S1 Science: Classification And Dichotomous Keys (Paper 2 (intermediate))

S1 Science: Classification and Dichotomous Keys (Paper 2 (intermediate))

2026-11-14

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Tutor Prep Guide · The order of classification ranks, the five kingdoms, binomial names and step by step identification with a dichotomous key

S1 Science: Classification and Dichotomous Keys (Paper 2 (intermediate))

This paper compares the order of ranks, the five kingdom system and the definition of a species, and estimates key levels with powers of two.

Direct answers　Order lies between class and family, species are defined by fertile offspring, and n levels separate at most 2 to the power n kinds.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S1 Science: Classification and Dichotomous Keys
Level	S1

02　Questions (10 items)

FoundationWhich rank lies between class and family?
FoundationWhich five kingdoms make up the widely used five kingdom system?
FoundationIn the name Panthera leo, what is Panthera?
IntermediateIn a dichotomous key the specimen fits neither side at one step. What does that usually mean?
IntermediateA whale looks like a fish. What evidence puts it among mammals?
IntermediateWhat is the biological definition of a species?
ChallengeGoing down from kingdom to species, how do the shared features change?
ChallengeTwelve kinds must be separated. What is the minimum number of levels in the key?
ChallengeTwo organisms share an order but differ in family. Can we conclude they share a genus?
Error redoA student uses living in water as the defining feature of fish. Why is that wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	Order	In kingdom, phylum, class, order, family, genus, species, order sits below class and above family.
2	Monera, Protista, Fungi, Plantae and Animalia	The split rests mainly on whether the cell has a nucleus and on how the organism obtains food.
3	The genus name, which starts with a capital	The second word leo is the specific epithet and is written in lower case.
4	The feature is poorly described or the specimen is incomplete, so the specimen must be checked again	A sound key uses features that are mutually exclusive and visible.
5	It breathes with lungs, gives birth to live young and feeds them milk	Similar appearance does not mean close kinship.
6	A group whose members can interbreed naturally and produce fertile offspring	A horse and a donkey produce a sterile mule, so they belong to different species.
7	More features are shared and fewer organisms fit the group	That is why the species is the most basic and most specific unit.
8	4 levels	Three levels give only 8 endpoints while four levels give 16, enough for twelve kinds.
9	No, because order is a larger group than family or genus	You must compare rank by rank below the order before deciding the genus.
10	Habitat is not a classification criterion, since whales and dolphins live in water yet are mammals	Classification uses internal features such as body structure, development and reproduction.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

For classification questions ask three things: is the feature observable, are the two options mutually exclusive, and is the question about rank order or about relatedness.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.