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biochemistry MRQ...

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1 The prokaryotic cell contains A. B. C. D. E.

A single chromosome surrounded by a nuclear membrane A cytoplasm rich in ribosomes Inclusion bodies made of proteins Mitochondria A cell wall made of cross-linked peptidoglycan

The following statements relate to the features and properties of eukaryotic cells: A. B. C. D. E.

Eukaryotic cells are always multicellular Eukaryotic cells have a membrane bound nucleus Eukaryotic cells are generally smaller than prokaryotic cells Eukaryotic cells contain membrane bound organelles Eukaryotic cells contain a protein based cytoskeleton

Consider the following statements about cells: A. B. C. D.

Human beings contain eukaryotic cells Viruses and bacteria are similar in size Both plant and animal cells contain mitochondria Both prokaryotic and eukaryotic cells contain DNA that is associated with histone proteins E. All eukaryotic cells contain approximately the same amount of rough endoplasmic reticulum Which of the following statements about intracellular organelles are true, and which are false? A. Protein synthesis takes place in the nucleus B. Mitochondria are surrounded by a double membrane C. Smooth endoplasmic reticulum is the site of synthesis of lipids such as cholesterol D. The only function of the plasma membrane is to keep cell contents separate E. Glycolysis takes place in the cytosol Which of the following statements about intracellular organelles are true, and which are false? A. B. C. D. E.

ATP synthesis takes place in the outer mitochondrial membrane Lysosomes contain degradative enzymes Chloroplasts contain stacks of membranes called grana The cytoskeleton contains the proteins actin and tubulin The nucleolus is an area within the nucleus where mRNA is made

The following are membrane bound organelles of the eukaryotic cell: A. B. C. D. E.

Ribosomes. Endoplasmic reticulum. Periplasmic space. Mitochondria. Golgi bodies.

Endosymbiotic theory concerns the following events in the evolution of cellular life: A. B. C. D. E.

Chemiosmotic coupling and the synthesis of ATP The development of a membrane-bound nucleus The development of mitochondria from a prokaryotic ancestor The generation of a charge potential at the cell membrane The development of chloroplasts from a prokaryotic ancestor

The following features are unique to the Archaea: A. B. C. D. E.

The presence of pseudopeptidoglycan in the cell wall Phospholipids in the cell membrane contain ester linkages The cell membrane can comprise a phospholipid monolayer The presence of 70S ribosomes The presence of flagella

The following features are found in all forms of cellular life and imply a common ancestor: A. B. C. D. E.

Templated polymerisation Enclosure in a membrane composed of phospholipid Transcription carried out by ribosomes Chemiosmotic coupling Membrane-bound organelles

Concerning protists: A. B. C. D. E.

Some have the capability to cause disease in humans They are members of a single Eukaryotic supergroup They use a variety of different locomotor organelles for motility Several members can form hyphae Their cell walls can contain chitin

The alkaline vent theory of cellular life suggests: A. B. C. D.

Iron-sulphur bubbles were responsible for the formation of organic compounds DNA was the first self-replicating molecule to arise Ribozymes pre-dated enzymes The emergence of a charge potential occurred before the formation of phospholipid membranes E. Eukaryotes emerged before prokaryotes

Consider the following statements A. Ionic bonds form between atoms which need to gain or lose small numbers of electrons to gain a full outer shell B. Ionic bonds are formed when two electrons are shared between two atoms C. A carboxyl group can be ionised D. Proteins are formed via condensation reactions E. Induced dipoles only occur between charged groups

Which of the following statements about the features highlighted on the molecule below are true, and which are false?

A. The bond marked A is a double bond, in which two pairs of electrons are shared B. The bond marked D will be shorter, stronger and more rigid than the bond marked A C. The group marked B is a carbonyl group D. The group marked C would be found on an amino acid E. The functional group marked E is a carboxylic acid group A condensation reaction: A. B. C. D. E.

Occurs when proteins are digested into individual amino acids Releases a water molecule Is similar to a hydrolysis reaction Is necessary to build up starch Is important for polymer formation

Consider the following statements about bonding A. B. C. D. E.

Ionic bonds are weak bonds Carbon atoms only form covalent bonds in biological molecules Water molecules form hydrogen bonds Hydrogen-bonds are weak bonds Hydrophilic molecules form covalent bonds with water in solution, causing them to be soluble in water

Which of the following are weak bonds? A. B. C. D. E.

