Chemistry
Which of the two following statements about carbon is correct?
A. Its atomic number is 8
B. Its electronic configuration is 1s2 2s2 3s2
C. Its commonest isotope has an atomic mass of 12 Da
D. Its most typical valency is 4
E. It is more electronegative than oxygen
C. Its commonest isotope has an atomic mass of 12 Da
D. Its most typical valency is 4
Which TWO of the following are true of the folding of a soluble globular protein?
A. As the protein folds, its configurational entropy increases
B. The folding usually buries hydrophobic residues inside a globular protein
C. The reorganisation of water around the folding protein increases the water's entropy
D. Protein folding generally requires an external source of free energy to drive it
E. Protein folding is driven mostly by the formation of disulfide bonds
B. The folding usually buries hydrophobic residues inside a globular protein
C. The reorganisation of water around the folding protein increases the water's entropy
Anaerobic respiration in bacteria such as Pseudomonas typically produces which ONE of the following products?
A. Ethanol
B. Lactate
C. Nitrogen
D. Oxygen
E. Hydrogen sulfide
C. Nitrogen
Why can't carbon dating be used to date fossils older than about 70,000 years? (Select ONE answer.)
A. Because the half-life of carbon-14 is too short
B. Because carbon dating is a form of relative dating
C. Because carbon dating requires volcanic rocks
D. Because the earth was too hot more than 70,000 years ago
E. Because carbon dating cannot be used to date fossils directly
A. Because the half-life of carbon-14 is too short
You enter a candy store with shelves full of delicious carbohydrates. Unfortunately, someone has filled all the rest of the space in the store with lignin. What ONE of the following would be the best strategy to get at and eat the delicious carbohydrates?
A. Release hydrolytic exoenzymes like cellulases, hemicellulases and pectinases ONLY
B. Release oxidative exoenzymes ONLY
C. Release oxidative exoenzymes first and then hydrolytic exoenzymes later
D. Release hydrolytic exoenzymes first and then oxidative exoenzymes later
E. Start a fire
C. Release oxidative exoenzymes first and then hydrolytic exoenzymes later
Which THREE of the statements below about first-order reactions are true? v is velocity, k is a rate constant.
A. Their rate law is of the form v = k
B. They have a well-defined, constant half-life, given by t½ = ln(2)/k
C. The concentration of the reactant in a first-order reaction shows exponential decay
D. The SN1 alkaline hydrolysis of a tertiary halogenoalkane (e.g. (CH3)3CBr) shows first order kinetics with respect to [OH−]
E. Radioactive decay can typically be modelled as first order with respect to the concentration of radioisotope
B. They have a well-defined, constant half-life, given by t½ = ln(2)/k
C. The concentration of the reactant in a first-order reaction shows exponential decay
E. Radioactive decay can typically be modelled as first order with respect to the concentration of radioisotope
Which ONE of the following comparisons of C3 metabolism and CAM are accurate?
A. C3 is mostly found in xerophytic plants; whereas CAM is mostly found in tropical plants
B. C3 requires RuBisCO; but CAM does NOT, so this enzyme is not expressed in CAM plants
C. C3 is a feature of cactuses; CAM is found in many grasses
D. C3 plants typically have kranz anatomy; whereas CAM typically have large vacuoles
E. C3 plants typically photorespire; but CAM plants do NOT photorespire to any significant extent
E. C3 plants typically photorespire; but CAM plants do NOT photorespire to any significant extent
Which THREE of the following statements about bacterial appendages are correct?
A. Flagellar rotation in bacteria is directly dependent on ATP hydrolysis
B. The F-pilus of Escherichia coli is involved in bacterial conjugation
C. Pili can be used for a form of motility known as twitching motility
D. Escherichia coli has a single polar flagellum
E. Pili can be used to attach bacteria to surfaces
B. The F-pilus of Escherichia coli is involved in bacterial conjugation
C. Pili can be used for a form of motility known as twitching motility
E. Pili can be used to attach bacteria to surfaces
The conquest of land by plants transformed the atmosphere and biosphere; it is associated with the early evolution (c. 450 MYA) of: (Select THREE answers.)
