1. Can personalised learning strategies such as concept
mapping and cooperative learning be used to
overcome blocks to learning caused by difficult to
understand topics in biology.
Candidate number: 120127735
Supervisor: Dr Jonathan Graves
Word count: 4997
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Biological Introduction
Pathogens
The Oxford Dictionary definition of a pathogen is “a bacterium, virus, or other microorganism
that can cause disease”(Stevenson, 2010), with the link between diseases and pathogens often
being highly specific (Singleton, 1997). Pathogens are of major interest to biologists, especially
those that directly or indirectly impact humans. There is vast research into how to treat
pathogens, but also interest in their biochemistry, microbiology and evolution. Pathogens have
incredible phylogenetic diversity (Alberts et al, 2002); also within each group of pathogens
there is huge diversity in size, shape and lifestyle. Pathogens can be obligate, where they only
replicate within the cells of the human body; or facultative, where they replicate in the
environment then infect their host. To survive and replicate pathogens must complete the five
stages of pathogenicity which are; adhere to host tissues, invade host tissues, multiply in host
tissues, evade host defences, and cause damage (Williams, Ketley and Salmond, 1998; Alberts et
al, 2002). All pathogens evolve specific ways to enter the host, and avoid their immune system.
Bacteria are tiny, single-celled organisms, which are found everywhere on earth (Singleton,
1997). They are the only known pathogenic prokaryotes (Campbell and Reece, 2011).
Prokaryotes are different from eukaryotes in several ways (Singleton, 1997). They have no
nuclear membrane, and contain simple chromosomes. They don’t reproduce by mitosis or
meiosis, but by binary fission or gene transmission. They lack internal, membrane bound
organelles, and are devoid of mitochondria and chloroplasts. The cell walls are made of
peptidoglycan, which is why antibiotics only destroy bacterial cells and not human cells. Illness
is caused by bacteria producing either exo or endotoxins (Campbell and Reece, 2011). The
difference being exotoxins are proteins secreted by certain bacteria, where as endotoxins are
the lipopolysaccaride parts of the bacterial cell walls, and are only released when the bacteria
begins to break down after death.
Viruses are even smaller than bacteria; they range from 10-300 µm (Wyss and Eklund, 1971).
They are simply nucleic acid surrounded by a protein coat, known as the capsid, which is
sometimes enclosed by a lipid envelope (Voyles, 1993). Their genomes are unconventional and
can be double or single stranded DNA or RNA, but never both. They are intracellular parasites
(Voyles, 1993), they have no metabolic machinery of their own (Wyss and Eklund, 1971), and
manipulate hosts enzymatic apparatus to produce more viruses, thus are reliant on host cells to
survive and replicate. They’re effective pathogens as a single viron which infects a host cell can
produce thousands of new virons (Alberts et al, 2002). Viruses are different from all other
microorganisms for two reasons; firstly they have no ribosomes or other cellular organelles,
secondly in RNA viruses all genetic information is encoded in RNA (Fenner et al, 1974).
Pathogenic fungi make up around 30% of all known species of fungi (Campbell and Reece, 2011).
They tend to be pathogens of plants, and can produce compounds in crop plants which are toxic
to humans. This is of high interest to researchers due to food security issues. Fungi tend not to
infect animals as much as they do plants, but there are around 500 species of fungi that are
pathogens to animals. Mycosis is the term used for an infection caused by a fungus; systemic
mycoses can cause very serious illnesses by spreading throughout the body. Pathogenic fungi
are difficult to treat without harming the host, as many antifungal treatments are damaging.
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They also have complex life cycles and drugs don’t typically treat all stages, meaning pathogenic
fungi can evade treatment (Alberts et al 2002).
Host defences
Pathogens enter the body via any interface with the environment. The skin often acts as a
protective barrier from pathogens (Singleton, 1997), meaning that they mainly gain entrance
via the mouth, leading to mucous membranes which are vulnerable to infection. However if the
skin is broken via a wound or bite, the pathogen can enter directly into the body.
Pathogens cause disease by many different mechanisms, for example producing toxins that stop
specific physiological processes; or invading cells and tissues, where toxins may also be
produced (Singleton, 1997). The body’s physiological response to an infection is known as
sepsis. The body defends itself against attack from pathogens through several mechanisms. The
body’s first barrier to pathogens is the skin. Then mucous membrane secretions discourage
pathogens due to their antibacterial qualities. Specialised cells called phagocytes then destroy
anything that is seen as foreign to the body. Finally antibodies are released by the body’s
immune system as a response to specific pathogens. Hosts can also have immunity to pathogens
and artificial immunity can be produced via the use of vaccines (Wyss and Eklund, 1971).