Electrostatic interactions Hydrophobic interactions Single covalent bonds Polar bonds Induced dipoles

Which of the following statements about functional groups are true, and which are false? A. B. C. D. E.

Thiol groups contain a sulphur atom Phosphate groups are positively charged at pH 7 Glucose contains several hydroxyl groups Amino groups can be either uncharged or positively charged Aldehyde groups contain a carbon-oxygen double bond

Consider the following statements about the these amino acids A. B. C. D. E.

Phenylalanine has a hydrophobic R group Leucine has a polar R group Isoleucine has a non-polar R group Methionine contains sulphur and can form disulphide bridges Glutamate contains a charged R group

Consider the following statements A. B. C. D. E.

An aqueous solution with a high pH has a high concentration of protons At pH 1, the carboxyl group on an amino acid would be uncharged The amino group on an amino acid would act as a buffer at pH 9 The pKa of a charged group is the pH at which the group is fully ionised When amino acids are incorporated into a protein, it is their R groups that contribute to the charge on the protein

Which statements about amino acids are true and which are false? A. B. C. D. E.

At physiological pH, many amino acids exist as zwitterions. The R group on acidic amino acids have a positive charge at physiological pH. The R group on glutamine is a hydrogen. Valine has a polar R group Cysteine and methionine contain a sulphur atom.

Which statements about buffers are true and which are false? A. Strong acids and bases are effective buffers B. A buffer contains both a conjugate acid and a conjugate base C. When hydrogen ions are added to a buffer solution, the conjugate base reacts with the hydrogen ions, preventing the pH from decreasing D. The pH of a buffer can be determined using the equation pH = -log10 [H+] E. Bicarbonate and phosphate are common buffers in living organisms

Consider the ionisation of the amino acid shown below:

A. B. C. D. E.

At pH 2 the molecule would have an overall positive charge This amino acid would act as a buffer at pH 4 At pH 7 the amino acid would have an overall negative charge pKa2 is the pH at which the amino group is 50% ionized When incorporated into a polypeptide, this amino acid would be negatively charged at pH 7

Consider the following statements about cellular macromolecules. A. B. C. D. E.

Starch is a storage polysaccharide in plants Triacylglycerols are mainly found in cell membranes Nucleotides are the building blocks of DNA Proteins are made up of chains of the same repeated amino acid ATP is an example of a monosaccharide

Which of the following are examples of a carbohydrate? A. B. C. D. E.

ribose cellulose alanine glyceraldehyde cytosine

Which of the following statements concerning carbohydrates are true and which are false? A. B. C. D. E.

Only the L isomers of sugars are found in living cells. The empirical formula of a carbohydrate is CH2O. Each monosaccharide contains one chiral carbon. A pentose contains 5 carbon atoms Glucose is an example of a ketose

Which of the following statements concerning carbohydrates are true and which are false? A. B. C. D. E.

Sucrose is composed of glucose and fructose Disaccharides are connected by glycosidic bonds In solution, glucose exist mainly as α-D-glucopyranose Cellulose contains only β(1, 4) bonds giving it a flat structure Glycogen contains both α(1, 4) and α(1, 6) bonds, giving a branched structure

Which of the following statements concerning cellular polysaccharides are true and which are false? A. Glycogen is a structural polysaccharide found in animal cells. B. Glycogen contains many glucose monosaccharides linked by glycosidic bonds. C. The α (1, 4) glycosidic bonds in starch cause the molecule to curve into a helical structure. D. Cellulose is a mixture of amylose and amylopectin E. Short chains of carbohydrates can be found attached to proteins and lipids Which of the following statements about nucleic acids are true and which are false? A. B. C. D. E.

Adenine and thymine are purines Purines have a 9- membered double ring structure Uracil is a pyrimidine base found in RNA but not DNA Adenosine is a nucleotide Deoxyguanosine contains a deoxyribose sugar attached to a guanosine base

Which of the following statements about nucleic acids are true and which are false? A. B. C. D. E.

