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From Kognity
Carbon can form a diversity of stable compounds due to?
Its ability to form covalent bonds with atoms of carbon or other elements.
Which of the following statements on carbon is false?
All carbon-containing compounds are called organic compounds.
Which of the following molecules is ribose?
Pentagon structure with a CH2OH group to the top left
Name the type of molecule provided below: CH3(CH2)xCOOH
Fatty acid
Anabolism is the process in which
Larger molecules are synthesised from smaller molecules.
Which of the following is an example of a catabolic reaction?
Breakdown of glucose during cellular respiration.
In 1828, Friedrich Wöhler artificially produced urea (organic compound) by an internal rearrangement of the atoms of ammonium cyanate (inorganic compound). What important principle did this experiment show?
Organic compounds can be synthesised without the need of a vital force.
Which of the following is false about urea?
The artificial synthesis of urea supported the theory of vitalism.
A hydrophilic substance is one that
Is soluble in water.
Which of the following substances is hydrophobic?
Butter
Which category of compounds can be dissolved in water?
Polar
Which of the following statements about water is false?
It takes very little heat to change the temperature of water.
What causes water to have a relatively high specific heat capacity?
Hydrogen bonds between hydrogen and oxygen of different water molecules
What property of water makes it an excellent coolant?
Water molecules are dipolar, allowing strong cohesive forces between the molecules.
Which materials are dissolved in the blood?
Amino acids, sodium chloride and carbon dioxide.
Which group of compounds would NOT be transported in the blood?
Glucose, starch and amino acids
The latent heats of vaporisation of methane and water are 760 J/g and 2257 J/g, respectively. This implies that:
Less energy is required to evaporate methane.
Which statement is correct?
Methane has lower melting and boiling points than water
How is maltose formed?
Glucose and glucose with a condensation reaction
Cellulose is a polysaccharide made up of?
Numerous glucose molecules joined together
What is the name of the reaction in which monomers are joined together and form a polymer?
Condensation reaction
What polysaccharides is starch made up of?
Amylose and amylopectin
Which of the following is a function of cellulose in plants?
Formation of cell walls
Which of these statements is true?:
Starch consists of both branched and unbranched chains of glucose monomers. Cellulose is a polymer of glucose and galactose. Glycogen is a storage substance in plant tubers. Starch is made up of unbranched chains of glucose.
Starch consists of both branched and unbranched chains of glucose monomers.
Identify the type of carbohydrate molecule shown below: Picture of two circular structures bound together with an O and a CH2
A disaccharide
Which molecules would you find in a triglyceride molecule?
Glycerol and three fatty acids
What type of fatty acid is shown in this diagram? A long chain with a double bond between two carbons in the middle and a hydrogen on each side
Unsaturated trans fatty acid
Which substances are examples of steroids?
Cholesterol and sex hormones
Which of the following statements are true for triglycerides?
They are insoluble in water.
What is an advantage of storing lipids instead of the carbohydrate glycogen for long-term storage?
It stores a larger amount of energy for the same body mass.
Which statement describes a function of triglycerides?
They act as heat insulators.
What are health risks that may be caused by excessive intake of fats?
Obesity, CHD and cancer
Scientists have found trans fats in fatty deposits inside the arteries of more than 300 people who have died of heart attack. This evidence suggests that...?
There is a positive correlation between trans fats and CHD.
John is 1.78 m tall and weighs 90 kg. Calculate his BMI (to 3 significant figures).
28.4
The BMI of a person is 30. Use Table 1 to determine his weight status.
Obese class I
How many water molecules would be released from the condensation reaction shown? Picture of triglyceride structure (glycerol and three fatty acids)
3
Where is cellulose most commonly found?
As part of the cell wall in plant cells.
Which disaccharide is made up of glucose and fructose?
Sucrose
X is a polysaccharide made up of long straight chains of beta-glucose molecules. These long, straight chains are joined by (type of) Y bonds in order to provide stability and strength to the molecule.