Antibiotic resistance
Evolution of bacterial strains to be resistant to antibiotics is a huge threat to public health. Due
to the rapid reproduction of bacteria, resistant bacteria can produce huge resistant populations
in very short time periods (Campbell and Reece, 2011). Antibiotics stop the peptidoglycan
bacterial cell wall from forming, causing osmotic lysis, and cell destruction. There is a selection
pressure for bacteria which are not destroyed by antibiotics; this enhances the production of
large resistant populations. Both vertical and horizontal gene transfer can spread resistant
genes throughout populations. A mutation can cause resistance by either altering a target
protein or enzyme within the bacterial cell so the antibiotic can no longer affect it, or by
preventing the antibiotic from entering the cell (Boyle and Senior, 2008).
Antibiotic resistance has led to such public health scares as MRSA, where there are no
antibiotics to treat them (Boyle and Senior, 2008). It is generally caused by over-prescription of
antibiotics by doctors, to treat infections that may not even be caused by bacteria. Made worse
when patients don’t finish their courses of antibiotics, meaning even partially resistant bacteria
can cause an infection.
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Further your learning
HIV – Will science ever find a
cure?
Human immune-
odeficiency virus
(HIV), the virus that
causes AIDS,
targets specific cells
in the immune system, known as T cells (Boyle and
Senior, 2008).
HIV is a retrovirus, carrying the enzyme reverse
transcriptase. Once the virus enters the host cell it uses
this enzyme to make viral DNA from viral RNA. The viral
DNA is incorporated into the hosts own DNA, allowing
the production of thousands of new viruses. This
process causes the weakening of the immune system
(Campbell and Reece, 2010) that leaves sufferers
vulnerable to other infections such as tuberculosis and
malaria. The main issue in the
treatment of HIV is the fast evolution of the viruses’
surface proteins meaning that anti-viral drugs rapidly
lose effectiveness (Boyle and Senior, 2008).
However there have been recent developments by
scientists (Hayden, 2015), who have discovered an
antibody (3BNC117) that reduces levels of the virus in
humans. In clinical trials, 29 participants were tested, 8
of them were given the highest dose of 3BNC117, and
this was found to reduce virus levels by between 8 and
250 times. However there are still issues; this treatment
is incredibly expensive, with one course of antibodies
costing thousands of dollars and most sufferers live in
poorer countries. Also the rapid evolution of HIV still
effects this treatment with patients who received the
highest dose of antibody finding it was 80% less
effective after 28 days. Scientists suggest that this new
antibody will need to be used in conjunction with other
antibodies to combat this problem.
The Ebola epidemic - here to stay?
The infamous Ebola virus has caused over 10,000 deaths
in 2014 alone (CDC, 2014). The recent outbreak was
caused by the Zaire species (Nice, 2014). With a fatality
percentage of 69%, it is thought to be the most virulent
species, begging urgent research attention.
The Ebola virus owes its virulence to the mechanisms it
uses to disarm the immune response. The virus inhibits
cells that signal for the T-cells to destroy them before
infection spreads. With no T-cell activation, there is no
activation of antibodies. From here the virus travels in the
blood to the organs, and causes macrophages to release
coagulants to clot the blood causing haemorrhaging
(Servick, 2013).
Current treatments for Ebola include blood transfusions
from Ebola survivors, but research is also looking into two
vaccines that may be able to stop the disease (Nice, 2014).
Research also shows that survival may be down to
genetics, as survivors have more activated T-cells due to
possessing a different gene variant (Servick, 2013). Much
research is also going into making the diagnosis of Ebola
easier with the creation of a rapid diagnostic kit.
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Can bacteria really control behaviour?
Weird Wolbacia
Wolbacia bacteria which live inside the reproductive
tissues of Arthropods are famous for being able to
change their hosts’ physiology to increase their chance
of being passed on to offspring (Werren, 1997). The
Wolbacia bacteria are only passed on via female hosts,
this leads them to change their hosts to make sure that
they maximise their population. In parasitic wasps
Wolbacia induce
parthenogenesis in hosts.
This means that offspring
can form from unfertilised
eggs; this guarantees that
the bacteria will be present in the offspring.
It has also been seen in crustaceans that Wolbacia
causes the feminization of genetic males. The bacterium
converts males into reproductively competent females.
All of these mechanisms give a selection advantage to
the bacterium that has led to them being widespread
throughout the animal kingdom.
Bizarre Buchnera
Buchnera are round-shaped bacteria which live in
specific cells called bacteriocytes in most aphid species
(Shigenobu et al, 2000). These bacteria are maternally
transmitted to eggs, and neither the aphid nor buchnera
can reproduce alone. These bacteria provision the
aphids with essential amino acids (Douglas, 1998), which
are not present in the sticky phloem sap on which the
aphids feed. In return the bacteria live within the aphid,
and are passed on generation after generation.
Bacteria and the dinosaurs
Bacteria are important in a process called exceptional
preservation, where structures like skin, feathers and
organs which are not normally preserved are fossilised
(Franzen, 1985). This has led to major discoveries such
as theropod dinosaurs were actually covered in feathers.