ATP is a nucleoside phosphate Cytosine is a pyrimidine A nucleoside is composed of a base bonded to a pentose sugar dCTP has three phosphate groups attached to the cytosine base 3’5’ cyclic AMP is involved in intracellular signalling

Consider the following statements about DNA and RNA. A. The nucleotides in DNA are connected by glycosidic bonds B. Bonds between nucleotides form between the 3’ carbon on one sugar molecule, and the 5’ carbon on the next C. RNA is usually double stranded D. RNA is a structural component of ribosomes E. There are several forms of both DNA and RNA Consider the statements about fatty acids A. B. C. D. E.

Fatty acids are made up of carbon, hydrogen, oxygen, and nitrogen. Fatty acids contain a carboxylic acid group. Fatty acids that contain one or more double bonds are saturated fatty acids. The double bonds in fatty acids are almost always cis The carbon atom next to the carboxylate carbon is the alpha (α) carbon.

Consider the following statements about fatty acids A. B. C. D. E.

Fatty acids are important energy storage compounds. Fatty acids are stored as triacylglycerol. Fatty acids are important components of biological membranes. Fatty acids that contain double bonds are unsaturated fatty acids. Double bonds in fatty acids are always trans.

Which of the following statements about the roles of lipids are true and which are false? A. B. C. D.

Prostaglandins may act as hormones. Sphingolipids are important in nervous tissue Triacylglycerols act as energy storage molecules. Glycerophospholipids are composed of a hydrophilic head group attached to three fatty acids E. Glycerophospholipids are a major component of cell membranes

Cholesterol: A. B. C. D. E.

contains three six-membered and one 5-membered ring is amphipathic is the major sterol found in plants is a vital component of cell membranes is required for the synthesis of vitamin C

Which of the following statements about the structures of lipids are true and which are false? A. B. C. D. E.

Saturated fats contain at least one carbon-carbon double bond. Most unsaturated fatty acids are in the “trans”-conformation. The fatty acids in a triacylglycerol may have different chain length. Waxes have very long chain lengths. Glycerophospholipids contain two fatty acid chains.

Hereditary information: A. B. C. D. E.

is passed on via templated polymerisation was shown to be carried via DNA by the transformation of S. pneumonia is encoded by 20 types of L-amino acids is always accurately passed on to the next generation depends upon the complementary double-stranded nature of DNA

Regarding chromosomes A. B. C. D. E.

Their numbers are similar among all mammals Bacteria have a single linear chromosome that forms the nucleoid They consist of DNA complexed with proteins They contain all the hereditary information in prokaryotes and eukaryotes Humans have 46 in the nucleus of all their somatic cells.

Crick’s “Central Dogma of Molecular Biology” states that hereditary information can move from A. B. C. D. E.

RNA to DNA DNA to RNA protein to RNA protein to DNA DNA to DNA

Consider the following statements A. B. C. D. E.

The entire genome of an organism is transcribed Genes are defined as regions that encode proteins The same genes in all human cells are transcribed E. coli encodes proteins on both strands of its chromosomal DNA Humans have the largest genome size of all species.

Consider the following statements A. Synteny can be observed when comparing mammalian chromosomes. B. Genome size always matches body size C. DNA is less condensed in the interphase nucleus than in metaphase chromosomes. D. Euchromatin is more accessible than heterochromatin. E. Euchromatin is predominantly found on metaphase chromosomes.

Gene Duplication A. describes the duplicate copies of each gene that individual inherit from their parents B. may precede the creation of a pseudogene C. results in the deletion of regions of DNA within the chromosome D. leads to the creation of telomeres E. is responsible for the creation of families of related proteins

The human genome A. B. C. D. E.

consists of 3.2 million base pairs of DNA encodes approximate 30,000 genes has high-copy-number repetitive elements that make up 50% of the total DNA contains no intron regions has protein-coding sequences that make up 89% of the total DNA.

Non-coding regions in eukaryotic genomes include A. B. C. D. E.

telomeres centromeres RNA genes exons replication origins

Chromatin remodelling to expose active genes A. B. C. D. E.

Involves histone proteins Occurs only during metaphase Results in the formation of two chromatids Enables dynamic access to different genes in different cell types Involves the movement of chromosomes within the nucleus.

Consider the following statements about DNA structure A. Nitrogenous bases are linked to the pentose sugar at carbon no. 3 B. Nitrogenous bases are linked to the pentose sugar at carbon no. 1 C. A phosphodiester bond links carbons 5 and 1 of adjacent sugars within a DNA strand D. A phosphodiester bond is a strong ionic bond E. The two strands of a DNA double helix are held together by covalent bonds

Consider the following statements about DNA A. B. C. D. E.

