BMAT 2017-S2

Explanation

The correct answer is A.

P is the gallbladder, Q is the stomach and R is the pancreas. The gallbladder stores bile, the stomach secretes protease and HCl and the pancreas secretes insulin, protease, lipase and amylase. So A is the answer.

Explanation

The correct answer is E.

Oxidation occurs at the anode and reduction at the cathode. Copper has a lower reactivity than both hydrogen and sulfate ions, so copper will be oxidised (lose electrons) at the anode and reduced (gain electrons) at the cathode.

Explanation

The correct answer is A.

Microwaves have the second largest wavelength (after radiowaves), so statement 1 is incorrect. All EM waves travel at 300,000,000 metres per second (m/s) through a vacuum, so 2 is incorrect. As stated before, radiowaves have the largest wavelength, so 3 is incorrect. Since there is no option for statement 4 to be correct on its own, all 4 statements must be incorrect.

Explanation

The correct answer is F.

Explanation

The correct answer is G.

If the allele of the gene coding for the enzyme was different, the function of the enzyme may also be different, so 1 is correct. The different allele could change the amino acid sequence in the enzyme, so 2 is also correct. The order of bases in the gene coding for the enzyme will determine the amino acid sequence, so 3 is correct. A change in the shape of the active site of the enzyme would affect its function so statement 4 is also correct. Therefore all 4 statements could be possible.

Explanation

The correct answer is D.

The number of electrons is equal to the atomic number of the element plus the magnitude of the charge if it is a negative ion or minus the charge if it is a positive ion. The number of electrons for each option are: 1)=16+2=18, 2)=17+1=18, 3)=18, 4)=19-1=18, 5)=20, so eliminate 5). The number of neutrons is given by the mass number minus the proton number: 1)=34-16=8, 2)=37-17=20, 3)=40-18=22, 4)39-19=20, so eliminate 1) and 3). Therefore only 2) and 4) have both 20 neutrons and 18 electrons.

Explanation

The correct answer is F.

The first statement is correct because the water molecules have more kinetic energy at higher temperatures, causing them to move faster and further apart to convert to gaseous state. 2 is incorrect because a greater airflow above the puddle would give the water molecules more energy and assist in their evaporation. 3 is correct because the water molecules have a larger area from which they can evaporate per unit time. So statements 1 and 3 only are correct.

Explanation

The correct answer is A.

The probability that the first patient picked suffered from migraines is 5/20. If the first person chosen suffered from migraines, there would be one less person remaining who suffered from migraines and one less person in the group overall, so the probability that the second person picked suffered from migraines would be 4/19. Therefore the probability that both people picked suffered from migraines would be: 5/20 x 4/19= 20/380= 1/19.

Explanation

The correct answer is E.

In experiments 1 and 2, the same liquid is present on either side of the partially permeable membrane, so there would be no net movement or glucose or water. However, the question is asking about movement not net movement. If a certain type of molecule is present in one/both of the solutions in an experiment, there will be movement regardless of if a concentration gradient exists across the membrane. In experiment 1, there is no glucose present, so there would be no movement of glucose across the membrane. However glucose is present in the remaining experiments, and water in present in all 4 experiments, so the answer is E.

Explanation

The correct answer is C.

2 is correct because as the reaction progresses, more HCl is used up, so its concentration would decrease. 3 is incorrect as only the presence of a catalyst can alter the activation energy of a reaction. Therefore only the second statement can explain the observation.

Explanation

The correct answer is C.

For a series circuit, the total voltage is determined by the sum of the voltages of each component within the circuit. As the two resistors have different resistances, and because V=IR, they will also have different voltages, so statement 1 is incorrect. According to V=IR, if the resistance doubles whilst the current remains constant, the voltage will also double, so 2 is correct. 3 is the opposite of 2, so 3 must be incorrect. For a series circuit, the current is the same throughout the circuit, so 4 is correct, and hence 5 and 6 must be incorrect because they contradict statement 4. Therefore only statements 2 and 4 are correct.

Explanation

The correct answer is F.

To determine the length of PS, we need to find the length of PT and add this to the length of TS given. The triangles PRS and PQT are similar, therefore we can use ratios to determine their side lengths. QT/RS=0.3/1.5=0.2. This will be equal to the ratio of PT/PS. Using algebra:

Therefore PS=0.45+1.8=2.25cm.

Explanation

The correct answer is E.

Gametes contain the haploid number of chromosomes, and since the diploid cell contained 54 chromosomes, the gamete would contain 27, so statement 1 is correct. 2 is correct because the embryo is not yet formed at step 4, so the cells have not yet differentiated. Gametes are produced by meiosis so 3 is incorrect. Therefore only statements 1 and 2 are correct.

Explanation

The correct answer is E.

In reaction 1, iron is being oxidised (loses electrons) and copper is being reduced (gains electrons), so this is not a disproportionation reaction. In 2, copper is both oxidised (to 2+) and reduced (to 0), so this is a disproportionation reaction. In 3, chlorine is both oxidised (to +1) and reduced (to -1). In 4, the oxidation states of all the elements are unchanged. In 5, Hg+ is oxidised (to 2+) and reduced (to 0), so this is a disproportionation reaction. Therefore, the reactions 2, 3 and 5 only are disproportionation reactions.

