Biology
Monosaccharides are major components of:
A. DNA, RNA and Oil
B. DNA, NAD and Hemoglobin
C. DNA, ATP and Milk sugar
D. None of these
C. DNA, ATP and Milk sugar
0.200 mol ethanenitrile reacts with an excess of dilute sodium hydroxide. The reaction produces organic compound S and ammonia gas only.
The reaction has an 80.0% yield.
Which mass of S is produced?
13.1 g
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At what values of x does the graph of y = sec x have a horizontal tangent?
A line is horizontal when and only when its slope is 0. The slope of the tangent line is y′ = Dx(sec x) = sec x tan x. Hence, we must solve sec x tan x = 0. Since sec x = 1/cos x, sec x is never 0. Hence, tan x = 0. But, since tan x = sin x / cos x, tan x = 0 is equivalent to sin x = 0. The latter occurs when and only when x = nπ for some integer n.
A. n(pi)
B. 2n(pi)
C. (n+1)(pi)
D. (n-1)(pi)
A. n(pi)
Which statement about a ball that strikes a tennis racket and rebounds is always correct?
A. Total kinetic energy of the ball is conserved.
B. Total kinetic energy of the system is conserved.
C. Total momentum of the ball is conserved.
D. Total momentum of the system is conserved.
D. Total momentum of the system is conserved.
What is correct option about tRNA?
I. It consists of 55 to 70 nucleotides.
II. Its cloverleaf shape in 2-D views.
III. Its 5' end always terminates in guanine.
IV. It is single-stranded molecule.
A. I and II
B. I and IV
C. II and III
D. I, II, III and IV
C. II and III
Structural isomerism and stereoisomerism should be considered when answering this question.
A colorless liquid, C5H11C1, exists as a mixture of two optical isomers.
When heated with sodium hydroxide in ethanol, a mixture of only two alkenes is formed.
What could the colorless liquid be?
A. (CH3CH2)2CHCl
B. CH3CH2CH2CHClCH3
C. (CH3)2CHCHClCH3
D. CH3CH2CCl(CH3)2
C. (CH3)2CHCHClCH3
Name 7 special purpose registers
• Program Counter (PC)
• Memory Data Register (MDR)
• Memory Address Register (MAR)
• The Accumulator (ACC)
• Index Register (IX)
• Current Instruction Register (CIR)
• Status Register
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A parallel beam of light of wavelength 450 nm falls normally on a diffraction grating which has 300 lines/mm.
What is the total number of transmitted maxima?
A. 7
B. 8
C. 14
D. 15
D. 15
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the "lack of photosystem II" in these organisms would be:
A. To determine if they have thylakoids in the chloroplasts.
B. To test for liberation of O2 in light.
C. To test for CO2 fixation in the dark.
D. To do experiments to generate an action spectrum.
B. To test for liberation of O2 in light.
A transition metal ion, M²⁺, reacts with acidified dichromate(VI) ions to form M⁴⁺ ions, Cr³⁺ ions, and H₂O.
Which equation correctly represents this reaction?
A. Cr₂O₇²⁻ + 14H⁺ + M²⁺ → 2Cr³⁺ + 7H₂O + M⁴⁺
B. Cr₂O₇²⁻ + 14H⁺ + 2M²⁺ → 2Cr³⁺ + 7H₂O + 2M⁴⁺
C. Cr₂O₇²⁻ + 14H⁺ + 3M²⁺ → 2Cr³⁺ + 7H₂O + 3M⁴⁺
D. Cr₂O₇²⁻ + 14H⁺ + 6M²⁺ → 2Cr³⁺ + 7H₂O + 6M⁴⁺
C. Cr₂O₇²⁻ + 14H⁺ + 3M²⁺ → 2Cr³⁺ + 7H₂O + 3M⁴⁺
What are three differences between fiber-optic cables and copper cables
Fiber optic data is transmitted using light, copper cable through electrical signals
Fiber optic has higher bandwidth than copper cable // Fiber optic has higher transmission rates than copper cable
Fiber optic has smaller risk of (noise) interference than copper cable
Fiber optic can be used over longer distances than copper cable before repeaters are needed
Fiber optic is much more difficult to hack into than copper cable
Fiber optic is more prone to damage than copper cable
Five 1st year students and three 2nd year students are standing next to each other, for a photograph to be taken.
