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Algerian BEM - independent subject foundations study materials
Algerian BEM - independent subject foundations study resources

Algerian BEM - independent subject foundations practice questions

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Question 1Lower-secondary number, algebra, geometry and data

Using the Euclidean algorithm (successive division), what is the greatest common divisor (PGCD) of 494 and 143?

  1. 11
  2. 13 Correct answer.
  3. 26
  4. 1

Explanation

Applying the Euclidean algorithm: 494 = 143 × 3 + 65, then 143 = 65 × 2 + 13, and finally 65 = 13 × 5 + 0. The last non-zero remainder in successive divisions is 13, so PGCD(494, 143) = 13.

Question 2Lower-secondary number, algebra, geometry and data

Using the result PGCD(494, 143) = 13, which of the following is the irreducible form of the fraction 494 / 143?

  1. 19 / 7
  2. 33 / 11
  3. 38 / 11 Correct answer.
  4. 42 / 13

Explanation

To make a fraction irreducible, divide both numerator and denominator by their greatest common divisor: 494 ÷ 13 = 38, and 143 ÷ 13 = 11. Since 38 and 11 share no common factors other than 1, the irreducible fraction is 38 / 11.

Question 3Lower-secondary number, algebra, geometry and data

A florist has 378 red roses and 270 white roses. She wants to assemble the maximum number of identical bouquets without leaving any roses over. How many bouquets can she make, and how many flowers of each color will each bouquet contain?

  1. 54 bouquets, each containing 7 red roses and 5 white roses Correct answer.
  2. 27 bouquets, each containing 14 red roses and 10 white roses
  3. 18 bouquets, each containing 21 red roses and 15 white roses
  4. 36 bouquets, each containing 10 red roses and 8 white roses

Explanation

The maximum number of identical bouquets corresponds to PGCD(378, 270). By the Euclidean algorithm: 378 = 270 × 1 + 108; 270 = 108 × 2 + 54; 108 = 54 × 2 + 0. Thus PGCD(378, 270) = 54 bouquets. Dividing each total by 54 yields 378 ÷ 54 = 7 red roses and 270 ÷ 54 = 5 white roses per bouquet.

Question 4Lower-secondary number, algebra, geometry and data

Simplify the expression A = √75 - 2√27 + √12 into the form a√3, where a is an integer.

  1. 3√3
  2. 2√3
  3. 5√3
  4. √3 Correct answer.

Explanation

Decompose each radicand: √75 = √(25 × 3) = 5√3; 2√27 = 2√(9 × 3) = 2 × 3√3 = 6√3; √12 = √(4 × 3) = 2√3. Combining like terms gives A = 5√3 - 6√3 + 2√3 = (5 - 6 + 2)√3 = 1√3 = √3.

Question 5Lower-secondary number, algebra, geometry and data

Which of the following expressions represents 4 / (√7 - √3) rewritten with a rational denominator?

  1. 2(√7 + √3)
  2. √7 + √3 Correct answer.
  3. √7 - √3
  4. 4(√7 - √3)

Explanation

Multiply both numerator and denominator by the conjugate (√7 + √3): [4(√7 + √3)] / [(√7 - √3)(√7 + √3)]. The denominator simplifies using the identity (a - b)(a + b) = a² - b² to (√7)² - (√3)² = 7 - 3 = 4. The 4 in the numerator and denominator cancel out, leaving √7 + √3.

Question 6Lower-secondary number, algebra, geometry and data

A rectangle has length L = 3 + √7 cm and width W = 3 - √7 cm. What is the area of this rectangle?

  1. 16 cm²
  2. 9 cm²
  3. 2 cm² Correct answer.
  4. 4√7 cm²

Explanation

The area of a rectangle is length multiplied by width: Area = (3 + √7)(3 - √7). Using the remarkable identity (a + b)(a - b) = a² - b², we obtain 3² - (√7)² = 9 - 7 = 2 cm².

Question 7Lower-secondary number, algebra, geometry and data

A square has side length (2x - 3) units. Which expression gives its area after expansion?

  1. 4x² - 12x + 9 Correct answer.
  2. 4x² - 9
  3. 4x² - 6x + 9
  4. 2x² - 12x + 9

Explanation

Applying the identity (a - b)² = a² - 2ab + b²: here a = 2x and b = 3, so (2x)² - 2(2x)(3) + 3² = 4x² - 12x + 9.

