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32 important questions on Self assessment

What is true about hydrophobic molecules / groups?
These are non-polar molecules/groups
These are polar molecules/groups
They can make hydrogen bonds
They cannot make hydrogen bonds
They repel each other
They attract each other

These are non-polar molecules/groups
These are polar molecules/groups
They can make hydrogen bonds
They cannot make hydrogen bonds
They repel each other
They attract each other

Between which two atoms do hydrogen bonds take place?
hydrogen atoms with a slight positive charge
any hydrogen atoms
any atom with a slight positive charge
any atom with a slight negative charge
an oxygen atom with a slight negative charge
any oxygen atom

hydrogen atoms with a slight positive charge
any hydrogen atoms
any atom with a slight positive charge
any atom with a slight negative charge
an oxygen atom with a slight negative charge
any oxygen atom

What is true about hydrogen bonds?

They are inter-molecular interactions (between molecules)
They are intra-molecular interactions (within molecules)
They are interactions between water molecules
They are interactions between water molecules and polar molecules
They are interactions between water molecules and non-polar molecules

They are inter-molecular interactions (between molecules)
They are intra-molecular interactions (within molecules)
They are interactions between water molecules
They are interactions between water molecules and polar molecules
They are interactions between water molecules and non-polar molecules

Which interaction is most important for the solubility of proteins and carbohydrates in water?
Hydrogen bonds
Electrostatic interactions
Hydrophobic interactions
VanderWaals interactions

Hydrogen bonds
Electrostatic interactions
Hydrophobic interactions
VanderWaals interactions

Which groups, often present in food molecules, can possess a charge under normal food conditions (pH 3 – 7) and what kind of charge?

1) -NH2
No charge
Positive charge
Negative charge
2) -CONH2
No charge
Positive charge
Negative charge
3) -OH
No charge
Positive charge
Negative charge
4) -COOH
No charge
Positive charge
Negative charge
5) -SH
No charge
Positive charge
Negative charge

1) -NH2
No charge
Positive charge
Negative charge
2) -CONH2
No charge
Positive charge
Negative charge
3) -OH
No charge
Positive charge
Negative charge
4) -COOH
No charge
Positive charge
Negative charge
5) -SH
No charge
Positive charge
Negative charge

Which of the two statements is/are true about the interactions between similarly charged particles when free ions (salt) are added?

The Debye double layer increases in size
The distance that particles can approach each other increases

Both true
Both false
Statement 1 is true, statement 2 is false
Statement 1 is false, statement 2 is true

Both true
Both false
Statement 1 is true, statement 2 is false
Statement 1 is false, statement 2 is true

What is the DLVO theory?

Describes several interactions between particles as function of distance.
Describes only electrostatic interactions between particles as function of distance.
Describes only VanderWaals interactions between particles as function of distance.

Describes several interactions between particles as function of distance.
Describes only electrostatic interactions between particles as function of distance.
Describes only VanderWaals interactions between particles as function of distance.

Which ion(s) could form a bridge between two negatively charged polysaccharides?

Na+
Ca2+
Cl-
SO42-

Na+
Ca2+
Cl-
SO42-

Select the correct groups.

All free amino acids have the following groups:
Amino group
Carbonyl group
Carboxyl group
Hydroxyl group
Amide group

Amino group
Carbonyl group
Carboxyl group
Hydroxyl group
Amide group

The tertiary structure of a protein is mainly stabilized by which three molecular interactions?
Pick three options.

VanderWaals interactions
Hydrophobic interactions
Electrostatic interactions
Hydrogen bonding
Disulphide bridges

VanderWaals interactions
Hydrophobic interactions
Electrostatic interactions
Hydrogen bonding
Disulphide bridges

Which two interactions play a role in interactions between proteins?

Complete the two sentences by matching the A and B with the corresponding interactions in the dropdown boxes.
When two proteins repel each other when they come close to each other, this is because A is larger than B.
When two proteins aggregate when they come close to each other, this is because A is smaller than B.

electrostatic repulsion
electrostatic attraction
hydrophobic repulsion
hydrophobic attraction
hydrogen bonds
Impossible to tell

1) electrostatic repulsion

2) hydrophobic attraction

Match these:
globular proteins
fibrillar proteins
random coil proteins

Are entirely arranged into a single regular secondary structure
Have secondary structural elements next to random coil parts
Have no secondary structural elements

globular proteins + Have secondary structural elements next to random coil parts

fibrillar proteins + Are entirely arranged into a single regular secondary structure

random coil proteins + Have no secondary structural elements

The amino acid lysine has three pKavalues: 8.90 (for the alpha-NH2 group), 2.20 (for the alpha-COOH group) and 10.28 (for the NH2 group in the side chain).

