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100+ Free Bac D Bénin Practice Questions

Prepare for the Baccalauréat Série D (Biologie - Géologie) — Bénin exam with instant access — no signup required.

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2026 Statistics

Key Facts: Bac D Bénin Exam

Coeff 13/20

Combined weight of SVT (5), Mathematics (4), and Physical Sciences (4)

Office du Baccalauréat du Bénin

10.00 / 20

Minimum weighted average required for direct admission

MESRS Bénin

5,000 XOF

Official candidate registration fee (+ 1,000 XOF relevé de notes)

Office du Baccalauréat du Bénin

Free 100-question English MCQ study adaptation for the Benin Baccalauréat Série D (officially Biologie - Géologie). The official exam is administered in French by the Office du Baccalauréat du Bénin (OBB) with a 10/20 weighted pass threshold across SVT (coeff 5), Mathématiques (coeff 4), Sciences Physiques (coeff 4) and humanities, followed by a compulsory second-group oral in Français and Anglais for candidates averaging 9.00 to 9.99/20.

Sample Bac D Bénin Practice Questions

Try these sample questions to test your Bac D Bénin exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a classical Mendelian monohybrid cross between two heterozygous tall pea plants (Tt x Tt), where tall (T) is completely dominant over dwarf (t), what is the expected phenotypic ratio among the offspring?
A.1 tall : 1 dwarf (50% tall, 50% dwarf)
B.3 tall : 1 dwarf (75% tall, 25% dwarf)
C.1 tall : 2 intermediate : 1 dwarf (25% : 50% : 25%)
D.All tall (100% tall)
Explanation: A monohybrid cross between two heterozygotes (Tt x Tt) yields a genotypic ratio of 1 TT : 2 Tt : 1 tt (1/4 TT, 1/2 Tt, 1/4 tt). Because allele T is completely dominant over t, both TT and Tt genotypes express the tall phenotype (1/4 + 2/4 = 3/4 or 75%), while only tt expresses the dwarf phenotype (1/4 or 25%). This produces the classic 3:1 phenotypic ratio.
2Two dihybrid individuals with independent, non-linked genes (AaBb x AaBb) are crossed. Assuming complete dominance for both traits, what is the theoretical probability of obtaining an offspring displaying the dominant phenotype for the first gene and the recessive phenotype for the second gene ([A-bb])?
A.9/16 (56.25%)
B.3/16 (18.75%)
C.1/16 (6.25%)
D.6/16 (37.50%)
Explanation: According to Mendel's Law of Independent Assortment, the phenotypic segregation for two independent heterozygous genes (AaBb x AaBb) follows the 9:3:3:1 ratio: 9/16 [A-B-], 3/16 [A-bb], 3/16 [aaB-], and 1/16 [aabb]. The probability of dominant phenotype for A is P(A-) = 3/4, and the probability of recessive phenotype for B is P(bb) = 1/4. Multiplying these independent probabilities gives P([A-bb]) = (3/4) * (1/4) = 3/16 (18.75%).
3A testcross is performed between a heterozygous female Drosophila with linked genes in coupling phase (AB/ab) and a double homozygous recessive male (ab/ab). The cross yields 1000 total offspring: 420 [AB], 420 [ab], 80 [Ab], and 80 [aB]. What is the genetic map distance between loci A and B?
A.8 centimorgans (cM)
B.16 centimorgans (cM)
C.32 centimorgans (cM)
D.84 centimorgans (cM)
Explanation: Recombinant offspring result from crossing-over between loci A and B during female gametogenesis. The recombinant phenotypes are [Ab] (80) and [aB] (80), giving a total of 80 + 80 = 160 recombinant individuals. The recombination frequency (p) is: p = (Total Recombinants / Total Offspring) * 100% = (160 / 1000) * 100% = 16%. Since 1% recombination frequency equals 1 map unit or 1 centimorgan (cM), the distance between loci A and B is 16 cM.
4Hemophilia A is an X-linked recessive bleeding disorder. A phenotypically normal woman whose father was hemophilic marries a healthy, non-hemophilic man. What is the probability that their first son will be affected by hemophilia?
A.0% (0.00)
B.25% (0.25)
C.50% (0.50)
D.100% (1.00)
Explanation: Because her father had hemophilia (X^h Y), the woman must have inherited his X^h chromosome, making her an obligate carrier (X^H X^h). The father has normal clotting (X^H Y). A male offspring inherits the Y chromosome from the father and either X^H or X^h from the mother with equal probability (1/2). Therefore, among male children, the probability of receiving X^h and thus having hemophilia is 1/2 or 50%.
5During DNA replication in eukaryotic cells, which enzyme is responsible for unwinding the double helix at the replication fork by breaking hydrogen bonds between complementary base pairs?
A.DNA Polymerase III
B.DNA Helicase
C.DNA Ligase