Question 8Lower-secondary number, algebra, geometry and data

Factor the expression A(x) = (3x + 2)² - (3x + 2)(x - 5) completely into a product of first-degree linear factors.

  1. (3x + 2)(4x - 3)
  2. (3x + 2)(2x - 3)
  3. (3x + 2)(2x + 3)
  4. (3x + 2)(2x + 7) Correct answer.

Explanation

Factor out the common binomial term (3x + 2): A(x) = (3x + 2)[(3x + 2) - (x - 5)]. Distributing the negative sign inside the brackets gives 3x + 2 - x + 5 = 2x + 7. Thus, A(x) = (3x + 2)(2x + 7).

Question 9Lower-secondary number, algebra, geometry and data

What are all real solutions to the equation (3x - 1)(2x + 5) = 0?

  1. x = -1/3 or x = 5/2
  2. x = 1/3 or x = -5/2 Correct answer.
  3. x = 3 or x = -2/5
  4. x = -3 or x = 5/2

Explanation

A product of factors equals zero if and only if at least one factor is zero: 3x - 1 = 0 yields x = 1/3, and 2x + 5 = 0 yields 2x = -5, so x = -5/2.

Question 10Lower-secondary number, algebra, geometry and data

Which set of real numbers satisfies the linear inequality 5x - 4 ≤ 2x + 8?

  1. x ≥ 4
  2. x < 4
  3. x ≤ 4 Correct answer.
  4. x ≤ 12

Explanation

Subtract 2x from both sides: 3x - 4 ≤ 8. Add 4 to both sides: 3x ≤ 12. Dividing by positive 3 preserves the inequality direction: x ≤ 4. In interval notation, the solution set is (-∞, 4].

Question 11Lower-secondary number, algebra, geometry and data

Solve the system of linear equations: x + y = 35 2x + 4y = 110

  1. (x = 15, y = 20) Correct answer.
  2. (x = 20, y = 15)
  3. (x = 10, y = 25)
  4. (x = 25, y = 10)

Explanation

Divide the second equation by 2: x + 2y = 55. Subtract the first equation (x + y = 35) from this: (x + 2y) - (x + y) = 55 - 35, which yields y = 20. Substitute y = 20 into x + y = 35 to find x = 15. The unique solution is (15, 20).

Question 12Lower-secondary number, algebra, geometry and data

In a triangle ABC, the side lengths are AB = 4.8 cm, AC = 6.4 cm, and BC = 8.0 cm. Which geometric conclusion is valid?

  1. Triangle ABC is obtuse at B because BC > AC + AB
  2. Triangle ABC is right-angled at C with hypotenuse [AB]
  3. Triangle ABC is isosceles with apex A
  4. Triangle ABC is right-angled at A with hypotenuse [BC] Correct answer.

Explanation

Calculate the squares of the side lengths: AB² = 4.8² = 23.04; AC² = 6.4² = 40.96; and BC² = 8.0² = 64.00. Notice that AB² + AC² = 23.04 + 40.96 = 64.00 = BC². By the converse of Pythagoras' theorem, triangle ABC is right-angled at vertex A, and segment [BC] is its hypotenuse.

Question 13Lower-secondary number, algebra, geometry and data

In triangle ABC, point M lies on segment [AB] and point N lies on segment [AC] such that (MN) is parallel to (BC). Given AM = 3 cm, AB = 9 cm, and BC = 15 cm, what is the length of segment [MN]?

  1. 3 cm
  2. 5 cm Correct answer.
  3. 6 cm
  4. 7.5 cm

Explanation

By Thales' theorem in triangle ABC with (MN) ∥ (BC), the side ratios are equal: AM / AB = AN / AC = MN / BC. Substituting the given values gives 3 / 9 = MN / 15. Since 3 / 9 = 1 / 3, we have MN = 15 × (1 / 3) = 5 cm.

Question 14Lower-secondary number, algebra, geometry and data

Points A, M, B and points A, N, C are aligned in the same order on two intersecting lines. If AM = 4 cm, AB = 10 cm, AN = 6 cm, and AC = 15 cm, are lines (MN) and (BC) parallel?

  1. No, because 4/10 is not equal to 6/15
  2. No, because the lines are perpendicular
  3. Yes, because AM/AB = AN/AC = 0.4 and points are aligned in the same order Correct answer.
  4. Yes, because AM × AB = AN × AC

Explanation

Calculate the ratios of corresponding segments: AM / AB = 4 / 10 = 0.4, and AN / AC = 6 / 15 = 2 / 5 = 0.4. Since AM / AB = AN / AC and the points A, M, B and A, N, C are aligned in the exact same relative order, the converse of Thales' theorem proves that lines (MN) and (BC) are parallel.