The process of exceptional preservation occurs when an
organism dies in environments with certain
characteristics, for example, places where scavengers
can’t eat the carcasses and anoxic environments so that
bacteria can’t degrade it. These tend to be lakes or ash
falls from volcanoes. However microbial mats have also
been found to allow exceptional preservation.
In Grube Messel site in Germany there are fossils which
are fully articulated, and some soft tissue even remains.
When a PhD student examined the fossils with an
electron microscope, they found the fossil to be made up
of rod and spherical microbes. From this they deduced
that there was a layer of bacteria on the underside of the
body, which had become petrified when the carcass
landed on them. These bacteria were then cemented in
place by organic material from plants. These sorts of
discoveries can tell us a lot about the past, and evolution.
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Educational introduction
Educational placement
High Storrs School is an above average sized school with 1596 students, aged 11-18. It has been
designated a specialist school in Performing Arts, Maths and Computing. The 2013 Ofsted
inspection deemed the school “good” due to the above average GCSE attainment of students and
the good and sometimes outstanding teaching. Students’ behaviour was deemed “outstanding”,
which is consistent with my observations. I observed 17 lessons; six year 8 lessons, with pupils
aged 12-13 years, where I saw a mix of sets, from the highest set to the lowest set. Eleven year
12 lessons, with pupils aged 16-17, of the same class.
I taught one lesson to the year 12 class that I had been observing; there were 17 mixed ability
students in this class. During my time at the school they were preparing for their exams and
there practical exam (EMPA) so I was asked to teach a revision session. As I wanted this to be a
useful lesson for them I asked them what topics they would like to revise. They suggested
mitosis and meiosis or antibiotics. I later was asked to teach them a topic that would be on their
EMPA so I ended up teaching a lesson on pathogens and antibiotics.
From my observations of classes across all age ranges I saw that students had better
engagement when:
1) They were given short activities to do and then move on quickly to the next activity. This
reduced boredom with an activity and increased engagement.
2) When lessons were made interactive, whether it be that students were involved in a
discussion, or there was a practical. Students remained engaged when they were
allowed to physically do things in lessons.
Students tended to lose interest:
1) During cross over between activities, if the next activity wasn’t immediately ready.
2) When they spent too long on activities or the teacher spent too long explaining an idea.
From this I could see that it was necessary to make sure that all activities are ready for the
students one after another. To make sure that there are short introductions and instructions to
each topic. To make sure that activities are interactive and engaging. It is also important for
students to feel that they are in charge of their learning.
Implementation
From observations of both year 12 and year 8 classes I saw that students learn information via
rote learning. Students tend to recall information, not necessarily make links between concepts.
When year 12’s answered practice exam questions they would often struggle and need help
when a question was asking them to apply their knowledge, rather than just recall. The students
suggested they struggled with antibiotic resistance – this may be due to the fact that this
concept draws from other areas of biology, such as evolution, and without making those links it
could be a confusing concept. I will incorporate concept mapping into my lesson plan. This could
help the students make the transition from rote learning to meaningful learning that is
necessary for higher education.
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I also observed that students were most engaged with a task when they were allowed to work in
groups. They would discuss ideas with each other and so were better able to understand and
answer questions during and after these activities. I will incorporate collaborative learning into
my lesson in the form of study groups. By getting students to study together and explain
challenging concepts to each other I hope that confusing concepts become clearer, and more
memorable, when explained by a group member.
Educational background
Introduction
Blocks to learning are especially detrimental in the sciences; this is due the inter-relatedness
between topics and concepts within science disciplines. Within Biology it is important to be able
to draw knowledge from many different areas to allow interpretation of information. It is
integral to progression in biology that individuals can form these links between ideas and
different topics. When this does not occur, it is often difficult for students to understand certain
concepts, due to these blocks to learning. Less students’ progress into science subjects at
tertiary education, this may be due to these blocks to learning that are hard to overcome
without the necessary learning strategies. Strategies such as concept mapping and collaborative
learning could help students to understand difficult topics in biology, by helping them to make
connections between different topics, and draw information from many different areas of
biology.
Blocks to learning faced by students
Blocks to learning can be detrimental to students especially in science, often inhibiting their
progression into tertiary education. It is important to understand what blocks to learning are
faced by students; once the blocks are understood then learning mechanisms can be put in to
place to overcome them. Students often find topics difficult to understand if they have
previously misinterpreted or have not assimilated information related to the topic (Williams et
al 2012). There is also a suggestion that students struggle with ideas that relate to other
information within the topic or even outside the topic (Shanahan, Fisher and Frey, 2012), this is
because understanding difficult concepts is centred on an individual’s prior knowledge of the
subject. Students also struggle to understand ideas if they are complex with many components
(Graesser, Leon and Otero, 2002), especially where there are connections between components.
This is due to students learning primarily through rote learning, which is centred around
memorisation of information, this makes it difficult for students to make connections between
different topics.
