A Science teacher by trade, I've also been known to be found teaching Maths and PE! However, strange as it may seem, my real love is designing resources that can be used by other teachers to maximise the experience of the students. I am constantly thinking of new ways to engage a student with a topic and try to implement that in the design of the lessons.
A Science teacher by trade, I've also been known to be found teaching Maths and PE! However, strange as it may seem, my real love is designing resources that can be used by other teachers to maximise the experience of the students. I am constantly thinking of new ways to engage a student with a topic and try to implement that in the design of the lessons.
This fully-resourced lesson describes the ultrastructure of eukaryotic cells and the functions of each of the organelles in these cells. The engaging and detailed PowerPoint and accompanying resources have been designed to cover points 3.1, 3.2 & 3.3 of the Edexcel International A-level Biology specification and therefore this lesson also describes how all living organisms are made of cells and that these cells are organised into tissues, organs and organ system in multicellular organisms.
As cells are the building blocks of living organisms, it makes sense that they would be heavily involved in all of the 8 topics in the Edexcel course and intricate planning has ensured that links to previously covered topics as well as upcoming ones are made throughout the lesson. The cell theory is introduced at the start of the lesson and the first 2 principles are explained. Students will see how epithelial cells are grouped together to form different types of epithelium in the respiratory tract and their prior knowledge of gas exchange at the alveoli from topic 2 is tested with a series of questions.
The rest of the lesson uses a wide range of activities, that include exam-style questions, class discussion points and quick quiz competitions, to maintain motivation and engagement whilst describing the relationship between the structure and function of the following organelles:
nucleus
nucleolus
centrioles
ribosomes
rough endoplasmic reticulum
Golgi apparatus
lysosomes
smooth endoplasmic reticulum
mitochondria
cell surface membrane
All of the worksheets have been differentiated to support students of differing abilities whilst maintaining challenge
Due to the detail that is included in this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to go through all of the tasks
This detailed and fully-resourced lesson describes the relationship between the structure and function of glycogen and amylose and amylopectin as components of starch. The engaging PowerPoint and accompanying resources have been designed to cover the fourth part of points 1.2 & 1.4 of the Edexcel International A-level Biology specification and links are continuously made to the previous lessons in this topic where the monosaccharides and disaccharides were introduced.
The lesson begins with the CARBOHYDRATE WALL where students have to use their prior knowledge to collect the 9 carbohydrates on show into 3 groups. This results in glycogen, starch and cellulose being grouped together as polysaccharides and the structure and roles of the first two are covered over the course of the lesson. Cellulose is covered in a lesson in topic 4. Students will learn how key structural features like the 1 - 4 and 1 - 6 glycosidic bonds and the hydrogen bonds dictate whether the polysaccharide chain is branched or unbranched and also allows for spiralling. Following the description of the structure of glycogen, students are challenged to design an exam question in the form of a comparison table so that it can be completed as the lesson progresses and they learn more about starch. This includes a split in the starch section of the table so that the differing structures and properties of amylose and amylopectin can be considered. The importance of the compact structure for storage is discussed as well as the branched chains of amylopectin acting as quick source of energy when it is needed. The lesson concludes with a question and answer section that guides the students when answering a question about the importance of the lower solubility of the polysaccharides when compared to the monosaccharides.
This lesson describes how monosaccharides are joined together during condensation reactions to form maltose, sucrose and lactose. The PowerPoint and accompanying resource have been designed to cover the third part of point 1.2 & 1.4 of the Edexcel International A-level Biology specification but also make links to the previous lesson on monosaccharides when considering the different components of these three disaccharides.
The first section of the lesson focuses on a prefix and a suffix so that the students can recognise that the names of the common disaccharides end in -ose. In line with this, a quick quiz round is used to introduce maltose, sucrose and lactose before students are challenged on their prior knowledge as they have to describe how condensation reactions and the formation of glycosidic bonds were involved in the synthesis of each one. The main task of the lesson again challenges the students to recall details of a previous lesson as they have to identify the monomers of each disaccharide when presented with the displayed formula. Time is taken to show how their knowledge of these simple sugars will be important in later topics such as digestion, translocation in the phloem and the Lac Operon in the control of gene expression. The lesson finishes with two exam-style questions where students have to demonstrate and apply their newly acquired knowledge and the mark schemes are included within the lesson PowerPoint so students can assess their understanding and address any misconceptions if they have arisen.
