as level biology exam-style questions (all topics) Flashcards
a coenzyme is a non-protein molecule that activates the enzyme. what is the difference in the molecular structure of the enzyme and the coenzyme?
an enzyme contains amino acids but a coenzyme does not
to what category of macromolecules do most enzymes belong?
proteins
how does the reduction in activation energy by an enzyme affect a chemical reaction?
the reaction proceeds at a faster rate
what causes tomatoes to ripen much more slowly in a refrigerator than they do if left on a table at room temperature?
low temperatures reduce the action of ripening enzymes
the graph shows the optimum temperature of two enzymes. which does this information suggest?
different enzymes perform best at different temperatures, depending on where they function
the diagram illustrates a biochemical process that occurs in organisms, the substance labelled catalyst is also known as an…
enzyme
many biochemical reactions in living systems would occur at a rate too slow to sustain life without the action of enzymes to catalyse the reaction. what is the function of the enzymes?
they decrease the activation energy
ATPases are enzymes that help convert ATP into ADP in cells. when a person exercises, ATPases directly increase which of the following?
the amount of energy released in muscle cells
which of the following roles does an enzyme play when the body processes sucrose (table sugar) into glucose and fructose?
an enzyme increases the rate at which the sucrose breaks down
overheating an enzyme results in the enzymes loss of…
ability to catalyse a reaction
which of the following statements about enzymes is NOT true?
all enzymes have the same shape as their substrates
the graph shows how the concentration of the enzymes amylase affects the breakdown of starch, a common carbohydrate. what can you conclude about their relationship?
reaction rate increases with increasing enzyme
substance X + substance Y (ENZYME C) –> substance W
the equation above represent a chemical reaction that occurs in humans. to support the hypothesis that enzyme C works best in a slightly basic environment, data should be collected about…
the amount of substance W produced at various pH levels
some snake venoms are harmful because they contain enzymes that destroy blood cells or tissues. the damage caused by such a snakebite could best be slowed by…
applying ice to the bitten area
a student and his lab partner perform an experiment in which they measure the effect of temperature on amylase, an enzyme found in saliva that digests starch. their results are shown on the graph. use the graph to determine the humans average body temperature?
37oC
a student and his lab partner perform an experiment in which they measure the effect of temperature on amylase, an enzyme found in saliva that digests starch. what would happen if the enzyme amylase did not exist in the saliva?
starch digestion would not be possible
which enzyme would have the most activity in humans?
enzyme X
trypsin is an enzyme from pancreatic juice (a clear alkaline secretion of pancreatic enzymes as trypsin and lipase that flows into the small intestine and acts on food already acted on by the gastric juice and saliva). the graph shows its activity at various pH levels. what conclusion can be drawn about the activity of trypsin?
trypsin works best at a pH of 6.5
fresh pineapple contains an enzyme that digests proteins. adding fresh pineapple to gelatin (a protein) prevents it from setting or jelling. however, adding cooked or canned pineapple does not have this effect and the gelatin can set normally. what would account for the difference in the results?
cooked or canned pineapple contain denatured enzymes
what would you expect to happen if you increased the substrate concentration in the presence of a fixed amount of enzyme?
the rate of reaction with increase to a point and then remain at a maximum level
some people experience gas and discomfort after eating vegetables, grains, beans, and other high-fiber foods. there is an enzyme product called “BEANO” that breaks down the complex carbohydrates (long chains of sugars) into simple sugars. do you think that the enzyme in BEANO will work to digest the lactose in milk? explain why or why not.
the enzyme BEANO would work to break down lactose as lactose is a sugar which is something BEANO breaks down. it would be broken down into galactose and glucose
what name is given to the condition of stability enabled by a set of processes such as those involved in the maintenance of internal body temperature?
homeostasis
acidic pH levels would be…
below pH 7
alkaline pH levels would be…
above pH 7
the best pH levels to maintain homeostasis in the body would be…
close to pH 7
the best temperature to maintain homeostasis in the body would be…
37oC
what is an example of the human body achieving homeostasis through thermoregulation?
sweat is produced when exercising to keep the body cool
in order for the body to maintain homeostasis, the chemical decomposition of food to produce energy must be followed by…
waste removal
______ digestion takes places from the mouth to the stomach but ______ digestion occurs in the small intestine only
mechanical
chemical
the increased breathing rate signalled by the brain serves…
to increase the O2 levels in the body
the graph shows evidence of disease in the human body. a disruption in the dynamic equilibrium is indicated by the temperature change that occurs between points…
C and D
which of the following correctly describes a positive feedback mechanism?
the response increases the stimulus
the human thermostat is the…
hypothalamus
the nervous system coordinates…
rapid response called reflexes
hormones are chemical signals that are secreted from the…
all of the others
the purpose of insulin in the body is to…
maintain energy homeostasis
which of the following is an example of positive feedback?
blood clotting
which of the following MUST be maintained in order to achieve homeostasis?
all of the others
the feedback loop that regulates blood glucose level in the blood is…
negative feedbackt
the feedback loop that regulates dehydration is…
negative feedback
the feedback loop that regulates childbirth is…
positive feedback
dopamine is a neurotransmitter that is released in the brain when you learn. it rewards you with a feeling of happiness and euphoria. is this a positive or negative feedback mechanism? justify your reasoning.
this is a positive feedback mechanism as it is encouraging you to increase the stimulus more often so that the response can be created increasingly, which basically rewards you.