Constructivist theory
Constructivist theory and learning approaches such as scaffolded knowledge integration
framework can be used to address blocks to learning, as are directly linked to the issues
surrounding accumulation of previous knowledge. The theory of constructivism was founded in
the 1980’s due to Jean Piaget’s work (Glynn, Yeany and Britton, 1991). He suggested that
humans construct knowledge based on previous information and experiences with the
environment. Individuals thus construct new knowledge by adding or modifying existing ideas
that they possess (Keogh and Naylor, 1996). However previous knowledge can be detrimental
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to students learning, especially misconceptions, which make it difficult for students to
understand or incorporate new information (Thompson and Zamboanaga, 2003).
Scaffolded knowledge integration framework is a teaching approach within the constructivist
theory (Williams et al 2012) that emphasises the importance of learning by adding, sorting and
reorganising scientific ideas. The key aims behind this theory are; using activities which prompt
students to think about how ideas are connected, learning from others using discussion and
debates, and allowing for a learning technique which can be applied to numerous problems.
Concept maps
Concept maps are a technique that can be implemented to allow students to overcome blocks in
their learning caused by difficult to understand ideas. Concept maps which were first proposed
by Joseph Novak, are thought to facilitate meaningful learning (Okebukola and Jegede, 1989),
where a person purposely relates new knowledge to relevant knowledge they already have.
Rather than rote learning where knowledge is randomly incorporated into the cognitive
structure (Novak, Gowin and Johansen, 1983). Concept maps are graphical representations of
knowledge (Novak and Cañas, 2008). They include “concepts” which are placed inside circles;
relationships between concepts which are represented by a connecting line, and a word is
placed on the line to identify the relationship between concepts. Constructivist theory suggests
that knowledge is constructed based on what an individual already knows (Novak 1991), and
concept maps can be used to organise knowledge and relate it to what is already known by the
student, which allows meaningful learning. However students must choose to learn
meaningfully (Novak and Cañas, 2006); the teacher only has indirect control over this by
motivating students. Students need to attempt to incorporate new meanings into their prior
knowledge rather than just memorising the information on a superficial basis. They initially
struggle with concept mapping due to previous rote learning, the transfer to meaningful
learning is problematic for students (Heige, 2012).
Concept maps can be used as an effective revision tool. To create new knowledge, information
must be moved from the short-term into the long-term memory (Watson and Gable 2010); the
working memory facilitates this. The working memory has a limited capacity of 5-9 pieces of
information, once the working memory is overloaded there are negative effects on learning and
understanding. Concept maps can help students to learn more information and increase
understanding as the concepts are linked, creating chunks of information, (Heige 2012) which
make large amounts of information more manageable, meaningful and memorable. As well as
making relationships between new and old information, concept maps allow more to be
remembered by the working memory (Novak and Cañas, 2006). Concept mapping has also been
found to reduce anxiety in students when they were learning difficult concepts (Okebukola and
Jegede, 1989). Unfortunately exams don’t necessarily require anything more than rote learning,
for example recalling statements or definitions. Meaningful learning can actually make these
exams difficult as the assimilation of information into frameworks stops them being able to
recall things such as definitions (Novak and Cañas, 2006).
Current studies into the effectiveness of concept mapping
A meta-analysis of studies (Heige, 2012) which used concept mapping as a learning technique
reported that it is a more effective technique for retention of information than ‘traditional’
learning methods such as reading text, lecture style lessons or discussions. Heige (2012) also
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found that 54% of 171 kinesiology undergraduates ranked concept maps as the most beneficial
learning technique, and 71% ranked them as one of the top three learning techniques. 2/3rds of
students said they used concept maps to help them answer exam questions. Conceiҫão and
Taylor (2007) looked at concept mapping with student nurses. They found that concept
mapping allowed students to make new connections to information, integrate previous
knowledge and validate existing knowledge. Briscoe and LaMaster (1991) introduced concept
mapping to Biology college students. They found that it helped students to solve novel problems,
and answer questions that required synthesis of information. However they found that whether
students chose to learn meaningfully depended on what kind of exam questions students
anticipated. Regis and Albertazzi (1996) looked into using concept maps with chemistry
students aged 16-18. They found that on average students needed four to six 45 minute sessions
to understand how to construct a concept map. As the students went on their concept maps
developed and became more complex, leading to better linkages between information. They
also allowed for teachers to see where there were misconceptions in students’ previous
knowledge. They encouraged students to discuss their maps and be critical of them to
encourage active learning. They found that students found concept maps so useful they started
using them in other subjects.
Collaborative learning
Learning with others can be particularly helpful when students face blocks in their learning. By
discussing the difficult to understand concepts in biology students can start to build up links
between other concepts and integrate them into their previous knowledge. “Cooperative
learning is when students work together in small heterogeneous groups performing group tasks
set by the teacher” (Shoval and Shulruf, 2011). Children build their own understandings and
meanings about information through activity, where they can discover and internalise new
information (Glynn, Yeany and Britton, 1991). Children also learn though social interaction
(Nyikos and Hashimoto, 1997). Social constructivism emphasises that social interaction is
incredibly important in individuals cognitive development as information experience through
social activity is internalised. Nyikos and Hashimoto (1997) wanted to see if collaborative
learning was useful in adults. They observed a graduate teacher education class where there
was a collaboratively written paper. They found that group members with more knowledge
helped their less knowledgeable colleagues. They found that discussing problems made them
easier to solve. In general cooperative learning was successful as rated by the students.