This fully-resourced lesson describes the relationship between the structure of monosaccharides and their roles in living organisms. The engaging PowerPoint and accompanying resources have been designed to cover the second part of points 1.2 & 1.4 of the Edexcel International A-level Biology specification and describes alpha-glucose, galactose, fructose, deoxyribose and ribose.
The lesson begins by reminding students that monosaccharides are the simplest sugars and that these monomers provide energy. Using the molecular formula of glucose as a guide, students will be given the general formula for the monosaccharides and will learn that deoxyribose is an exception to the rule that the number of carbon and oxygen atoms are equal. Moving forwards, students have to study the displayed formula of glucose for two minutes without being able to note anything down before they are challenged to recreate what they saw in a test of their observational skills. At this point of the lesson, the idea of numbering the carbons is introduced so that the different glycosidic bonds can be understood in an upcoming lesson as well as the recognition of the different isomers of glucose. The difference between alpha and beta-glucose is provided but students do not need to consider the beta form until topic 4. The remainder of the lesson focuses on the roles of the monosaccharides and the final task involves a series of application questions where the students are challenged to suggest why ribose could be considered important for active transport and muscle contraction
This lesson describes the differences between monosaccharides, disaccharides and polysaccharides, including glycogen and starch. The PowerPoint and accompanying resource have been designed to cover point 1.2 (i) of the Edexcel International A-level Biology specification and the main aim of the lesson is to prepare the students for the upcoming lessons on the individual carbohydrate groups.
The lesson begins with a made-up round of the quiz show POINTLESS, where students have to try to identify four answers to do with carbohydrates. In doing so, they will learn or recall that these molecules are made from carbon, hydrogen and oxygen, that they are a source of energy which can sometimes be rightly or wrongly associated with obesity and that the names of the three main groups is derived from the Greek word sakkharon. A number of quick quiz rounds have been written into the lesson to introduce key terms in a fun and memorable way and the first round allows the students to meet some of common monosaccharides. Moving forwards, students will learn that a disaccharide is formed when two of these monomers are joined together and they are then challenged on their knowledge of condensation reactions which were originally encountered during the lesson on water. Students will understand how multiple reactions and multiple glycosidic bonds will result in the formation of a polysaccharide and glycogen and starch are introduced as well as amylose and amylopectin as components of this latter polymer.
Hours and hours of planning have gone into each and every lesson that’s included in this bundle to ensure that the students are engaged and motivated whilst the detailed content of topic 2 of the Edexcel International A-level Biology specification is covered. Membranes, proteins, DNA and gene expression represent some of the most important structures, molecules and processes involved in this subject and a deep understanding of their role in living organisms is important for a student’s success.
The 20 lesson PowerPoints and accompanying resources contain a wide range of activities which cover the following topic 2 specification points:
Know the properties of gas exchange surfaces in living organisms
Understand how the rate of diffusion can be calculated using Fick’s Law of Diffusion
Understand how the structure of the mammalian lung is adapted for rapid gas exchange
The structure and properties of cell membranes
The movement of free water molecules by osmosis
The movement across membranes by passive and active transport
The role of channel and carrier proteins in membrane transport
The basic structure of an amino acid
The formation of polypeptides and proteins
The structure of proteins
The mechanism of action and specificity of enzymes
Enzymes are biological catalysts
Intracellular and extracellular enzymes
The basic structure of mononucleotides
The structure of DNA and RNA
The process of DNA replication
The nature of the genetic code
A gene as a sequence of bases on DNA that codes for a sequence of amino acids
The process of transcription and translation
Errors in DNA replication give rise to mutations
Mutations give rise to disorders but many mutations have no observable effect
The meaning of key genetic terms
Understanding the pattern of monohybrid inheritance
Sex linkage on the X chromosome
Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems
The uses and implications of genetic screening and prenatal testing
Due to the detail included in all of these lessons, it is estimated that it will take in excess of 2 months of allocated A-level teaching time to complete the teaching of the bundle
If you would like to sample the quality of these lessons, then download the rapid gas exchange, osmosis, DNA & RNA, genetic code, genetic terms and cystic fibrosis lessons as these have been uploaded for free.
