Evidence for Evolution Worksheet with Answers (Grade 11 Biology)
A free printable evidence for evolution worksheet for Grade 11 biology.
This free evidence for evolution worksheet asks students to think like scientists and weigh the evidence. They match four lines of evidence to examples, compare the forelimb bones of a human, cat, whale and bat, and sort six examples into homologous, analogous and vestigial structures.
They then read cytochrome c data to rank how closely species are related, match types of reproductive isolation to real examples, explain how new species form, and use rock layers and Tiktaalik to interpret the fossil record.
- Grade 11 Biology
- 24 marks
- 40–50 minutes
- Full answer key
What's in This Evidence for Evolution Worksheet
| Part | Skill practised | Marks |
|---|---|---|
| A | Types of evidence | 2 |
| B | Homologous limbs | 4 |
| C | Homologous, analogous or vestigial? | 3 |
| D | Molecular evidence (cytochrome c) | 4 |
| E | Speciation and reproductive isolation | 5 |
| F | The fossil record | 4 |
| G | Spot the mistake | 2 |
It supports the Ontario Grade 11 biology curriculum expectations in the Evolution unit. Part A of the evidence for evolution worksheet starts with four lines of evidence:
| Line of evidence | What it involves |
|---|---|
| Fossil record | Remains or traces of organisms preserved in rock |
| Comparative embryology | Comparing early stages of development, e.g. gill slits in all vertebrate embryos |
| Molecular evidence | Comparing DNA or protein sequences between species |
| Biogeography | Similar species live near each other; island species resemble those on the nearest mainland |
Comparative Anatomy
Part B of the evidence for evolution worksheet compares four mammal forelimbs. Each one has the same set of bones in the same order: one upper arm bone, two forearm bones, a cluster of wrist bones, and hand and finger bones. Only their shapes differ, suiting each animal to grasping, walking, swimming or flying.
These are homologous structures, inherited from a common ancestor. Analogous structures, such as a butterfly wing and a bird wing, do the same job but evolved separately. Vestigial structures, such as the tiny pelvis bones inside a whale, are reduced leftovers of features that were useful in ancestors. Part C asks students to sort six examples:
| Example | Type |
|---|---|
| A whale's flipper and a human arm | Homologous |
| A butterfly wing and a bird wing | Analogous |
| Small pelvis bones inside a whale's body | Vestigial |
| A shark's fin and a dolphin's flipper | Analogous |
| The human tailbone (coccyx) | Vestigial |
| A cat's front leg and a bat's wing | Homologous |
For more background, see evidence of common descent on Wikipedia.
Molecular Evidence
Cytochrome c is a protein used in cellular respiration by almost every living thing, which makes it perfect for comparing species. The graph in Part D of the evidence for evolution worksheet shows approximate amino acid differences from the human version:
Chimpanzees have no differences and rhesus monkeys only one, while yeast has 44. Human cytochrome c has 104 amino acids, so chickens share (104 − 13) ÷ 104 = 87.5% of them with us. The pattern matches what anatomy and fossils already suggest: the longer ago two species split from a common ancestor, the more mutations have built up. DNA itself is explored in the DNA replication worksheet.
Speciation
Part E of the evidence for evolution worksheet turns to new species. A species is a group that can interbreed in nature and produce fertile offspring. New species form when populations become reproductively isolated:
| Type of isolation | Example |
|---|---|
| Geographic isolation | Squirrel populations on opposite sides of the Grand Canyon can no longer meet |
| Temporal isolation | Two frog species live in the same pond, but one breeds in April and the other in June |
| Behavioural isolation | Two bird species ignore each other because their mating songs are different |
| Hybrid sterility | A horse and a donkey produce a mule, which cannot reproduce |
In allopatric speciation, a barrier such as a canyon or ocean splits a population. Each group faces different conditions, so natural selection and mutation change them separately until they can no longer interbreed. Natural selection itself is covered in detail in the natural selection worksheet.
The Fossil Record
In undisturbed rock, the deepest layers formed first, so the fossils in them are the oldest. This is the law of superposition. Part F of the evidence for evolution worksheet uses this rock column:
The fossils go from oldest to youngest as W, X, Y, Z. Transitional fossils such as Tiktaalik, a 375-million-year-old animal with gills and scales but also a neck and wrist bones, show steps between major groups. The record still has gaps, because fossilization needs rare conditions and soft-bodied organisms seldom fossilize. To see how scientists group organisms based on this evidence, try the classification and taxonomy worksheet.
Evidence for Evolution Worksheet Practice Questions
These questions match the evidence for evolution worksheet PDF, which has the limb diagram, bar graph, rock column and ruled answer space.
Part A – Types of Evidence
- Fossil record
- Comparative embryology
- Molecular evidence
- Biogeography
Part B – Homologous Limbs
- Name the bone shown in green in all four limbs.
- Why are these limbs described as homologous structures?