Question 15Lower-secondary number, algebra, geometry and data

In triangle DEF right-angled at E, the adjacent side DE = 6 cm and the hypotenuse DF = 10 cm. What is the value of cos(ED̂F)?

  1. 0.6 Correct answer.
  2. 0.8
  3. 0.75
  4. 1.25

Explanation

In a right-angled triangle, the cosine of an acute angle is defined as the length of the adjacent side divided by the hypotenuse: cos(ED̂F) = DE / DF = 6 / 10 = 0.6.

Question 16Lower-secondary number, algebra, geometry and data

Let α be an acute angle such that sin(α) = 0.8. Using the fundamental trigonometric identities, what is tan(α)?

  1. 0.6
  2. 0.75
  3. 1.0
  4. 4/3 Correct answer.

Explanation

Using cos²(α) + sin²(α) = 1, we get cos²(α) = 1 - 0.8² = 1 - 0.64 = 0.36. Since α is acute, cos(α) = √0.36 = 0.6. Then tan(α) = sin(α) / cos(α) = 0.8 / 0.6 = 8 / 6 = 4/3 (approximately 1.33).

Question 17Lower-secondary number, algebra, geometry and data

According to Chasles' relation (relation de Chasles) for vector addition, which vector is equivalent to the sum AB + BC?

  1. BA
  2. AC Correct answer.
  3. CA
  4. 0

Explanation

Chasles' relation states that for any three points A, B, and C in the plane, vector AB + vector BC = vector AC. The terminal point of the first vector matches the initial point of the second vector.

Question 18Lower-secondary number, algebra, geometry and data

In an orthonormal coordinate plane (O, i, j), given point A(2, -3) and point B(-1, 4), what are the coordinates of vector AB?

  1. (1, 1)
  2. (3, -7)
  3. (-3, 7) Correct answer.
  4. (-2, -12)

Explanation

The coordinates of vector AB are given by (xB - xA, yB - yA). Substituting the coordinates yields x = -1 - 2 = -3, and y = 4 - (-3) = 4 + 3 = 7. Thus, vector AB has coordinates (-3, 7).

Question 19Lower-secondary number, algebra, geometry and data

A linear function f is defined by f(x) = ax. If f(4) = -12, what is the formula of f(x) and the value of f(-3)?

  1. f(x) = -3x and f(-3) = 9 Correct answer.
  2. f(x) = 3x and f(-3) = -9
  3. f(x) = -3x and f(-3) = -9
  4. f(x) = -1/3 x and f(-3) = 1

Explanation

Since f is linear, f(4) = a × 4 = -12, which gives a = -12 / 4 = -3. Therefore, the function formula is f(x) = -3x. Evaluating at x = -3 gives f(-3) = -3 × (-3) = 9.

Question 20Lower-secondary number, algebra, geometry and data

An affine function g(x) = ax + b satisfies g(1) = 5 and g(3) = 11. What is the formula of g(x)?

  1. g(x) = 2x + 3
  2. g(x) = 3x - 2
  3. g(x) = 6x - 1
  4. g(x) = 3x + 2 Correct answer.

Explanation

The rate of change (slope) is a = [g(3) - g(1)] / (3 - 1) = (11 - 5) / 2 = 6 / 2 = 3. Using g(1) = 5: 3(1) + b = 5, which implies b = 5 - 3 = 2. Thus, the formula is g(x) = 3x + 2.

Question 21Mechanics, fields, thermal behavior, waves and modern models

An oscilloscope display shows a sinusoidal alternating voltage. The vertical sensitivity is set to Sv = 5 V/div and the maximum vertical peak reaches Y = 3 divisions from the central zero line. What is the maximum voltage (Umax)?

  1. 5 V
  2. 10 V
  3. 30 V
  4. 15 V Correct answer.

Explanation

The maximum voltage is calculated using the formula Umax = Y × Sv, where Y is the vertical deviation in divisions from the central axis to the peak. Here Umax = 3 div × 5 V/div = 15 V.

Question 22Mechanics, fields, thermal behavior, waves and modern models

A digital multimeter set to AC voltmeter mode measures an effective voltage of Ueff = 230 V across a socket. What is the approximate peak maximum voltage (Umax)?