This lesson describes how molecules move across cell membranes by passive transport, as exemplified by simple and facilitated diffusion. The PowerPoint and accompanying resource have been designed to cover the first part of specification point 2.5 of the Edexcel International A-level Biology specification and the factors that increase the rate of diffusion are covered along with the limitations imposed by the phospholipid bilayer and the role of channel and carrier proteins
The structure and properties of cell membranes were described in the lesson covering 2.2, so this lesson has been written to include continual references to the content of that lesson. This enables links to be made between the movement across a cell membrane with the concentration gradient, the parts of the membrane that are involved and any features that may increase the rate at which the molecules move. A quick quiz competition challenges students to recall Fick’s law of diffusion and a series of questions and tasks are used to demonstrate how a large surface area, a short diffusion distance and the maintenance of a steep concentration gradient will increase the rate of simple diffusion. Another quick quiz round is then used to introduce temperature and size of molecule as two further factors that can affect simple diffusion. The remainder of the lesson focuses on facilitated diffusion and describes how transmembrane proteins are needed to move small, polar or large molecules from a high concentration to a lower concentration across a partially permeable membrane
This lesson describes how the structure of the mammalian lung is adapted for rapid gaseous exchange. The engaging PowerPoint has been designed to cover point 2.1 (iii) of the Edexcel International A-level Biology specification and focuses on the essential features of the alveolar epithelium as well as the mechanism of ventilation to maintain a steep concentration gradient for the simple diffusion of oxygen and carbon dioxide.
Gas exchange at the alveoli is a topic that was covered at GCSE and considered during the previous lessons in topic 2.1 so this lesson has been written to challenge the recall of that knowledge and to build on it. The main focus of the first half of the lesson is the type of epithelium found lining the alveoli and students will discover that a single layer of flattened cells known as simple, squamous epithelium acts to reduce the diffusion distance.
The following features of the alveolar epithelium are also covered:
Surface area
Moist lining
Production of surfactant
The maintenance of a steep concentration gradient is the role of the respiratory system and the next part of the lesson focuses on the diaphragm and intercostal muscles. As the mechanism of inhalation is a cascade of events, the details of this process are covered in a step by step format using bullet points. At each step, time is taken to discuss the key details which includes an introduction to Boyle’s law that reveals the inverse relationship between volume and pressure. It is crucial that students are able to describe how the actions of the diaphragm, external intercostal muscles and ribcage result in an increased volume of the thoracic cavity and a subsequent decrease in the pressure, which is below the pressure outside of the body. At this point, their recall of the structures of the mammalian gas exchange system is tested, to ensure that they can describe the pathway the air takes on moving into the lungs.
This fully-resourced lesson describes the inheritance of genes with loci on the X chromosomes and considers biological examples. The detailed PowerPoint and accompanying resources have been designed to cover point 2.15 (ii) of the Edexcel International A-level specification and focuses on the inheritance of red-green colour blindness and haemophilia in humans
Key genetic terminology is used throughout and the lesson begins with a check on their ability to identify the definition of homologous chromosomes. Students will recall that the sex chromosomes are not fully homologous and that the smaller Y chromosome lacks some of the genes that are found on the X. This leads into one of the numerous discussion points, where students are encouraged to consider whether females or males are more likely to suffer from sex-linked diseases. In terms of humans, the lesson focuses on haemophilia and red-green colour blindness and a step-by-step guide is used to demonstrate how these specific genetic diagrams should be constructed and how the phenotypes should then be interpreted. The final task of the lesson challenge the students to apply their knowledge to an exam question about chickens and how the rate of feather production in chicks can be used to determine gender.
All of the tasks are differentiated so that students of differing abilities can access the work and all exam questions have fully-explained, visual mark schemes to allow them to assess their progress and address any misconceptions
This fully-resourced lesson uses step by step guides to walk students through the interpretation of genetic pedigree diagrams for monohybrid inheritance. The PowerPoint and accompanying resources have been designed to cover point 2.15 (ii) of the Edexcel International A-level Biology specification and includes the inheritance when there are more than two alleles at a gene locus as well as those that demonstrate codominance.
