MCV4U UNIT 4 – EXTENSIONS
ASSESSMENT OF LEARNING
COMPREHENSIVE STUDY GUIDE 2026
FULL QUESTIONS AND SOLUTIONS
GRADED A+
◍ When a nerve impulse arrives at a synapse, it causes the release of
neurotransmitter from vesicles in the presynaptic knob. Describe how..
Answer: 1. (Nerve impulse/depolarisation of membrane) causes Ca2+
channel (proteins) to open;2. Ca2+ enter by (facilitated) diffusion;3. Causes
(synaptic) vesicles to fuse with (presynaptic) membrane;
◍ Use your knowledge of how myosin and actin interact to suggest the myosin
molecule moves the mitochondrion towards the presynaptic membrane. Do
not include the roles of calcium ions and tropomyosin in your answer..
Answer: 1. Myosin head attaches to actin and bends/performs powerstroke2.
This pulls mitochondria past/along the actin3. Other/next myosin attaches to
actin and bends/performs powerstroke
◍ This movement of mitochondria happens when nerve impulses arrive at the
synapse. Suggest and explain one advantage of the movement of
mitochondria towards the presynaptic membrane when nerve impulses
arrive at the synapse..
Answer: 1. (Mitochondria) supply (additional) ATP / energy;2. To move
vesicles / for active transport of ions / for myosin to move past
actinORRe-synthesis / reabsorption of neurotransmitter / named
neurotransmitter;
◍ Give two examples of biological molecules containing nitrogen that would
, be removed when a crop is harvested.
Answer: amino acid/protein/polypeptide/peptide;2.
nucleicacid/nucleotide/base;3. DNA;4. RNA;5. ATP/ADP;6. NAD/NADP
(reduced ornot);7. Cyclic AMP/cAMP;8. Chlorophyll;
◍ Outline a method the ecologists could have used to determine the plant
species richness at one site..
Answer: 1. A method of selecting sampling sites at random;2. Use of
quadrat;3. Identify (plant) species (at site / in each quadrat)ORCount
number of (different plant) species (at site / in each quadrat);
◍ Name two enzymes involved in the semi-conservative replication of DNA.
Answer: 1. DNA helicase2. DNA polymerase
◍ Sometimes, damage occurs during DNA replication. One enzyme involved
in repairing damage to DNA is called AT
R. ATR works as follows.• ATR phosphorylates other enzymes involved in
repairing DN
A. • ATR also phosphorylates substrates required to repair DN
A. When ATR phosphorylates other enzymes, these enzymes become able
to bind to their substrates.Use your knowledge of enzyme structure to
suggest why..
Answer: 1. Changes tertiary structure of the enzyme;2. (Enzyme) active site
formed / able to be formed / active site becomes complementary;
◍ The enzyme-catalysed reactions activated by ATR only occur if the
substrates have been phosphorylated.Use your knowledge of energy changes
in enzyme-catalysed reactions to suggest why..
Answer: (Phosphorylation / phosphate) makes substrates more reactive /
raises their energy level(s) / lowers activation energy for the reaction;
◍ Sometimes, a mutagenic agent causes DNA to break. A different enzyme
called ATM binds to the broken DN
A. This leads to the activation of a protein coded for by a tumour suppressor
gene. The effect of ATM binding is to stop cell division until DNA is
repaired.A mutation could result in a person having non-functional forms of
, the gene that produces AT
M. What can you predict about the possible effects of having a
non-functional form of ATM?.
Answer: 1. ATM will not bind to (broken) DNA;2. DNA not repaired/ cell
still has broken DNA;3. Cell division continues/tumour forms;4. Tumour
suppressor (gene) not effective/ notactivated;5. May have no effect in
diploid/heterozygous(organism);6. (Which) still has a functional ATM/ATM
gene;
◍ The student wanted to determine the rate of water loss per mm2 of surface
area of the leaves of the shoot in Figure 5. Outline a method she could have
used to find this rate. You should assume that all water loss from the shoot
is from the leaves..
Answer: 1. Method for measuring area;e.g. draw round (each) leaf on graph
paper and count squares;2. Of both sides of (each) leaf;3. Divide rate (of
water loss / uptake from potometer) by (total) surface area (of leaves);
◍ The rate of water movement through a shoot in a potometer maybe not be
the same as the rate of water movement through the shoot of a whole plant.
Suggest one reason why..
Answer: Plant has rootsXylem cells very narrow
◍ The transgenic poplars still produced some PIP1. Suggest why..
Answer: Not all of mRNA bound to single-stranded RNA/there is more
mRNA than interfering RNAORNot all mRNA destroyed/disabled;
◍ The scientists first produced transgenic poplar trees. These trees all had a
length of foreign DNA inserted into them. This DNA led to the production
of single-stranded RNA that specifically inhibited expression of the gene for
PIP1. The scientists then measured the difference in the amount of PIP1 in
leaves of transgenic poplars and in leaves of wild type poplars without the
foreign DN
A. The amount of PIP1 in the transgenic poplars was approximately 15% of
that in the wild type poplars. Using this information, what can you conclude
about the effect of the foreign DNA in the transgenic poplar trees?.
