Concours d'accès à l'APESA — IAV Hassan II (Morocco)

In plant and animal cellular bioenergetics, ATP synthesis during oxidative phosphorylation and photophosphorylation is coupled to transmembrane proton gradients. Which statement accurately describes the orientation of proton pumping and the catalytic domain of ATP synthase in mitochondria?

• AProtons are pumped from the matrix into the intermembrane space, and the F1 catalytic hea…
• BProtons are pumped from the intermembrane space into the matrix, and the F1 catalytic hea…
• CProtons are pumped from the matrix into the cytoplasm, and ATP is synthesized exclusively…
• DProtons accumulate in the mitochondrial matrix creating an acidic matrix, and the F0 chan…

During semiconservative DNA replication in eukaryotic chromosomes, discontinuous synthesis on the lagging strand requires multiple coordinated enzymes. What is the precise sequential action required to process Okazaki fragments into a continuous DNA strand?

• ADNA ligase synthesizes an RNA primer, DNA helicase extends the DNA strand, and DNA topois…
• BRNA primase lays down an RNA primer, DNA polymerase extends the fragment, RNA primers are…
• CDNA polymerase alpha synthesizes the entire Okazaki fragment continuously, followed by ex…
• DReverse transcriptase synthesizes a complementary cDNA primer, which is elongated by RNA…

In molecular genetics, the universal canonical genetic code is described as degenerate, non-overlapping, and unambiguous. What does 'degeneracy' (or redundancy) of the genetic code mean?

• AAdjacent codons share overlapping nucleotides during translation along the mRNA strand
• BA single triplet codon can code for multiple distinct amino acids depending on cellular c…
• CMost amino acids are encoded by more than one triplet codon
• DCodons can be read interchangeably in either the 5'-to-3' or 3'-to-5' direction

A mature eukaryotic mRNA transcript contains an uninterrupted open reading frame (ORF) of exactly 1,200 nucleotides, beginning with the initiation codon AUG and ending with the stop codon UAA. Assuming no post-translational cleavage and an average amino acid molecular mass of 110 Daltons (Da), what is the number of amino acids in the translated polypeptide and its approximate molecular mass?

• A398 amino acids, with an approximate molecular mass of 43.78 kDa
• B400 amino acids, with an approximate molecular mass of 44.00 kDa
• C1,197 amino acids, with an approximate molecular mass of 131.67 kDa
• D399 amino acids, with an approximate molecular mass of 43.89 kDa

In enzyme kinetics governed by the Michaelis-Menten model, how does a reversible competitive inhibitor alter the apparent Michaelis constant (Km) and the maximum reaction velocity (Vmax)?

• AApparent Km decreases while Vmax decreases
• BApparent Km increases while Vmax remains unchanged
• CApparent Km remains unchanged while Vmax decreases
• DBoth apparent Km and Vmax increase proportionally

An agricultural soil urease extracted from rhizospheric bacteria exhibits Michaelis-Menten kinetics with a maximum velocity Vmax = 120 micromol/(min*mg protein) and a Michaelis constant Km = 15 mM. When urea is added to a soil assay at a substrate concentration [S] = 30 mM, what is the initial enzymatic reaction velocity (v0)?

• A90 micromol/(min*mg protein)
• B60 micromol/(min*mg protein)
• C80 micromol/(min*mg protein)
• D40 micromol/(min*mg protein)

Glycolysis is the primordial anaerobic catabolic pathway occurring in the cytosol of eukaryotic cells. What is the net chemical equation for the conversion of one molecule of glucose during glycolysis?

• A1 Glucose + 2 NAD+ + 32 ADP + 32 Pi -> 6 CO2 + 2 NADH + 32 ATP + 6 H2O
• B1 Glucose + 4 NAD+ + 4 ADP + 4 Pi -> 2 Pyruvate + 4 NADH + 4 H+ + 4 ATP + 2 H2O
• C1 Glucose + 2 FAD + 2 ADP + 2 Pi -> 2 Lactate + 2 FADH2 + 2 ATP
• D1 Glucose + 2 NAD+ + 2 ADP + 2 Pi -> 2 Pyruvate + 2 NADH + 2 H+ + 2 ATP + 2 H2O

Using modern biochemical stoichiometry with mechanistic P/O ratios (2.5 ATP produced per matrix NADH oxidized and 1.5 ATP per FADH2 oxidized), what is the total theoretical net yield of ATP synthesized from the complete aerobic oxidation of one mole of glucose in a cell utilizing the malate-aspartate shuttle?

