All Practice Exams

Free Practice Questions for Aragón PAU Biology

Exam-style questions and explanations by OpenExamPrep.

✓ No registration✓ No credit card

Loading practice questions...

Exam Review

Key Facts: Aragón PAU Biology Exam

90 min

Exam Time Limit

UNIZAR PAU Commission

0–10

Grading Scale

Gobierno de Aragón / UNIZAR

4.0

Min. Access Phase Score

PAU Access Rules

EUR 75.00

Ordinary Registration Fee

UNIZAR PAU inscription page 2026

6 Blocks

Basic Knowledge Syllabus Areas

2º Bachillerato Biology Curriculum

The Aragón PAU Biology exam (Biología) is organized by the PAU Organising Commission of Aragón and Universidad de Zaragoza (UNIZAR) for 2nd Bachillerato students. The 90-minute exam is scored on a 0–10 scale (minimum 4.0 required in Access Phase). Our 100-question practice set provides an English-language MCQ study tool covering the complete 2nd Bachillerato biology curriculum.

Sample Aragón PAU Biology Practice Questions

Try these sample questions to review concepts for the Aragón PAU Biology exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which physical property of water is primarily responsible for its ability to absorb large amounts of heat energy without experiencing a drastic change in temperature?
A.High specific heat capacity
B.High surface tension
C.Low latent heat of vaporization
D.Maximum density at 0 °C
Explanation: Water has a high specific heat capacity (4.184 J/g·°C) due to its extensive intermolecular hydrogen bonding network. Absorbed thermal energy is initially consumed in breaking these hydrogen bonds rather than immediately increasing molecular kinetic energy, stabilizing intracellular temperatures and aquatic environments.
2The upward movement of water through xylem vessels in tall plants relies on the force of attraction between water molecules and the hydrophilic cell walls of vessel elements. What is this phenomenon called?
A.Adhesion
B.Cohesion
C.Viscosity
D.Plasmolysis
Explanation: Adhesion refers to the attractive forces between water molecules and different polar or charged surfaces, such as the cellulose and lignin in xylem walls. Cohesion is the attraction between water molecules themselves. Together, cohesion and adhesion support transpirational pull under tension.
3What primary buffer system maintains human blood plasma pH within the narrow physiological range of 7.35 to 7.45?
A.Ammonium buffer system
B.Phosphate buffer system
C.Bicarbonate / carbonic acid buffer system
D.Acetate buffer system
Explanation: The carbonic acid-bicarbonate buffer system (H2CO3 / HCO3-) is the primary extracellular buffer in human blood. Excess hydrogen ions are neutralized by bicarbonate to form carbonic acid, which dissociates into water and carbon dioxide exhaled by the lungs.
4When human red blood cells are placed in a concentrated (hypertonic) sodium chloride solution, water leaves the cells by osmosis. What happens to the erythrocytes?
A.Turgor
B.Plasmolysis
C.Hemolysis
D.Crenation
Explanation: In a hypertonic extracellular environment, water exits animal cells down its water potential gradient, causing red blood cells to shrink and form notched, spiny surfaces—a process termed crenation. Hemolysis occurs in hypotonic media.
5Which inorganic bioelement functions as an essential cofactor for chlorophyll and is required for muscle contraction and enzymatic ATP cleavage?
A.Potassium (K+)
B.Calcium (Ca2+)
C.Iron (Fe2+/Fe3+)
D.Magnesium (Mg2+)
Explanation: Magnesium (Mg2+) is the central metal ion in the porphyrin ring of chlorophyll molecules. It also acts as an essential cofactor for kinases and ATPases, stabilizing ATP complexes during enzymatic reactions.
6Which of the following monosaccharides is structurally classified as a ketohexose?
A.D-Galactose
B.D-Fructose
C.D-Ribose
D.D-Glucose
Explanation: D-Fructose contains six carbon atoms (hexose) and a ketone functional group at C2 (ketohexose). In aqueous solution, it predominantly forms a five-membered furanose ring. D-Glucose and D-Galactose are aldohexoses.
7Which disaccharide is non-reducing because its glycosidic bond involves the anomeric carbon atoms of both constituent monosaccharides (alpha-D-glucopyranosyl-(1->2)-beta-D-fructofuranoside)?
A.Lactose
B.Sucrose
C.Cellobiose
D.Maltose
Explanation: Sucrose is formed by an alpha(1->2) glycosidic linkage between C1 of alpha-D-glucose and C2 of beta-D-fructose. Because both anomeric carbons are engaged in the bond, no free hemiacetal or hemiketal group remains to reduce Benedict's or Fehling's reagents.
8Which structural polysaccharide consists of unbranched chains of D-glucose molecules joined by beta-1,4-glycosidic bonds, forming rigid microfibrils in plant cell walls?
A.Cellulose
B.Amylose
C.Glycogen
D.Chitin
Explanation: Cellulose is an unbranched polymer of glucose connected by beta-1,4-glycosidic bonds. Hydrogen bonding between adjacent parallel linear chains forms rigid microfibrils that provide tensile strength to plant cell walls.
9Triacylglycerols (triglycerides) are classified as saponifiable lipids because they contain which chemical linkage between glycerol and three fatty acid chains?
A.Ester linkage
B.Ether linkage
C.Peptide bond
D.Phosphodiester bond
Explanation: Triacylglycerols are formed by condensation reactions establishing three ester linkages between the three hydroxyl groups of glycerol and the carboxyl groups of three fatty acids. Alkaline hydrolysis (saponification) cleaves ester bonds to release glycerol and fatty acid salts (soaps).
10Glycerophospholipids spontaneously assemble into lipid bilayers in aqueous environments due to their amphipathic nature. Which component forms the hydrophilic polar head group?
A.Hydrocarbon tail of a saturated fatty acid
B.Hydrocarbon tail of an unsaturated fatty acid
C.Phosphate group bonded to an alcohol (e.g., choline, ethanolamine, or serine)
D.Glycerol backbone esterified to three fatty acids
Explanation: Glycerophospholipids possess a hydrophilic head consisting of a negatively charged phosphate group linked to a polar head group alcohol (such as choline, ethanolamine, or serine) attached to C3 of glycerol. The two fatty acid chains attached to C1 and C2 constitute the hydrophobic tails.

