UNIVERSITY OF ALABAMA — BSC 108
BSC 108 Kennedy Exam 3
Practice Question Bank
Comprehensive Review with Biological Rationales
Introduction to Biology — DNA Structure, Gene Expression, Evolution, Ecology
85 Comprehensive Questions with Verified Answers
Edition 1 · August 2026
✓ Institution Verification
VERIFIED This document was independently verified as belonging to University of
Alabama — BSC 108 Introduction to Biology. This comprehensive review covers DNA
structure, replication, transcription, translation, mutations, biotechnology, evolution, natural
selection, speciation, ecology, and ecosystems.
Table of Contents
,1. Instructions for Use 2
2. Practice Questions with Answers & Rationales 2
3. Appreciation & Review 12
BSC 108 · University of Alabama Page 1
,BSC 108 KENNEDY EXAM 3 STUDY GUIDE INSTRUCTIONS & PRACTICE QUESTIONS
How to Use This Guide
Read each stem carefully, choose your answer, then review the rationale directly below. Each
correct option is marked, and every wrong option is explained so you understand why it's
incorrect — not just that it is. These questions are designed to mirror the exam format and
biological reasoning required for BSC 108.
Category: Biology — DNA Structure, Gene Expression, Evolution, Ecology
1 What is the structure of a strand of DNA?
A Double helix, twisted ladder
B Single helix, straight ladder
C Triple helix, twisted ladder
D Double helix, straight ladder
Why A is correct: DNA has a double helix structure, which resembles a twisted ladder. The
two strands are twisted around each other to form the helical shape.
B — DNA is double-stranded, not single-stranded.
C — DNA is double-stranded, not triple-stranded.
D — DNA is twisted (helical), not straight.
, 2 What is DNA composed of?
A Amino acid subunits
B Nucleotide subunits
C Fatty acid subunits
D Monosaccharide subunits
Why B is correct: DNA is composed of nucleotide subunits. Each nucleotide consists of a
phosphate group, a deoxyribose sugar, and a nitrogen-containing base.
A — Amino acids are the building blocks of proteins.
C — Fatty acids are components of lipids.
D — Monosaccharides are the building blocks of carbohydrates.
3 What is the backbone of DNA?
A Deoxyribose and a nitrogen-containing base
B Deoxyribose and a phosphate group
C Phosphate group and a nitrogen-containing base
D Two nitrogen-containing bases
Why B is correct: The backbone of DNA is composed of deoxyribose (sugar) and
phosphate groups. These alternate to form the structural framework of each DNA strand.
A — Nitrogen-containing bases project inward from the backbone.
C — The phosphate group is part of the backbone, but bases are not.
D — Bases are not part of the backbone structure.
BSC 108 Kennedy Exam 3
Practice Question Bank
Comprehensive Review with Biological Rationales
Introduction to Biology — DNA Structure, Gene Expression, Evolution, Ecology
85 Comprehensive Questions with Verified Answers
Edition 1 · August 2026
✓ Institution Verification
VERIFIED This document was independently verified as belonging to University of
Alabama — BSC 108 Introduction to Biology. This comprehensive review covers DNA
structure, replication, transcription, translation, mutations, biotechnology, evolution, natural
selection, speciation, ecology, and ecosystems.
Table of Contents
,1. Instructions for Use 2
2. Practice Questions with Answers & Rationales 2
3. Appreciation & Review 12
BSC 108 · University of Alabama Page 1
,BSC 108 KENNEDY EXAM 3 STUDY GUIDE INSTRUCTIONS & PRACTICE QUESTIONS
How to Use This Guide
Read each stem carefully, choose your answer, then review the rationale directly below. Each
correct option is marked, and every wrong option is explained so you understand why it's
incorrect — not just that it is. These questions are designed to mirror the exam format and
biological reasoning required for BSC 108.
Category: Biology — DNA Structure, Gene Expression, Evolution, Ecology
1 What is the structure of a strand of DNA?
A Double helix, twisted ladder
B Single helix, straight ladder
C Triple helix, twisted ladder
D Double helix, straight ladder
Why A is correct: DNA has a double helix structure, which resembles a twisted ladder. The
two strands are twisted around each other to form the helical shape.
B — DNA is double-stranded, not single-stranded.
C — DNA is double-stranded, not triple-stranded.
D — DNA is twisted (helical), not straight.
, 2 What is DNA composed of?
A Amino acid subunits
B Nucleotide subunits
C Fatty acid subunits
D Monosaccharide subunits
Why B is correct: DNA is composed of nucleotide subunits. Each nucleotide consists of a
phosphate group, a deoxyribose sugar, and a nitrogen-containing base.
A — Amino acids are the building blocks of proteins.
C — Fatty acids are components of lipids.
D — Monosaccharides are the building blocks of carbohydrates.
3 What is the backbone of DNA?
A Deoxyribose and a nitrogen-containing base
B Deoxyribose and a phosphate group
C Phosphate group and a nitrogen-containing base
D Two nitrogen-containing bases
Why B is correct: The backbone of DNA is composed of deoxyribose (sugar) and
phosphate groups. These alternate to form the structural framework of each DNA strand.
A — Nitrogen-containing bases project inward from the backbone.
C — The phosphate group is part of the backbone, but bases are not.
D — Bases are not part of the backbone structure.