Based on the Henderson-Hasselbalch equation, pH = pKa + log[A-]/[HA], in a lysine solution what percentage of lysine molecules have a charged carboxyl groups at pH 3.8?

2.5%
39.8%
60.2%
97.5%

2.5%
39.8%
60.2%
97.5%

What is true about denaturation? Pick one or more options.

Is caused by a reaction between different proteins
Is caused by breaking of the peptide bonds
Increases the mass of the protein
Exposes charged groups
Exposes hydrophobic groups

Is caused by a reaction between different proteins
Is caused by breaking of the peptide bonds
Increases the mass of the protein
Exposes charged groups
Exposes hydrophobic groups

Denaturation of a protein influences the properties of proteins. Indicate for each property whether this becomes higher or lower upon denaturation.
Solubility
Chance of aggregation
Degradability by enzymes
Biological activity (in the case the protein is an enzyme)

Solubility --> lower

Chance of aggregation --> higher
Degradability by enzymes --> higher
Biological activity (in the case the protein is an enzyme) --> lower

Which sentence is correct?

Globular proteins are most soluble at a pH far from the iso-electric point
Globular proteins are most soluble at a pH near the iso-electric point
pH has no influence on the solubility of a globular protein

Globular proteins are most soluble at a pH far from the iso-electric point
Globular proteins are most soluble at a pH near the iso-electric point
pH has no influence on the solubility of a globular protein

A protein has a low solubility at pH 4. Which interactions are involved that explain this low solubility at this pH? You need to select two sentences.
Proteins repel each other because they have a net positive charge.
Proteins do not repel each other because they have a net zero charge.
Proteins attract each other because of hydrophobic interaction.
Proteins attract each other because they have both positive and negative charges.
Proteins attract each other because of hydrogen bonds.

Proteins repel each other because they have a net positive charge.
Proteins do not repel each other because they have a net zero charge.
Proteins attract each other because of hydrophobic interaction.
Proteins attract each other because they have both positive and negative charges.
Proteins attract each other because of hydrogen bonds.

How does salt influence the solubility of proteins?

Solubility increases with increasing salt concentration
Solubility decreases with increasing salt concentration
Solubility increases with increasing salt concentration until a maximum after which it decreases
Solubility decreases with increasing salt concentration until a minimum after which it increases

Solubility increases with increasing salt concentration
Solubility decreases with increasing salt concentration
Solubility increases with increasing salt concentration until a maximum after which it decreases
Solubility decreases with increasing salt concentration until a minimum after which it increases

Below the names of different saccharides are shown with their corresponding DP (degree of polymerisation, number of sugar units in the molecule).

Classify each molecule in the correct class of saccharides (monosaccharide, oligosaccharide, polysaccharide)
Starch: DP 3000
Lactose: DP 2
Glucose: DP 1
Saccharose: DP 2
Stachyose: DP 3

Starch: DP 3000 --> polysaccharide
Lactose: DP 2 --> oligosaccharide
Glucose: DP 1 --> monosaccharide
Saccharose: DP 2--> oligosaccharide
Stachyose: DP 3 --> oligosaccharide

Is this structure an α-anomer or a β-anomer?

α-anomer because the OH-group on C1 is pointing down
α-anomer because there is a second CH2OH group
β-anomer because the OH-group on C1 is pointing down
β-anomer because there is a second CH2OH group

α-anomer because the OH-group on C1 is pointing down
α-anomer because there is a second CH2OH group
β-anomer because the OH-group on C1 is pointing down
β-anomer because there is a second CH2OH group

What is true about reducing sugars?
Pick one or more options.