D.RNA Primase
Explanation: DNA Helicase is the motor protein that separates the two antiparallel strands of the double helix by breaking the hydrogen bonds between complementary nitrogenous bases (A-T and G-C), creating the replication fork. DNA polymerase synthesizes new strands, ligase joins Okazaki fragments, and primase synthesizes RNA primers.
6A mature mRNA transcript contains the coding sequence 5'-AUG-GCA-UUC-UGA-3'. Based on the standard genetic code (AUG = Met, GCA = Ala, UUC = Phe, UGA = Stop), what peptide is produced upon ribosomal translation?
A.A tetrapeptide: Met-Ala-Phe-Uga
B.A tripeptide: Met-Ala-Phe
C.A dipeptide: Ala-Phe
D.A polypeptide of 4 amino acids including Selenocysteine
Explanation: Translation begins at the start codon 5'-AUG-3' (Methionine), continues with 5'-GCA-3' (Alanine) and 5'-UUC-3' (Phenylalanine), and terminates upon reaching the stop codon 5'-UGA-3'. Stop codons (UAA, UAG, UGA) do not code for amino acids; instead, they bind release factors that trigger hydrolysis of the peptidyl-tRNA bond. The resulting peptide is therefore a tripeptide: Met-Ala-Phe.
7Sickle cell anemia (drépanocytose) is caused by a point mutation in codon 6 of the human beta-globin gene, where the triplet GAG is replaced by GTG (transcribed to GUG in mRNA). What type of mutation is this, and what is its direct molecular consequence on the protein?
A.Nonsense mutation leading to premature chain termination
B.Frameshift mutation altering all downstream amino acid codons
C.Missense mutation replacing hydrophilic glutamic acid with hydrophobic valine
D.Silent mutation leaving the primary protein sequence unchanged
Explanation: Sickle cell anemia is caused by a single nucleotide substitution (transversion of A to T in the coding strand: GAG -> GTG). In mRNA, codon 6 becomes GUG instead of GAG. This is a missense mutation that substitutes glutamic acid (Glu, a polar negatively charged amino acid) with valine (Val, a non-polar hydrophobic amino acid). The hydrophobic valine creates a sticky patch on deoxygenated hemoglobin S, causing polymerisation into fibrous aggregates and red blood cell sickling.
8In the human ABO blood group system, the I^A and I^B alleles are codominant, while the i allele is recessive. A mother with blood group A (genotype I^A i) and a father with blood group B (genotype I^B i) have children. Which blood group phenotypes can theoretically appear among their biological offspring?
A.Only group AB
B.Only groups A and B
C.Groups A, B, and AB only
D.Groups A, B, AB, and O
Explanation: The mother produces gametes I^A and i with equal frequency (1/2 each). The father produces gametes I^B and i with equal frequency (1/2 each). Combining them yields four genotypes in equal proportions (25% each): I^A I^B (Group AB), I^A i (Group A), I^B i (Group B), and i i (Group O). Thus, all four ABO blood group phenotypes are possible.
9In a human family pedigree, two phenotypically healthy parents have a child affected by an autosomal recessive metabolic disorder. What is the probability that their next, phenotypically healthy child is a heterozygous carrier of the mutant allele?
A.1/4 (25%)
B.1/2 (50%)
C.2/3 (66.7%)
D.3/4 (75%)
Explanation: Because the parents are healthy but have an affected child (aa), both parents are obligate heterozygous carriers (Aa x Aa). The possible genotypes for any child are 1/4 AA, 1/2 Aa, and 1/4 aa. We are given the condition that the child is phenotypically healthy, which eliminates the homozygous recessive genotype (aa). Among the remaining healthy genotypes (1 AA + 2 Aa = 3 total possibilities), 2 out of 3 are heterozygous carriers (Aa). Therefore, the conditional probability is 2/3 (~66.7%).
10What is the structural architecture of a monomeric immunoglobulin G (IgG) antibody molecule?
A.A single polypeptide chain folded into three beta-pleated domains
B.Two identical heavy (H) chains and two identical light (L) chains connected by interchain disulfide bonds
C.Four identical alpha chains joined to a central carbohydrate core
D.A pentamer of identical light chains linked by a J chain
Explanation: A monomeric antibody (such as IgG) consists of four polypeptide chains: two identical heavy (H) chains (~50 kDa each) and two identical light (L) chains (~25 kDa each), forming a Y-shaped quaternary structure held together by interchain disulfide bonds. Each arm contains a variable region (Fab) that binds specific antigens, while the stem (Fc) mediates effector functions such as complement activation and phagocyte binding.