• A38 ATP
• B32 ATP
• C30 ATP
• D26 ATP

In the mitochondrial electron transport chain, how does the metabolic poison cyanide (CN-) inhibit cellular respiration and what is its immediate effect on mitochondrial oxygen consumption?

• ACyanide uncouples the inner membrane by acting as a protonophore, stimulating maximum oxy…
• BCyanide competitively inhibits succinate dehydrogenase (Complex II), shifting electrons d…
• CCyanide binds with high affinity at cytochrome c oxidase (Complex IV), blocking electron…
• DCyanide blocks the F0 subunit of ATP synthase, allowing electron transport and oxygen red…

During the light-dependent reactions of oxygenic photosynthesis in higher plants, what is the immediate biochemical source of the molecular oxygen (O2) released into the atmosphere?

• ADecarboxylation of 3-phosphoglycerate during the reduction phase of the Calvin cycle
• BSplitting of carbon dioxide by RuBisCO in the chloroplast stroma
• COxidation of plastoquinone by the cytochrome b6f complex
• DPhotolysis of water at the oxygen-evolving manganese cluster of Photosystem II

In the stroma of chloroplasts, the carboxylase activity of RuBisCO catalyzes the initial step of carbon fixation in C3 plants. Which substrate does RuBisCO carboxylate, and what immediate stable product is formed?

• APhosphoenolpyruvate (PEP) is carboxylated to yield oxaloacetate
• BRibulose-1,5-bisphosphate (RuBP) is carboxylated to yield two molecules of 3-phosphoglyce…
• CGlyceraldehyde-3-phosphate (G3P) is carboxylated to yield glucose-6-phosphate
• DRibulose-5-phosphate is carboxylated to yield one molecule of citrate

For the net synthesis and export of exactly one mole of a six-carbon hexose (such as glucose) via the Calvin-Benson cycle in C3 plants, what are the precise stoichiometric requirements for carbon dioxide (CO2), ATP, and NADPH?

• A3 CO2, 9 ATP, and 6 NADPH
• B6 CO2, 12 ATP, and 12 NADPH
• C6 CO2, 18 ATP, and 12 NADPH
• D1 CO2, 3 ATP, and 2 NADPH

C4 crops (such as maize and sorghum) show significantly higher water-use and photosynthetic efficiency in hot, arid agricultural regions compared to C3 crops (such as wheat). What anatomical and biochemical adaptation is primarily responsible for minimizing photorespiration in C4 plants?

• ATemporal separation where stomata open only at night to fix CO2 into malate stored in the…
• BComplete replacement of RuBisCO with nitrogenase in leaf vascular parenchyma
• CElimination of the light-dependent reactions to prevent water splitting and oxygen accumu…
• DSpatial separation of initial CO2 fixation by PEP carboxylase in mesophyll cells from the…

According to the cohesion-tension theory, what physical mechanism primarily drives the continuous long-distance upward transport of water in the xylem vessels of tall vascular plants?

• APositive root hydrostatic pressure pushing xylem sap upward via continuous active ion pum…
• BNegative hydrostatic pressure (tension) generated by transpiration pull in leaf mesophyll…
• CCapillary action alone pulling water upward due to adhesive forces along dead tracheid wa…
• DPeristaltic muscular contractions of vascular bundle sheath cells bordering the xylem

A fully characterized plant parenchymal cell has an internal solute potential (Psi_s) of -0.80 MPa and a turgor pressure potential (Psi_p) of +0.35 MPa. The cell is submerged in an open beaker containing an aqueous sucrose solution with a solute potential (Psi_s) of -0.65 MPa. What is the total water potential of the cell, and in which direction will net water movement occur?

• ACell Psi = -1.15 MPa; net water moves INTO the cell from the sucrose solution
• BCell Psi = +0.45 MPa; the cell is in dynamic equilibrium and no net water movement occurs
• CCell Psi = -0.45 MPa; net water moves OUT of the cell into the sucrose solution
• DCell Psi = -0.45 MPa; net water moves INTO the cell from the sucrose solution

Phloem translocation in vascular plants moves photoassimilates from photosynthetic source leaves to growing sink organs according to the pressure-flow hypothesis. What creates the hydrostatic pressure gradient driving this bulk flow?