DNA is synthesised in the 3’ to 5’ direction There are 12 base pairs per complete turn Nucleotides are linked by 5’ to 3’ phosphodiester bonds Base pair stacking contributes to the stability of the double helix The two strands of the double helix are antiparallel

Which of the following statements about RNA molecules are true? A. B. C. D. E.

They can form secondary structures They are between 19-22 nucleotides in length They are always base-paired They often fold into compact structures They are chemically distinct from DNA

Consider the following statements about natural DNA replication A. A short strand of DNA is used as the primer B. DNA polymerase III can remove nucleotides from the 3’ end of the growing strand C. The primer remains a component of the newly formed DNA strand D. There are multiple replication initiation sites in eukaryotes E. DNA helicase, with the use of ATP, separates the two strands Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive thymine had been added. What would happen if a cell replicated once in the presence of this radioactive base? A. B. C. D. E.

One of the daughter cells, but not the other, would have radioactive DNA. Neither of the two daughter cells would be radioactive. All four bases of the DNA would be radioactive. Radioactive thymine would pair with nonradioactive guanine. DNA in both daughter cells would be radioactive.

Which of the following statements about mRNAs are true? A. B. C. D. E.

mRNAs contain a region called the promoter mRNAs in prokaryotes can be polycistronic mRNAs can sometimes include regulatory elements mRNAs must be charged via an aminoacyl synthetase relative mRNAs levels in a cell often correlate to the levels of proteins they encode

Consider the following statements about genes A. The protein coding region determines when and how strongly a gene is transcribed B. The translation start codon represents the beginning of the gene C. mRNA often covers more than the protein coding region of a gene D. Gene transcription and gene translation are coupled in eukaryotes E. The translational start codon is written as AUG also encodes methionin The translational start-codon on mRNA is: A. B. C. D. E.

ATG UUG AUG UAG GUA

Translational stop-codons are encoded by the following DNA triplets: A. B. C. D. E.

TAA TTG GAG TGA UAG

Which of the following statements about ribosomes are true? A. B. C. D. E.

They are found in the nucleus of cells They are complex molecular machines They are DNA-protein complexes They have a large and a small subunit They are numerous in the cell

When the coding region of a bacterial gene encodes 321 codons: A. B. C. D. E.

The encoded protein contains 963 nucleotides; The transcribed mRNA may contain introns; The encoded protein is composed of 320 amino acid residues; The encoded protein contains a sixth of 960 amino acid residues; The coding region of the gene is 963 base pairs in length.

In Eukaryotes, translation A. B. C. D. E.

occurs in the nucleus occurs at the same time as transcription is carried out by ribosomes can take place on the rough endoplasmic reticulum surface can occur at a polyribosome

Prokaryotic genes A. B. C. D. E.

Generally contain introns Can be polycistronic Are only found on chromosomal DNA Are translated when they are transcribed Are often efficiently packed onto the genome sequence

Protein synthesis by ribosomes: A. B. C. D. E.

Does not cost energy, but depends on the availability of amino acids Involves directed movement of the ribosome on the mRNA strand Requires activated tRNAs which carry amino acids Is catalyzed by the RNA component Starts from the C-terminus of the nascent chain

During the transformation of competent E. coli using a plasmid A. B. C. D. E.

all the bacterial cells take up the plasmid. the plasmid is replicated multiple times in each bacterial cell. a colony can form from a single transformed bacterial cell. the origin of replication encodes antibiotic resistance. the multiple cloning site is cleaved by restriction enzymes

Regarding alkaline lysis plasmid preparation A. B. C. D. E.

chromosomal DNA re-hybridises during the neutralisation stage bacterial cell proteins are denatured and aggregate RNAase is denatured during the SDS/NaOH lysis stage plasmid DNA remains soluble throughout the lysis and neutralisation. cellular RNA aggregates and becomes insoluble.

A plasmid of 5000 base pairs containing three EcoRI restriction enzyme sites at positions 200, 1900, 2900 A. B. C. D. E.

will yield 4 fragments when fully digested will yield three fragments of equal size when fully digested will yield three fragments ...