X: Cellulose Y: Hydrogen
X have more energy per gram than carbohydrates and are excellent heat
Lipids
Which chemical reaction is taking place when a dipeptide is converted to two amino acids?
Hydrolysis
Name the bond that forms when two amino acids react together in a condensation reaction.
Peptide bond
Which molecules are monomers for polypeptides?
Amino acids
What is the role of DNA in the formation of proteins?
The structure of enzymes is determined by DNA.
Which one of these statements about proteins and polypeptides is true?
A protein may consist of a single polypeptide or more than one polypeptide linked together.
Which characteristic of hemoglobin allows it to be considered a protein with quaternary structure?
It consists of four polypeptide chains.
What would happen if a single amino acid in a protein consisting of 325 amino acids were changed?
The primary structure of the protein would be altered, as well as its tertiary structure. (Because the primary structure decides all the other structures of the protein as well. The code is key.)
The following diagram shows the structure of lysozyme, a protein consisting of a single polypeptide, found in egg white. What is the name given to this level of protein shape?
Tertiary
When comparing the proteome of a yeast cell with that of a human cell, the latter is more complex because:
Yeast is a simple organism and humans are complex. The human genome codes for more proteins than the genome of yeast. The chromosomes of yeast are smaller than those of humans. The yeast proteome consists of smaller proteins.
The human genome codes for more proteins than the genome of yeast.
What does the proteome refer to?
The unique set of proteins that an organism possesses.
Which option (A-D) gives the correct classification of rhodopsin, collagen and hemoglobin as globular and fibrous proteins?
A: Rhodopsin as globular, Collagen as fibrous, Hemoglobin as globular
State the name of the protein that catalyses the fixation of CO2 in chloroplasts.
Rubisco
The optimum pH for an enzyme is 7.8 and the optimum temperature is 37 °C. What would happen to the functionality of this protein if the temperature was raised by 20 °C above its optimum, but the pH stayed the same?
Loss of functionality as it denatures. (Because even if pH stays the same you only need a change in one to cause denaturation).
Which of these statements about the denaturation of protein is true?
The secondary, tertiary and in some cases, the quaternary structures of the protein are irreversibly changed.
What occurs in the induced fit model for enzyme-catalysed reactions?
The enzyme can change its three-dimensional shape to accommodate the substrate.
What is an active site?
The sequence of amino acids responsible for the catalytic activity of enzymes.
What does enzyme-substrate specificity mean?
Enzymes can only catalyse one type of reaction.
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of a reaction by lowering the activation energy.
The diagram below shows the energy levels of a reaction in the presence or absence of an enzyme. What is the best explanation of the different energy levels labelled I, II and III?
iii. where: I = absence of an enzyme II = presence of an enzyme III = exergonic reaction
Carbonic anhydrase (CA) catalyses the production of bicarbonate and protons from carbon dioxide and water. Carbonic anhydrase was purified from bacterium A (represented by circles on the graph) and bacterium B (squares). The activity of the two samples was measured at different pH values. What can be concluded from these results?
Bacterium A carbonic anhydrase works better than bacterium B carbonic anhydrase when the pH is above 10.
A student performed hydrolysis of starch to maltose using the enzyme amylase. He found that at a temperature of 10 °C, the rate of the reaction was very slow. What could account for this slow rate?
The temperature was too low, therefore hardly any collisions occurred between the enzyme and substrate molecules.
Which of the following could cause denaturation of an enzyme?
High temperature.
Proteins have four levels of structural organisation. State which two of these are more likely to be affected when enzymes are denatured.
Tertiary and quaternary structure.
Yogurt is tolerated better than milk by lactose-intolerant people because: The lactose in yogurt is denatured by bacteria. Yogurt has no lactose. The lactose in yogurt is immobilised by bacteria. Lactase from bacteria in yogurt helps digest the lactose.
Lactase from bacteria in yogurt helps digest the lactose.
