Bio
Powerhouse of the cell.
Mitochondria.
What happens when you add aqueous bromine to a alkene?
The aqueous bromine is decolourised.
What is the dot product of these vectors?
(1 , 5) and (2 , 4)
[pretend the first value is x and the second value is y because I can’t make brackets that are two lines tall]
Dot product = X1X2 + Y1Y2
(1 , 5) • (2 , 4) = 2 + 20
= 22
What are the three main types of mass movement?
Slide, Heave, Flow
[Fall is technically one of them so I’ll count that if you said it]
Which world leader out of these had the highest direct kill ratio? (Mao, Stalin, Castro, Austrian Painter)
Mao
What is the role of the proto-oncogene?
The proto-oncogene controls cell growth and division.
Suggest a simple test to distinguish propanal and propanone.
EITHER:
Add Fehling’s solution to 1cm depth of both propanal and propanone in a test tube and warm in a hot water bath. Propanal will give a brick-red ppt while propanone will not.
OR
Add Tollen’s reagent to 1cm depth of both propanal and propanone in a test tube and warm in a hot water bath. Propanal will produce a silver mirror on the test tube while propanone will not.
Find the derivative of x2cos(2x).
d/dx [x2cos(2x)] = 2xcos(2x) - 2x2sin(2x)
= 2x[cos(2x) - xsin(2x)]
State and briefly explain two impacts climate change has on the environment.
[No economic or social impacts]
Sea level rise, displacement of flora and fauna, increasing air temperature, melting of sea ice, melting of land ice, increased sea temperature, coral bleaching, more extreme weather events, increased risk of forest fires, increased frequency/intensity of flooding, destruction of natural habitats, etc.
(Accept anything else that makes sense)
Which disease wiped out almost half of Europe
Bubonic plague
What is the main difference in the reproduction cycle of the T4 phage and the lambda phage?
The T4 phage replicates through the lytic cycle, where the phage DNA is expressed as soon as it is injected into the host bacterium, which ultimately results in the bacterium lysing and releasing the phages.
The lambda phage replicates through the lysogenic cycle, where the phage DNA is incorporated into the bacterium and the bacterium is allowed to replicate until conditions are favourable, then the phage enters the lytic cycle, releasing the phages.
Explain why C6H5COOH is a stronger acid than CH3COOH.
C6H5COO- is more stable than CH3COO-, as C6H5COOH has a benzene ring that contains a delocalised electron cloud. The pi electrons of the carboxyl carbon in the C6H5COO- ion and the two oxygen atoms delocalise into the ring of delocalised electrons above the benzene ring, distributing the negative charge it has over a wider area. This makes the C6H5COO- ion more stable than the CH3COO- ion, and thus C6H5COOH is the stronger acid.
A geometric series has first term 10 and common ratio r. Given that its sum to infinity is 150, find r.
a = 10
S∞ = 150
a = 150(1 - r)
150(1 - r) = 10
1 - r = 1/15
r = 14/15
How does poor waste management lead to lower liveability in cities?
[Explain at least one impact]
Poor waste management leads to pollution
This causes health risks (e.g. respiratory problems, skin diseases, creates breeding ground for bacteria), increased healthcare spending, loss of quality of life, poor city image (unpleasant odours, visual pollution), erosion of community pride, impact on property values, etc.
(Accept anything else that makes sense)
What revolution did the younger brother of Jesus Christ start?
Taiping rebellion
How are proteins synthesised from mRNA? (Explain as fully as you can)
The proteins are synthesised through translation. The small ribosomal unit first binds to the mRNA. Then, an aminoacyl-tRNA molecule containing the methionine amino acid binds to the start codon. Finally, the large ribosomal unit binds to the small ribosomal unit, with the P site over the start codon. The ribosome recruits more aminoacyl-tRNA molecules with the corresponding anticodon to the next codon in the mRNA binds to the codon at the A site. Peptidyl transferase catalyses the formation of a peptide bond between the two amino acids. The ribosome then shifts from the 5’ to the 3’ position. The first tRNA molecule is now at the E site and is removed. The second tRNA molecule is now at the P site. The cycle then repeats until the stop codon is reached. At this point, a release factor enters the A site and causes the protein to be cleaved off. The ribosomal subunits are then disassembled.
Determine the solubility of AgCl in 1.5 mol dm-3 NaCl.
[Ksp of AgCl at 25˚C = 1.6 x 10-10]
Let y mol dm-3 be the solubility of AgCl in the solution at 25˚C
AgCl <—> Ag+ + Cl-
eqm conc - y y + 1.5
Ksp of AgCl = [Ag+][Cl-] = y(y + 1.5)
AgCl is sparingly soluble, so y is small. Hence, (y + 1.5) ≈ 1.5
Ksp = y(1.5)
1.6 x 10-10 = 1.5y
y = 1.07 x 10-10 mol dm-3 (3sf)
In a class, there are 10 students who take Bio, 7 students who take Chem and 6 students who take Physics. Each student only takes one subject
Find the number of committees of 5 students that can be formed where there is at least one student that takes Bio, one that takes Chem and one that takes Physics.