• AActive pumping of potassium ions out of the sieve tube elements at the source creates an…
• BTranspirational pull in the xylem creates a vacuum that pulls phloem sap simultaneously t…
• CContinuous gravity-assisted drainage of dense sap through open sieve plates from upper sh…
• DActive loading of sucrose at the source draws water osmotically from the xylem, raising t…

When an oat or wheat coleoptile is illuminated with unilateral blue light, it bends phototropically toward the light source. What cellular mechanism mediates this directional growth response according to the Cholodny-Went model?

• AAuxin is selectively degraded on the shaded side by light-activated oxidases, preventing…
• BPhototropin activation stimulates lateral translocation of auxin (IAA) to the shaded side…
• CEthylene gas accumulates on the illuminated side, causing hyper-elongation of cells facin…
• DGibberellins are inactivated on the shaded side, inducing localized cell division and sto…

In the mammalian kidney nephron, the loop of Henle establishes a high corticomedullary osmotic gradient through a countercurrent multiplier mechanism. What distinct transport characteristics of the descending and ascending limbs enable this gradient?

• AThe descending limb actively pumps out NaCl and is impermeable to water; the ascending li…
• BBoth limbs are freely permeable to water, and urea secretion in the proximal tubule creat…
• CThe descending limb is highly permeable to water and impermeable to NaCl; the thick ascen…
• DActive transport of glucose and amino acids in the loop of Henle creates an osmotic pull…

In a veterinary clinical physiology evaluation, glomerular filtration rate (GFR) is measured in a sheep using inulin clearance. The sheep has a steady plasma inulin concentration (P) of 0.50 mg/mL, a urine inulin concentration (U) of 30.0 mg/mL, and a timed urine flow rate (V) of 2.0 mL/min. What is the calculated glomerular filtration rate (GFR)?

• A120 mL/min
• B60 mL/min
• C7.5 mL/min
• D300 mL/min

In homeostatic regulation of blood glucose in ruminants and monogastric animals, how do pancreatic endocrine secretions coordinate hepatic carbohydrate metabolism during fasting (hypoglycemia)?

• ABeta-cells secrete insulin, activating glycogen synthase and inhibiting glucose-6-phospha…
• BDelta-cells secrete somatostatin, directly stimulating hepatic glycolysis and peripheral…
• CAcinar cells secrete secretin, stimulating hepatic conversion of lactate into triglycerid…
• DAlpha-cells secrete glucagon, activating glycogen phosphorylase and gluconeogenesis via c…

In classic Mendelian genetics, two pea plants heterozygous for a single gene controlling seed texture (Rr, where round R is completely dominant to wrinkled r) are self-fertilized. What phenotypic and genotypic ratios are expected among their progeny?

• APhenotypic ratio of 3 round : 1 wrinkled; genotypic ratio of 1 RR : 2 Rr : 1 rr
• BPhenotypic ratio of 1 round : 2 intermediate : 1 wrinkled; genotypic ratio of 1 RR : 2 Rr…
• CPhenotypic ratio of 9 round : 3 wrinkled; genotypic ratio of 3 RR : 1 rr
• DPhenotypic ratio of 1 round : 1 wrinkled; genotypic ratio of 1 Rr : 1 rr

In an agronomic breeding experiment with tomatoes, two independently assorting autosomal genes govern fruit color (R = red, dominant; r = yellow, recessive) and plant height (T = tall, dominant; t = dwarf, recessive). If two dihybrid plants (RrTt) are crossed, what is the probability of producing an offspring that is dwarf with yellow fruit?

• A1/16 (6.25%)
• B3/16 (18.75%)
• C9/16 (56.25%)
• D1/4 (25.00%)

In maize breeding, two linked seed genes, A (colored vs colorless) and B (starchy vs waxy), are located on the same chromosome. A dihybrid female plant (configuration AB/ab) is testcrossed with a double recessive male (ab/ab). The testcross yields 1,000 progeny with the following phenotypes: 420 Colored-Starchy, 380 Colorless-Waxy, 105 Colored-Waxy, and 95 Colorless-Starchy. What is the recombination frequency between these two loci and the corresponding genetic map distance?