About the Aragón PAU Biology Exam

The Aragón PAU Biology exam (Biología 2º Bachillerato) evaluates upper secondary school students across Aragón (Universidad de Zaragoza) on core life science topics including biochemistry, cellular structures, metabolic pathways, molecular genetics, biotechnology, microbiology, and immunology. Note: The official PAU examination in Aragón consists of written open-ended and structured questions in Spanish; the 100 practice questions provided on this platform are an English-language multiple-choice adaptation designed to test core concept mastery and syllabus knowledge.

Exam sponsor: PAU Organising Commission of Aragón / UNIZAR. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

90-minute written examination featuring 5 questions (2 mandatory competency questions and 3 choice questions); local questions are an English-language MCQ study adaptation.

Time Limit

90 minutes (1.5 hours)

Passing Score

Marked on a 0–10 scale. Minimum 4.0 required in Access Phase to combine with Bachillerato GPA (60% Bachillerato + 40% PAU >= 5.0 to pass).

Exam / Certification Fees

EUR 75.00 ordinary registration fee (Access Phase plus two voluntary subjects); EUR 30.93 per additional voluntary subject (UNIZAR 2026)

Exam sponsor website

Reported exam pass rate: About 95% of Bachillerato candidates passed the Aragón PAU Access Phase in the June 2025 ordinary sitting (regional reported results).. This describes exam candidates, not OpenExamPrep users or results from using our resources. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

25%

Biochemistry and Biomolecules

Water structure and physical properties, bioelements, trace elements, mineral salts, osmotic regulation, pH buffers, monosaccharides, disaccharides, polysaccharides, saponifiable and non-saponifiable lipids, amino acids, peptide bonds, protein levels of structure, enzyme catalysis, and nucleic acid polymers (DNA and RNA).

