Grade 8 Evidence Of Evolution Worksheets 2024 - Free Printable

Let's solve this "Evidence of Evolution Worksheet" step by step and provide clear explanations for each answer.

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Part 1: Match the term to its definition

We are given terms on the left and definitions (a–e) on the right. We need to match them correctly.

1. vestigial structure
→ e) structures that have reduced in size because they no longer serve an important function
✔ *Example: Human appendix or tail bone.*

2. homologous structures
→ c) related organisms have the same bone makeup
✔ *Example: The forelimbs of humans, whales, and bats have similar bone structures despite different functions.*

3. DNA sequence
→ b) similarities and differences in nucleotide sequences between organisms
✔ *DNA comparison helps determine evolutionary relationships.*

4. fossil record
→ a) remains of dead organisms
✔ *Fossils are preserved remains or traces of ancient life.*

5. embryology
→ d) in the early stages of development dogs, pigs, and humans resemble one another
✔ *This shows shared ancestry — embryos of different vertebrates look similar early on.*

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Part 2: Match the keyword to the correct diagram model

Now we match keywords with diagrams labeled a, b, c, d.

6. vestigial structure → Diagram c
✔ *The image shows a whale skeleton with small pelvic bones — vestigial remnants of legs from land ancestors.*

7. homologous structures → Diagram b
✔ *Shows how the same bones (like humerus, radius, ulna) are present in different animals — human, bat, whale, etc., though modified for different uses.*

8. transitional fossil → Diagram d
✔ *Shows Tiktaalik (a fish-like creature with limb-like fins), which is a transitional fossil between fish and tetrapods.*

9. embryology → Diagram a
✔ *Shows embryos of different species (fish, reptile, bird, mammal) at early stages — all look very similar, supporting common ancestry.*

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Part 3: Fill in the blanks using vocabulary terms

Vocabulary box:
- vestigial structure
- radiometric dating
- transitional fossil
- DNA sequence
- plate tectonics
- amino acid sequence

Now fill in:

> The strongest evidence for evolution is the (10) DNA sequence and that code can be used to build a(n) (11) amino acid sequence. When a species has a body part that is no longer useful, like the tail bone in human, that is called a(n) (12) vestigial structure. Scientists can approximate the age of something old by (13) radiometric dating. By inspecting the fossils of organisms, scientists predict they will find a(n) (14) transitional fossil. Organisms across the Earth used to live on one super continent but became separated by (15) plate tectonics.

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✔ Final Answers:

#### Part 1:
1. e – vestigial structure
2. c – homologous structures
3. b – DNA sequence
4. a – fossil record
5. d – embryology

#### Part 2:
6. c – vestigial structure
7. b – homologous structures
8. d – transitional fossil
9. a – embryology

#### Part 3:
10. DNA sequence
11. amino acid sequence
12. vestigial structure
13. radiometric dating
14. transitional fossil
15. plate tectonics

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🔍 Explanation Summary:

- DNA sequence is key because it reveals genetic similarities and differences across species.
- Amino acid sequences are derived from DNA and show functional protein similarities.
- Vestigial structures are remnants of once-useful traits (e.g., human appendix).
- Radiometric dating measures radioactive decay to estimate fossil ages.
- Transitional fossils (like *Tiktaalik*) show intermediate forms between major groups.
- Plate tectonics explains why similar species are found on continents now separated by oceans (continental drift).

This worksheet demonstrates multiple lines of evidence for evolution: molecular, anatomical, fossil, developmental, and geographical.

✔ All answers are consistent with scientific understanding of evolutionary biology.