Conclusion
It is clear that students struggle due to difficulty understanding complex concepts. These blocks
in learning are caused when previous knowledge is either misinterpreted or not assimilated
correctly, this causes new information to become challenging to students. Constructivists
suggest this is because the ease at which students learn new information is based on what
knowledge they already possess. It has been shown in previous studies that concept mapping
and collaborative learning are effective techniques in overcoming these difficult ideas, and are
useful to students tackling these blocks to learning. Secondary education exams don’t often ask
for more than rote learning, so students tend to memorise information, and then struggle in
analytical questions. However students need to progress to learning meaningfully and have
strategies to overcome blocks in their learning to advance to tertiary education, without this we
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find a decrease in the number of students progressing into more complex subjects like science
and maths.
Educational aims and objectives
Aims:
- Tackle the issue of blocks to learning in challenging topics such as antibiotics.
- To use concept maps to encourage students to understand how different areas of
biology interact.
- To use collaborative learning to reinforce learning in a social context.
- To encourage students to start assimilating information in a meaningful way, rather
than by rote learning.
- To allow students the mechanisms to approach revision using meaningful learning.
Objectives:
- To be able to say how pathogens cause disease.
- To be able to explain how pathogens enter the body, and what pathogens infect different
systems of the body.
- To understand how antibiotics destroy bacteria.
- To understand what antibiotic resistance is and how it evolves.
- To have drawn a concept map, and to understand why they are useful in terms of
meaningful learning.
- To understand how different revision techniques can be effective.
Assessment of effectiveness
Starter and introduction of the topic:
The starter was received well by the students. It was good to see what they already knew, and
they understood that that is how they should approach their future revision. In general I spent
too much time explaining the background information for a revision session and there should
have been more time spent focusing on interpreting the information instead. Students were able
to recall the information, and didn’t need it explained again. The teacher suggested that I should
have asked the students to feedback their ideas or answers more so they were actively
contributing to the lesson.
Activity 1 – Concept mapping:
The students found concept mapping difficult to do, this is because they are used to rote
learning, and for example they suggested that they preferred using lists to revise. It is difficult to
change the students’ technique of learning in one lesson, especially as studies suggest they need
4-6 sessions to fully understand how to use of concept maps. When asked if they would use it in
their revision again only one student said yes. However they did understand how to use them,
and why they were useful, and by the end of the task they were all able to see how different
concepts linked together.
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The teacher suggested that I should have given more detailed instruction on how to construct a
concept map; I could have been more thorough in my explanation. I also didn’t fully explain the
concept map I constructed myself, and they teacher suggested it would have been useful for the
students to understand why and how I constructed it.
Activity 2 – Study groups:
The students worked reasonably well in study groups and all managed to get something
prepared to show each other. There were many different ways that students used to
demonstrate the topic they had been given. Several students drew storyboards, several just gave
explanations, several turned their topic into a story, creating characters, and one student made
a rap about his topic and one played charades and made her group guess what pathogen it was.
It worked well in that several students said they would remember the topic because of how it
had been portrayed to them by their peers, but also because they had to fully understand it to
then teach it to others. Collaborative learning is extremely important in internalising
information and knowledge, especially when it is done in a memorable way. The teacher felt I
should have taken advantage of the fact that the students were of differing abilities and put
them in groups myself so that they are in groups of the same ability. Although this would be
beneficial as higher ability groups could have been given harder work, I feel that for two reasons
it was better to let them choose their own groups; 1) if they were to form study groups
themselves they would do so in friendship groups, 2) if the groups are mixed ability that means
that higher ability students could help lower ability students to understand concepts, and they
would be forced to think about the idea in an easily explainable way.
Activity 3 – Who wants to be a millionaire quiz:
The students really enjoyed this part of the lesson, and were engaged though out. It was good to
see how much they had learnt through the lesson or how much they remembered. I was starting
to run out of time during this part of the lesson and I would have liked to have taken more time
to explain the answers thoroughly.
Conclusion:
I think that the lesson was a success overall, and the students enjoyed the lesson on the whole.
Due to the nature of the lesson it probably wasn’t the best lesson at conveying the topic, it was
primarily a lesson to teach students how to deal with challenging concepts and how to approach
revision in a meaningful way, and I feel the lesson did this well. By the end of the lesson
students seemed to be able to apply knowledge to questions they were asked, as well as being
able to compose their own learning resources to effectively teach other students. The teacher
was very positive about my lesson, and said I was confident in my delivery and the students
were responsive to me. They were happy to get involved in discussions and activities, and there
were no behaviour issues.