A. Flowers for reproduction on land
B. Sporopollenin to protect spores from dehydration and UV radiation
C. Symbiosis with fungi for mineral nutrient uptake
D. Stomata to allow gas exchange
E. Animal dispersal of pollen
B. Sporopollenin to protect spores from dehydration and UV radiation
C. Symbiosis with fungi for mineral nutrient uptake
D. Stomata to allow gas exchange
In flowering plants: (Select ONE answer.)
A. Double fertilization means that two sperm nuclei fertilize the egg cell
B. One sperm fertilizes each synergid cell
C. One sperm fertilizes the polar cell and another fertilizes the egg cell
D. Double fertilization means that two sperm nuclei fertilize the polar cell
E. Each sperm nucleus undergoes karyogamy with each polar nucleus
C. One sperm fertilizes the polar cell and another fertilizes the egg cell
Which TWO of these statements about functional groups are accurate?
A. Amides are usually more basic than amines
B. Aromatic alcohols like phenol are usually more acidic than aliphatic ones like methanol
C. Thiols react with carboxylic acids to form ethers
D. An imine is a compound that contains a heterocyclic nitrogen atom
E. In open-chain form, monosaccharides typically contain alcohol groups and ketone/aldehyde groups
B. Aromatic alcohols like phenol are usually more acidic than aliphatic ones like methanol
E. In open-chain form, monosaccharides typically contain alcohol groups and ketone/aldehyde groups
The activity of enzymes is frequently regulated. Which THREE of the following are true?
A. Citrate provides negative feedback from Krebs on glycolysis by allosterically inhibiting phosphofructokinase
B. Oxaloacetate provides positive feedforward in Krebs cycle by allosterically activating succinate dehydrogenase
C. Kinases often activate enzymes by transferring a phosphate group from ATP to an alcoholic amino acid residue in the protein
D. Trypsin can be switched on and off by reversible removal of part of its peptide backbone
E. In many allosterically modulated enzymes, the substrate itself also acts as an allosteric activator
A. Citrate provides negative feedback from Krebs on glycolysis by allosterically inhibiting phosphofructokinase
C. Kinases often activate enzymes by transferring a phosphate group from ATP to an alcoholic amino acid residue in the protein
E. In many allosterically modulated enzymes, the substrate itself also acts as an allosteric activator
When making a defined medium for growth of a chemoorganoheterotroph, a source of which TWO of the following would typically be added as trace elements?
A. Carbon
B. Zinc
C. Phosphorus
D. Sulfur
E. Copper
B. Zinc
E. Copper
If two or more species possess a shared derived character: (Select TWO answers.)
A. They must form a paraphyletic group
B. They must be in possession of an analogous character
C. At least one species must be the direct ancestor of another species
D. They form a clade (i.e. are each other’s sister group)
E. They can be said to share a synapomorphy
D. They form a clade (i.e. are each other’s sister group)
E. They can be said to share a synapomorphy
Which TWO of the following eukaryotic supergroups have been described accurately below?
A. The excavates are a clade of multicellular, photosynthetic eukaryotes with silica cell walls
B. The heterokonts are a clade containing both photosynthetic and heterotrophic organisms
C. The fungi are more closely related to the plants (sensu lato, i.e. Archaeplastida) than they are to the animals
D. The Rhizaria include the foraminifera, which are amoebae with calcium carbonate shells
E. The alveolates have three main subgroups: the coccolithophores, the slime-moulds, and the euglenid algae
B. The heterokonts are a clade containing both photosynthetic and heterotrophic organisms
D. The Rhizaria include the foraminifera, which are amoebae with calcium carbonate shells
Which TWO of the following statements about amino acids are correct?
A. ALL of the proteinogenic amino acids are chiral
B. At pH 7 the amino acid alanine exists as zwitterion
C. An amino acid contains an amine group and a carboxylic acid group
D. There are 30 standard proteinogenic amino acids
E. An alanine residue in a protein can form a phosphodiester bond
B. At pH 7 the amino acid alanine exists as zwitterion
C. An amino acid contains an amine group and a carboxylic acid group
Photosynthesis is regulated to integrate its various components. Which ONE of the following processes contribute to this regulation?
