BMAT 2016-S2

Explanation

The correct answer is D.

The correct answer is D: 3 is the renal vein, as this is the filtered blood obtained from the kidneys. During filtration, urea is removed from the blood, and the renal vein carries blood towards the heart. Hence, it has the lowest concentration of urea. 5 is the ureter which contains the highest concentration of urea. This is as, the filtrate contains urea which is filtered by the kidney to be excreted by the body.

Explanation

The correct answer is F.

The correct answer is F: Statements 2, 3 and 4 are correct only.

Statement 1 is incorrect: A group of an element tells you the number of outer electrons, hence the element cannot be in group 12, as there are only 3 electrons in its outer shell. In a period, the number of electron shells are the same, and the period number is determined by the number of electron shells. Period 3 is correct, however, Group 12 is not.

Statement 5 is incorrect: Alkali metals occupy group 1 in the periodic table – they only have 1 electron in their outermost shell. Whereas, element X is in Group 3.

Statement 4 is correct: The atomic number is the number of protons, which is also the number of electrons, in the atom. Adding up the electrons in the 3 shells: 2 + 8 + 3 =13.

Statement 3 is correct: Bromine is in Group 7, hence has 7 electrons in its outermost shell. It needs 1 electron to complete its shell, which can hold a maximum of 8 electrons. Element X can give 3 electrons to gain a complete shell, which is composed of 8 electrons – below the outermost shell. Hence, X donates 1 electron each to 3 Bromine atoms, forming XBr3.

Statement 2 is correct: Oxygen is in Group 6, hence it has 6 electrons in its outermost shell – requiring 2 electrons to complete its shell. Element X has 3 electrons, and so one electron will remain spare! However, to resolve this issue, a lowest common multiple (LCM) of 2 and 3 must be found 6.

If there are 2X atoms, they have 6 electrons in total. If there are 3O atoms, they have 18 electrons in total. One X atom can give 2 electrons to each O atom. Hence, the formula is X2O3.

Explanation

The correct answer is D.

The correct answer is D: This is a displacement question. However, 2 solid objects are placed here. The

volume of displacement is: 350 – 250 = 100.

The mass of water initially: 170 – 20 = 150g ; The mass of the object (when singly placed): 470 – 170 = 300g.

When 2 objects added – mass: 2(300) = 600 mass overall: 600 + 170 = 770g

Difference in mass (from 0 solids 2 solids): 770 – 170 = 600

Density = Mass/Volume = 600 / 100 = 300 / 50

Explanation

The correct answer is A.

The correct answer is A: An equation of a parallel line has the same gradient as the line PQ. Gradient: 

y2–y1/ x2–x1 => yQ–yP/xQ– xP→ 9 – 3/6 – (-3) = 6/9 = 2/3

Hence, the gradient is 2/3. We are given no information on the coordinates of the parallel line, hence we cannot find the y intercept. Hence, the answer is y=2x/3 – 3

Explanation

The correct answer is B.

The correct answer is B: W – Chromosome, which is shown by its characteristic ‘X’ shape during metaphase. X – restriction enzyme, as restriction enzymes are used to cut out a portion of DNA from the donor organism. Y – restriction enzyme, as the plasmid (shown by its circular structure) has to be cut up using the same restriction enzymes as used to cut the donor DNA, as they leave the same sticky ends. Z – ligase. This enzyme seals up and joins together the sticky ends of the plasmid – donor DNA – gene complex.

Explanation

The correct answer is E.

Ethanol and water cannot be separated by a separating funnel. This is as, ethanol is soluble in water, as it forms hydrogen bonds with water molecules. Hence, distillation can separate them.

Explanation

The correct answer is D.

Statements 1 and 2 are correct. Isotopes have the same chemical properties, as they have the same atomic number. The atomic number dictates how many protons occupy the atom, which is also the same number as the electrons. If the electron number is the same, then the isotopes will have the same chemical properties. Statement 3 is incorrect: Beware, the question only gives mass numbers, not neutron numbers. Mass number = atomic number + number of neutrons. Hence, Statement 3 can be corrected by: 62 – 28 = 34. Hence, one of them has a nucleus containing 34 neutrons.

Explanation

The correct answer is B.

The correct answer is B: 75 = Total mass/N J+K+L + Total Mass/N+3 = 78

J+K+L/3 = 90

Hence, J+K+L = 270

Substitute this into second equation: 270 + Total Mass /(N+3) = 78

Total Mass (from equation 1): 75N

270 + 75N/(N+3) = 78 78(N+3) = 270 + 75N 78N+234 = 270 + 75N 3N = 36

Hence, N = 12

Explanation

The correct answer is F.

These statements all apply to protease. Protease works in optimally acidic conditions. The lower the pH, the greater the acidity of the solution. The hydrochloric (HCl) acid in the stomach ranges from pH 1.5 – 3.5 for protease to catalyse the breakdown of proteins. Protease digests proteins into amino acids. Protease, like all digestive enzymes, have an optimum temperature of 37°C.