Her final feedback was “A great, entertaining lesson. Students really enjoyed the interactive
nature of the lesson. All students were engaged and focussed throughout. You could have done
something on interpreting exam questions, structuring long answer questions.” I think that
having an exam question in the last 10 minutes of the lesson would have been useful, especially
questions that involved linking concepts. In retrospect I should have put some other worksheets
or exam questions in their resource pack.
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Students were hesitant towards both concept mapping and collaborative learning, this may be
due to the way they have always learnt, and it is difficult to change their entire learning process
in one lesson. However they could all see the benefits of learning in this way. In secondary
learning they aren’t always pushed to learn meaningfully and often exams favour rote learning,
however I hope I equipped them with the skills to go further into tertiary learning where rote
learning is no longer enough.
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Appendix 1:
Lesson plan 17/04/2015 – Lesson on the genetic variation of bacteria and pathogens.
Start time: 12.55pm - Starter activity
5 minutes to settle down and get seated.
With starter activity; ask students to write down what they remember of the topics from
what they learnt.
1.00pm – Introduction to topics
10 minutes to introduce the topics.
1.10pm – Concept map explanation
15 minutes. How to construct a concept map – giving an example of an easy concept
map.
1.25pm – Construct concept maps
20 minutes. Give them A4 paper and ask them to construct concept maps on genetic
variation of bacteria and pathogens.
Run through the concept maps with students.
1.45pm – Study groups
15 minutes. Split students into groups of 4. Give each student a part of the topic to
research and create resources.
10 minutes. They then have to use these resources to explain the topic to each other.
From each group one person will come up and explain it.
10 minutes. Explanations.
2.20pm – Who wants to be a millionaire quiz
30 minutes. Who wants to be a millionaire.
Split into groups of 4 again. Each group will have a whiteboard and put answers to
questions.
2 minutes for reading and answering of each question.
2.50pm
5 minutes. Pack away and handing out of resource packs.
Resource packs contain three pages with concepts for concept maps and two further
learning pages, one on mitosis and meiosis, and one on pathogens.
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Slide 2
Aims and objectives
To recap these two topics
To understand concept mapping as a
revision technique
To use study groups as an effective
revision technique
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Slide 3
What do you remember?
How do pathogens harm humans?
How can pathogens enter the human
body?
What is the difference between a virus
and a bacteria?
How do antibiotics effect bacteria?
How is antibiotic resistance caused?
Slide notes
- Ask students to think about the answers to the questions for 5 minutes.
- Explain when they start revision they need to write down what they remember about a
topic before continuing.
- This is how students should approach revision with a clear understanding of what they
already know.
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Slide 4
What you need to know
• Bacteria, viruses and fungi.
• Cause disease, by producing toxins that
damage host cells.
• Viruses – made up of DNA/RNA, a
protein coat and lipid envelope.
• Bacteria – are prokaryotes
• Fungal – are eukaryotes.
Slide notes
- Explain they need to then go through what they need to know from the syllabus. This is
the approach they should take before beginning revision.
- As it was revision I would ask them related questions such as “how do pathogens cause
disease?” before I put the slide up.
- I asked them to tell me how a prokaryote was different to a eukaryote.
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Slide 5
• Enter the body via any interface with
the environment.
• Contaminated food and water
- E.coli and cholera
• Airborne infections
- flu, measles, tuberculosis and meningitis
• Via the skin
- Tetanus and malaria
• Direct contact
- HIV and STDs
Slide notes
- I asked students what famous pathogens they could think of for each pathway into the
body.
- I also asked students what symptoms they knew for each disease.
- We also discussed the symptoms of meningitis.
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Slide 6
Bacteria and antibiotics
• Antibiotics only affect bacteria
• They don’t affect host cells
• Cause death of bacteria via many
pathways
• Prevent cell walls from forming causing
osmotic lysis
Slide notes
- Asked students what osmotic lysis was, and to explain how it would cause cell death.
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Slide 7
Antibiotic resistance
• Bacteria become resistant to antibiotics
when there is a mutation in the DNA
• If it is adaptive it is selected for
• It can be passed on via horizontal or
vertical transmission
• MRSA
Slide notes
- I asked students to tell me the difference between horizontal and vertical gene
transmission.
- I asked students to tell me what MRSA was and why it is such a big problem.
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Slide 8
Concept maps
• To tie together information in a
meaningful way.
• Concepts are linked together by words,
generally verbs.
• Try to really think about how concepts
relate to each other.
• On an A3 piece of paper create a
concept map, use pictures and colours to
make it memorable.
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Slide 9
Slide notes
- Explain to students that the concept map starts at DNA. Get them to take some time to
look at how the concept map is constructed.
- Make sure they pay attention to the joining words on the arrows.