  1. 325 V Correct answer.
  2. 230 V
  3. 163 V
  4. 460 V

Explanation

For a sinusoidal alternating voltage, the relationship between peak voltage and effective voltage is Umax = Ueff × √2. With Ueff = 230 V and √2 ≈ 1.414, we calculate Umax ≈ 230 × 1.414 ≈ 325.2 V, approximately 325 V.

Question 23Mechanics, fields, thermal behavior, waves and modern models

An oscilloscope displays an AC voltage waveform with a horizontal time-base setting of Sh = 5 ms/div. One complete period corresponds to X = 4 horizontal divisions. What is the frequency (f) of this signal?

  1. 20 Hz
  2. 50 Hz Correct answer.
  3. 100 Hz
  4. 200 Hz

Explanation

The period T is computed as T = X × Sh = 4 div × 5 ms/div = 20 ms = 0.02 s. Frequency f is the reciprocal of the period: f = 1 / T = 1 / 0.02 s = 50 Hz, which is the standard mains frequency in Algeria.

Question 24Mechanics, fields, thermal behavior, waves and modern models

What are the two necessary and sufficient conditions for a rigid solid body subjected to two forces F1 and F2 to remain in static equilibrium?

  1. The forces must have perpendicular directions and identical magnitudes
  2. The forces must act at the same contact point and point in the same direction
  3. The forces must share the same line of action, have opposite directions, and possess equal magnitudes (F1 + F2 = 0) Correct answer.
  4. The forces must have equal magnitudes regardless of their lines of action

Explanation

A solid body subjected to two forces is in static equilibrium if and only if both forces share the exact same line of action (collinear), act in opposite directions, and have equal magnitudes, satisfying the vector condition F1 + F2 = 0.

Question 25Mechanics, fields, thermal behavior, waves and modern models

A solid object is suspended in equilibrium from a spring dynamometer whose stiffness constant is k = 40 N/m. The spring elongates by ΔL = 5 cm. What is the tension force (T) exerted by the spring on the object?

  1. 200 N
  2. 8.0 N
  3. 0.5 N
  4. 2.0 N Correct answer.

Explanation

First convert the elongation to SI units: ΔL = 5 cm = 0.05 m. Using Hooke's law for spring tension: T = k × ΔL = 40 N/m × 0.05 m = 2.0 N.

Question 26Mechanics, fields, thermal behavior, waves and modern models

A solid body is maintained in equilibrium under the action of three non-parallel coplanar forces F1, F2, and F3. Which condition must be met by these forces?

  1. Their lines of action must intersect at a single common point (concurrent) and their vector sum must equal zero (F1 + F2 + F3 = 0) Correct answer.
  2. Their lines of action must be mutually perpendicular and their magnitudes must be equal
  3. Their vector sum must be positive and point toward the center of gravity
  4. Two forces must be parallel while the third is perpendicular to both

Explanation

For a body in equilibrium under three non-parallel coplanar forces, their lines of action must intersect at a single concurrent point, and the vector sum of the three forces must be zero (F1 + F2 + F3 = 0), forming a closed vector polygon.

Question 27Mechanics, fields, thermal behavior, waves and modern models

An astronaut has a mass of m = 70 kg on Earth (where g_earth ≈ 9.8 N/kg). If the astronaut travels to the Moon where the gravitational field strength is g_moon ≈ 1.6 N/kg, what are the astronaut's mass and weight on the Moon?

  1. Mass = 11.4 kg; Weight = 112 N
  2. Mass = 70 kg; Weight = 112 N Correct answer.
  3. Mass = 70 kg; Weight = 686 N
  4. Mass = 112 kg; Weight = 70 N

Explanation

Mass is an intrinsic property representing the amount of matter in a body and remains constant anywhere in the universe (m = 70 kg). Weight is the local gravitational attraction force: P = m × g_moon = 70 kg × 1.6 N/kg = 112 N.

Question 28Mechanics, fields, thermal behavior, waves and modern models

Which statement accurately expresses the physical distinction between mass and weight?

  1. Mass is measured in Newtons using a dynamometer, while weight is measured in kilograms using a balance
  2. Weight is an invariant intrinsic property, while mass varies with altitude and latitude
  3. Mass and weight are identical physical quantities expressed in interchangeable units
  4. Mass is an intrinsic measure of quantity of matter (measured in kg), while weight is the gravitational force exerted by a celestial body (measured in N) Correct answer.

