hundreds could sit side by side across the full stop at the end of this sentence; they liv…», reached through the option's own match among the sentences about the question's things. What matched: the same doer «bacteria» (+2); the same property (+2); the same light verb (be, have, do, get, go) (+1). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 2 · wrong ✗

«got a stinking cold, doc better give me antibiotics» What is right?

1. Antibiotics do not work on cold viruses — ✓ the right answer · score 3
2. Antibiotics cure a cold in an hour — no support
3. Only strong antibiotics work on colds — ← Mova's choice · score 6
4. Antibiotics make you catch more colds — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 6, against 3 for the next best. Its support: lesson 72, line 16: «In 1928 Alexander Fleming noticed that a mould, Penicillium, had killed bacteria on a dish, which led to penicillin; antibiotics only work on bacteria, and tak…», reached through the option's own match among the sentences about the question's things. What matched: the same action «work» (+4); the same doer «antibiotics» (+2). The right option, 1, scored 3. · the question and its options parsed, with trees and pragmatics

Test 3 · wrong ✗

Count them: 1 bacterium splits in two every 20 minutes. How many are there after 1 hour?

1. 6 — ← Mova's choice · no support
2. 3 — no support
3. 60 — no support
4. 8 — ✓ 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 · right ✓

«my nan says dirt's good for kids, so no need to wash hands before tea» What is right?

1. No, children should never go outdoors — no support
2. Playing outdoors may help, but you should still wash hands before eating — ← Mova's choice · ✓ the right answer · score 5
3. Right, washing your hands is bad for you, so you should never do it at all — score 5
4. Right, dirt is a healthy food — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, tied with another option at 5 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 32, line 10: «Touching a toad does not give you warts, which are caused by a human virus, but toads have a bitter poison behind their eyes, so wash your hands.», reached through the remembered sentence the question matched. What matched: the same thing acted on «hands» (+4); the same action «wash» (+1). · the question and its options parsed, with trees and pragmatics

Test 5 · right ✓

What would happen if there were no decomposers like bacteria?

1. Nothing would ever die — no support
2. Dead leaves and bodies would pile up and soil would lose its nutrients — ← Mova's choice · ✓ the right answer · score 3
3. Plants would grow much faster, with no bacteria about to steal their food — no support
4. The air would fill with oxygen — no support

Why: It took the question to ask what happens next. It chose option 2 with score 3, the only option with support. Its support: lesson 68, line 16: «Brain freeze happens when very cold food chills the roof of the mouth quickly; blood vessels there change size and nerves send a pain signal felt in the forehe…», reached through what followed the sentence the question matched. What matched: the same doer «cold food» (+3). · the question and its options parsed, with trees and pragmatics

Test 6 · right ✓

Why did many doctors in 1847 laugh at Semmelweis?

1. Nobody yet knew about germs, so handwashing seemed pointless — ← Mova's choice · ✓ the right answer · score 9
2. His own hands were too dirty for anybody to listen — no support
3. He wanted them to wash their hands in warm milk instead of in water — score 5
4. He was only a child — no support

Why: It took the question to ask why something happens (its cause). It chose option 1 with score 9, against 5 for the next best. Its support: lesson 257, line 13: «In 1847 the doctor Ignaz Semmelweis found that handwashing by doctors saved mothers' lives, but many other doctors laughed at him, because nobody yet knew that…», reached through the cause of the sentence the question matched. What matched: the same action «know» (+6); the same doer «nobody» (+3). · the question and its options parsed, with trees and pragmatics

Test 7 · wrong ✗

A jug of milk stays on the table all day in summer. Why does it go sour?

1. Milk always goes sour after noon — ← Mova's choice · no support
2. Air pushes the cream to the bottom — no support
3. The sunlight coming in turns the milk into lemon juice — no support
4. Bacteria multiply in the warm milk and make acid — ✓ 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 8 · right ✓

«are we even human then if half of us is bacteria» What is the best answer?

1. No, bacteria cannot live inside people — no support
2. We are human, with a crowd of mostly helpful bacteria living with us — ← Mova's choice · ✓ the right answer · score 3
3. Yes, but the bacteria in our guts control our brains and choose what we do — no support
4. No, we are really bacteria dressed up in a human costume — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 3, the only option with support. Its support: lesson 75, line 16: «The first humans of our kind appeared only about 300,000 years ago, and Stegosaurus lived longer before T. rex than T. rex lived before us.», reached through the option's own match among the sentences about the question's things. What matched: the same action «live» (+4); the same circumstance (+1). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 9 · wrong ✗

Where would you look for some of the toughest bacteria on Earth?