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Slide 10
Virus Bacteria Disease Digestive tract
Fungal E.coli Infection Cholera
Gas exchange Antibiotics Cells HIV
Cells Toxins Protein coat MRSA
Prokaryote Lipid envelope Cell wall
Narrow spectrum Eukaryote Osmotic lysis
Selection pressure Broad spectrum
Mutations Resistant Horizontal gene transfer
Vertical gene transfer
Slide notes
- Ask students to construct a concept map using these concepts.
- Make it clear that they can use concepts more than once or not at all. They can also use
their own concepts.
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Slide 12
Study groups
• Study groups are a really good way to
revise!
• In groups of 4 you will be given a section
of this topic to research
• You will then explain it to the rest of your
group
• Try and make it as interesting as possible,
draw a poster with pictures, tell a story,
make them act it out – anything!
Slide notes
- Give each member of the group a different set of questions from the study group sheet
(see page 30).
- Make sure to give lots of examples of how they could present the topics to the other
students ie. Drawings, a story, acting it out.
- Get students to use their revision notes and textbooks to find the information.
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Explain antibiotic resistance:
How does it occur?
What problems can this cause?
How does it relate to evolution?
Explain what viruses are:
What are they made of?
How do they cause infections?
How can they be treated?
Explain how antibiotics destroy bacteria:
What are the different ways antibiotics destroy bacteria?
Why don’t they harm human cells?
Why don’t they work on viruses?
Explain how pathogens enter the body:
What are the different ways pathogens enter the body?
What are some famous pathogens and their symptoms?
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Slide 13
A. They cause viruses
B. They stunt organisms
growth
C. They destroy tissue and
produce toxins
D. They cause red tides
How do bacteria cause disease?
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Slide 14
A. Viral infections B. Binary fission
C. Fungal infections D. Bacterial resistance
Overuse and improper use of antibiotics may cause:
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Slide 15
A. Neither bacterial nor
viral infections
B. Viral infections only
C. Bacterial infections only
D. Bacterial and viral
infections
The use of antibiotics is an effective treatment for:
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Slide 16
A. Binary fission B. Budding
C. Spore formation D. Parthenogenesis
How do bacteria reproduce asexually?
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Slide 17
A. An antibiotic B. A virus
C. A vaccine D. Water
A chemical that can kill bacteria without harming the
human body is:
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Slide 18
A. Conjugate with other
viruses
B. Invade a host cell
C. Manufacture extra food D. Remain hidden
In order to multiply, a virus must:
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Slide 19
A. Immune B. Endocrine
C. Reproductive D. Digestive
HIV virus affects what system of the body?
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Slide 20
A. Flagella B. Cell wall
C. Pilli D. Capsule
During conjugation how do bacteria exchange
information?
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Slide 21
A. A nucleoid region B. An endospore
C. A nucleus D. A heterospore
Bacteria normally contain their genome in:
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Slide 22
A. Eukaryotes generally
are larger than bacteria
B. Bacteria lack internal
compartmentalisation
C. Both types of organisms
reproduce by mitosis
D. Bacteria are single-
celled
Which one of the following statements is false about
bacteria and eukaryotes?
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Slide 23
A. Flagella B. Pilli
C. Capsule D. Rough ER
Which of the following does a prokaryotic cell not
contain?
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Slide 24
A. Lentivirus B. Retrovirus
C. Adenovirus D. Adeno-associated virus
What type of virus is HIV?
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Slide 25
A. E.coli B. Salmonella
C. V. cholerae D. C.botulinum
Which of these pathogens does not affect the digestive
system?
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Slide 26
A. Photoautotrophs B. Chemoautotrophs
C. Detrtivores D. Heterotrophs
Organisms that obtain their energy by oxidising inorganic
chemical sources are called:
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Slide 27
A. Mycosis B. Sepsis
C. Campylobacter D. Encephalitus
What is the term used for an infection caused by a fungal
parasite?
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GENES
Locus DNA Base sequence Polypeptides Mutation
Alleles Triplet Amino acid Amino acid sequence
Introns Non-functional proteins Base sequence differences
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ENZYMES
Protein Denature Active site Specific pH Optimum
Temperature Inactive Activation energy Saturation Inhibitors
Competitive Non-competitive Enzyme concentration Rate of reaction
Substrate concentration Enzyme-substrate complex
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Further your learning
HIV – Will science ever find a
cure?
Human immune-
odeficiency virus
(HIV), the virus that
causes AIDS,
targets specific cells
in the immune system, known as T cells [2].
HIV is a retrovirus, carrying the enzyme reverse
transcriptase. Once the virus enters the host cell it uses
this enzyme to make viral DNA from viral RNA. The viral
DNA is incorporated into the hosts own DNA, allowing
the production of thousands of new viruses. This
process causes the weakening of the immune system
[3] that leaves sufferers vulnerable to other infections
such as tuberculosis and malaria. The main issue in
the
treatment of HIV is the fast evolution of the viruses’
surface proteins meaning that anti-viral drugs lose
effectiveness fast [2].
