MCV4U UNIT 4 – EXTENSIONS
ASSESSMENT OF LEARNING ACTUAL
EXAM PAPER 2026 QUESTIONS WITH
ANSWERS GRADED A+
◍ What are the useful properties of water and why ?.
Answer: 1) Water is a metabolite - in many metabolic reactions including
condensation and hydrolysis 2) Water is a solvent - medium in which
enzyme catalysed reactions take place (metabolic reactions ) and readily
dissolves substances like inorganic ions ( as water is dipolar so totally
surrounds the ions) , excretory products (urea/ammonia) , respiratory gases
and small hydrophilic molecules ( amino acids , etc)3) Water has a high
latent heat of vaporisation (lots of energy required to break hydrogen bonds
between water molecules so a lot of energy is used up when water
evaporates ) so helps with temperature control as evaporation of sweat cools
humans down 4) Water has a high specific heat capacity ( to separate the
many hydrogen bonds requires a lot of energy) so acts as a buffer and resists
temperature changes to maintain a constant internal body temperature 5)
Water has large cohesive forces ( as hydrogen bonds stick together) so
allows transportation of substances( water travelling in columns in xylem)
and means water has a high surface tension when it comes into contact with
air ( allowing pond skaters to walk on its surface)
◍ Describe how pacing corpuscle produces generator potential3 marks.
Answer: Stretch mediated sodium ion channels,Sodium channels
open,Sodium ions diffuse in
◍ All or nothing principle2 marks.
Answer: Action potential only generated when threshold is reached ,High
, pressure is above stimulus,
◍ Time period between 0.6 and 4.01 mark.
Answer: Refractory period
◍ Why is water dipolar ?.
Answer: As water is made up of two hydrogen atoms and one oxygen atom ,
the hydrogen atoms have a slightly positive pole and the oxygen atom has a
slightly negative pole making water dipolar.
◍ Hydrogen bonds.
Answer: Slightly negatively charged oxygen atom is attracted to the slightly
positively charged hydrogen atom of other water molecules. The attraction
between opposite charges is called hydrogen bonding, which are weak
bonds but strong in large numbers. This makes water a major component in
cells
◍ Hydrolysis.
Answer: Breaks a bond between two molecules by the addition of a
molecule of water
◍ Two variable to control in respiration yeast experiment1 mark.
Answer: Mass of glucose,Mass of yeast
◍ Yeast rate of co2 production 2 marks.
Answer: 2.5 x10-2
◍ Condensation.
Answer: Joins two molecules together with the formation of a bond by the
removal of a molecule of water
◍ Polymer.
Answer: A molecule ( carbohydrate, nucleotide or protein) made up of many
monomers ( small repeating units) joined together by condensation reactions
and broken down my hydrolysis
◍ Monosaccharides.
Answer: Are the monomers from which larger carbohydrates are made and
, contain the elements C H and O. They are sweet and soluble and there are
three types : fructose , glucose and galactose. Hexose sugars (glucose) have
the formula C6H12O6
◍ Why was yeast slower in maltose over glucose 2 marks.
Answer: Maltose is dissaccharide,Hydrolysed into glucose
◍ Glucose is the product of photosynthesis and a major substrate of respiration
, draw the two structural isomers of glucose in long and short hand and state
the difference between them.
Answer: On carbon 1 in beta glucose the hydroxyl group (OH) points
upwards and in alpha glucose the hydroxyl group points down on carbon 1
◍ Sucrose.
Answer: Glucose and fructose
◍ Method of respiration less accurate because? This could be improved by-2
marks.
Answer: Less accurate - colour is subjectiveImproved by - have a colour
standard of the yellow as a reference for the end point
◍ Maltose.
Answer: Glucose and glucose
◍ Link reaction , A B C D2 marks.
Answer: A-PyruvateB-NADHC-Coenzyme AD-acetylcoenzyme A
◍ Prokaryote tick box 1 mark.
Answer: Second Box
◍ Lactose.
Answer: Glucose and galactose
◍ How do monosaccharides join together.
Answer: By condensation to form a glycosidic bond between two
monosaccharides and a disaccharide and a molecule of water are formed
◍ Mean no of bacteria in culture.
Answer: 9.144x 10 to power of 8
, ◍ Disaccharide.
Answer: Two monosaccharides joined together by condensation forming a
glycosidic bond. There are three types : maltose, sucrose and lactose. They
have the chemical formula C12H22O11
◍ Draw the hydrolysis of maltose in structural formula and short hand
formula.
Answer: nan
◍ Test for starch.
Answer: Add iodine solution to the test sample , if starch is present colour
changes from yellow to a blue-black colour.
◍ Log question to bacteria one1 mark.
Answer: 30 generation
◍ Test for a reducing sugar.
Answer: Heat with Benedict's reagent ( blue) and if reducing sugar is present
a brick red precipitate will form
◍ Two reasons why bacteria could grow in culture containing
chloramphenicol2 marks.
Answer: Concentration was too low to kill all,Mutation
◍ How is SCFR destroyed by lysosome2 marks.
Answer: Vesicle binds with a lysosome,Lysosomes digest SCFR
◍ Issues with the Benedict's test ?.
Answer: 1) It is non specific - doesn't tell which reducing sugar is present , a
biosensor can be used to detect for specific sugars 2) It's qualitative so
colour change is being measured so can't obtain concentration of reducing
sugar but allows an estimate for how much is present in the strength of the
colour3) Is subjective
◍ How to quantify results on the concentration of unknown glucose
concentration?.
