Learn and test your biological vocabulary for 2.3 Carbohydrates and Lipids using these flashcards.
Summary list for 2.3 Carbohydrates & Lipids
- Condensation reactions link Monosaccharide monomers together to
form disaccharides (Sucrose, lactose and maltose) and polysaccharides (cellulose starch and glycogen). - Fatty acids can be saturated, monounsaturated or polyunsaturated.
- and cis or trans isomers if they are unsaturated. (Molecule names not required).
- Three fatty acids and one glycerol molecules can form a Triglycerides by condensation reactions.
- How the structure of cellulose and starch (amylose & amylopectin) in plants and glycogen in humans relates to function.
- For long-term energy storage in humans lipids are better than carbohydrates.
- Potatoes have been genetically modified to reduce the level of amylose to produce a more effective adhesive.
- Evaluate the conflicting evidence for health risks of trans fats and saturated fatty acids and evaluate the methods used.
- Ability to use molecular visualisation software like jmol to compare cellulose, starch and glycogen.
- Ability to work out a BMI using a nomogram or by calculation.
Mindmaps
This diagram summaries the main sections of topic 2.3.
Test if you can draw something like these concept maps from memory.
Even better, design your own.
Exam style question about carbohydrate structure
Understanding the structure of carbohydrates is an important skill from this topic.
Answer the question below on a piece of paper, then check your answer with the model answer below.
There are unsaturated fats in nuts, olive oil, and avocados that are important in a healthy diet. Health authorities around the world encourage people to reduce their consumption of saturated fats, in other types of food.
Compare and contrast the structures of saturated and unsaturated fatty acids. [6]
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Click the + icon to see a model answer.
This question tests a student's ability to interpret images from visualisation software and to describe these molecule structures
The image below shows a carbohydrate macromolecule found in plants, together with an extract of that molecule and an interpretation of the image drawn as a structural formula.
a) Use the molecular visualisation and the extracts to determine the name of the macromolecule shown [1]
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b) Explain how the molecule can be identified using evidence from the images [2]
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Click the + icon to see a model answer.
Multiple choice questions
This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.
START QUIZ!
Which of the following are all carbohydrate monomers?
The simple sugars which act as monomers in larger carbohydrate molecules are, glucose, fructose, and galactose.
They are often joined together, e.g. glucose and glucose form maltose.
Long chains of glucose molecules form polysaccharides.
The image below shows a molecule commonly found in the human digestive system
What type of molecule is this?
Each of the monomer units is a glucose molecule, so this is a disaccharide, in fact maltose.
What are the functions of the molecules, Cellulose, and Starch in plants?
Plant cells walls are built of cellulose mainly.
There is starch in the cell but this is found in the chloroplast, or in the cytoplasm. It is used to store energy.
What is the difference in structure between amylose and amylopectin?
Amylose is an unbranched polysaccharide, and Amylopectin is a branched polysaccharide.
Both are found in starch.
The molecules below are both of the same type, fatty acids.
Which of the descriptions below is the best description of these two molecules.
The terms cis- and trans- apply to unsaturated fatty acids but from these diagrams we cannot tell.
Saturated fatty acids have no double bonds in the carbon chain (except the =0 in the carboxylic acid)
Both of these are unsaturated fatty acids.
Which of the following molecules are monosaccharides?
- Lactose
- Galactose
- Sucrose
- Fructose
- Glucose
Monosaccharides are Galactose, Fructose and Glucose.
The three disaccharides named in the syllabus are Maltose, Sucrose and Lactose.
The diagram below shows a graph of the results of a long study into the incidence of heart disease (CHD).
When saturated fat replaced 5% of the energy in a diet the % incidence of CHD increased by 20%
Which of the following conclusions could be made about Trans-fat?
An ability to evaluate evidence about the health impact of trans-fats is expected.
In this case the evidence strongly suggests that trans-fat increases the risk of CHD more than other fat types.
What type of reaction is it that makes a macromolecule from smaller monomer units?
Condensation reactions are those where two -OH groups join forming a covalent bond and releasing a water molecule.
These reactions often join molecules together, e.g. glucose and glucose form maltose.
Long chains of glucose molecules form polysaccharides.
Drag and drop activities
Test your ability to construct biological explanations using the drag and drop questions below.
Examples of carbohydrate structure and function
Drag and drop the correct term into the gap to describe the strructure and functions of carbohydrates.
starch galactose storage monomer respiratory aerobic glycogen cellulose milk monosaccharide disaccharide polysaccharide
Glucose is a which is the main substrate, used by mitochondria to make ATP energy by respiration.
Sucrose is a composed of glucose and fructose bonded by a glycosidid bond. It is used in transport in plants.
Lactose is a disaccharide of glucose and found in mammalian .
Polysaccharides of glucose units, depending how the monomer units are bonded, can form for energy in animals, for energy storage in plants and for cell walls in plant cells.
Explanation/Examiner hint. You need to know the structure of simple and complex carbohydrates and some of their roles in living organisms. These examples reoccur throughout the syllabus content.
Just for fun
Everyone needs something a bit light hearted from time to time when revising. That's the aim of this last activity.
Cabohydrates & Lipids - Matching cards memory games
The idea is that this game is fun to do but it still counts as revision.
How much of Carbohydrates & Lipids 2.3 have you understood?
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