- Give the main function of each limb.
- What do these similar bone patterns suggest about the ancestry of these mammals?
Part C – Homologous, Analogous or Vestigial?
- A whale's flipper and a human arm
- A butterfly wing and a bird wing
- Small pelvis bones inside a whale's body
- A shark's fin and a dolphin's flipper
- The human tailbone (coccyx)
- A cat's front leg and a bat's wing
Part D – Molecular Evidence
- Which organism is most closely related to humans? Explain using the data.
- Rank the organisms from most to least closely related to humans.
- Why do more distant relatives have more differences?
- Human cytochrome c is 104 amino acids long. What percentage of the amino acids are the same in chickens and humans?
Part E – Speciation
- Geographic isolation
- Temporal isolation
- Behavioural isolation
- Hybrid sterility
- What is a species, according to the biological species concept?
- Describe how a single population can become two species through geographic isolation. (2 marks)
Part F – The Fossil Record
- Which fossil is the oldest? Explain how you know.
- List the fossils from oldest to youngest.
- Tiktaalik is a 375-million-year-old fossil with fish gills and scales but also a neck and limb-like fins with wrist bones. Why is it called a transitional fossil?
- Give one reason the fossil record has gaps.
Part G – Spot the Mistake
- A student writes: “Humans evolved from chimpanzees.” Explain the error and correct it.
- A student writes: “Vestigial structures are completely useless and will disappear soon.” Explain the error and correct it.
Evidence for Evolution Worksheet Answer Key
Open each part of the evidence for evolution worksheet answers to check your work. The printable key is at the end of the PDF.
Part A answers (Q1–4)
- Fossil record: b (remains or traces of organisms preserved in rock)
- Comparative embryology: d (comparing early stages of development, e.g. gill slits in all vertebrate embryos)
- Molecular evidence: a (comparing dna or protein sequences between species)
- Biogeography: c (similar species live near each other; island species resemble those on the nearest mainland)
Part B answers (Q5–8)
- The humerus (upper arm bone)
- Same bones in the same order, inherited from a common ancestor.
- Grasping; walking; swimming; flying
- A common ancestor; selection modified the limb for each lifestyle.
Part C answers (Q9–14)
- Homologous
- Analogous
- Vestigial
- Analogous
- Vestigial
- Homologous
Part D answers (Q15–18)
- Chimpanzee: 0 differences, the fewest.
- Chimpanzee, rhesus monkey, dog, chicken, tuna, yeast
- An older common ancestor gives more time for mutations to build up.
- (104 − 13) ÷ 104 × 100 = 87.5%
Part E answers (Q19–24)
- Geographic isolation: c
- Temporal isolation: a
- Behavioural isolation: d
- Hybrid sterility: b
- A group of organisms that can interbreed in nature and produce fertile offspring.
- A barrier splits the population; mutations and natural selection change each group separately until they can no longer interbreed.
Part F answers (Q25–28)
- W: the deepest layer formed first (law of superposition).
- W, X, Y, Z
- It has features of both fish and four-legged animals, a step from water to land.
- Fossilization is rare; soft bodies seldom fossilize; erosion destroys many.
Part G answers (Q29–30)
- They share a common ancestor; each species evolved separately from it.
- They are reduced remnants of ancestral structures; some keep minor functions and may persist for a long time.
5 Common Mistakes on an Evidence for Evolution Worksheet
- Saying humans evolved from chimpanzees. We share a common ancestor.
- Mixing up homologous and analogous. Homologous = same origin; analogous = same job.
- Calling vestigial structures useless. They are reduced, and some keep minor functions.
- Reading the rock column upside down. The bottom layers are the oldest.
- Thinking individuals evolve. Populations evolve over many generations.
How to Use This Evidence for Evolution Worksheet in Class
- Lesson 1: Parts A–D of the evidence for evolution worksheet, with chicken wing or model skeleton comparisons.
- Lesson 2: Parts E–G, then a short debate: which line of evidence is most convincing, and why?
Review with the evolution quiz and the natural selection quiz.
Frequently Asked Questions
Is this evidence for evolution worksheet free?
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
What are the main types of evidence for evolution?
The fossil record, comparative anatomy (homologous, analogous and vestigial structures), comparative embryology, molecular evidence from DNA and proteins, and biogeography, the distribution of species around the world.
What is the difference between homologous and analogous structures?
Homologous structures share the same basic structure because they come from a common ancestor, like a human arm and a whale flipper. Analogous structures do the same job but evolved separately, like a bird wing and a butterfly wing.
How does DNA show that species are related?
Closely related species have very similar DNA and protein sequences. The fewer differences there are, the more recently the two species shared a common ancestor.
How does a new species form?
A population is split, often by a geographic barrier. Each group evolves separately through mutation and natural selection until the two groups can no longer interbreed, even if they meet again.
More Free Grade 11 Biology Resources
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