It is assumed that the eight students positioned themselves at random.
a) Find the probability that all the 1st year students are standing next to each other.
b) Determine the probability that all the 1st year students are standing next to each other and all the 2nd year students are standing next to each other.
c) Find the probability that no 2nd year students are standing next to each other.
a) 1/14
b) 1/28
c) 5/14
A steel sphere is dropped vertically onto a horizontal metal plate. The sphere hits the plate with a speed u, leaves it at a speed v, and rebounds vertically to half of its original height.
Which expression gives the value of v/u ?
A. 1/2²
B. 1/2
C. 1/√2
D. 1 - 1/√2
C. 1/√2
If 12 NADPH are used in Calvin cycle, then how many glucose molecules will be formed?
One
W, X, Y and Z are Group 2 elements barium, calcium, magnesium and strontium but not in that order.
W reacts faster with dilute hydrochloric acid than Y.
The hydroxide of X is less soluble in water than the hydroxide of W.
The sulfate of Y is the most soluble of the sulfates of W, X, Y and Z.
The carbonate of Z decomposes more slowly than the carbonate of W at the same temperature.
What is the Mr of the nitrate of W?
A. 148.3
B. 164.1
C. 211.6
D. 261.3
C. 211.6
A magnetic hard disk is used to store data on the computer.
Describe the principal operations of a magnetic hard disk.
The hard disk has (one or more) platter/plate/disk
Each surface of the platter/disk is (ferrous oxide which is) capable of being magnetised
The platters/disks are mounted on a (central) spindle
The entire mechanism is contained inside a sealed (aluminium) box.
The disks are rotated (at high-speed) (Each surface of the disk) has a read/write head mounted on an arm (positioned just above the surface)
Electronic circuits control the movement of the arm (and hence the heads)
The surface of the platter/disk is divided into concentric tracks / circles
The surface of the platter/disk is divided into sectors
One track in one sector is the basic unit of storage called a block
The data is encoded as a magnetic pattern for each block
When writing to disk, a variation in the current in the head produces a variation in magnetic field on the disk
When reading from disk, a variation in magnetic field produces a variation in current through the head
Find the general solution of the following equation
An electric railway locomotive has a maximum mechanical output power of 4.0 MW. Electrical power is delivered at 25 kV from overhead wires. The overall efficiency of the locomotive in converting electrical power to mechanical power is 80%.
What is the current from the overhead wires when the locomotive is operating at its maximum power?
A. 130 A
B. 160 A
C. 200 A
D. 250 A
C. 200 A
Name a receptor mediated process of transport?
Endocytosis
Reagent X is added separately to 2-methylbutan-1-ol and 3-methylbutan-2-ol.
The visible results are different.
What is reagent X?
A. Na(s)
B. alkaline I₂(aq)
C. PCl₅
D. acidified KMnO₄
B. alkaline I₂(aq)
Describe the basic internal operations of a speaker
Takes an electrical signal and translates it into physical vibrations to create sound waves
An electric current in the coil creates an electro-magnetic field
Changes in the audio signal causes the direction of the electric current to change
The direction of the current determines the polarity of the electro-magnet //changing the direction of the current changes the direction of the polarity of the electro-magnet
The electro-magnet is repelled by or attracted to the permanent magnet
Causing the coil to vibrate
The movement of the coil causes the cone / diaphragm to vibrate
That vibration is transmitted to the air in front of the cone / diaphragm as sound waves
The amount of movement will determine the frequency and amplitude of the sound wave produced
Two cannons both fire balls at speed 100ms-1. One of the cannons is fixed at an angle of 45° to the horizontal and the other is fixed at angle 30° to the horizontal. The cannons are set up facing each other at a distance D from each other. One cannon is fired and then, T seconds later, the other cannon fired.
The balls subsequently strike each other in mid air.
Assuming that the cannon at an angle of 45° is fired first, show that that T must lie within a range of values and that both T and D must be greater than zero.
10(√2-1)<T<10√2
A rectangular metal bar exerts a pressure of 15 200 Pa on the horizontal surface on which it rests.
If the height of the metal bar is 80 cm, what is the density of the metal?
A. 190 kg m-³
B. 1900 kg m-³
C. 19 000 kg m-³
D. 190 000 kg m-³
B. 1900 kg m-³