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Quizzes > Science

Biology CLEP Practice Test: Prep With Realistic Questions

Quick CLEP biology exam practice with instant results and answer explanations.

Editorial: Review CompletedCreated By: Perry ThorntonUpdated Aug 27, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper cutout quiz header with CLEP biology practice test title and DNA strand leaf microscope icons on sky blue background

This Biology CLEP practice test helps you check core topics with exam-style questions and instant feedback. Use it to find weak spots before test day, then review basics with a biology chapter 1 practice test, try a general biology quiz for broader refresh, or drill with biology questions with answers to build speed and accuracy.

Which organelle is responsible for ATP production in eukaryotic cells?
Nucleus
Mitochondrion
Endoplasmic reticulum
Golgi apparatus
Mitochondria are known as the powerhouse of the cell because they generate ATP through oxidative phosphorylation. They host the electron transport chain and ATP synthase in their inner membranes. Other organelles like the nucleus and Golgi apparatus have different functions, such as housing genetic material or modifying proteins.
What is the basic unit of heredity?
Allele
Chromosome
Gene
Trait
A gene is a segment of DNA that contains the information to produce a functional product, usually a protein or RNA. Alleles are variant forms of a gene. Chromosomes are structures that package many genes, and traits are the observable characteristics influenced by genes.
Which biomolecule is the main component of cell membranes?
Proteins
Phospholipids
Cholesterol
Polysaccharides
Phospholipids form a bilayer that makes up the fundamental structure of cellular membranes. Their hydrophilic heads face outward toward aqueous environments while hydrophobic tails face inward. Membrane proteins and cholesterol intersperse to provide fluidity and function.
What is the process by which plants convert light energy into chemical energy?
Fermentation
Transpiration
Cellular respiration
Photosynthesis
Photosynthesis takes place in chloroplasts where light energy is used to convert carbon dioxide and water into glucose and oxygen. Cellular respiration is the reverse process, breaking down glucose for energy. Transpiration refers to water loss in plants, and fermentation is an anaerobic process in some organisms.
What is the pH of pure water at 25°C?
6
7
5
8
Pure water at 25°C has equal concentrations of hydrogen and hydroxide ions, giving it a neutral pH of 7. Solutions with pH less than 7 are acidic, and those above 7 are basic. Temperature changes can slightly shift this neutral pH value.
Which macromolecule serves as the primary genetic material in all living organisms?
Protein
RNA
DNA
Lipid
DNA (deoxyribonucleic acid) stores genetic information in the sequence of its four bases. RNA can also carry genetic information in some viruses and is involved in protein synthesis. Proteins and lipids have other structural and functional roles but do not encode hereditary information.
What is the primary function of ribosomes in cells?
ATP production
Protein synthesis
Lipid synthesis
DNA replication
Ribosomes read mRNA sequences and assemble amino acids into polypeptide chains, a process known as translation. They can be free in the cytosol or bound to the endoplasmic reticulum. Other organelles carry out lipid synthesis, energy production, and DNA replication.
What type of bond holds together amino acids in a polypeptide chain?
Glycosidic bond
Peptide bond
Hydrogen bond
Ionic bond
A peptide bond forms between the amino group of one amino acid and the carboxyl group of another, linking them in a polypeptide chain. Hydrogen and ionic bonds contribute to tertiary and quaternary structure but do not link amino acids covalently. Glycosidic bonds connect sugars.
During which phase of mitosis do sister chromatids separate and move toward opposite poles?
Prophase
Anaphase
Metaphase
Telophase
Anaphase is characterized by the splitting of sister chromatids at the centromere and their movement toward opposite spindle poles. In metaphase, chromosomes align at the cell equator. Prophase involves chromosome condensation, and telophase rebuilds the nuclear envelope.
Which process results in the production of two genetically identical daughter cells?
Mitosis
Conjugation
Meiosis
Binary fission
Mitosis produces two daughter cells that are genetically identical to the parent cell, maintaining the same chromosome number. Meiosis reduces chromosome number by half and generates genetic diversity. Binary fission is similar to mitosis but occurs in prokaryotes, and conjugation is gene transfer between bacteria.
What term describes the observable characteristics of an organism resulting from gene expression?
Chromosome
Genotype
Phenotype
Allele
Phenotype refers to the physical traits and behaviors of an organism determined by both genetic makeup and environmental factors. Genotype is the genetic constitution. Alleles are different versions of a gene, and chromosomes are DNA-protein structures.
In a dihybrid cross exhibiting independent assortment, what phenotypic ratio is expected in the F2 generation?
9:3:3:1
1:1
3:1
9:7