About the Bac D Bénin Exam

The Baccalauréat Série D is Benin's premier national secondary school leaving examination in the biological and natural sciences (Sciences de la Vie et de la Terre). Administered by the Office du Baccalauréat du Bénin (OBB) under the Ministère de l'Enseignement Supérieur et de la Recherche Scientifique (MESRS), Série D serves as the primary prerequisite for entry into university faculties of medicine, pharmacy, agronomy, health sciences, and environmental biology. The official examination is administered in French through intensive multi-hour written problem sets, experiments analysis, and synthesis essays. This practice bank provides 100 comprehensive English-language multiple-choice questions with rigorous calculation steps and conceptual explanations, adapted to help students master core scientific and general curriculum competencies.

Assessment

First group (écrit), per the OBB coefficient table: SVT (coeff 5, 3h), Mathématiques (coeff 4, 4h), Sciences Physiques (coeff 4, 4h), Français (coeff 2, 4h), Anglais / Langue Vivante 1 (coeff 2, 3h), Histoire-Géographie (coeff 2, 2h) and Philosophie (coeff 2, 2h) — Total 1 = 21 coefficients (420 points) — plus EPS (coeff 1) for 22 coefficients / 440 points. Candidates averaging 9.00 to 9.99/20 are declared admissible to the second group, a compulsory oral in Français (coeff 2) and Anglais (coeff 2) worth 80 points, giving a 26-coefficient / 520-point total. The 2026 session sat 15–18 June. This bank is an English-language MCQ study adaptation, not an official translation or a simulation of the written and oral papers.

Time Limit

22 hours of written papers, sat across the 4-day national session

Passing Score

10/20 (Weighted average >= 10.00 / 20; 9.00–9.99 qualifies for the second-group oral)

Exam Fee

5,000 XOF registration for Beninese candidates; 35,000 XOF for foreign candidates; plus 1,000 XOF for the relevé de notes and 2,000 XOF photo-scanning/form-printing for candidats libres (OBB note de service, 20 November 2025) (Office du Baccalauréat du Bénin (OBB) — Ministère de l'Enseignement Supérieur et de la Recherche Scientifique)

Bac D Bénin Exam Content Outline

Coeff 5 (~25%)

Sciences de la Vie et de la Terre (SVT)

Genetics (Mendelian, molecular, human), immunology, neurophysiology, and geology (plate tectonics, petrology, West African geology).

Coeff 4 (~20%)

Mathématiques

Analysis (real functions, logarithms, exponentials, integrals), numerical sequences, probability and statistics, vector geometry.

Coeff 4 (~20%)

Sciences Physiques (Physique-Chimie)

Newtonian mechanics, electrical circuits (RC, RL, RLC), acid-base equilibria and pH, chemical kinetics, organic chemistry.