They have a ring structure that can open up
They can change the α-anomer into the β-anomer and vice versa
They can react in the Maillard reaction
They are always mono- or disaccharides
They have a reducing end
They are more sensitive to hydrolysis than non-reducing sugars

They have a ring structure that can open up
They can change the α-anomer into the β-anomer and vice versa
They can react in the Maillard reaction
They are always mono- or disaccharides
They have a reducing end
They are more sensitive to hydrolysis than non-reducing sugars

What happens with the number of reducing ends if a starch solution is treated with an enzyme that hydrolyses the starch?

The number of reducing ends decreases
The number of reducing ends increases
The number of reducing ends stays the same
Impossible to tell what happens with the number of reducing ends

The number of reducing ends decreases
The number of reducing ends increases
The number of reducing ends stays the same
Impossible to tell what happens with the number of reducing ends

The uronic acid of glucose is called glucuronic acid. Which of the following structures is glucuronic acid?

Structure A
Structure B
Structure C
Structure D
Structure E

Structure A
Structure B
Structure C
Structure D
Structure E

Match the description of the polysaccharide (rows) with the correct classification (columns).
1) Linear polysaccharide consisting of two or more types of monomers
2) Linear polysaccharide consisting of one type of monomer
3) Branched polysaccharide consisting of one type of monomer
4) Branched polysaccharide consisting of two or more types of monomers, but only one type of monomer in the main chain
5) Branched polysaccharide consisting of two or more types of monomers in the main chain, but only one type of monomer in the side chains

1) Linear polysaccharide consisting of two or more types of monomers --> heteroglycan
2) Linear polysaccharide consisting of one type of monomer --> homoglycan
3) Branched polysaccharide consisting of one type of monomer --> homoglycan
4) Branched polysaccharide consisting of two or more types of monomers, but only one type of monomer in the main chain --> heteroglycan
5) Branched polysaccharide consisting of two or more types of monomers in the main chain, but only one type of monomer in the side chains --> heteroglycan

Indicate for each sentence whether it is true or false, assuming the same concentration.
1) Long polysaccharides often give a higher viscosity than shorter polysaccharides.
2) Branched polysaccharides often give a higher viscosity than linear polysaccharides (with the same number of units).
3) Charged polysaccharides often give a higher viscosity than uncharged polysaccharides (with the same number of units).

1) Long polysaccharides often give a higher viscosity than shorter polysaccharides. --> True
2) Branched polysaccharides often give a higher viscosity than linear polysaccharides (with the same number of units). --> False
3) Charged polysaccharides often give a higher viscosity than uncharged polysaccharides (with the same number of units). --> True

Sans-serifMatch each description to the matching material. (viscous, elastic, viscoelastic)
After deformation of a material, the material does not return to its original shape
After deformation of a material, the material goes back into its original shape
After deformation of a material, the material partly goes back into its original shape

After deformation of a material, the material does not return to its original shape --> viscous
After deformation of a material, the material goes back into its original shape --> elastic
After deformation of a material, the material partly goes back into its original shape --> viscoelastic

To measure viscoelastic properties the following measurement should be done:
Measure viscosity with a viscometer
Measure deformation with a texture analyser
Measure storage and loss modulus with a rheometer
Measure fracture properties with a texture analyser

Measure viscosity with a viscometer
Measure deformation with a texture analyser
Measure storage and loss modulus with a rheometer
Measure fracture properties with a texture analyser

Which two descriptions below correctly describe the following figure?

Shear rate thinning
Shear rate thickening
Newtonian liquid
Viscosity is constant with increasing shear rate
Viscosity decreases with increasing shear rate
Viscosity increases with increasing shear rate

Shear rate thinning
Shear rate thickening
Newtonian liquid
Viscosity is constant with increasing shear rate
Viscosity decreases with increasing shear rate
Viscosity increases with increasing shear rate

What is a shear thickening product?

This is a product that increases in viscosity when stirred.
This is a product with a yield stress.
This is a product with a high viscosity.
This is a product that flows more upon deformation.

This is a product that increases in viscosity when stirred.
This is a product with a yield stress.
This is a product with a high viscosity.
This is a product that flows more upon deformation.

Choose the three correct answers.

Materials with a yield stress ...
... are typically shear thinning.
... are typically Newtonian.
... have an positive off-set in the graph of shear stress versus shear rate.
... have a negative off-set in the graph of shear stress versus shear rate.
... are made from non-interacting particles.
... are made from particles that form a network.