Explanation

The correct answer is F.

When converting uranium-238 to plutonium-239, the change in mass number is 1+ and the atomic number changes by 2+. We know that the 3 stages cannot involve emission of an alpha particle because this would cause a reduction in mass number of 4 and a reduction in atomic number of 2, after which the element cannot be altered by the other two stages in a way which would give the desired mass and atomic numbers. Therefore we can eliminate A,B,C and E. This leaves D and F, which both have the same events but in different orders. F is the correct answer because the absorption of a neutron in stage 1 would result in the emission of the beta particles.

Explanation

The correct answer is A.

Explanation

The correct answer is G.

The artery shown is a coronary artery. Statement 1 is incorrect because artery walls are impermeable so glucose and oxygen would not diffuse through them. 2 is correct because arterial blood pressure is generally high, as the blood has come directly from the heart and not yet been slowed down by passing through tissues. 3 is also correct because there is smooth muscle present in arterial walls which contract to cause vasoconstriction. Therefore, statements 2 and 3 only are correct.

Explanation

The correct answer is C.

Propanoic acid is a monoprotic acid, which means is loses only 1 proton (H+) per molecule when it dissociates, forming an ion with a 1- charge. However, because Mg is a group 2 metal, it will lose 2 electrons when it reacts to form a 2+ ion. Therefore, in order for the number of electrons and hence charge to remain balanced, 2 moles of propanoic acid must react with every 1 mole of magnesium. Therefore the answer must be A, C or D. Because only C is balanced correctly, C is the answer.

Explanation

The correct answer is E.

The sound made travels 2m to the closest wall and then 2m back to the detector placed at the sound source, but also travels 8m in the opposite direction to the further wall and then travels 8m back to the detector. Therefore, the reflection from the wall 2m away travels 4m, and the reflection from 8m away travels 16m. Because the second sound detected travelled 16/4=4 times the distance of the first sound, it would have taken 4 times the amount of time taken for the first sound to be detected (as the speed of sound in water is constant). We can form an equation where x is time taken for the first sound to be detected:

4x-x=0.010

3x=0.010

x=0.010/3

Speed=distance/time, and the first sound detected travelled 4m so:

4/(0.010/3)

=12/0.010

=12×10²

=1200 m/s

Explanation

The correct answer is E.

Explanation

The correct answer is D.

The allele causing the presence of freckles must be dominant (F) because 5 and 6 both have freckles but neither of their children do, so 5 and 6 must also each have the recessive allele for no freckles (f), which they passed onto their offspring. The genotype of 2 is therefore ff. The genotype of 1 must be Ff, because 1 and 2 have children both with and without freckles. In the cross Ffxff, the 2 of the offspring would have freckles and 2 would not, so the probability of a child produced having freckles is 0.5. The genotype for both 5 and 6 is Ff, and a heterozygous cross produces offspring with phenotypes in the ratio of dominant:recessive=3:1, so the probability that one of their offspring has freckles is 0.75. Therefore the answer is D.

Explanation

The correct answer is B.

64+32+(16×4)+5((1×2)+16)=64+32+64+90=250

Mass/Mr=moles: 10/250=0.04mol

100cm³=0.1dm³

Concentration=moles/volume: 0.04/0.1=0.4moldm³

Explanation

The correct answer is F.

Newton’s third law is: whenever two objects interact, they exert equal and opposite forces on each other. The force acting opposite to force P is the force that the table exerts on the floor, which is answer F.

Explanation

The correct answer is C.

The area of the triangle is given by 1/2 x base x height. Use pythagoras to work out the length of the base: 9² – 6² = 81 – 36 = 45, so base=√45=3√5cm. So the area of the triangle is: 0.5 x 3√5 x 6 = 9√5. The area of the quarter circle is given by 1/4 x r²: 0.25 x π x 6 x 6 = 9. So the total area is 9π + 9√5.

Explanation

The correct answer is G.

Enzyme activity causes a darker coat. If this cat had grown up in a warmer environment its ears, front of face, paws and tail would be paler, which means the enzyme is inactivated at higher temperatures. Statement 1 is incorrect because the coat of the cat is superficial, so the enzyme would not be working at internal body temperature. 2 is correct as we know that a darker coat is caused by increased enzyme activity. Statement 3 is correct because the enzyme is coded for by a gene but its activity is affected by temperature. Therefore statements 2 and 3 only are correct.

Explanation

The correct answer is B.

Na+H2O→ NaOH+1/2H2

Moles=mass/Mr: 0.23/23=0.01mol of Na

0.01/2=0.005mol of H2

0.005×24=0.12dm³

Explanation

The correct answer is C.

Kinetic energy=1/2mv². 

KE=0.5×2.5v²

KE=1.25v²

The kinetic energy is directly proportional to the square of the velocity (or speed with direction) according to the equation. As KE and v are the variables, 1.25 must be the gradient of the line. Comparing the equation  to y=mx²+c, KE=y, v=x and 1.25=m