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100+ Free Galicia PAU Biology Practice Questions
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2026 Statistics
Key Facts: Galicia PAU Biology Exam
90 min
Exam Time Limit
Comisión Interuniversitaria de Galicia
0–10
Grading Scale
CIUG Regulations
4.0
Min. Access Phase Score
CIUG Admission Rules
EUR 63.67
Ordinary Registration Fee
CIUG Official Rates
5 Blocks
Curriculum Content Areas
2º Bachillerato Biology Syllabus
The Galicia PAU Biology exam (Biología / Bioloxía) is administered by the Comisión Interuniversitaria de Galicia (CIUG) for students completing 2nd Bachillerato. The exam lasts 90 minutes and is graded on a 0–10 scale (minimum 4.0 required in the Access Phase). Note that local questions on this platform are an English-language MCQ study adaptation created to help students master the underlying 2nd Bachillerato curriculum.
Sample Galicia PAU Biology Practice Questions
Try these sample questions to test your Galicia PAU Biology exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1Which property of liquid water explains its high specific heat capacity and high heat of vaporization?
A.Covalent peptide bonds
B.Intermolecular hydrogen bonding network
C.Ionic cross-linking
D.Van der Waals dispersion forces
Explanation: Water molecules form a dense network of hydrogen bonds between partial negative oxygen and partial positive hydrogen atoms. Breaking these bonds requires substantial energy input, resulting in a high specific heat capacity and high heat of vaporization that help regulate thermal homeostasis in living organisms.
2When human red blood cells are placed in a hypertonic sodium chloride solution, what phenomenon occurs?
A.Turgor pressure expansion
B.Cellular crenation due to osmotic efflux of water
C.Osmotic lysis due to rapid water entry
D.Plasmolysis of the cell wall
Explanation: In a hypertonic environment, water moves out of the cell across the semipermeable plasma membrane by osmosis toward the higher solute concentration. This water loss causes the erythrocyte to shrink and form spikes, a process called crenation.
3Which extracellular buffer system is primarily responsible for maintaining human arterial blood pH near 7.40?
A.Phosphate buffer system (HPO4^2- / H2PO4-)
B.Bicarbonate buffer system (HCO3- / H2CO3)
C.Histidine protein buffer system
D.Ammonium buffer system (NH4+ / NH3)
Explanation: The carbonic acid-bicarbonate buffer system is the primary extracellular buffer in blood plasma. Carbon dioxide produced by cellular respiration reacts with water to form carbonic acid, which dissociates into bicarbonate ions and protons to cushion against pH alterations.
4Which structural feature distinguishes alpha-D-glucose from beta-D-glucose in aqueous solution?
A.The orientation of the hydroxyl group on the anomeric carbon C1
B.The carbon position of the carbonyl group in open-chain form
C.The presence of an amino group at carbon C2
D.The molecular formula and total molecular weight
Explanation: Alpha-D-glucose and beta-D-glucose are anomers that differ in the stereochemical configuration at carbon C1 (the anomeric carbon). In the Haworth projection of alpha-D-glucose, the hydroxyl group at C1 is trans to the CH2OH group (pointing down), whereas in beta-D-glucose it is cis (pointing up).
5Which polysaccharide functions as the primary energy storage molecule in animal liver and muscle tissues?
A.Amylose
B.Cellulose
C.Glycogen
D.Chitin
Explanation: Glycogen is a highly branched polymer of alpha-D-glucose linked by alpha-1,4-glycosidic bonds with alpha-1,6-glycosidic branch points occurring every 8 to 12 glucose residues. This architecture allows rapid enzymatic mobilization of glucose in liver and muscle cells.
6What type of chemical linkage connects glycerol to fatty acids in a triglyceride molecule?
A.Ester bond
B.Glycosidic bond
C.Phosphodiester bond
D.Peptide bond
Explanation: Triglycerides consist of one glycerol backbone molecule esterified to three fatty acid molecules. The reaction between a carboxyl group of a fatty acid and a hydroxyl group of glycerol produces an ester bond along with the release of a water molecule.
7Which lipid class is amphipathic and forms the lipid bilayer matrix of biological membranes?
A.Triacylglycerols
B.Phospholipids
C.Waxes
D.Steroid esters
Explanation: Phospholipids possess a hydrophilic polar head group (glycerol, phosphate, and an alcohol moiety) and two hydrophobic nonpolar fatty acid tails. This amphipathic nature causes them to spontaneously assemble into lipid bilayers in aqueous environments.
8Which level of protein structure is held together predominantly by hydrogen bonds between backbone peptide carbonyl oxygens and amide hydrogens?
A.Primary structure
B.Secondary structure
C.Tertiary structure
D.Quaternary structure
Explanation: Secondary structure refers to localized repeating conformations of the polypeptide backbone, such as alpha-helices and beta-pleated sheets. These structures are stabilized by periodic hydrogen bonds between peptide backbone carbonyl oxygens and amide nitrogens.
9What is the zwitterionic form of an amino acid at its isoelectric point (pI)?
A.A net positively charged cation with protonated carboxyl and amino groups
B.A net negatively charged anion with deprotonated carboxyl and amino groups
C.A dipolar ion with a negatively charged carboxylate group and a positively charged amino group
D.An uncharged molecule with no ionized functional groups
Explanation: At its isoelectric point (pI), an amino acid exists as a zwitterion: the alpha-carboxyl group is deprotonated (-COO-) and the alpha-amino group is protonated (-NH3+), yielding a molecule with equal positive and negative charges and a net electrical charge of zero.
10How does a competitive enzyme inhibitor affect the kinetic parameters Vmax and Km?
A.Vmax decreases while Km remains unchanged
B.Km increases while Vmax remains unchanged
C.Both Vmax and Km decrease proportionally
D.Both Vmax and Km increase
Explanation: A competitive inhibitor binds reversibly to the active site of the free enzyme, competing directly with the substrate. Increasing substrate concentration can outcompete the inhibitor, so the maximum reaction velocity (Vmax) is unchanged, but a higher substrate concentration is needed to reach half-Vmax, increasing the apparent Km.
About the Galicia PAU Biology Practice Questions
Verified exam format metadata for Galicia PAU Biology (Biología / Bioloxía 2º Bachillerato) is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.