Explanation

The correct answer is F.

To calculate the mass, the mass numbers of all elements are needed. Hence (in order of the formula):

2(14 + 4(1)) + 56 + 2(32 + 4(16)) + 6( 2(1) + 16) = 36 + 56 + 192 + 108 = 392

Explanation

The correct answer is B.

Rotating the coil at a faster constant speed, increases the induced voltage produced. Hence, it leads to an increase in amplitude of the oscilloscope graph. This is as, a large voltage corresponds to the y axis. As the coil rotates at a faster speed, voltage is induced at a faster rate, hence the time period decreases, as voltage is being induced faster due to faster relative motion. This increases the frequency of the induced voltage, hence more waves are observed on the oscilloscope graph.

Explanation

The correct answer is D.

To find the shaded area, the formula: A =  π

r2is needed. We are given the diameter of the artery as 1.6cm, with the extension from the artery wall being 1mm. Be careful of units here – convert all into mm, as the answers are in mm. Hence, the diameter of the artery is 16mm. In order to get the radius of the artery wall, 2mm must be subtracted from the artery diameter – 2mm as t=1mm, which extends in both directions from the diameter.

Hence, 16-2=14. Radius=Diameter/2, hence r=7. A= π  

(7)2=49 π

Explanation

The correct answer is B.

Glucose is involved in both aerobic and anaerobic respiration. Carbon dioxide and water are products of aerobic respiration, whereas lactic acid is a product of anaerobic respiration. Hence, Statements 1 and 3 are incorrect, as they don’t apply to both respiratory processes; glucose is required for both processes to occur.

Explanation

The correct answer is C.

The electrolysis of an aqueous solution of potassium sulfate using inert electrodes produces hydrogen at the cathode and oxygen at the anode and a neutral solution of sodium sulfate remains unaltered by the electrolysis. This is as inert electrodes are used. Hence, it cannot be A, B, or D as they produce a metal at the electrodes. For this to occur, the electrodes must be of that metal i.e. Copper electrodes with CuSO₄ would lead to copper being deposited on the electrodes.

Anode half equation (At the positive electrode, negatively charged ions lose electrons. This is oxidation.) : 2H₂O O₂ + 4H+ + 4e-

Hence, oxygen is formed at the anode.

Cathode half equation (At the negative electrode, positively charged ions gain electrons. This is reduction.) : 4H₂O + 4e- 2H₂ + 4OH-

Hence, hydrogen is formed at the cathode.

Explanation

The correct answer is D.

Microwaves are used for satellite communication.

Total distance = 2 ( 45000 x 1000) = 9 X 107m

Speed = Distance/Time 

9 X 107/(3 X 108) = 0.30s

The frequency given is irrelevant, as it does not partake in the calculation.

Explanation

The correct answer is C.

tan θ= Opposite/Adjacent = 4/3

To find the area, we must divide the shape into a right angled triangle PQX (where X is the vertex of this triangle on the line PS), and a rectangle QRSX.

The area of the triangle = 1⁄2 bh; The opposite to θ is the height (4) and the adjacent to θ is the base (3). However, the actual length of PX is 11-5=6. Remember tan is a ratio of sides, hence the ratio of O:A is 4:3. The actual length is O:6, hence O = 8 as the factor is 2.

Area of triangle = 1⁄2 x 6 x 8 = 24

Area of rectangle = 8 x 5 = 40

Area of quadrilateral = area of triangle + area of rectangle = 24 + 40 = 64

Explanation

The correct answer is G.

All 4 Statements are correct. A mutation leads to a change in the base sequence of amino acids, which in turn leads to a change in the structure of the protein that is produced. Each triplet of bases codes for one amino acid. The order of bases determines the sequence of amino acids, thus dictating which protein is coded for. A mutation can occur through: substitution (in a base is substituted by another base) , deletion (a base is not added to the sequence) and addition (an extra base is added in the sequence) of bases. These all include the possibilities of either a functional/non functional protein being coded for, depending upon which base is deleted /added/ substituted. Hence, both Statements 3 and 4 are correct, as enzymes are proteins (including protease), and the mutation can have a negative, positive or no effect on the non functional protein (the protease enzyme may not perform its role, but it may lead to other consequences, or it may not affect cellular activity at all). Statements 1 and 2 are correct, as the change of protease structure may cause it to bind more tightly to protein substrates, or loosely; hence, this determines the efficiency of the protease.

Explanation

The correct answer is E.

As the acid is diprotic, and NaOH neutralises the acid, 2 moles of NaOH are needed.

n = c x v x 10-3 n (Diprotic) = 30 x 0.2 x 10-3 = 0.006

As 2 NaOH, n(NaOH) = 2 x 0.006 = 0.012

For base (NaOH): v = (n/c) x 1000 v = (0.012/0.1) x 1000 = 120 cm3

Explanation

The correct answer is D.

