These practice questions cover essential concepts in enzymes, digestion, and... Show more
Biology556 views·Updated Jun 5, 2026·13 pagesProteins and Enzymes AQA Biology Exam Questions
YoYo A @yoyo1234
1 / 10
1
of 10
Digestive Enzymes and Locations
Ever wondered where your body produces the enzymes that break down your food? This question tests your knowledge of enzyme production in different digestive organs.
Amylase is produced by the pancreas and salivary glands - it's the enzyme that starts breaking down starch in your mouth and continues the job in your small intestine. Maltase, however, is produced by the small intestine itself, specifically in the brush border of intestinal cells.
The key concept here is enzyme specificity - maltase only catalyses the hydrolysis of maltose because enzymes have a specific active site shape. Think of it like a lock and key - maltase's active site perfectly complements maltose's shape, but won't fit other substrates.
Quick Tip: Remember that enzyme specificity comes from the unique 3D shape of the active site, which is determined by the enzyme's tertiary structure.
2
of 10
Industrial Enzyme Applications
Why would you attach lactase to beads instead of just mixing it directly into milk? This is all about industrial efficiency and cost-effectiveness.
Immobilised enzymes (attached to beads) offer three major advantages. First, you can easily separate and reuse the enzyme - no wastage! Second, the enzyme remains stable and doesn't get contaminated with the product. Third, you get continuous production as milk flows over the beads.
Here's something interesting about taste: lactose-free milk tastes sweeter than regular milk because lactase breaks down lactose into glucose and galactose. Both of these monosaccharides taste much sweeter than the original disaccharide lactose.
Remember: Immobilised enzymes are crucial in biotechnology because they're reusable, easily separated, and provide continuous production.
3
of 10
Bacterial Toxins and Stomach Ulcers
Helicobacter pylori isn't just any bacteria - it's the sneaky culprit behind most stomach ulcers. This experiment cleverly separates bacterial cells from their toxic products to see what actually causes damage.
Centrifugation works by spinning samples at high speed - heavier bacterial cells get forced to the bottom, leaving a clear, cell-free liquid containing only the substances the bacteria released. It's like using a super-powered spin cycle to separate different components.
The bacteria produce an acid-neutralising enzyme for survival - your stomach is incredibly acidic , so this enzyme creates a more comfortable environment for H. pylori to live and multiply. Pretty clever for a microscopic organism!
Key Insight: Lysosomes digest worn-out organelles and break down harmful substances - measuring their activity indicates cell damage levels.
4
of 10
Experimental Analysis and Toxin Effects
The data reveals something fascinating about bacterial pathogenesis. Strain A causes the most cell damage, while strain B (enzyme only) causes almost none.
This suggests the toxin is the main damage-causing agent, not the acid-neutralising enzyme. The enzyme might actually help the toxin work more effectively by creating better conditions for bacterial survival.
When scientists treated strain A's liquid with protein-digesting enzymes, all cell damage stopped. This proves the toxin must be a protein - once it's broken down, it can't harm cells anymore. This finding could be crucial for developing treatments.
Exam Tip: Always look at error bars in graphs - they show data reliability and help you make valid comparisons between results.
5
of 10
Homeostasis and Blood pH
Your blood pH must stay around 7.4 - even tiny changes can be deadly. This isn't just biological pickiness; it's absolutely essential for survival.
Enzymes are incredibly pH-sensitive because changes in pH alter their shape and destroy their active sites. If blood pH shifts, crucial enzymes stop working properly, disrupting vital metabolic processes throughout your body.
Think about it - every single chemical reaction in your body depends on enzymes. When pH changes disrupt enzyme function, you get a cascade of problems affecting everything from oxygen transport to cellular respiration.
Critical Point: Maintaining constant blood pH is vital because enzyme function depends on optimal pH conditions.
6
of 10
Cyanide Poisoning and Cellular Respiration
Cyanide is terrifyingly effective because it targets cytochrome oxidase, a crucial enzyme in the electron transport chain. Without this enzyme, electrons can't reach oxygen, and ATP production grinds to a halt.
The cyanide acts as a competitive inhibitor - it binds to the enzyme's active site, blocking the normal substrate and preventing the enzyme from functioning. This is why the antidote works by binding to cyanide molecules, effectively removing them from circulation.
Different organs show varying sensitivity to cyanide - notice how kidney tissues generally use more oxygen than liver tissues, and rat organs are more active than sheep or ox organs. This reflects the different metabolic demands of various tissues.
Life-Saver Fact: Antidotes work by binding to the poison, making it unavailable to interfere with normal biological processes.