• A20.0% recombination frequency, corresponding to 20.0 centimorgans (cM)
• B10.0% recombination frequency, corresponding to 10.0 centimorgans (cM)
• C40.0% recombination frequency, corresponding to 40.0 centimorgans (cM)
• D50.0% recombination frequency, corresponding to unlinked assortment

In horses, an X-linked recessive gene variant causes severe combined immunodeficiency (SCID) when expressed. If a phenotypically normal stallion (X^A Y) is mated with a phenotypically normal mare who is a confirmed carrier (X^A X^a), what is the probability that a male foal (colt) born from this mating will be affected by the disorder?

• A50%
• B25%
• C100%
• D0%

The Hardy-Weinberg principle states that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. Which set of conditions is necessary for a population to remain in Hardy-Weinberg equilibrium?

• AInfinitely large population, random mating (panmixia), no mutation, no migration (gene fl…
• BSmall population size, assortative mating, high mutation rate, and directional natural se…
• CIntense sexual selection, high immigration rate, and dominant lethal mutations
• DFrequent genetic drift, reproductive isolation of subpopulations, and differential reprod…

In an indigenous Moroccan Sardi sheep flock, an autosomal recessive trait affecting wool pigmentation occurs in 4% of newborn lambs (phenotypic frequency of recessive homozygotes = 0.04). Assuming the flock is in Hardy-Weinberg equilibrium with two alleles (dominant W and recessive w), what is the estimated carrier (heterozygote) frequency in this flock?

• A16%
• B32%
• C64%
• D4%

In small, geographically isolated livestock populations (such as local Moroccan desert goat breeds in oasis habitats), which evolutionary mechanism is most responsible for random fluctuations in allele frequencies and potential loss of heterozygosity?

• ABalancing natural selection favoring heterozygous genotypes across generations
• BHigh rates of gene flow and continuous pollen/gamete immigration from adjacent valleys
• CGenetic drift due to random sampling errors across generations in small breeding cohorts
• DDirectional sexual selection selecting exclusively for maximum body mass

Biological nitrogen fixation (BNF) in the root nodules of leguminous forage crops (such as alfalfa and faba beans) is an essential driver of agricultural sustainability. Which statement correctly identifies the responsible symbiont and the biochemical reaction catalyzed?

• AMycorrhizal fungi oxidize nitrate (NO3-) into nitrite (NO2-) using nitrate reductase
• BNitrifying Nitrosomonas bacteria oxidize ammonia into atmospheric dinitrogen gas (N2)
• CDenitrifying Pseudomonas bacteria reduce atmospheric nitrogen into plant-available organi…
• DSymbiotic Rhizobium bacteria reduce atmospheric dinitrogen (N2) into ammonia (NH3) using…

In the calcareous, alkaline agricultural soils prevalent across central and eastern Morocco (pH 7.8 to 8.5), applied phosphorus fertilizers frequently suffer from rapid fixation. What chemical mechanism causes this phosphorus immobilization?

• ASoluble orthophosphates react with aluminum and iron oxyhydroxides to form insoluble vari…
• BSoluble orthophosphates (H2PO4-) react with abundant calcium ions (Ca2+) and calcium carb…
• CPhosphates are volatilized into phosphine gas (PH3) by alkaline soil urease enzymes
• DFree orthophosphates are rapidly consumed by methanogenic archaea and transformed into el…

In a semi-arid Moroccan rangeland ecosystem, primary producers generate a net primary productivity (NPP) of 80,000 kJ/(m^2 * year). Assuming a constant Lindeman ecological trophic efficiency of 10% between consecutive trophic levels, what is the annual energy available per square meter to tertiary consumers (trophic level 4)?

• A8,000 kJ/(m^2 * year)
• B800 kJ/(m^2 * year)
• C80 kJ/(m^2 * year)
• D8 kJ/(m^2 * year)

What is the value of the mathematical limit: lim_{x -> 0} (sqrt(x + 4) - 2) / x?

• A1/4
• B1/2
• C0
• DInfinity

What is the value of the trigonometric limit: lim_{x -> 0} (1 - cos(2x)) / x^2?