... are typically shear thinning.
... are typically Newtonian.
... have an positive off-set in the graph of shear stress versus shear rate.
... have a negative off-set in the graph of shear stress versus shear rate.
... are made from non-interacting particles.
... are made from particles that form a network.

Match each description to the matching material. (reversible/not reversible)
Stretching
Elastic behaviour
Disentanglements

Stretching --> reversible
Elastic behaviour --> reversible
Disentanglements --> not reversible

In small deformation tests the elastic and viscous moduli of a gel are determined.

The Viscous modulus is G’’ (or E’’) and the elastic modulus is G’ (or E’)
The Viscous modulus is G’ (or E’) and the elastic modulus is G’’ (or E’’)

The Viscous modulus is G’’ (or E’’) and the elastic modulus is G’ (or E’)
The Viscous modulus is G’ (or E’) and the elastic modulus is G’’ (or E’’)

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Self assessment

32 important questions on Self assessment

What is true about hydrophobic molecules / groups?These are non-polar molecules/groupsThese are polar molecules/groupsThey can make hydrogen bondsThey cannot make hydrogen bondsThey repel each otherThey attract each other

Between which two atoms do hydrogen bonds take place?hydrogen atoms with a slight positive chargeany hydrogen atomsany atom with a slight positive chargeany atom with a slight negative chargean oxygen atom with a slight negative chargeany oxygen atom

Which interaction is most important for the solubility of proteins and carbohydrates in water?Hydrogen bondsElectrostatic interactionsHydrophobic interactionsVanderWaals interactions

What is the DLVO theory?Describes several interactions between particles as function of distance.Describes only electrostatic interactions between particles as function of distance.Describes only VanderWaals interactions between particles as function of distance.

Which ion(s) could form a bridge between two negatively charged polysaccharides?Na+Ca2+Cl-SO42-

Select the correct groups.All free amino acids have the following groups:Amino groupCarbonyl groupCarboxyl groupHydroxyl groupAmide group

The tertiary structure of a protein is mainly stabilized by which three molecular interactions?Pick three options.VanderWaals interactionsHydrophobic interactionsElectrostatic interactionsHydrogen bondingDisulphide bridges

Match these:globular proteinsfibrillar proteinsrandom coil proteinsAre entirely arranged into a single regular secondary structureHave secondary structural elements next to random coil partsHave no secondary structural elements

What is true about denaturation? Pick one or more options.Is caused by a reaction between different proteinsIs caused by breaking of the peptide bondsIncreases the mass of the proteinExposes charged groupsExposes hydrophobic groups

Denaturation of a protein influences the properties of proteins. Indicate for each property whether this becomes higher or lower upon denaturation.SolubilityChance of aggregationDegradability by enzymesBiological activity (in the case the protein is an enzyme)

Which sentence is correct?Globular proteins are most soluble at a pH far from the iso-electric pointGlobular proteins are most soluble at a pH near the iso-electric pointpH has no influence on the solubility of a globular protein

Is this structure an α-anomer or a β-anomer?α-anomer because the OH-group on C1 is pointing downα-anomer because there is a second CH2OH groupβ-anomer because the OH-group on C1 is pointing downβ-anomer because there is a second CH2OH group

The uronic acid of glucose is called glucuronic acid. Which of the following structures is glucuronic acid?Structure AStructure BStructure CStructure DStructure E

To measure viscoelastic properties the following measurement should be done:Measure viscosity with a viscometerMeasure deformation with a texture analyserMeasure storage and loss modulus with a rheometerMeasure fracture properties with a texture analyser

Which two descriptions below correctly describe the following figure?Shear rate thinningShear rate thickeningNewtonian liquidViscosity is constant with increasing shear rateViscosity decreases with increasing shear rateViscosity increases with increasing shear rate

What is a shear thickening product?This is a product that increases in viscosity when stirred.This is a product with a yield stress.This is a product with a high viscosity.This is a product that flows more upon deformation.

Match each description to the matching material. (reversible/not reversible)StretchingElastic behaviourDisentanglements

In small deformation tests the elastic and viscous moduli of a gel are determined.The Viscous modulus is G’’ (or E’’) and the elastic modulus is G’ (or E’)The Viscous modulus is G’ (or E’) and the elastic modulus is G’’ (or E’’)

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