A 9:3:3:1 ratio arises when two genes assort independently and each gene has two alleles with simple dominance. This pattern reflects combinations of dominant and recessive traits in the F2 generation. Deviations occur if linkage or epistasis is present.
Which enzyme is responsible for unwinding the DNA helix during replication?
Primase
Ligase
Helicase
Polymerase
Helicase breaks hydrogen bonds between DNA strands, separating them to allow replication. Primase lays down RNA primers, DNA polymerase adds nucleotides, and ligase seals nicks in the sugar-phosphate backbone.
What is the final electron acceptor in the mitochondrial electron transport chain?
Oxygen
Water
FAD
NAD+
Oxygen accepts electrons from Complex IV and combines with protons to form water. This step maintains the flow of electrons down the chain and drives ATP synthesis. Without oxygen, the chain backs up, halting ATP production.
Which stage of cellular respiration generates the most ATP?
Glycolysis
Krebs cycle
Fermentation
Oxidative phosphorylation
Oxidative phosphorylation, which includes the electron transport chain and ATP synthase, yields around 28 - 34 ATP per glucose. Glycolysis and the Krebs cycle produce only a few ATP directly. Fermentation does not involve an electron transport chain and yields no additional ATP beyond glycolysis.
How do enzymes affect the activation energy of biochemical reactions?
They lower the activation energy of the reaction
They change the reaction equilibrium
They produce energy for the reaction
They raise the activation energy
Enzymes function as catalysts by stabilizing the transition state, which lowers the activation energy required for a reaction. They do not alter the overall Gibbs free energy or equilibrium position. Their action speeds up the rate at which equilibrium is reached.
According to the Hardy - Weinberg principle, if the frequency of allele p is 0.7 and q is 0.3, what percentage of the population is expected to be heterozygous?
49%
9%
30%
42%
In Hardy - Weinberg equilibrium, heterozygote frequency is calculated as 2pq. Here, 2 × 0.7 × 0.3 = 0.42 or 42%. The homozygous frequencies are p² (49%) and q² (9%).
The enzyme Rubisco catalyzes the fixation of CO? to which molecule in the Calvin cycle?
Ribulose-1,5-bisphosphate
Glyceraldehyde-3-phosphate
Fructose-6-phosphate
3-Phosphoglycerate
Rubisco catalyzes the carboxylation of ribulose-1,5-bisphosphate (RuBP) to form two molecules of 3-phosphoglycerate. This is the primary CO? fixation step in the Calvin cycle. Other molecules are produced later in the cycle.
In competitive inhibition of an enzyme, which parameter is altered and how?
Km decreases, Vmax unchanged
Vmax decreases, Km unchanged
Km and Vmax both decrease
Km increases, Vmax unchanged
Competitive inhibitors bind to the active site, increasing the apparent Km since more substrate is needed to reach half Vmax. Vmax remains unchanged because high substrate concentrations can outcompete the inhibitor.
Which product of the light-dependent reactions provides reducing power for the Calvin cycle?
O?
ATP
CO?
NADPH
NADPH generated by photosystem I supplies the electrons needed to reduce 3-phosphoglycerate into glyceraldehyde-3-phosphate in the Calvin cycle. ATP provides energy but not reducing equivalents. Oxygen is released as a byproduct.
Insulin is secreted by which specialized cell type in the pancreatic islets?
Beta cells
Delta cells
Alpha cells
Acinar cells
Beta cells in the islets of Langerhans produce and secrete insulin in response to elevated blood glucose. Alpha cells secrete glucagon, delta cells secrete somatostatin, and acinar cells produce digestive enzymes.
Which process involves the removal of introns from a pre-mRNA transcript?
Translation
DNA replication
RNA splicing
Transcription
RNA splicing is carried out by the spliceosome to remove non-coding introns and join exons in pre-mRNA. Transcription produces the pre-mRNA, translation synthesizes protein, and replication duplicates DNA.
Which complex in the mitochondrial electron transport chain does NOT contribute to proton pumping?
Complex III
Complex II
Complex I
Complex IV
Complex II (succinate dehydrogenase) transfers electrons from FADH? to ubiquinone but does not pump protons. Complexes I, III, and IV all move protons across the inner mitochondrial membrane to build the proton gradient.
For an enzyme following Michaelis - Menten kinetics, when substrate concentration [S] equals Km, what fraction of Vmax is achieved?
Three-quarters of Vmax
Equal to Vmax
One-quarter of Vmax
One-half of Vmax
By definition of Km, when [S] = Km, the reaction velocity equals Vmax/2. This relationship is a cornerstone of Michaelis - Menten enzyme kinetics and helps characterize enzyme affinity.
Which enzyme complex remodels chromatin structure by acetylating histone tails to enhance transcriptional activation?
DNA topoisomerase
Histone deacetylase
DNA methyltransferase
Histone acetyltransferase
Histone acetyltransferases (HATs) transfer acetyl groups to lysine residues on histone tails, loosening chromatin structure and facilitating transcription. Histone deacetylases remove these groups, condensing chromatin. DNA methyltransferases add methyl groups to DNA, and topoisomerases manage DNA supercoiling.
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Study Outcomes