In order to minimise the likelihood of errors and misconceptions, the guides that are included within the lesson will support the students with the following:
Writing parent genotypes
Working out the different gametes that are made following meiosis
Interpreting Punnett crosses to work out phenotypic ratios
Students can often find pedigree trees the most difficult to interpret and to explain so exemplar answers are used and the worksheets are differentiated so students can seek assistance if necessary.
This lesson explains the meaning of gene, allele, genotype, phenotype,
recessive, dominant, codominance, homozygote and heterozygote. The engaging PowerPoint and accompanying resources have been designed to cover specification point 2.15 (i) of the Edexcel International A-level Biology but also covers the meaning of genome, gene locus, homologous chromosomes, multiple alleles, autosomes and sex chromosomes as a recognition of these will be useful for upcoming lessons.
As some of these terms were met at GCSE, this fully-resourced lesson has been designed to include a wide range of activities that build on this prior knowledge and provide clear explanations as to their meanings as well as numerous examples of their use in both questions and exemplary answers. The main task provides the students with an opportunity to apply their understanding by recognising a dominance hierarchy in a multiple alleles characteristic and then calculating a phenotypic ratio when given a completed genetic diagram. Other tasks include prior knowledge checks, discussion points to encourage students to consider the implementation of the genetic terms and quiz competitions to introduce new terms, maintain engagement and to act as an understanding check.
This fully-resourced lesson describes how the mutations that occur during DNA replication can effect a protein’s primary structure and lead to disorders. The engaging and detailed PowerPoint and accompanying resources have been designed to cover points 2.14 (i) & (ii) as detailed in the Edexcel International A-level Biology specification and focuses on the effects of substitutions, deletions and insertions and considers a real life biological example in sickle cell anaemia.
In order to understand how a change in the base sequence can affect the order of the amino acids, students must be confident in their understanding and application of protein synthesis which was covered in the previous lessons. Therefore, the start of the lesson focuses on transcription and translation and students are reminder of how to use the codon table to identify amino acids. Moving forwards, a task called known as THE WALL is used to introduce to the names of three types of mutation whilst challenging the students to recognise three terms which are associated with the genetic code. The main focus of the lesson is base substitutions and how these mutations may or may not cause a change to the amino acid sequence. The students are challenged to use their knowledge of the degenerate nature of the genetic code to explain how a silent mutation can result. Students will learn that a substitution is responsible for the new allele that causes sickle cell anaemia and they are tested on their understanding through an exam-style question. As with all of the questions, a mark scheme is included in the PowerPoint which can be displayed to allow the students to assess their understanding.
The rest of the lesson looks at base deletions and base insertions and students are introduced to the idea of a frameshift mutation. One particular task challenges the students to evaluate the statement that base deletions have a bigger impact on primary structure than base substitutions. This is a differentiated task and they have to compare the fact that the reading frame is shifted by a deletion against the change in a single base by a substitution
This detailed lesson describes the role of the mRNA, tRNA, ribosomes and start and stop codons during the second stage of protein synthesis - translation. This lesson is the second in a series of two, which have been designed together to cover point 2.13 of the Edexcel International A-level Biology specification. The first lesson in this series describes transcription.
Translation is a topic which is often poorly understood and so this lesson has been written to enable the students to understand how to answer the different types of questions by knowing and including the key details of the structures involved. The lesson begins by challenging the students to consider why it is so important that the amino acids are assembled in the correct order during the formation of the chain. Moving forwards, a quick quiz round called “LOST IN TRANSLATION” is used to check on their prior knowledge of the mRNA strand, the tRNA molecules, the genetic code and the ribosomes. The next task involves a very detailed description of translation that has been divided into 14 statements which the students have to put into the correct order. By giving them a passage that consists of this considerable detail, they can pick out the important parts to use in the next task where they have to answer shorter questions worth between 3 and 4 marks. These types of questions are common in the assessments and by building up through the lesson, their confidence to answer this type should increase. The final two tasks of the lesson involve another quiz, where the teams compete to transcribe and translate in the quickest time before using all that they have learnt to answer some exam-style questions which involve the genetic code and the mRNA codon table.
This detailed lesson describes the sequence of events that occur during the first stage of protein synthesis, which is known as transcription. The detailed lesson PowerPoint and accompanying worksheet are the first in a series of two lesson resources that have been designed to cover the details of point 2.13 of the Edexcel International A-level Biology specification and include details of the DNA template strand, RNA polymerase and messenger RNA.
