Standard Achievement Admission Test, Scientific (Tahsili, SAAT): free practice test

Past exam question Unit: Biology and Ecology

1. AAn increase in algae

   Algae do not prey on mussels or reduce their numbers.

2. BA fall in the number of predators of mussels

   Fewer predators means fewer mussels eaten, so their numbers would rise.

3. CMore food available for the mussels

   More food helps mussels grow and reproduce, so their numbers would rise.

4. DAn increase in the number of predatory sea stars ✓ Correct answer

   When predators become more numerous, more prey are eaten and the mussel population falls.

Reference: Saudi secondary curriculum (track system), Biology: ecology: relationships among organisms

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Past exam question Unit: Biology and Ecology

1. A25% ✓ Correct answer

   Correct: daughter X^{C}X^{c} × healthy father X^{C}Y gives four equal outcomes, one of which is an affected son X^{c}Y, i.e. 25%.

2. B50%

   50% is the proportion among sons only, not all children.

3. C0%

   The daughter is a carrier, so the trait can appear in her children.

4. D100%

   Not all children can be affected because the father is healthy.

Reference: Saudi secondary curriculum (track system), Biology: Sex-linked inheritance

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Past exam question Unit: Biology and Ecology

1. AViroid

   A viroid is a small circular RNA molecule, not a protein.

2. BPlasmid

   A plasmid is a small circular DNA molecule in bacteria.

3. CBacteriophage

   A bacteriophage has genetic material inside a protein coat; it is not protein alone.

4. DPrion ✓ Correct answer

   A prion is an infectious protein formed by misfolding of a normal protein, and it causes neurological diseases such as mad cow disease.

Reference: Saudi secondary curriculum (track system), Biology: classification and diversity of living things

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Past exam question Unit: Chemistry

1. A\frac{1}{4}

   This ratio would appear if energy were proportional to \frac{1}{n} rather than \frac{1}{n^2}.

2. B4

   The ratio 4 inverts numerator and denominator; the first level has the largest magnitude of energy.

3. C\frac{1}{16} ✓ Correct answer

   \frac{E_4}{E_1}=\frac{1/4^2}{1/1^2}=\frac{1}{16}.

4. D2

   The ratio 2 does not follow from E\propto-\frac{1}{n^2}; it comes from simply dividing the level numbers.

Reference: Saudi secondary curriculum (track system), Chemistry: Atomic structure: energy levels of the hydrogen atom

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Past exam question Unit: Chemistry

1. A1.0\,\text{mol}

   This value would correspond to a mass of only 44\,\text{g}.

2. B2.0\,\text{mol}

   This comes from dividing by 33, which is not the molar mass.

3. C1.5\,\text{mol} ✓ Correct answer

   The molar mass is 12+2\times16=44\,\text{g/mol}, so the moles are 66\div44=1.5\,\text{mol}.

4. D3.0\,\text{mol}

   This comes from dividing by 22, which is half the molar mass.

Reference: Saudi secondary curriculum (track system), Chemistry: stoichiometry: the mole and molar mass

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Past exam question Unit: Chemistry

1. A+2

   This fits \text{Fe(OH)}_2, which has two hydroxide groups.

2. B+1

   This fits only a single hydroxide group.

3. C+3 ✓ Correct answer

   Each \text{OH}^- carries -1 and there are three, so iron is +3.

4. D-3

   Iron is a metal that loses electrons, so its oxidation number cannot be negative.

Reference: Saudi secondary curriculum (track system), Chemistry: redox: oxidation numbers

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Past exam question Unit: Physics

1. A0.4\,\text{N}

   This value comes from using \omega instead of \omega^2 in the formula; the angular speed must be squared.

2. B1.6\,\text{N}

   This value is twice the correct result, so it is larger than the formula gives for the stated data.

3. C3.2\,\text{N}

   This value is four times the correct result and comes from an error in finding \omega or from dropping a factor in the formula.

4. D0.8\,\text{N} ✓ Correct answer

   The centripetal force is F_c = m\dfrac{4\pi^2 r}{T^2}; with \omega = 2\pi/T = 2\,\text{rad/s} this gives F_c = 0.2\times 4\times 1 = 0.8\,\text{N}.

Reference: Saudi secondary curriculum (track system), Physics: Circular motion and centripetal force

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Past exam question Unit: Physics

1. A18000

   This value is the peak power V_{max}I_{max}, not the average power.

2. B9000\sqrt{2}

   This value comes from multiplying by \sqrt{2} instead of dividing by 2.

3. C\dfrac{9000}{\sqrt{2}}

   This value divides the correct result by \sqrt{2} a second time for no reason.

4. D9000 ✓ Correct answer

   P_{avg} = \tfrac{1}{2}I_{max}V_{max} = \tfrac{1}{2}\times 180\times 100 = 9000\,\text{W}.

Reference: Saudi secondary curriculum (track system), Physics: Alternating current: average power

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Past exam question Unit: Mathematics

1. A\dfrac{1}{5}

   This is the probability that Ahmad stands in the middle only, without the condition on Omar's position.

2. B\dfrac{1}{60}

   This value assumes a third person is also fixed in a specific position, which is not required.

3. C\dfrac{1}{120}

   This is the probability of one fully specified arrangement of all five people, but here three people remain and can be arranged in 3! ways.

4. D\dfrac{1}{20} ✓ Correct answer

   The total number of arrangements is 5!=120, and the favorable ones are 3!=6 (Ahmad and Omar fixed, the other three permute): \frac{6}{120}=\frac1{20}.

Reference: Saudi secondary curriculum (track system), Mathematics: Permutations and probability

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Past exam question Unit: Mathematics

1. A27

   This is r^3, not r.

2. B9

   If r=9 then r^3=729, but the required value is r^3=\frac{702}{26}=27.

3. C3 ✓ Correct answer

   The sum of terms 4 to 6 equals r^3 times the first sum: r^3=\frac{702}{26}=27, so r=3.

4. D\frac13

   A ratio below 1 makes terms decrease, so the second sum would be smaller than 26.

Reference: Saudi secondary curriculum (track system), Mathematics: sequences and series

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