1. In near-boiling hot springs and in Antarctic ice — ✓ the right answer · no support
2. Only in clean hospitals — no support
3. Nowhere, bacteria cannot live in hard places — ← Mova's choice · score 5
4. Only in warm bathrooms — no support

Why: It took the question to ask where. It chose option 3 with score 5, the only option with support. Its support: lesson 252, line 1: «Trees cannot walk, shout or run away, but they are not as silent as they look. Under the forest floor, thin threads of fungi wrap around their roots, and in th…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same place «air» (+2); a different doer (counts against) (+1). Against it: a different action (counts against) (-1). The right option, 1, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 10 · right ✓

Do we owe the air we breathe partly to bacteria?

1. No, oxygen was always in the air, right from the very start of the Earth — no support
2. No, volcanoes made all of it — no support
3. Yes, cyanobacteria made the first oxygen billions of years ago — ← Mova's choice · ✓ the right answer · score 8
4. Yes, but only the bacteria in our gut — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 8, the only option with support. Its support: lesson 257, line 18: «Billions of years ago, cyanobacteria made the first oxygen in the air by photosynthesis, and the rocks they built, called stromatolites, still grow in Shark Ba…», reached through the option's own match among the sentences about the question's things. What matched: the same action «make» (+4); the same doer «cyanobacteria» (+2); the same property (+2). · the question and its options parsed, with trees and pragmatics

Test 11 · right ✓

Why is a squid's glowing belly like camouflage?

1. It shows the squid's friends where it is — no support
2. It makes the squid look just like a fish — no support
3. It hides the squid's dark shadow against the moonlit water above — ← Mova's choice · ✓ the right answer · score 5
4. It blinds the hunter for ever with one very bright flash of white light — no support

Why: It took the question to ask why something happens (its cause). It chose option 3 with score 5, the only option with support. Its support: lesson 257, line 16: «The bobtail squid carries glowing bacteria on its belly that match the moonlight and hide its shadow from hunters below.», reached through the option's own match among the sentences about the question's things. What matched: the same action «hide» (+3); the same thing acted on «shadow» (+3). Against it: a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · right ✓

Identify the principal reason for which antibiotics are not prescribed for the common cold.

1. Antibiotics are effective only during the summer months — no support
2. The common cold is caused by an excess of bacteria in the gut, which antibiotics remove — score 3
3. Antibiotics render the patient permanently susceptible to colds — no support
4. The common cold is caused by viruses, against which antibiotics are without effect — ← Mova's choice · ✓ the right answer · score 7

Why: It took the question to ask which statement is true. It chose option 4 with score 7, against 3 for the next best. Its support: lesson 72, line 8: «Colds are caused by viruses, most often rhinoviruses; antibiotics do nothing against viruses, and going out with wet hair does not give you a cold.», reached through the option's own match among the sentences about the question's things. What matched: the same action «cause» (+4); the same doer «viruses» (+2); the same thing acted on «colds» (+1). · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · right ✓

Select the response consistent with the established facts concerning the discovery made by Alexander Fleming in 1928.

1. A mould upon a culture dish was observed to have destroyed the surrounding bacteria — ← Mova's choice · ✓ the right answer · no support
2. Handwashing was demonstrated to prevent illness — no support
3. The first vaccine was prepared from cowpox — no support
4. Bacteria were observed for the first time through a microscope — 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 3 · formal language · wrong ✗

Which of the following statements most accurately characterises bacteria in general?

1. Bacteria inhabit only unclean environments, such as drains and refuse — score 3
2. The majority are harmless or beneficial, a small minority being the cause of disease — ✓ the right answer · no support
3. All bacteria are invariably the cause of disease — score 3
4. Bacteria are multicellular animals possessing eyes, mouths and minute limbs — ← Mova's choice · score 5

Why: It took the question to ask who or what does it. It chose option 4 with score 5, against 3 for the next best. Its support: lesson 257, line 17: «Bacteria and fungi are decomposers: in compost and in soil they break down peelings, dead leaves and dead animals, give off heat as they work, and return nutri…», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «peelings» (+2); it fills the role the question asks for (+2); the same doer «bacteria» (+1). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · right ✓

Ascertain the effect of refrigeration upon bacteria present in food.

1. They are transformed into fungi — no support
2. They are entirely destroyed within the space of one night — no support
3. Their multiplication is retarded, although they are not destroyed — ← Mova's choice · ✓ the right answer · score 6
4. Their multiplication is greatly accelerated — score 6

Why: It took the question to ask which statement is true. It chose option 3 with score 6, tied with another option at 6 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 257, line 5: «Bacteria multiply by splitting in two, as often as every 20 minutes, which is why milk left out on a warm day goes sour so fast and why food lasts longer in th…», reached through the option's own match among the sentences about the question's things. What matched: the same action «multiply» (+4); the same doer «bacteria» (+2). · the question and its options parsed, with trees and pragmatics

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