The lesson begins by challenging the students to work out that most of the nuclear DNA in eukaryotes does not code for polypeptides. This allows the promoter region and terminator region to be introduced, along with the structural gene. Through the use of an engaging quiz competition, students will learn that the strand of DNA involved in transcription is known as the DNA template (or antisense) strand and the other strand is the coding strand. Links to previous lessons on DNA and RNA structure are made throughout and students are continuously challenged on their prior knowledge as well as they current understanding of the lesson topic. Moving forwards, the actual process of transcription is covered in a 7 step bullet point description where the students are asked to complete each passage using the information previously provided. An exam-style question is used to check on their understanding before the final task of the lesson looks at the journey of mRNA to the ribosome for the next stage of translation.
This lesson has been written to directly lead into the following lesson on translation
This lesson describes the nature of the genetic code as near universal, non-overlapping and degenerate and relates this to the triplet code. The engaging lesson PowerPoint has been designed to cover point 2.11 of the Edexcel International A-level Biology specification and clear links are made to protein synthesis and gene mutations which students will meet in the next lot of lessons.
At the start of the lesson, the students are challenged to use their knowledge of the bases in DNA and RNA to complete a definition which describes the genetic code as being near universal, non-overlapping and degenerate. Time is taken to explain how three bases on DNA (a triplet) and three bases on mRNA (a codon) encode for a single amino acid or a stop codon and this is the triplet code. A quick quiz competition is used to generate the number 20 so that the students can learn that there are 20 proteinogenic amino acids in the genetic code. This leads into a challenge, where they have to use their prior knowledge of DNA to calculate the number of different DNA triplets (64) and the mismatch in number is then discussed and related back to the lesson topic. Moving forwards, base substitutions and base deletions are briefly introduced so that they can see how although one substitution can change the primary structure, another will change the codon but not the encoded amino acid. The lesson concludes with a brief look at the non-overlapping nature of the code so that the impact of a base deletion (or insertion) can be understood when covered in greater detail in the lesson covering point 2.14
This fully-resourced lesson describes the process of DNA replication and includes key details of the role of DNA polymerase. The detailed PowerPoint and accompanying resources have been designed to cover point 2.10 (i) of the Edexcel International A-level Biology specification and also includes descriptions of the roles of DNA helicase and DNA ligase and an introduction of this type of replication as semi-conservative.
As the main focus of this lesson is the roles of the enzymes, students will understand how DNA helicase breaks the hydrogen bonds between nucleotide bases, DNA polymerase forms the growing nucleotide strands and DNA ligase joins the nucleic acid fragments. The specification specifically mentions DNA polymerase and in line with this, extra time is taken to explain key details, such as the assembly of strands in the 5’-to-3’ direction by this enzyme, so that the continuous manner in which the leading strand is synthesised can be compared against that of the lagging strand. The students are constantly challenged to make links to previous topics such as DNA structure and hydrolysis reactions through a range of exam questions and answers are displayed so that any misconceptions are quickly addressed. The main task of the lesson asks the students to use the information provided in the lesson to order the sequence of events in DNA replication before discussing how the presence of a conserved strand and a newly built strand in each new DNA molecule shows that it is semi-conservative.
This lesson describes the basic structure of mononucleotides and the resulting structural similarities and differences between DNA and RNA. The PowerPoint and accompanying resource have been designed to cover points 2.9 (i) and (ii) of the Edexcel International A-level Biology specification and makes regular links to upcoming lessons which cover DNA replication and protein synthesis.
In a lesson in topic 1, the students were introduced to monosaccharides as an example of a monomer and were informed that a nucleotide was another example. In line with this, the start of the lesson challenges them to recognise the key term nucleotide when only the letters U, C and T are shown. The next part of the lesson describes the structure of a DNA nucleotide and an RNA nucleotide so that the pentose sugar and the bases adenine, cytosine and guanine can be recognised as similarities whilst deoxyribose and ribose and thymine and uracil are seen as the differences. Time is taken to discuss how a phosphodiester bond is formed between adjacent nucleotides and their prior knowledge and understanding of condensation reactions is tested through a series of questions. Students are then introduced to the purine and pyrimidine bases and this leads into the description of the double-helical structure of DNA and the hydrogen bonds between complementary bases. The final section of the lesson describes the structure of mRNA, tRNA and rRNA and students are challenged to explain why this single stranded polynucleotide is shorter than DNA
In addition to the current understanding and prior knowledge checks, a number of quiz rounds have been written into the lesson to introduce key terms in a fun and memorable way and the final round acts as a final check on the structures of DNA and RNA.