20%

Cell Biology and Cell Division

Prokaryotic versus eukaryotic cellular architecture, plasma membrane structure (fluid mosaic model), active/passive transport, endocytosis/exocytosis, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria, chloroplasts, cytoskeleton, nucleus, mitosis stages, and meiosis with genetic recombination.

20%

Metabolism and Energy Transformation

Anabolic and catabolic pathways, ATP structure and role, NAD+/NADP+/FAD electron carriers, enzyme kinetics, glycolysis, pyruvate dehydrogenase complex, Krebs cycle, mitochondrial electron transport chain and chemiosmosis, fermentations, photophosphorylation, and Calvin cycle carbon fixation.

20%

Molecular Genetics and Evolution

Semi-conservative DNA replication mechanism and enzymes, transcription in prokaryotes and eukaryotes, RNA processing, genetic code degenerateness and universality, translation steps, gene mutations (point mutations, frameshifts), chromosomal mutations, and molecular mechanisms of evolution.

15%

Microbiology, Biotechnology, and Immunology

Bacterial cell structure and binary fission, viral structure and lytic/lysogenic cycles, prions, recombinant DNA technology, PCR, gel electrophoresis, innate immunity barriers, cellular and humoral adaptive immune responses, immunoglobulins (IgG, IgM, IgA, IgE, IgD), MHC molecules, vaccines, hypersensitivity reactions, and autoimmune disorders.

Preparing for the Aragón PAU Biology Exam

What You Need to Know

  • Passing score: Marked on a 0–10 scale. Minimum 4.0 required in Access Phase to combine with Bachillerato GPA (60% Bachillerato + 40% PAU >= 5.0 to pass).
  • Assessment: 90-minute written examination featuring 5 questions (2 mandatory competency questions and 3 choice questions); local questions are an English-language MCQ study adaptation.
  • Time limit: 90 minutes (1.5 hours)
  • Exam / certification fees: EUR 75.00 ordinary registration fee (Access Phase plus two voluntary subjects); EUR 30.93 per additional voluntary subject (UNIZAR 2026) Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Aragón PAU Biology: Suggested Study Strategy

1Master chemical structure and bonding in biomolecules (water, carbohydrates, lipids, proteins, and nucleic acids).
2Memorize every step, subcellular location, reactant, and product of glycolysis, the Krebs cycle, oxidative phosphorylation, and photosynthesis.
3Understand molecular genetics mechanisms: DNA replication enzymes, RNA transcription steps, genetic code reading, and ribosome translation.
4Differentiate between innate and adaptive immunity, humoral vs cell-mediated pathways, and antibody structure/classes.
5Practice drawing and labeling cell organelles, membrane transport mechanisms, and stages of mitosis and meiosis.

Frequently Asked Questions

What is the structure of the official UNIZAR Aragón PAU Biology exam?

The official Aragón PAU Biology exam is a 90-minute paper with 5 questions worth 2 points each (2 compulsory competency questions and 3 questions with choice between option A or B). Questions require written responses, diagrams, or problem solving in Spanish. The 100 questions here are an English MCQ study adaptation.

What passing score is required for Aragón PAU Biology?

The exam is graded on a 0–10 scale. A minimum of 4.0 points in the Access Phase is required to combine with the 2nd Bachillerato GPA (60% Bachillerato GPA + 40% PAU Access Phase >= 5.0 to pass).

What is the fee for taking the PAU exam in Aragón?

The base registration fee for the PAU Access Phase at Universidad de Zaragoza (UNIZAR) is EUR 75.00, with reductions available for large families or qualified fee-exempt categories.

Which syllabus topics are covered in Aragón PAU Biology?

The exam covers the 6 basic blocks of the official 2nd Bachillerato curriculum: Biomolecules, Cell Biology, Metabolism, Molecular Genetics, Biotechnology, and Immunology.

Why are these practice questions presented as English MCQs?

These 100 questions serve as an English-language study adaptation to help students, bilingual learners, and international candidates test their understanding of fundamental biological concepts required by the UNIZAR curriculum.