Immobilised enzymes are used in industry because: Enzymes are denatured. Enzymes are less stable to temperature changes. Enzymes can be recycled and used several times. Enzymes can be kept at high temperatures for a long time.
Enzymes can be recycled and used several times.
In an experiment, a student added 2 ml of milk to 2 ml of 0.1% lipase solution at room temperature and recorded the change in pH after 10 minutes. He repeated the experiment several times in water baths set at different temperatures. State the independent variable in this experiment.
Temperature
In a preliminary experiment, a student added 2 ml of full cream milk to 2 ml of 0.1% lipase solution at room temperature (22 °C) and recorded the change in pH after 10 minutes. She observed that there was hardly any change in pH at this time. Which of the following changes would not cause a measurable decrease in pH?
Decreasing the enzyme concentration
Why is the graph below not an accurate representation of how the rate of reaction of an enzyme catalyzed reaction changes with temperature?
Because enzymes denature at high temperatures.
Which part of an enzyme catalyses reactions?
The active site.
What happens to enzymes when you increase the amount of substrate?
An increase in enzyme activity until the point of saturation where they work at their maximum rate.
Which of the following would form an enzyme-substrate complex?
Lactase and lactose
How is the the DNA structure usually described?
Double helix
What is the name of the pentose present in DNA molecules?
Deoxyribose sugar
Which statement about RNA is correct?
RNA consists of uracil instead of thymine.
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40
Which method was used in the discovery of the DNA double helix?
X-ray
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
Which is the correct sequence of events for DNA replication?
Unwinding DNA, synthesis of a new DNA strand, winding DNA
Name the enzyme that separates the two strands of the DNA double helix during replication.
Helicase
In the experiments performed by Meselson and Stahl, E. coli were grown for many generations in a medium containing 15N, then for one generation in 14N. What results for the DNA of the last generation showed that replication was semi-conservative?
One strand containing only 15N and one strand containing only 14N.
DNA replication occurs by a:
Semi-conservative method
Which method was used in Meselson and Stahl's experiment to prove their theory about the semi-conservative nature of the DNA replication?
Use of isotopes
A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is?
UCA
Which of the following enzymes is responsible for uncoiling and separating the DNA strands during transcription?
RNA polymerase
Deduce the DNA base sequence of the antisense strand used to generate the following bases on the mRNA: UAG CCA UCC GGC.
ATC GGT AGG CCG
(Use the table with the genetic code to answer this) A possible sequence of nucleotides in the mRNA that would code for the polypeptide sequence Phe-Leu-Ile-Val would be:
UUU-CUU-AUU-GUU
What is the role of tRNA in translation?
It brings amino acids to the ribosome.
Refer to the genetic code table below to deduce the codon for phenylalanine (Phe).
UUU
Which components are needed for PCR?
Primers, Taq polymerase and DNA nucleotides.
What is the characteristic feature of Taq polymerase that allows its use in PCR?
Taq polymerase does not denature at high temperatures (between 50 to 80 degrees Celsius).
A unicellular organism that carries a specific gene from another organism is called a ______ organism.
transgenic
The production of human insulin in bacteria is possible because of?
The universality of the genetic code, which allows gene transfer between species.
Which organelles are used in transferring genes from one organism to another?
Plasmids
A tRNA molecule with anticodon CAG carries the amino acid phenylalanine. Which codon of mRNA will the tRNA join?
GUC
If a polypeptide consists of 240 amino acids, what is the minimum number of nucleotides needed on the sense strand of a gene to code for it?
720
Which of the following is true about DNA replication?
DNA replication happens during the S phase of the cell cycle.
Which of the following would be listed as the earliest occurrance during DNA replication?
Free nucleotides base pair to original polynucleotide.
Where does glycolysis take place in eukaryotic cells?
In the cytoplasm
What is the function of ATP molecules?
They provide energy for biochemical processes such as pumping molecules across membranes.
Where is the electron transport chain located in the diagram of a mitochondrion below?
C (inner membrane)
Note 
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