ASSESSMENT OF LEARNING
COMPREHENSIVE STUDY GUIDE 2026
FULL QUESTIONS AND SOLUTIONS
GRADED A+
◍ When a nerve impulse arrives at a synapse, it causes the release of
neurotransmitter from vesicles in the presynaptic knob. Describe how..
Answer: 1. (Nerve impulse/depolarisation of membrane) causes Ca2+
channel (proteins) to open;2. Ca2+ enter by (facilitated) diffusion;3. Causes
(synaptic) vesicles to fuse with (presynaptic) membrane;
◍ Use your knowledge of how myosin and actin interact to suggest the myosin
molecule moves the mitochondrion towards the presynaptic membrane. Do
not include the roles of calcium ions and tropomyosin in your answer..
Answer: 1. Myosin head attaches to actin and bends/performs powerstroke2.
This pulls mitochondria past/along the actin3. Other/next myosin attaches to
actin and bends/performs powerstroke
◍ This movement of mitochondria happens when nerve impulses arrive at the
synapse. Suggest and explain one advantage of the movement of
mitochondria towards the presynaptic membrane when nerve impulses
arrive at the synapse..
Answer: 1. (Mitochondria) supply (additional) ATP / energy;2. To move
vesicles / for active transport of ions / for myosin to move past
actinORRe-synthesis / reabsorption of neurotransmitter / named
neurotransmitter;
◍ Give two examples of biological molecules containing nitrogen that would
, be removed when a crop is harvested.
Answer: amino acid/protein/polypeptide/peptide;2.
nucleicacid/nucleotide/base;3. DNA;4. RNA;5. ATP/ADP;6. NAD/NADP
(reduced ornot);7. Cyclic AMP/cAMP;8. Chlorophyll;
◍ Outline a method the ecologists could have used to determine the plant
species richness at one site..
Answer: 1. A method of selecting sampling sites at random;2. Use of
quadrat;3. Identify (plant) species (at site / in each quadrat)ORCount
number of (different plant) species (at site / in each quadrat);
◍ Name two enzymes involved in the semi-conservative replication of DNA.
Answer: 1. DNA helicase2. DNA polymerase
◍ Sometimes, damage occurs during DNA replication. One enzyme involved
in repairing damage to DNA is called AT
R. ATR works as follows.• ATR phosphorylates other enzymes involved in
repairing DN
A. • ATR also phosphorylates substrates required to repair DN
A. When ATR phosphorylates other enzymes, these enzymes become able
to bind to their substrates.Use your knowledge of enzyme structure to
suggest why..
Answer: 1. Changes tertiary structure of the enzyme;2. (Enzyme) active site
formed / able to be formed / active site becomes complementary;
◍ The enzyme-catalysed reactions activated by ATR only occur if the
substrates have been phosphorylated.Use your knowledge of energy changes
in enzyme-catalysed reactions to suggest why..
Answer: (Phosphorylation / phosphate) makes substrates more reactive /
raises their energy level(s) / lowers activation energy for the reaction;
◍ Sometimes, a mutagenic agent causes DNA to break. A different enzyme
called ATM binds to the broken DN
A. This leads to the activation of a protein coded for by a tumour suppressor
gene. The effect of ATM binding is to stop cell division until DNA is
repaired.A mutation could result in a person having non-functional forms of
, the gene that produces AT
M. What can you predict about the possible effects of having a
non-functional form of ATM?.
Answer: 1. ATM will not bind to (broken) DNA;2. DNA not repaired/ cell
still has broken DNA;3. Cell division continues/tumour forms;4. Tumour
suppressor (gene) not effective/ notactivated;5. May have no effect in
diploid/heterozygous(organism);6. (Which) still has a functional ATM/ATM
gene;
◍ The student wanted to determine the rate of water loss per mm2 of surface
area of the leaves of the shoot in Figure 5. Outline a method she could have
used to find this rate. You should assume that all water loss from the shoot
is from the leaves..
Answer: 1. Method for measuring area;e.g. draw round (each) leaf on graph
paper and count squares;2. Of both sides of (each) leaf;3. Divide rate (of
water loss / uptake from potometer) by (total) surface area (of leaves);
◍ The rate of water movement through a shoot in a potometer maybe not be
the same as the rate of water movement through the shoot of a whole plant.
Suggest one reason why..
Answer: Plant has rootsXylem cells very narrow
◍ The transgenic poplars still produced some PIP1. Suggest why..
Answer: Not all of mRNA bound to single-stranded RNA/there is more
mRNA than interfering RNAORNot all mRNA destroyed/disabled;
◍ The scientists first produced transgenic poplar trees. These trees all had a
length of foreign DNA inserted into them. This DNA led to the production
of single-stranded RNA that specifically inhibited expression of the gene for
PIP1. The scientists then measured the difference in the amount of PIP1 in
leaves of transgenic poplars and in leaves of wild type poplars without the
foreign DN
A. The amount of PIP1 in the transgenic poplars was approximately 15% of
that in the wild type poplars. Using this information, what can you conclude
about the effect of the foreign DNA in the transgenic poplar trees?.