7
of 10
Experimental Design and Data Analysis
This experiment demonstrates brilliant scientific methodology - using multiple animal organs and different cyanide concentrations provides robust, comparable data.
The grouping system allows for meaningful comparisons: you can compare different organs from the same animal, the same organ from different animals, or the effects of different cyanide concentrations. Group 1 (sheep liver vs kidney) shows kidneys are much more sensitive to cyanide than livers.
For the percentage calculation: rat liver drops from 10.0 to 1.9 oxygen units, giving a percentage difference of 81%. This massive drop demonstrates just how effectively cyanide shuts down cellular respiration.
Method Tip: Good experimental design always includes multiple comparisons and controls to ensure reliable, interpretable results.
8
of 10
Temperature Effects on Enzyme Activity
This classic enzyme experiment shows the temperature-activity relationship that's fundamental to biochemistry. The technician would need to control pH, substrate concentration, and enzyme concentration for valid results.
At 25°C, calculate the rate using the gradient of the initial straight-line portion of the curve. This gives you the initial rate of reaction before substrate depletion affects the results.
The 37°C curve shows faster initial reaction rate (steeper gradient) because higher temperature increases molecular motion and enzyme-substrate collisions. However, both curves level off as substrate gets used up - you can't make product faster than substrate availability allows.
Graph Skills: Always use the steepest part of the curve to calculate enzyme reaction rates - this represents optimal conditions before limiting factors take effect.
9
of 10
Rate Calculations and Curve Analysis
The rate calculation requires measuring the gradient of the steepest part of each curve - this represents maximum enzyme activity before substrate becomes limiting.
The differences between curves reflect the effect of temperature on enzyme kinetic energy. At 37°C, molecules move faster, leading to more frequent enzyme-substrate collisions and higher reaction rates initially.
Both curves eventually plateau because substrate concentration becomes the limiting factor. No matter how active your enzyme is, it can't work faster than substrate availability allows - this is a key principle in enzyme kinetics.
Calculation Reminder: Rate = change in concentration ÷ time, using the steepest linear portion of your curve for most accurate results.
10
of 10
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Biology556 views·Updated Jun 5, 2026·13 pagesProteins and Enzymes AQA Biology Exam Questions
YoYo A @yoyo1234
These practice questions cover essential concepts in enzymes, digestion, and cellular respiration that you'll need to master for your A-level Biology exams. From enzyme specificity to homeostasis and experimental design, these topics form the backbone of biological understanding.
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Digestive Enzymes and Locations
Ever wondered where your body produces the enzymes that break down your food? This question tests your knowledge of enzyme production in different digestive organs.
Amylase is produced by the pancreas and salivary glands - it's the enzyme that starts breaking down starch in your mouth and continues the job in your small intestine. Maltase, however, is produced by the small intestine itself, specifically in the brush border of intestinal cells.
The key concept here is enzyme specificity - maltase only catalyses the hydrolysis of maltose because enzymes have a specific active site shape. Think of it like a lock and key - maltase's active site perfectly complements maltose's shape, but won't fit other substrates.
Quick Tip: Remember that enzyme specificity comes from the unique 3D shape of the active site, which is determined by the enzyme's tertiary structure.
2
of 10Sign up to see the content. It's free!
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Industrial Enzyme Applications
Why would you attach lactase to beads instead of just mixing it directly into milk? This is all about industrial efficiency and cost-effectiveness.
Immobilised enzymes (attached to beads) offer three major advantages. First, you can easily separate and reuse the enzyme - no wastage! Second, the enzyme remains stable and doesn't get contaminated with the product. Third, you get continuous production as milk flows over the beads.
Here's something interesting about taste: lactose-free milk tastes sweeter than regular milk because lactase breaks down lactose into glucose and galactose. Both of these monosaccharides taste much sweeter than the original disaccharide lactose.
Remember: Immobilised enzymes are crucial in biotechnology because they're reusable, easily separated, and provide continuous production.
3
of 10Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Bacterial Toxins and Stomach Ulcers
Helicobacter pylori isn't just any bacteria - it's the sneaky culprit behind most stomach ulcers. This experiment cleverly separates bacterial cells from their toxic products to see what actually causes damage.
Centrifugation works by spinning samples at high speed - heavier bacterial cells get forced to the bottom, leaving a clear, cell-free liquid containing only the substances the bacteria released. It's like using a super-powered spin cycle to separate different components.
The bacteria produce an acid-neutralising enzyme for survival - your stomach is incredibly acidic , so this enzyme creates a more comfortable environment for H. pylori to live and multiply. Pretty clever for a microscopic organism!