This lesson describes how the primary structure determines the secondary structure, 3D structure and properties of a protein. The detailed and engaging PowerPoint and accompanying resources have been designed to cover points 2.6 (ii) & (iii) of the Edexcel International A-level Biology specification but also makes specific reference to genes and protein synthesis and therefore introduces students to processes covered later in topic 2.
The start of the lesson focuses on the formation of a peptide bond during a condensation reaction so that students can understand how a dipeptide is formed and therefore how a polypeptide forms when multiple reactions occur.
The main part of the lesson describes the different levels of protein structure. A step by step guide is used to demonstrate how the sequences of bases in a gene acts as a template to form a sequence of codons on a mRNA strand and how this is translated into a particular sequence of amino acids known as the primary structure. The students are then challenged to apply their understanding of this process by using three more gene sequences to work out three primary structures and recognise how different genes lead to different sequences. Moving forwards, students will learn how the order of amino acids in the primary structure determines the shape of the protein molecule, through its secondary, tertiary and quaternary structure and time is taken to consider the details of each of these. There is a particular focus on the different bonds that hold the 3D shape firmly in place and a quick quiz round then introduces the importance of this shape as exemplified by enzymes, antibodies and hormones. The lesson concludes with one final task where the students have to identify three errors in a passage about the hydrolysis of a dipeptide or polypeptide.
This engaging lesson describes the basic structure of an amino acid and introduces them as the monomers of polypeptides. The PowerPoint has been designed to cover point 2.6 (i) of the Edexcel International A-level Biology specification and has been specifically written to lead into the next lesson on dipeptides and polypeptides.
The lesson begins with a prior knowledge check, where the students have to use the 1st letters of 4 answers to uncover a key term. This 4-letter key term is gene and the lesson begins with this word because it is important for students to understand that these sequences of bases on DNA determine the specific sequence of amino acids in a polypeptide as covered later in the topic. Moving forwards, the students are given time to work out that there are 64 different DNA triplets and will learn that these encode for the 20 amino acids that are common to all organisms. The main task of the lesson is an observational one, where students are given time to study the displayed formula of 4 amino acids. They are not allowed to draw anything during this time but will be challenged with 3 multiple choice questions at the end. This task has been designed to allow the students to visualise how the 20 amino acids share common features in an amine and an acid group. A quick quiz round introduces the R group and time is taken to explain how the structure of this side chain is the only structural difference, before cysteine is considered in greater detail due to the presence of sulfur atoms. Students are briefly introduced to disulfide bridges so they will recognise how particular bonds form between the R groups in the tertiary structure which is covered in the next lesson. The lesson concludes with one more quiz round called LINK TO THE FUTURE where the students will see the roles played by amino acids in the later part of the course such as translation and dipeptides.
This fully-resourced lesson describes the movement of molecules by active transport, endocytosis and exocytosis. The PowerPoint and accompanying worksheets have been designed to cover the second part of specification points 2.5 (i) & (ii) of the Edexcel International A-level Biology specification and describes the role of ATP as an immediate source of energy as well as the role of the carrier proteins.
ATP is introduced at the start of the lesson and students will learn that this molecule is a phosphorylated nucleotide so they are able to make appropriate links when they cover the structure of DNA and RNA later in topic 2. Students will learn that adenosine triphosphate is the universal energy currency and that the hydrolysis of this molecule can be coupled to energy-requiring reactions within the cell and the rest of the lesson focuses on the use of this energy input for active transport, endocytosis and exocytosis. Students are challenged to answer a series of questions which compare active transport against the forms of passive transport and to use data from a bar chart to support this form of transport. In answering these questions they will discover that carrier proteins are specific to certain molecules and time is taken to look at the exact mechanism of these transmembrane proteins. A quick quiz round introduces endocytosis and the students will see how vesicles are involved along with the energy source of ATP to move large substances in or out of the cell. The lesson concludes with a link to a future topic as the students are shown how exocytosis is involved in a synapse.