Coeff 2 (~9%)

Français

Literary analysis, text comprehension, syntax, essay writing, and argumentation.

Coeff 2 (~9%)

Philosophie

Epistemology of natural sciences, ethics and bioethics, truth, human condition, and society.

Coeff 2 (~9%)

Histoire-Géographie

20th-century world history, African decolonization, economic and regional geography of Benin and West Africa.

Coeff 2 (~8%)

Langue Vivante 1 / Anglais

Reading comprehension on scientific and social themes, grammar, vocabulary, and guided writing.

How to Pass the Bac D Bénin Exam

What You Need to Know

  • Passing score: 10/20 (Weighted average >= 10.00 / 20; 9.00–9.99 qualifies for the second-group oral)
  • Assessment: First group (écrit), per the OBB coefficient table: SVT (coeff 5, 3h), Mathématiques (coeff 4, 4h), Sciences Physiques (coeff 4, 4h), Français (coeff 2, 4h), Anglais / Langue Vivante 1 (coeff 2, 3h), Histoire-Géographie (coeff 2, 2h) and Philosophie (coeff 2, 2h) — Total 1 = 21 coefficients (420 points) — plus EPS (coeff 1) for 22 coefficients / 440 points. Candidates averaging 9.00 to 9.99/20 are declared admissible to the second group, a compulsory oral in Français (coeff 2) and Anglais (coeff 2) worth 80 points, giving a 26-coefficient / 520-point total. The 2026 session sat 15–18 June. This bank is an English-language MCQ study adaptation, not an official translation or a simulation of the written and oral papers.
  • Time limit: 22 hours of written papers, sat across the 4-day national session
  • Exam fee: 5,000 XOF registration for Beninese candidates; 35,000 XOF for foreign candidates; plus 1,000 XOF for the relevé de notes and 2,000 XOF photo-scanning/form-printing for candidats libres (OBB note de service, 20 November 2025)

Keys to Passing

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

Bac D Bénin Study Tips from Top Performers

1Master SVT schematics and experimental reasoning: practise drawing reflex arcs, action potential curves, antibody-antigen complexes, and geological cross-sections from memory.
2Work through full calculation steps in physics-chemistry and mathematics, including calculus integrals, differential equations of circuits, and acid-base titration curves.
3Review French and philosophy essay structures regularly, as humanities make up a substantial share of the total weighted score.
4Practice under timed conditions using past OBB exam papers (annales) to build endurance for multi-hour sessions.

Frequently Asked Questions

Is the official Benin Baccalauréat Série D multiple choice?

No. The official examination organized by the Office du Baccalauréat du Bénin (OBB) consists of extensive written essay questions, experimental problem sets, and mathematical demonstrations conducted in French, followed by an oral second round for borderline candidates. This practice bank is an English-language MCQ study adaptation designed for conceptual mastery and self-assessment.

What is the passing score and grading system for Série D in Benin?

The examination is graded on a scale of 0 to 20. A candidate must achieve an overall weighted average (moyenne générale) of at least 10.00/20 across all subjects. Candidates obtaining an average between 9.00 and 9.99/20 are eligible for the second round oral defense (épreuves orales de contrôle) in Français and Anglais.

What are the subject coefficients in Série D?

Per the OBB list of examination papers, SVT carries the highest weight at coefficient 5 (3 hours). Mathématiques and Sciences Physiques carry coefficient 4 each (4 hours each). Français (4 hours), Anglais / LV1 (3 hours), Histoire-Géographie (2 hours) and Philosophie (2 hours) each carry coefficient 2, and EPS carries coefficient 1 — 22 coefficients in the first group. The second-group oral adds Français (coeff 2) and Anglais (coeff 2) for a 26-coefficient total.

What academic pathways are opened by obtaining the Bac D in Benin?

Bac D is the standard preparatory diploma for university faculties of medicine (FSS Cotonou / Parakou), pharmacy, agricultural sciences (FSA UAC), nursing, natural sciences (FAST), and biomedical technology programs across West Africa.