Explanation

Mass (m, in kg) is an intrinsic scalar quantity reflecting the quantity of matter, measured with a two-pan balance and invariant with position. Weight (P, in N) is the vector gravitational pull exerted on that mass, measured with a spring dynamometer and varying with altitude, latitude, and celestial body.

Question 29Mechanics, fields, thermal behavior, waves and modern models

A solid block of volume V = 5 × 10⁻⁴ m³ is completely immersed in pure water (density ρ = 1000 kg/m³, g = 10 N/kg). What is the magnitude of the buoyant force (Archimedes' upthrust, FA) acting on the block?

  1. 0.5 N
  2. 50 N
  3. 5.0 N Correct answer.
  4. 500 N

Explanation

According to Archimedes' principle, the buoyant force equals the weight of the displaced liquid: FA = ρ × V × g = 1000 kg/m³ × (5 × 10⁻⁴ m³) × 10 N/kg = 5.0 N.

Question 30Mechanics, fields, thermal behavior, waves and modern models

A metallic sphere weighs P = 8.5 N in air. When completely immersed in water, a dynamometer records an apparent weight of Papp = 6.0 N. What is the value of the Archimedes upthrust (FA)?

  1. 14.5 N
  2. 2.5 N Correct answer.
  3. 6.0 N
  4. 8.5 N

Explanation

The apparent weight is the real weight minus the buoyant upthrust: Papp = P - FA. Rearranging gives FA = P - Papp = 8.5 N - 6.0 N = 2.5 N.

Question 31Chemical structure, reactions and organic models

What is the stoichiometric balanced equation for the complete combustion of butane gas ($\text{C}_4\text{H}_{10}$) in dioxygen?

  1. $\text{C}_4\text{H}_{10} + 5\text{O}_2 \rightarrow 4\text{CO}_2 + 5\text{H}_2\text{O}$
  2. $2\text{C}_4\text{H}_{10} + 13\text{O}_2 \rightarrow 8\text{CO}_2 + 10\text{H}_2\text{O}$ Correct answer.
  3. $\text{C}_4\text{H}_{10} + 13\text{O}_2 \rightarrow 4\text{CO}_2 + 5\text{H}_2\text{O}$
  4. $2\text{C}_4\text{H}_{10} + 9\text{O}_2 \rightarrow 8\text{CO} + 10\text{H}_2\text{O}$

Explanation

In complete combustion of a hydrocarbon, carbon forms $\text{CO}_2$ and hydrogen forms $\text{H}_2\text{O}$. For butane: 8 carbons produce $8\text{CO}_2$ (16 oxygen atoms) and 20 hydrogens produce $10\text{H}_2\text{O}$ (10 oxygen atoms). Total oxygen atoms needed $= 16 + 10 = 26$, which corresponds to $13\text{O}_2$. Thus, $2\text{C}_4\text{H}_{10} + 13\text{O}_2 \rightarrow 8\text{CO}_2 + 10\text{H}_2\text{O}$.

Question 32Chemical structure, reactions and organic models

Given molar atomic masses $M(\text{H}) = 1\text{ g/mol}$, $M(\text{S}) = 32\text{ g/mol}$, and $M(\text{O}) = 16\text{ g/mol}$, what is the molar mass of sulfuric acid ($\text{H}_2\text{SO}_4$) and how many moles are contained in $19.6\text{ g}$ of pure $\text{H}_2\text{SO}_4$?

  1. $M = 98\text{ g/mol}$ and $n = 5.0\text{ mol}$
  2. $M = 49\text{ g/mol}$ and $n = 0.40\text{ mol}$
  3. $M = 98\text{ g/mol}$ and $n = 0.20\text{ mol}$ Correct answer.
  4. $M = 82\text{ g/mol}$ and $n = 0.24\text{ mol}$

Explanation

Molar mass $M(\text{H}_2\text{SO}_4) = 2(1) + 32 + 4(16) = 2 + 32 + 64 = 98\text{ g/mol}$. Number of moles $n = \frac{m}{M} = \frac{19.6\text{ g}}{98\text{ g/mol}} = 0.20\text{ mol}$.

Question 33Chemical structure, reactions and organic models

An aqueous solution has a $\text{pH} = 3$ at $25^\circ\text{C}$. What happens to its acidity and $\text{pH}$ value when it is diluted by adding pure distilled water?