By Systematic Listing,
Bio Chem Phys
1 1 3 10C1 x 7C1 x 6C3 = 1400
1 2 2 10C1 x 7C2 x 6C2 = 3150
1 3 1 10C1 x 7C3 x 6C1 = 2100
2 1 2 10C2 x 7C1 x 6C2 = 4725
2 2 1 10C2 x 7C2 x 6C1 = 5670
3 1 1 10C3 x 7C1 x 6C1 = 5040
Total = 22085
[Accept other methods]
Explain how tower karsts are formed.
Water enters cracks and fissures in limestone or dolomite and dissolves the calcium carbonate within the rock. The rocks are selectively weathered along these fissures, causing them to widen, deepen and combine. This creates a cockpit karst landscape. After a period of time, the limestone will erode down to an impermeable rock layer, and thus erosion can only occur sideways. This causes the individual cockpits to become steeper and slimmer, isolating the each cockpit to form tower karsts.
Oldest Democratic Government in continuous function (just state where they rule over today)
Tynwald (Isle of Man) over 1000 yaers old, oldest continuous functioning parliament
Iceland’s Alpingi was interrupted for 641 years, Faroe Island’s Logting interrupted too
When one pure-bred plant with white flowers and another pure-bred plant with purple flowers were crossed, the F1 generation had all purple flowers.
After F1 selfing, the phenotypic ratio was 9 purple flowers : 3 yellow flowers : 4 white flowers. Explain why this is so.
There are two genes, Y and P (accept any letter)
Both the Y and P gene codes for enzymes that contribute to the creation of a purple pigment.
The Y gene codes for an enzyme that converts a colourless precursor to a yellow pigment, and it is expressed when the gene is dominant.
The P gene codes for an enzyme that converts the yellow pigment into a purple pigment, and it is expressed when the gene is dominant.
When both dominant alleles are present, the colourless precursor is able to be converted to the yellow pigment and then the purple pigment due to the presence of both enzymes, producing purple flowers.
When only the Y allele is dominant and the P allele is recessive, the colourless precursor is only converted to the yellow pigment, producing yellow flowers.
When the Y allele is recessive, the colourless precursor is not converted into the yellow pigment. As such, white flowers are produced regardless of whether P is dominant or recessive.
Plan an investigation using the following to determine the percentage mass of copper carbonate in a mixture of copper carbonate and copper oxide.
- 2 g of a mixture of CuCO3 and CuO
- a weighing balance
- a crucible without a lid
- Bunsen burner
- the equipment normally found in a school or college laboratory
[Ar of Cu = 63.5; C = 12; O = 16]
1. Weigh an empty, dry and clean crucible and record it’s mass.
2. Transfer about 2.00 g of the mixture of CuCO3 and CuO into the crucible. Weigh the crucible and the contents and record the total mass.
3. Using a Bunsen burner, heat the crucible gently at first, then strongly for 10 minutes.
4. Allow the crucible and the contents to cool, then weigh the cooled crucible and its contents and record the total mass.
5. Repeat steps 3 and 4 until a constant mass is achieved.
Tabulation of results:
Mass of empty boiling tube/g: A
Mass of boiling tube and sample/g: B
Mass of boiling tube and contents
after first heating/g: C
after second heating/g: D
after third heating/g: D
Mass of mixture = (B-A) g
Mass of CO2 lost = (B-D) g
Mass of one mole of CO2 = 44.0 g
CuCO3 (s) ——> CuO (s) + CO2 (g)
n(CO2) lost = n(CuCO3) = [(B-D)/44.0] mol
Molar mass of CuCO3 = 123.5 g mol-1
Hence mass of CuCO3 in mixture = [[123.5(B-D)]/44.0] g
% by mass of CuCO3 in the mixture = [[123.5(B-D)/[44.0(B-A)]] x 100% = [[12350(B-D)/[44.0(B-A)]]%
Find the volume of the solid formed when the area bound by y = 0.5x + 1, y = x3, and the x axis for 0 ≤ x ≤ 1.583 is rotated 2pi degrees about the x axis.
[You can use Desmos/GC]
Volume of solid = pi01.583∫ (0.5x + 1 - x3)2 dx
= pi01.583∫ 0.25x2 + 1 + x6 + x - 2x3 - x4 dx
= pi [(x3/12) + x + (x7/7) + (x2/2) - (x4/2) - (x5/5)]01.583
= 5.02 (3sf)
Outline the benefits and challenges in slum management strategies, like slum upgrading or slum relocation.
[Either 2 benefits and 2 challenges briefly explained, or 1 benefit and one challenge explained in depth]
Slum upgrading:
Benefits: Provision of education, provision of health services, increasing access to electricity and water, improving building conditions, improved quality of life, etc.
Challenges: High cost, requires governmental will, slums often located in inaccessible terrain, high manpower cost, etc.
Slum relocation:
Benefits: More convenient, lower costs, improved city image, provides space for better housing to be built, etc.
Challenges: Requires mass eviction, pushback from residents due to change of environment/attachment to the slum, temporary dwellings needed for residents, displaces poor from opportunities, increased economic insecurity, etc.
(Accept any more that make sense)
What happened at the Dogger Bank incident?
The Russian Baltic Fleet fired on British fishing boats, thinking that they were Japanese torpedo boats (off the coast of DENMARK) and couldn’t sink them