Practise IB Biology HL C1.1 by explaining enzyme specificity, metabolic reactions, rate evidence, inhibition and feedback control in biological pathways.
162 questions in this syllabus scope, with question parts counted together.
117 papers analysed · Tagging incomplete
Outline the action of enzymes.
Metabolic pathways are dependent on enzyme-catalysed reactions. Which term corresponds with the description?
Term
Description
allosteric inhibition
the inhibitor binds to the active site of an enzyme
competitive inhibition
the maximum rate of a reaction is lowered as the substrate concentration increases
non-competitive inhibition
raises the maximum rate of reaction of a given enzyme reaction
end-product inhibition
the end-product in a metabolic pathway binds to an allosteric site of the first enzyme
Cell metabolism involves anabolic and catabolic reactions. Which process directly involves anabolism?
Active transport of ions
Release of energy from glucose
Production of intracellular enzymes
Breakdown of worn-out cell organelles by lysosomes
Define the active site of an enzyme.
(a) Draw a labelled diagram to show the molecular structure of a membrane.
Some proteins in membranes act as enzymes. Describe a model that accounts for the ability of enzymes to catalyse reactions.
The image shows leucyl-tRNA synthetase from Thermus thermophilus complexed with a tRNA. This tRNA-activating enzyme joins the amino acid leucine to tRNA using ATP.
Why is leucyl-tRNA synthetase not used to join the amino acid valine to tRNA?
Phosphorylation of valine occurs at a later stage.
Valine does not need to be activated to attach to tRNA.
Leucyl-tRNA synthetase is substrate-specific.
Valine has a different anticodon from leucine.
A solution of laundry detergent containing enzymes was used to soak some blood-stained clothes in order to remove the stains. Each item of stained clothing was soaked in a solution of a different temperature. After one hour, the stains remaining on the clothes were measured on a colour intensity scale.
What is a valid explanation for these results?
At the enzymes denature.
At the shape of some enzyme active sites change.
At the enzyme and substrate molecules have the greatest kinetic energy.
At the chance of successful binding between enzyme and substrate is low.
The inhibitory effect of three different statins ( S1, S2 and S3 ) on the activity of HMG-CoA reductase, an enzyme involved in cholesterol metabolism in the liver, was investigated.
Identify an independent variable in this investigation.
State one variable that needs to be controlled.
Outline how the rate of reaction of HMG-CoA reductase can be calculated.
The graph shows the energy changes during a chemical reaction. The horizontal lines represent the original energy values.
Which graph represents the energy changes once a suitable enzyme has been added?
What is secreted by the pancreas for digestion in the small intestine?
Lipase to break bond between phosphate and fatty acid
Insulin to digest glycogen to glucose
Amylopectin to digest starch to maltose
Endopeptidase to digest proteins to peptides
Common bottlenose dolphins, Tursiops truncatus, are marine mammals of temperate and tropical oceans throughout the world, where they feed on fish, squid and crustaceans.
Research has been carried out on a population of these dolphins in Sarasota Bay, Florida. The table shows the mean sea surface temperature in Sarasota Bay and catch per unit effort (CPUE) in winter and summer. A large CPUE indicates it would take little effort for the dolphin to catch a lot of prey.
Explain the differences in BMR between desert and polar mammals up to a mass of .
Above a body mass of 10 kg , there is little difference in BMR between desert and polar mammals.
Suggest reasons for this.
The reaction that produces urea in liver cells is shown.
This reaction forms part of a metabolic cycle. Outline one feature of a metabolic cycle that distinguishes it from a chain.
Chemicals are involved at all levels of biology: cell functions, structure of organisms, interactions with the environment.
Distinguish between competitive and non-competitive enzyme inhibition.
The graph illustrates how enzyme-catalysed reactions can be affected by inhibitors. Which curve shows the effect of statins on the rate of cholesterol synthesis in the body?
The production of isoleucine from threonine is summarized in the diagram. This process involves several steps and is regulated by feedback inhibition.
What occurs during isoleucine production?
Isoleucine inhibits the conversion of intermediate W to intermediate X .
Isoleucine inhibits the conversion of intermediate Y to intermediate Z .
Threonine inhibits threonine deaminase activity.
Isoleucine inhibits threonine deaminase activity.
No public sample questions are available for this syllabus point yet.