  1. The acidity increases and the $\text{pH}$ decreases towards 0
  2. The $\text{pH}$ remains strictly unchanged at 3
  3. The $\text{pH}$ instantly jumps to 14
  4. The acidity decreases and the $\text{pH}$ increases towards 7 (without ever exceeding 7) Correct answer.

Explanation

Diluting an acidic solution decreases the concentration of hydronium ions $[\text{H}_3\text{O}^+]$, which reduces its acidity. Consequently, the $\text{pH}$ value rises closer to the neutral $\text{pH}$ of pure water ($7.0$) but can never exceed 7 through pure water dilution alone.

Question 34Chemical structure, reactions and organic models

Which reagent is used in the laboratory to identify chloride ions ($\text{Cl}^-$) in an aqueous solution, and what is the positive visual result?

  1. Barium chloride solution ($\text{BaCl}_2$), which forms a yellow precipitate
  2. Silver nitrate solution ($\text{AgNO}_3$), which forms a white precipitate that blackens under light ($\text{AgCl}$) Correct answer.
  3. Sodium hydroxide solution ($\text{NaOH}$), which forms a blue precipitate
  4. Limewater (eau de chaux), which turns milky

Explanation

Chloride ions ($\text{Cl}^-$) react with silver ions ($\text{Ag}^+$) from silver nitrate ($\text{AgNO}_3$) to form silver chloride ($\text{AgCl}$), a characteristic white curdy precipitate that turns purple/black upon exposure to sunlight.

Question 35Chemical structure, reactions and organic models

In the dry reduction of black copper(II) oxide by carbon powder ($2\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_2$), which substance acts as the reducing agent (réducteur)?

  1. Copper(II) oxide ($\text{CuO}$), because it loses oxygen
  2. Metallic copper ($\text{Cu}$)
  3. Carbon ($\text{C}$), because it gains oxygen and is oxidized to $\text{CO}_2$ Correct answer.
  4. Carbon dioxide ($\text{CO}_2$)

Explanation

A reducing agent (réducteur) is the species that captures oxygen (or donates electrons) and undergoes oxidation. Carbon ($\text{C}$) captures oxygen from $\text{CuO}$ to become $\text{CO}_2$, thereby reducing $\text{CuO}$ to metallic copper.

Question 36Chemical structure, reactions and organic models

During the electrolysis of acidified water in a voltameter, what are the gas volumes collected at the negative electrode (cathode) and positive electrode (anode)?

  1. Cathode: 1 volume of dioxygen ($\text{O}_2$); Anode: 2 volumes of dihydrogen ($\text{H}_2$)
  2. Cathode: 1 volume of chlorine ($\text{Cl}_2$); Anode: 1 volume of dihydrogen ($\text{H}_2$)
  3. Cathode: 2 volumes of carbon monoxide ($\text{CO}$); Anode: 2 volumes of dioxygen ($\text{O}_2$)
  4. Cathode: 2 volumes of dihydrogen ($\text{H}_2$); Anode: 1 volume of dioxygen ($\text{O}_2$) Correct answer.

Explanation

The decomposition of water follows $2\text{H}_2\text{O} \rightarrow 2\text{H}_2 + \text{O}_2$. Dihydrogen gas is released at the cathode (negative electrode) with twice the volume ($2V$) of the dioxygen gas released at the anode (positive electrode, $1V$).

Question 37Biological organization, inheritance, regulation and ecosystems

In the human digestive system, which enzyme present in saliva initiates the chemical breakdown of cooked starch, and what is the resulting intermediate product?

  1. Pepsin, yielding amino acids
  2. Salivary amylase, yielding maltose Correct answer.
  3. Lipase, yielding fatty acids
  4. Maltase, yielding glucose

Explanation

Salivary amylase (ptyalin) in the mouth acts at neutral pH to hydrolyze complex cooked starch molecules into maltose, a disaccharide. Protein and lipid digestion do not occur in the mouth.

Question 38Biological organization, inheritance, regulation and ecosystems

What is the primary enzymatic function of pepsin (protease 1) in the human stomach?