A. The pH optimum of RuBisCO is on the acidic side of neutral
B. When conditions in the stroma are reducing (i.e. FdRED is abundant), RuBisCO is INACTIVATED by a kinase
C. Light harvesting complexes can be reversibly phosphorylated to balance flux into PS-I vs PS-II
D. RuBisCO is allosterically activated by citrate and phosphoenolpyruvate
E. Accumulation of oxidised plastoquinone (PQ) in the cytoplasm of the cell causes activation of PS-I
C. Light harvesting complexes can be reversibly phosphorylated to balance flux into PS-I vs. PS-II.
Which THREE of the following are characteristics of the bacterial genus Mycoplasma?
A. Mycoplasma have no cell wall
B. Mycoplasma are usually rod shaped
C. Phylogenetic analysis indicates Mycoplasma to be part of the Gram positive bacteria
D. Phylogenetic analysis indicates Mycoplasma to be Archaea
E. Mycoplasma are intracellular pathogens of eukaryotes
A. Mycoplasma have no cell wall
C. Phylogenetic analysis indicates Mycoplasma to be part of the Gram positive bacteria
E. Mycoplasma are intracellular pathogens of eukaryotes
The diagram below shows a hypothetical phylogenetic tree and a character matrix for the six species (A-F) shown in the tree. Given this data matrix and this tree, what is the length of the tree? (Select ONE answer.)
A. 1 step
B. 2 steps
C. 3 steps
D. 4 steps
E. 5 steps
D. 4 steps
During development and morphogenesis, the gradient of morphogen is often observed to be involved in controlling allometric growth. Which ONE statement best explains such an observation?
A. Morphogen gradient allows cells to make their own decisions to proliferate
B. Cells away from the morphogen source are less sensitive to the signal
C. Cell-cell signalling is required for allometric but not isometric growth
D. Non-linear morphogen gradient can be easily translated into differential growth
E. Diffusing morphogens normally inhibit cell proliferation and isometric growth
D. Non-linear morphogen gradient can be easily translated into differential growth
Which THREE of the following are true of methods of protein estimation?
A. A rule of thumb for A280 is that an absorbance of 1 means a concentration of c. 1 mg mL−1
B. The biuret reagent contains copper (II) ions
C. The Bradford method assumes the calibrant and analyte proteins contain similar amounts of lysine and arginine
D. The biuret method suffers from severe interference from nucleic acids
E. The Bradford method is a non-destructive method of protein estimation
A. A rule of thumb for A280 is that an absorbance of 1 means a concentration of c. 1 mg mL−1
B. The biuret reagent contains copper (II) ions
C. The Bradford method assumes the calibrant and analyte proteins contain similar amounts of lysine and arginine
Which ONE of the following is a good (but much simplified!) summary of what β-oxidation achieves? n represents the number of the named molecule (and assume this is even).
A. 1 triacylglycerol → 3 fatty acids + 1 glycerol
B. n fatty acids → 2n acetyl CoA
C. CH3(CH2)nCOOH → (n+2)/2 acetyl CoA
D. acetyl CoA → 2 CO2
E. C6H12O6 → 2 CH3COCOOH
C. CH3(CH2)nCOOH → (n+2)/2 acetyl CoA
Endospores are produced in only one bacterial clade. Which one?
A. Cyanobacteria
B. Firmicutes
C. Actinobacteria
D. Proteobacteria
B. Firmicutes
Which THREE of the following options have the Doushantou "metazoan embryo" fossils been claimed to be?
A. Giant bacteria
B. Volvocine algae
C. Holozoan parasites
D.Vascular plants
E. Lichen spores
A. Giant bacteria
B. Volvocine algae
C. Holozoan parasites
Which ONE of the following statements are true about Apicomplexan parasites?
A. They display a unique form of locomotion termed gliding motility that relies on cilia distributed around the apical complex
B. The apicoplast exports proteins involved in host cell recognition and invasion
C. Parasites with a defective apicoplast are unable to re-invade cells after an initial invasion event due to improper formation of the parasitophorous vacuole
D. Apicomplexan parasites ingest most of their nutrients through the flagellar pocket
E. They possess a large group of variant surface glycoprotein (VSG) genes that show high levels of antigenic variation
C. Parasites with a defective apicoplast are unable to re-invade cells after an initial invasion event due to improper formation of the parasitophorous vacuole