UNLV Bio 189 Final Exam
Updated Exam Questions and
Answers A+ Grade 2026-2027
Complete Biology Final Exam Study
Guide
1. How does the fossil record reveal information about evolutionary changes?
Correct Answer:
Species change over time, and all organisms descended from a single common ancestor.
Rationale:
The fossil record preserves organisms from different periods in Earth's history. Comparing fossils
in older and newer rock layers shows gradual changes in species over time, providing strong
evidence for evolution and common ancestry.
2. What features make Tiktaalik a transitional fossil, and what role do these fossils have in the
fossil record?
Correct Answer:
Tiktaalik has both fish characteristics (fins and scales) and early land-vertebrate characteristics
(a neck, wrists, and finger-like bones). Transitional fossils show how organisms evolved from
water to land.
Rationale:
Transitional fossils contain features of both ancestral and descendant groups. Tiktaalik
demonstrates the evolutionary transition between aquatic fish and the first four-limbed
vertebrates, making it important evidence for evolutionary change.
3. What can anatomy and DNA reveal about evolution?
, Correct Answer:
DNA shows how long ago two species shared a common ancestor, while anatomy reveals
evolutionary relationships through homologous structures.
Rationale:
Closely related organisms have more similar DNA sequences and comparable anatomical
structures. These similarities help scientists reconstruct evolutionary relationships and trace
common ancestry.
4. What are the major groups of organisms?
Correct Answer:
Bacteria, Archaea, and Eukarya.
Rationale:
These three domains represent the broadest level of biological classification. Bacteria and
Archaea are prokaryotes (cells without a nucleus), while Eukarya includes organisms with cells
that contain a nucleus and membrane-bound organelles.
5. What is the classification of species?
Correct Answer:
Kingdom → Phylum → Class → Order → Family → Genus → Species.
Rationale:
This taxonomic hierarchy helps scientists classify and identify organisms based on shared
characteristics. Each level becomes more specific, with species being the most precise
classification.
6. How do fossils form?
Correct Answer:
An organism dies and is preserved quickly by rapid freezing, burial in sediment, amber, or
similar conditions. If conditions are favorable, the organism fossilizes through mineralization,
molds, casts, or imprints.
Rationale:
Most organisms decay after death, but rapid burial or preservation protects remains from
, decomposition. Over long periods, minerals replace tissues or leave impressions that become
fossils.
7. What types of organisms are most likely or least likely to be fossilized?
Correct Answer:
• Most likely: Organisms with hard bones, teeth, or shells.
• Least likely: Soft-bodied organisms such as jellyfish and earthworms.
Rationale:
Hard body parts resist decay and are more easily preserved in sediments, while soft tissues
decompose quickly and rarely fossilize unless preserved under exceptional conditions.
8. Relative Dating
Correct Answer:
Determines the age of a fossil by comparing its position within rock layers and with nearby
fossils.
Rationale:
According to the Law of Superposition, older rock layers are found beneath younger layers.
Relative dating estimates whether fossils are older or younger without determining an exact
age.
9. Radiometric Dating
Correct Answer:
Uses radioactive isotopes and their decay rates to determine the absolute age of rocks and
fossils.
Rationale:
Radioactive elements decay at constant rates known as half-lives. Measuring the remaining
radioactive material allows scientists to calculate the actual age of fossils or rocks.
10. Homology
Updated Exam Questions and
Answers A+ Grade 2026-2027
Complete Biology Final Exam Study
Guide
1. How does the fossil record reveal information about evolutionary changes?
Correct Answer:
Species change over time, and all organisms descended from a single common ancestor.
Rationale:
The fossil record preserves organisms from different periods in Earth's history. Comparing fossils
in older and newer rock layers shows gradual changes in species over time, providing strong
evidence for evolution and common ancestry.
2. What features make Tiktaalik a transitional fossil, and what role do these fossils have in the
fossil record?
Correct Answer:
Tiktaalik has both fish characteristics (fins and scales) and early land-vertebrate characteristics
(a neck, wrists, and finger-like bones). Transitional fossils show how organisms evolved from
water to land.
Rationale:
Transitional fossils contain features of both ancestral and descendant groups. Tiktaalik
demonstrates the evolutionary transition between aquatic fish and the first four-limbed
vertebrates, making it important evidence for evolutionary change.
3. What can anatomy and DNA reveal about evolution?
, Correct Answer:
DNA shows how long ago two species shared a common ancestor, while anatomy reveals
evolutionary relationships through homologous structures.
Rationale:
Closely related organisms have more similar DNA sequences and comparable anatomical
structures. These similarities help scientists reconstruct evolutionary relationships and trace
common ancestry.
4. What are the major groups of organisms?
Correct Answer:
Bacteria, Archaea, and Eukarya.
Rationale:
These three domains represent the broadest level of biological classification. Bacteria and
Archaea are prokaryotes (cells without a nucleus), while Eukarya includes organisms with cells
that contain a nucleus and membrane-bound organelles.
5. What is the classification of species?
Correct Answer:
Kingdom → Phylum → Class → Order → Family → Genus → Species.
Rationale:
This taxonomic hierarchy helps scientists classify and identify organisms based on shared
characteristics. Each level becomes more specific, with species being the most precise
classification.
6. How do fossils form?
Correct Answer:
An organism dies and is preserved quickly by rapid freezing, burial in sediment, amber, or
similar conditions. If conditions are favorable, the organism fossilizes through mineralization,
molds, casts, or imprints.
Rationale:
Most organisms decay after death, but rapid burial or preservation protects remains from
, decomposition. Over long periods, minerals replace tissues or leave impressions that become
fossils.
7. What types of organisms are most likely or least likely to be fossilized?
Correct Answer:
• Most likely: Organisms with hard bones, teeth, or shells.
• Least likely: Soft-bodied organisms such as jellyfish and earthworms.
Rationale:
Hard body parts resist decay and are more easily preserved in sediments, while soft tissues
decompose quickly and rarely fossilize unless preserved under exceptional conditions.
8. Relative Dating
Correct Answer:
Determines the age of a fossil by comparing its position within rock layers and with nearby
fossils.
Rationale:
According to the Law of Superposition, older rock layers are found beneath younger layers.
Relative dating estimates whether fossils are older or younger without determining an exact
age.
9. Radiometric Dating
Correct Answer:
Uses radioactive isotopes and their decay rates to determine the absolute age of rocks and
fossils.
Rationale:
Radioactive elements decay at constant rates known as half-lives. Measuring the remaining
radioactive material allows scientists to calculate the actual age of fossils or rocks.
10. Homology