  1. Transforming emulsified lipids into glycerol and fatty acids in an alkaline medium
  2. Synthesizing glycogen from excess circulating glucose molecules
  3. Cleaving dietary proteins into polypeptide chains in an acidic hydrochloric acid environment Correct answer.
  4. Breaking down cellulose into simple monosaccharides

Explanation

Pepsin is secreted by gastric chief cells as inactive pepsinogen and activated by stomach hydrochloric acid (pH 1.5–2). It initiates protein digestion by breaking long peptide bonds to produce shorter polypeptide chains.

Question 39Biological organization, inheritance, regulation and ecosystems

Bile is synthesized by the liver and stored in the gallbladder. What is its specific physiological role during digestion?

  1. It emulsifies large lipid globules into microscopic droplets, greatly expanding the surface area for pancreatic lipase Correct answer.
  2. It is an enzyme that directly hydrolyzes polysaccharides into glucose
  3. It provides strong acidity to kill bacteria in the duodenum
  4. It absorbs glucose and amino acids directly across the stomach lining

Explanation

Bile contains bile salts rather than digestive enzymes. Its crucial role is mechanical emulsification: it disperses large fat droplets into tiny micelles, dramatically increasing the surface area available for pancreatic lipase to digest lipids efficiently.

Question 40Biological organization, inheritance, regulation and ecosystems

At the conclusion of the complete digestive process in the small intestine, what are the final absorbable nutrients (nutriments) derived from dietary proteins?

  1. Polypeptides and starches
  2. Amino acids Correct answer.
  3. Fatty acids and glycerol
  4. Glucose and fructose

Explanation

Dietary proteins undergo sequential hydrolysis by gastric pepsin, pancreatic trypsin, and intestinal peptidases until they are broken down into individual amino acids, which are small enough to be absorbed across the intestinal epithelium.

Question 41Biological organization, inheritance, regulation and ecosystems

Which structural features of the small intestine maximize the efficiency of nutrient absorption across the intestinal wall?

  1. A thick muscular wall with minimal vascularization and a smooth internal surface
  2. An impermeable keratin layer that prevents the passage of polar molecules
  3. A massive internal surface area created by circular folds, villi, and microvilli, combined with a monolayer epithelium and rich capillary networks Correct answer.
  4. A series of non-vascularized cartilaginous rings that slow peristalsis

Explanation

Circular folds, intestinal villi, and epithelial microvilli greatly enlarge the absorptive surface. A thin epithelial barrier and dense blood and lymphatic capillary networks then support efficient nutrient transport. Exact surface-area estimates depend on the measurement method and are unnecessary here.

Question 42Biological organization, inheritance, regulation and ecosystems

Following intestinal absorption, which nutrients travel predominantly via the lymphatic pathway (chyliferous vessels) rather than directly into the bloodstream?

  1. Glucose and amino acids
  2. Water-soluble vitamins B and C
  3. Mineral salts and simple sugars
  4. Long-chain lipid products that enter intestinal cells and are repackaged into triglyceride-rich chylomicrons Correct answer.

Explanation

Long-chain fatty acids and monoacylglycerols enter intestinal cells, where they are used to rebuild triglycerides and package them into chylomicrons. Chylomicrons enter lacteals, travel through lymph, and later reach the venous circulation.

Question 43Biological organization, inheritance, regulation and ecosystems

Nutrients absorbed through the blood pathway (such as glucose and amino acids) travel through which blood vessel directly from the small intestine to the liver?

  1. The hepatic portal vein (veine porte hépatique) Correct answer.
  2. The pulmonary artery
  3. The inferior vena cava
  4. The renal vein

Explanation

Blood capillaries from the intestinal villi converge into the hepatic portal vein, which carries nutrient-rich blood straight to the liver. This allows the liver to filter, process, and regulate circulating concentrations of glucose and amino acids prior to systemic circulation.

Question 44Biological organization, inheritance, regulation and ecosystems

How does the liver maintain a constant blood glucose concentration (glycemia around 1 g/L) following a carbohydrate-rich meal?

  1. It converts all circulating glucose into urea and excretes it via the kidneys
  2. It takes up excess blood glucose and polymerizes it into glycogen (glycogenesis) Correct answer.
  3. It releases digestive enzymes into the bloodstream to break down glucose into lactic acid
  4. It prevents glucose absorption in the small intestine

Explanation

Under the influence of insulin, liver hepatocytes take up excess glucose from the hepatic portal blood and store it as glycogen through glycogenesis. Between meals or during fasting, the liver hydrolyzes glycogen back into glucose (glycogenolysis) to keep blood glucose stable near 1 g/L.