Answer: Use a colorimeter, as a serial dilution of known glucose
ASSESSMENT OF LEARNING ACTUAL
EXAM PAPER 2026 QUESTIONS WITH
ANSWERS GRADED A+
◍ What are the useful properties of water and why ?.
Answer: 1) Water is a metabolite - in many metabolic reactions including
condensation and hydrolysis 2) Water is a solvent - medium in which
enzyme catalysed reactions take place (metabolic reactions ) and readily
dissolves substances like inorganic ions ( as water is dipolar so totally
surrounds the ions) , excretory products (urea/ammonia) , respiratory gases
and small hydrophilic molecules ( amino acids , etc)3) Water has a high
latent heat of vaporisation (lots of energy required to break hydrogen bonds
between water molecules so a lot of energy is used up when water
evaporates ) so helps with temperature control as evaporation of sweat cools
humans down 4) Water has a high specific heat capacity ( to separate the
many hydrogen bonds requires a lot of energy) so acts as a buffer and resists
temperature changes to maintain a constant internal body temperature 5)
Water has large cohesive forces ( as hydrogen bonds stick together) so
allows transportation of substances( water travelling in columns in xylem)
and means water has a high surface tension when it comes into contact with
air ( allowing pond skaters to walk on its surface)
◍ Describe how pacing corpuscle produces generator potential3 marks.
Answer: Stretch mediated sodium ion channels,Sodium channels
open,Sodium ions diffuse in
◍ All or nothing principle2 marks.
Answer: Action potential only generated when threshold is reached ,High
, pressure is above stimulus,
◍ Time period between 0.6 and 4.01 mark.
Answer: Refractory period
◍ Why is water dipolar ?.
Answer: As water is made up of two hydrogen atoms and one oxygen atom ,
the hydrogen atoms have a slightly positive pole and the oxygen atom has a
slightly negative pole making water dipolar.
◍ Hydrogen bonds.
Answer: Slightly negatively charged oxygen atom is attracted to the slightly
positively charged hydrogen atom of other water molecules. The attraction
between opposite charges is called hydrogen bonding, which are weak
bonds but strong in large numbers. This makes water a major component in
cells
◍ Hydrolysis.
Answer: Breaks a bond between two molecules by the addition of a
molecule of water
◍ Two variable to control in respiration yeast experiment1 mark.
Answer: Mass of glucose,Mass of yeast
◍ Yeast rate of co2 production 2 marks.
Answer: 2.5 x10-2
◍ Condensation.
Answer: Joins two molecules together with the formation of a bond by the
removal of a molecule of water
◍ Polymer.
Answer: A molecule ( carbohydrate, nucleotide or protein) made up of many
monomers ( small repeating units) joined together by condensation reactions
and broken down my hydrolysis
◍ Monosaccharides.
Answer: Are the monomers from which larger carbohydrates are made and
, contain the elements C H and O. They are sweet and soluble and there are
three types : fructose , glucose and galactose. Hexose sugars (glucose) have
the formula C6H12O6
◍ Why was yeast slower in maltose over glucose 2 marks.
Answer: Maltose is dissaccharide,Hydrolysed into glucose
◍ Glucose is the product of photosynthesis and a major substrate of respiration
, draw the two structural isomers of glucose in long and short hand and state
the difference between them.
Answer: On carbon 1 in beta glucose the hydroxyl group (OH) points
upwards and in alpha glucose the hydroxyl group points down on carbon 1
◍ Sucrose.
Answer: Glucose and fructose
◍ Method of respiration less accurate because? This could be improved by-2
marks.
Answer: Less accurate - colour is subjectiveImproved by - have a colour
standard of the yellow as a reference for the end point
◍ Maltose.
Answer: Glucose and glucose
◍ Link reaction , A B C D2 marks.
Answer: A-PyruvateB-NADHC-Coenzyme AD-acetylcoenzyme A
◍ Prokaryote tick box 1 mark.
Answer: Second Box
◍ Lactose.
Answer: Glucose and galactose
◍ How do monosaccharides join together.
Answer: By condensation to form a glycosidic bond between two
monosaccharides and a disaccharide and a molecule of water are formed
◍ Mean no of bacteria in culture.
Answer: 9.144x 10 to power of 8
, ◍ Disaccharide.
Answer: Two monosaccharides joined together by condensation forming a
glycosidic bond. There are three types : maltose, sucrose and lactose. They
have the chemical formula C12H22O11
◍ Draw the hydrolysis of maltose in structural formula and short hand
formula.
Answer: nan
◍ Test for starch.
Answer: Add iodine solution to the test sample , if starch is present colour
changes from yellow to a blue-black colour.
◍ Log question to bacteria one1 mark.
Answer: 30 generation
◍ Test for a reducing sugar.
Answer: Heat with Benedict's reagent ( blue) and if reducing sugar is present
a brick red precipitate will form
◍ Two reasons why bacteria could grow in culture containing
chloramphenicol2 marks.
Answer: Concentration was too low to kill all,Mutation
◍ How is SCFR destroyed by lysosome2 marks.
Answer: Vesicle binds with a lysosome,Lysosomes digest SCFR
◍ Issues with the Benedict's test ?.
Answer: 1) It is non specific - doesn't tell which reducing sugar is present , a
biosensor can be used to detect for specific sugars 2) It's qualitative so
colour change is being measured so can't obtain concentration of reducing
sugar but allows an estimate for how much is present in the strength of the
colour3) Is subjective
◍ How to quantify results on the concentration of unknown glucose
concentration?.
Answer: Use a colorimeter, as a serial dilution of known glucose