Energy = Power X Time = Current X Voltage X Time

125 = 500 x 10 x 10-3 x current

Current = 125/(500 x 10 x 10-3) = 250

Explanation

The correct answer is C.

 f needs to be made the subject.

Firstly, add here, we have cross multiplied fc and ed, as the lowest common multiple (LCM) of the denominator is fd.

Then, multiply both sides by fd in order to factorise later

Explanation

The correct answer is A.

Statement 1 and 4 are correct, as they involve division. Mitosis is the process of cell division, whereby 2 daughter cells are produced which have the same number of chromosomes, hence are genetically identical. Asexual reproduction produces genetically identical offspring, through mitosis (i.e. bacterial reproduction). Stem cells also produce genetically identical stem cells through mitosis. Be careful – mitosis makes new cells for growth, repair and replacement (i.e. cell replacement in humans, or reproduction in microorganisms). Statement 2 is incorrect as it mentions growth of a cell – mitosis produces cells for growth of a tissue, which is composed of many cells. Statement 3 is incorrect too, as a tissue is repaired through the production of cells by mitosis – not the cell itself.

Explanation

The correct answer is B.

moles = concentration x volume x 10-3

n (X): 100 x 1 x 10-3 = 0.1

mole ratio of 2HCl : CO2 = 2:1

n(B): 50 x 2 x 10-3 = 0.1

The moles for both conditions are the same, hence indicating that the final volume of CO2 produced is constant – the same. Hence, the line has to reach the same endpoint as X – it cannot be D, E or A. It’s either C or B. However, the time taken to reach the end point of X (the rate of reaction) will differ. The concentration of HCl is higher in the second experiment, hence this increases the rate of reaction. This is as, a higher concentration of HCl molecules increase the likelihood of successful collisions with calcium carbonate chips, as they are more densely occupied in a small volume. Hence, it cannot be C, as the time taken is longer to reach the end point. Hence, it has to be B, as the time taken is smaller.

Explanation

The correct answer is E.

W=mg – Mass of the object does not change on any planet, only the weight changes, due to the different gravitational strengths.

M = W/g hence, on Earth: 15/10 = 1.5 kg.

Kinetic energy gained on planet = gravitational energy lost on planet Mgh = gravitational energy lost (as no velocity is provided, cannot calculate kinetic energy directly, hence we use the conservation of energy). W = mg, hence use 3.0N as mg. Hence, 3 x 10 = 30J

Explanation

The correct answer is D.

Defining: P(AB’) = 0.45, P(BA’) = 0.09

P(A’B’)=0.43, P(AB)=0.03.

Rewrite probabilities as equations:

A(1-B) = 0.45 

A-AB=0.45

B(1-A) = 0.09 B-AB=0.09

(1-A)(1-B) = 0.43 AB – (A+B)+1=0.43

AB = 0.03

Hence, substituting AB = 0.03, A-0.03 = 0.45 , hence A = 0.48

B – 0.03 = 0.09 ; B = 0.12

To check: 0.03 – (0.12 + 0.48) + 1 = 1.03 – 0.60 = 0.43

Given the presence of Type B antigens, the probability off both types need to be found. This is, the probability of both/given

Hence, 0.03/0.12 = 1⁄4

Explanation

The correct answer is H.

This question asks for the maximum number of heterozygous mice.

We don’t know whether the characteristic Grey is dominant, or whether White is dominant. Hence, grey mice are either dominant or recessive, and the same applies for White mice.

To get the smallest number of heterozygous mice, we can assume that all dominant mice are heterozygous dominant (Cc), not homozygous dominant (CC).

All of the recessive mice are homozygous recessive (cc), as you cannot get heterozygous recessive.

There are 12 grey mice, and 4 white mice. Hence, it seems sensible to make the white colour recessive as the recessive mice are homozygous. We want to maximise heterozygous. Hence, at maximum, there are 12 heterozygous mice.

Explanation

The correct answer is D.

2X + Y 2Z. There is a 1:1 mole ratio between X and Z, and as moles are proportional to volume (in n=cv), the volume of X and Z must be the same. The question states that 2X and Y react together to form a compound which has the same moles as X. Hence, the final volume of Z is 100 cm3 too.

Explanation

The correct answer is C.

Frequency does not change when a light travels through a medium. Hence, the frequency of light through water should be

calculated first: c=fλ ; 3/4 x (3 X 108) = 2.25 x 108 2.25 x 108 = (360 x 10-9) x f

f = 2.25 x 108 / 360 x 10-9 = 6.25 x 1014

Glass: 2/3 x (3 X 108) = 2 x 108 2 x 108 / 6.25 x 1014 = 3.2 x 10-7 = 320 nm