Key Insight: Lysosomes digest worn-out organelles and break down harmful substances - measuring their activity indicates cell damage levels.
4
of 10Sign up to see the content. It's free!
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Experimental Analysis and Toxin Effects
The data reveals something fascinating about bacterial pathogenesis. Strain A causes the most cell damage, while strain B (enzyme only) causes almost none.
This suggests the toxin is the main damage-causing agent, not the acid-neutralising enzyme. The enzyme might actually help the toxin work more effectively by creating better conditions for bacterial survival.
When scientists treated strain A's liquid with protein-digesting enzymes, all cell damage stopped. This proves the toxin must be a protein - once it's broken down, it can't harm cells anymore. This finding could be crucial for developing treatments.
Exam Tip: Always look at error bars in graphs - they show data reliability and help you make valid comparisons between results.
5
of 10Sign up to see the content. It's free!
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Homeostasis and Blood pH
Your blood pH must stay around 7.4 - even tiny changes can be deadly. This isn't just biological pickiness; it's absolutely essential for survival.
Enzymes are incredibly pH-sensitive because changes in pH alter their shape and destroy their active sites. If blood pH shifts, crucial enzymes stop working properly, disrupting vital metabolic processes throughout your body.
Think about it - every single chemical reaction in your body depends on enzymes. When pH changes disrupt enzyme function, you get a cascade of problems affecting everything from oxygen transport to cellular respiration.
Critical Point: Maintaining constant blood pH is vital because enzyme function depends on optimal pH conditions.
6
of 10Sign up to see the content. It's free!
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Cyanide Poisoning and Cellular Respiration
Cyanide is terrifyingly effective because it targets cytochrome oxidase, a crucial enzyme in the electron transport chain. Without this enzyme, electrons can't reach oxygen, and ATP production grinds to a halt.
The cyanide acts as a competitive inhibitor - it binds to the enzyme's active site, blocking the normal substrate and preventing the enzyme from functioning. This is why the antidote works by binding to cyanide molecules, effectively removing them from circulation.
Different organs show varying sensitivity to cyanide - notice how kidney tissues generally use more oxygen than liver tissues, and rat organs are more active than sheep or ox organs. This reflects the different metabolic demands of various tissues.
Life-Saver Fact: Antidotes work by binding to the poison, making it unavailable to interfere with normal biological processes.
7
of 10Sign up to see the content. It's free!
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- Improve your grades
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Experimental Design and Data Analysis
This experiment demonstrates brilliant scientific methodology - using multiple animal organs and different cyanide concentrations provides robust, comparable data.
The grouping system allows for meaningful comparisons: you can compare different organs from the same animal, the same organ from different animals, or the effects of different cyanide concentrations. Group 1 (sheep liver vs kidney) shows kidneys are much more sensitive to cyanide than livers.
For the percentage calculation: rat liver drops from 10.0 to 1.9 oxygen units, giving a percentage difference of 81%. This massive drop demonstrates just how effectively cyanide shuts down cellular respiration.
Method Tip: Good experimental design always includes multiple comparisons and controls to ensure reliable, interpretable results.
8
of 10Sign up to see the content. It's free!
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Temperature Effects on Enzyme Activity
This classic enzyme experiment shows the temperature-activity relationship that's fundamental to biochemistry. The technician would need to control pH, substrate concentration, and enzyme concentration for valid results.
At 25°C, calculate the rate using the gradient of the initial straight-line portion of the curve. This gives you the initial rate of reaction before substrate depletion affects the results.
The 37°C curve shows faster initial reaction rate (steeper gradient) because higher temperature increases molecular motion and enzyme-substrate collisions. However, both curves level off as substrate gets used up - you can't make product faster than substrate availability allows.
Graph Skills: Always use the steepest part of the curve to calculate enzyme reaction rates - this represents optimal conditions before limiting factors take effect.
9
of 10Sign up to see the content. It's free!
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Rate Calculations and Curve Analysis
The rate calculation requires measuring the gradient of the steepest part of each curve - this represents maximum enzyme activity before substrate becomes limiting.
The differences between curves reflect the effect of temperature on enzyme kinetic energy. At 37°C, molecules move faster, leading to more frequent enzyme-substrate collisions and higher reaction rates initially.
Both curves eventually plateau because substrate concentration becomes the limiting factor. No matter how active your enzyme is, it can't work faster than substrate availability allows - this is a key principle in enzyme kinetics.
Calculation Reminder: Rate = change in concentration ÷ time, using the steepest linear portion of your curve for most accurate results.
10
of 10Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar content
Most popular content: Enzymes
9Most popular content in Biology
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user