  1. Understand Test Format -

    Familiarize yourself with the structure, timing, and question styles of the biology CLEP practice test to navigate the official exam confidently.

  2. Identify Cellular Structures & Functions -

    Use targeted CLEP biology practice questions to recall and describe the roles of organelles, macromolecules, and cellular processes.

  3. Analyze Genetic Inheritance Patterns -

    Tackle biology CLEP test questions on Mendelian genetics, DNA replication, and gene expression to interpret pedigrees and Punnett squares effectively.

  4. Apply Ecological & Evolutionary Principles -

    Engage with ecology and evolution scenarios in the biology CLEP practice test to connect theoretical concepts to real-world biological systems.

  5. Evaluate Performance & Target Weak Areas -

    Review explanations for each clep biology practice question to identify knowledge gaps and refine your study plan.

  6. Boost Exam Confidence & Strategy -

    Develop effective time-management and test-taking strategies by practicing with realistic biology CLEP test questions and monitoring your progress.

Cheat Sheet

  1. Cell Structure and Membrane Transport -

    Review organelle functions - mitochondria as the cell's "powerhouse" and ribosomes for protein synthesis - using reliable sources like Khan Academy or university biology departments. Remember transport processes: diffusion, osmosis, and active transport; a handy mnemonic is "SANE MAP" (Similarity, Assisted, Non-assisted, Endocytosis, Membrane pumps). These fundamentals frequently appear in biology clep practice test scenarios.

  2. Macromolecules and Their Functions -

    Focus on the four major macromolecules - carbohydrates, lipids, proteins, and nucleic acids - and their monomer building blocks using information from NIH and university biochemistry courses. A memory trick is "CLAP" (Carbs, Lipids, Amino acids, Phosphates) to recall each group's monomer and primary role. Knowledge of polymerization and hydrolysis is essential for biology clep test questions on chemical reactions.

  3. Mendelian Genetics and Probability -

    Brush up on Punnett squares and the laws of segregation and independent assortment by practicing clep biology practice questions from college websites. Use the probability formula P = (number of favorable outcomes)/(total outcomes) to predict genotype ratios and recall that heterozygous crosses yield a 3:1 phenotypic ratio. These concepts are central to many biology clep test questions.

  4. Photosynthesis and Cellular Respiration Equations -

    Memorize the overall reactions: 6CO₂ + 6H₂O → C₆H₝₂O₆ + 6O₂ for photosynthesis and C₆H₝₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP for respiration, endorsed by top university lecture notes. A mnemonic like "Peter Pan Can't Fly After Eight" helps sequence light reactions, Calvin cycle, Krebs cycle, and oxidative phosphorylation. These pathway basics often pop up in clep biology practice questions on metabolic processes.

  5. Ecology, Evolution, and Population Genetics -

    Understand ecological interactions - competition, predation, symbiosis - and foundational models like the Hardy - Weinberg equation (p² + 2pq + q² = 1) from ecology textbooks at major universities. Remember the acronym "I SPECS" (Immigration, Selection, Emigration, Mutation, Non-random mating, Small population size) to track factors affecting allele frequencies. Mastering these topics boosts your skills for the biology clep test and reinforces population-level thinking.

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