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WorksheetsUNIT 1 Topic 3: Internal membranes and Enzymes
Total questions: 20
Worksheet time: 37mins
A student set u an experiment to test the effects of substrate concentration on the rate of an enzyme catalysed reaction. Select the best description of the likely result:
At high concentrations of substrate, the rate of reaction does not continue to increase because the enzyme molecules are working at their maximum rate.
At high concentrations of substrate, the rate of reaction will continue to increase because enzymes are not used up or destroyed by the reactions they catalyse.
The rate of reaction will decrease as substrate concentration increases until the saturation point when all of the enzyme has been used up in the reaction.
The rate of reaction will increase as substrate concentration increases until the saturation point when all of the enzyme has been used up in the reaction.
When an apple is cut, an enzyme called polyphenol oxidase (PPO) causes compounds in the exposed tissue of the apple to react rapidly with oxygen. This starts a process that makes the apple go brown. If apple pieces are plunged into boiling water for five minutes, then cooled, the browning is slowed. Browning is not slowed if the apple pieces are plunged into cod water. Plunging apple into boiling water for five minutes slows the browning process because:
the substrate is denatured by the boiling water.
the enzyme permanently change shape.
the enzyme is washed off the apple in the water.
boiling water enters the apple cells by osmosis, causing them to burst.
Choose the correct statement abut the action of enzymes:
Increased amounts of substrate will always result in more products being made.
Increased amounts of enzyme will always result in more product being made.
Enzyme concentrations are regulated in response to the needs of a cell.
Non-competitive inhibitors bind to the active site of an enzyme.
An important early step in HIV infection is when an enzyme called reverse transcriptase enables the virus to make DNA from its RNA. This enzyme brings the nucleotide building blocks of DNA close together, enabling them to be joined to one another. AZT is one of the earliest and best-known drugs for treating HIV-infected patients. AZT has the same shape as one of the DNA building blocks, called thymine. It can therefore be incorporated into the growing DNA molecule in place of thymine. Once AZT is incorporated into the DNA, no additional nucleotides can be added, so the formation of DNA stops.
From this information, AZT interacts with reverse transcriptase as a:
non-competitive inhibitor.
competitive inhibitor.
coenzyme.
cofactor.
Which of the following ways correctly describes how temperature affects enzymes?
Enzymes show reduced activity at low temperatures because they become denatured.
Enzymes show reduced activity at high temperatures because of damage to the substrate.
Low temperatures change the shape of the active site of enzymes, reducing their activity.
At higher temperatures (within the enzyme's active range), rapid molecular motion causes the substrate and enzyme to collide more frequently.
Coenzymes:
play a minor role in metabolic pathways.
include inorganic substances such as magnesium ions and zinc ions.
are small molecules required for enzyme activity.
take the place of enzymes in some metabolic pathways.
Choose the correct statement abut the action of enzymes:
Increased amounts of substrate will always result in more products being made.
Increased amounts of enzyme will always result in more product being made.
Enzyme concentrations are regulated in response to the needs of a cell.
Non-competitive inhibitors bind to the active site of an enzyme.
Which is the primary energy source for most animals?
carbohydrates
proteins
fiber
fats
Approximately 20 amino acids are essential to living systems. How are amino acids linked together to form proteins?
genetic bonds
peptide bonds
acid-base bonds
hydrogen bonds
Which class of biomolecule includes monosaccharides such as the blood sugar glucose, and the fruit sugar, fructose, which is found in energy drinks?
lipids
proteins
nucleic acids
carbohydrates
Which statement about the function enzymes in living systems is MOST accurate?
Enzymes are proteins that raise the activation energy for chemical reactions.
Enzymes are proteins that lower the activation energy for chemical reactions.
Enzymes are nucleic acids that raise the activation energy of chemical reactions.
Enzymes are nucleic acids that lower the activation energy of chemical reactions.
Grizzly bears, such as the ones shown, gain 200 to 500 pounds of fat every summer, feasting on salmon, berries, and honey. In winter, almost all of this stored weight is lost during hibernation. What type of stored biomolecules allow the grizzly to hibernate this way, without starving to death?
carbohydrates
lipids
proteins
nucleic acids
What function do phospholipids perform in living organisms?
They are used for short-term energy storage.
They serve as the building blocks for proteins.
They make up the major component of cell membranes.
They store information in the nucleus of a cell.
Which statement regarding proteins is true?
Proteins are used to carry the genetic code in the nucleus of a cell.
Proteins make up most of the cell and tissue structures in animals.
Proteins are synthesized in the mitochondria of the cell.
Proteins are the building blocks of amino acids.
Identify the biological function of the biomolecule shown.
long-term energy storage
information coding
short-term energy storage
catalysis of chemical reactions in cells
The enzyme amylase is found in saliva and assists with the break down of starch into glucose. Explain how this occurs without affecting the chemical makeup of the amylase.
Amylase bonds to the starch to speed up the reaction and detaches itself when complete, without being affected.
Amylase does not take place in the starch reaction, but raises the temperature of the saliva to speed up the reaction.
Amylase changes starch into a vapor which increases the reaction rate, but is recreated by the glucose.
Amylase transfers all of its energy to the starch molecules to speed the reaction, but does not take place in the reaction.
Which of the following macromolecules are a prominent part of animal tissues that function in insulation, helping animals conserve heat?
Carbohydrates
Lipids
Proteins
Nucleic acids
What characteristic do all living things share?
They contain DNA.
They are made up of many parts.
They reproduce by mitosis.
They need oxygen to survive.
Which of the following factors is MOST likely to affect the function of an enzyme?
catalysts
size of beaker
proteins
temperature
Which group of macromolecules includes enzymes?
carbohydrates
proteins
lipid
nucleic acids