Question 45Biological organization, inheritance, regulation and ecosystems

In red blood cells, what protein binds reversibly to oxygen at the pulmonary alveoli to facilitate systemic oxygen transport, imparting a bright red color to oxygenated blood?

  1. Fibrinogen
  2. Albumin
  3. Hemoglobin Correct answer.
  4. Immunoglobulin

Explanation

Hemoglobin (Hb) is an iron-rich chromoprotein packed inside erythrocytes. In the pulmonary capillaries where oxygen partial pressure is high, it binds oxygen to form oxyhemoglobin: Hb + 4O2 ⇌ Hb(O2)4, which appears bright red.

Question 46Biological organization, inheritance, regulation and ecosystems

What is the primary physiological form in which carbon dioxide (CO2) produced by tissue metabolism is transported through the bloodstream to the lungs?

  1. As dissolved bicarbonate ions (HCO3⁻) in blood plasma Correct answer.
  2. Exclusively as carbon monoxide gas bubbles
  3. Stored inside white blood cells as insoluble calcium carbonate
  4. Bound tightly to platelet membranes

Explanation

Approximately 70% of metabolic carbon dioxide is converted inside erythrocytes by carbonic anhydrase into bicarbonate ions (HCO3⁻), which diffuse into plasma. About 20% binds to hemoglobin as carbaminohemoglobin, and roughly 7–10% dissolves directly as CO2 gas in plasma.

Question 47Biological organization, inheritance, regulation and ecosystems

Which balanced equation correctly represents aerobic cellular respiration in human body cells, supplying usable energy (ATP) for vital functions?

  1. 6CO2 + 6H2O + Light → C6H12O6 + 6O2
  2. C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP) Correct answer.
  3. C6H12O6 → 2C2H5OH + 2CO2 + Energy
  4. 2H2 + O2 → 2H2O + Heat

Explanation

Cellular respiration is an oxidative catabolic process in which cells consume glucose and oxygen to generate carbon dioxide, water, and ATP energy: C6H12O6 + 6O2 → 6CO2 + 6H2O + usable energy.

Question 48Biological organization, inheritance, regulation and ecosystems

What is the primary physiological function of a sensory receptor (such as a tactile corpuscle in the skin) when subjected to an effective stimulus?

  1. To directly contract surrounding skeletal muscles
  2. To secrete digestive enzymes into local tissue fluids
  3. To transform the external physical or chemical stimulus into an electrical sensory nerve impulse Correct answer.
  4. To produce specific neutralizing antibodies against mechanical pressure

Explanation

Sensory receptors act as transducers: when exposed to a specific adequate stimulus of sufficient threshold intensity, they convert that energy into an action potential-a sensory (afferent) electrical nerve impulse propagated along sensory nerve fibers toward the central nervous system.

Question 49Biological organization, inheritance, regulation and ecosystems

When a person accidentally touches a scorching hot stove, their hand withdraws instantaneously before perceiving pain. What is the precise anatomical pathway of this spinal reflex arc (arc réflexe médullaire)?

  1. Effector muscle → Motor nerve → Brain cortex → Sensory nerve → Skin
  2. Sensory receptor → Motor nerve → Spinal cord → Sensory nerve → Muscle
  3. Brain stem → Optic nerve → Spinal cord → Sensory receptor → Hand
  4. Sensory receptor (skin) → Sensory/afferent nerve → Spinal cord (nerve center) → Motor/efferent nerve → Effector (arm muscle) Correct answer.

Explanation

In an innate spinal reflex, the pathway follows: sensory receptor in the skin detects heat → afferent sensory nerve carries the impulse via the posterior root into the spinal cord (reflex center) → interneuron relays the signal → efferent motor nerve leaves via the anterior root → effector skeletal muscle contracts to withdraw the hand.

Question 50Biological organization, inheritance, regulation and ecosystems

In contrast to an involuntary spinal reflex, where does the nerve impulse for a voluntary motor movement (such as deciding to write with a pen) originate?

  1. In the motor area of the cerebral cortex (aire motrice du cortex cérébral) Correct answer.
  2. In the sensory corpuscles of the finger skin
  3. In the gray matter of the spinal cord exclusively
  4. Inside the tendons of the forearm

Explanation

Voluntary movements originate consciously in the primary motor cortex of the brain (frontal lobe). From there, pyramidal motor neurons transmit descending impulses down the spinal cord to peripheral motor nerves, commanding skeletal muscle contraction.