• A1/2
• B1
• C4
• D2

Evaluate the mathematical limit: lim_{x -> 0} (e^(3x) - 1 - 3x) / x^2?

• A3
• B9/2
• C9
• D3/2

Given the real-valued function f(x) = x^2 * e^x, what is its first derivative f'(x)?

• A2x * e^x
• Bx^2 * e^x
• Cx * (x + 2) * e^x
• D(2x + x^2) * e^(x-1)

What is the Cartesian equation of the tangent line to the curve y = ln(2x - 1) at the point where x = 1?

• Ay = 2x - 2
• By = 2x - 1
• Cy = x - 1
• Dy = 2x + 1

Consider the cubic polynomial function f(x) = x^3 - 6x^2 + 9x + 2 defined on R. What are the coordinates (x, y) of the inflection point of its graph?

• A(1, 6)
• B(2, 4)
• C(3, 2)
• D(0, 2)

An agronomist at an experimental farm in the Gharb plain needs to enclose a rectangular grazing pasture bounded on one side by a straight irrigation canal (requiring no fencing). The farm has exactly 400 meters of fencing available for the remaining three sides. What dimensions maximize the pasture area, and what is the maximum area?

• AWidth 133.3 m, Length 133.3 m; Maximum Area = 17,778 m^2
• BWidth 50 m, Length 300 m; Maximum Area = 15,000 m^2
• CWidth 100 m, Length 200 m; Maximum Area = 20,000 m^2
• DWidth 80 m, Length 240 m; Maximum Area = 19,200 m^2

Compute the value of the definite integral: I = \int_0^2 (3x^2 - 4x + 5) dx?

• A6
• B8
• C12
• D10

Evaluate the definite integral using u-substitution: I = \int_0^1 (2x) / (x^2 + 1) dx?

• Aln(2)
• Bln(3)
• C1/2
• D2 * ln(2)

Evaluate the definite integral using integration by parts: I = \int_0^1 x * e^(2x) dx?

• A(e^2 - 1) / 2
• B(e^2 + 1) / 4
• C(3e^2 - 1) / 4
• De^2 / 2

What is the total area of the finite plane region bounded between the two parabolas y = 2x - x^2 and y = x^2?

• A1/2
• B2/3
• C1/3
• D1

What is the real solution set of the logarithmic equation: ln(x) + ln(x - 2) = ln(3)?

• A{-1, 3}
• B{-1}
• C{3, 5}
• D{3}

Determine the equation of the slant (oblique) asymptote of the rational function f(x) = (2x^2 + 5x - 3) / (x + 2) as x approaches +/- infinity?

• Ay = 2x + 1
• By = 2x - 1
• Cy = 2x + 5
• Dy = x + 2

An agronomist models the population growth of an aphid infestation in a greenhouse by the differential equation dN/dt = 0.05 * N, where t is measured in days. Given an initial population N(0) = 400 aphids, what is the predicted population after exactly 40 days? (Take e^2 approximately equal to 7.39).

• A1,200 aphids
• B2,956 aphids
• C1,600 aphids
• D5,912 aphids

Solve the first-order linear differential equation y' + 2y = 6 subject to the initial condition y(0) = 5?

• Ay(x) = 3 + 2 * e^(2x)
• By(x) = 6 - e^(-2x)
• Cy(x) = 3 + 2 * e^(-2x)
• Dy(x) = 5 * e^(-2x) + 3

An agronomist needs to select 3 distinct soil sampling plots out of 8 available test plots to evaluate nitrogen mineralization. How many different subsets of 3 plots can be chosen?

• A336
• B24
• C120
• D56

An agricultural laboratory container holds 10 seed packets: 6 contain certified durum wheat and 4 contain common barley. If an agronomist draws 2 packets at random without replacement, what is the probability that both packets contain certified durum wheat?

• A1/3
• B9/25
• C3/5
• D1/2

In veterinary epidemiology, a bovine herd has a bovine viral diarrhea (BVD) true prevalence of 2% (P(D) = 0.02). A rapid diagnostic antigen test has a sensitivity of 95% (true positive rate) and a specificity of 90% (true negative rate). If a randomly selected calf tests positive, what is the posterior probability that the calf actually has the disease (Positive Predictive Value, PPV)?

• A95.0%
• B16.2%
• C50.0%
• D85.5%