However there have been recent developments by
scientists [7], who have discovered an antibody
(3BNC117) that reduces levels of the virus in humans.
In clinical trials, 29 participants were tested, 8 of them
were given the highest dose of 3BNC117, and this was
found to reduce virus levels by between 8 and 250
times. However there are still issues; this treatment is
incredibly expensive, with one course of antibodies
costing thousands of dollars and most sufferers live in
poorer countries. Also the rapid evolution of HIV still
effects this treatment with patients who received the
highest dose of antibody finding it was 80% less
effective after 28 days. Scientists suggest that this new
antibody will need to be used in conjunction with other
antibodies to combat this problem.
The Ebola epidemic - here to stay?
The infamous Ebola virus has caused over 10,000 deaths
in 2014 alone [4]. The recent outbreak was caused by the
Zaire species [9]. With a fatality percentage of 69%, it is
thought to be the most virulent species, begging urgent
research attention.
The Ebola virus owes its virulence to the mechanisms it
uses to disarm the immune response. The virus inhibits
cells that signal for the T-cells to destroy them before
infection spreads. With no T-cell activation, there is no
activation of antibodies. From here the virus travels in the
blood to the organs, and causes macrophages to release
coagulants to clot the blood causing haemorrhaging [11].
Current treatments for Ebola include blood transfusions
from Ebola survivors, but research is also looking into two
vaccines that may be able to stop the disease [9].
Research also shows that survival may be down to
genetics, as survivors have more activated T-cells due to
possessing a different gene variant [11]. Much research is
also going into making the diagnosis of Ebola easier with
the creation of a rapid diagnostic kit.
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1.
Bacteria and the dinosaurs
Bacteria are important in a process called exceptional
preservation, where structures like skin, feathers and
organs which are not normally preserved are fossilised
[6]. This has led to major discoveries such as theropod
dinosaurs were actually covered in feathers.
The process of exceptional preservation occurs when an
organism dies in environments with certain
characteristics, for example, places where scavengers
can’t eat the carcasses and anoxic environments so that
bacteria can’t degrade it. These tend to be lakes or ash
falls from volcanoes. However microbial mats have also
been found to allow exceptional preservation.
In Grube Messel sit in Germany there are fossils which
are fully articulated, and some soft tissue even remains.
When a PhD student examined the fossils with a electron
microscope, they found the fossil to be made up of rod
and spherical microbes. From this they deduced that
there was a layer of bacteria on the underside of the
body, which had become petrified when the carcass
landed on them. These bacteria were then cemented in
place by organic material from plants. These sorts of
discoveries can tell us lots about the past, and evolution.
Can bacteria really control behaviour?
Is it crazy to think that tiny single-celled bacteria could
control an organism’s behaviour? Well they do!
Weird Wolbacia
Wolbacia bacteria which live inside the reproductive
tissues of Arthropods are famous for being able to
change their hosts’ physiology to increase their chance
of being passed on to offspring [15]. The Wolbacia
bacteria are only passed on via female hosts, this leads
them to change their hosts to make sure that they
maximise their population. In parasitic wasps
Wolbacia induce
parthenogenesis in hosts.
This means that offspring
can form from unfertilised
eggs; this guarantees that
the bacteria will be present in the offspring.
It has also been seen in crustaceans that Wolbacia
causes the feminization of genetic males. The bacterium
converts males into reproductively competent females.
All of these mechanisms give a selection advantage to
the bacterium that has led to them being widespread
throughout the animal kingdom.
Bizarre Buchnera
Buchnera are round-shaped bacteria which live in
specific cells called bacteriocytes in most aphid species
[13]. These bacteria are maternally transmitted to eggs,
and neither the aphid nor buchnera can reproduce
alone. These bacteria provision the aphids with essential
amino acids [5], which are not present in the sticky
phloem sap on which the aphids feed. In return the
bacteria live within the aphid.
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The future of cancer research
Cancer is caused by the uncontrolled division of cells, [3]
this is due to a malfunction in mitosis. The University of
Bath researchers have been looking at ways to stop cells
dividing. They have discovered a target protein, RASSF7,
which is essential for building microtubules. Without
microtubules cell division doesn’t occur properly [14].
The University of Wisconsin has also been researching
ways to stop cancer [8]. They have found a new form of
cell division in humans known as klerokinesis. They
believe it is a natural back up mechanism to faulty cell
division, which prevents calls causing cancer. By placing
two nuclei in the cells they found the cells split without
mitosis, and normally during interphase. If scientists
could find a way to carry out this cell division it could help
stop cancer.
Cancer can be caused by mitotic spindles failing to
divide genetic material equally. At Warwick Medical
School [10], researchers have discovered a protein
complex called TACC3-ch-TOG-clathrin which holds the
spindles microtubules together. Some anti-cancer drugs
inhibit mitotic spindles from forming, but don’t distinguish
between normal and cancerous cells. Recent studies
have found that if the TACC3 protein is removed then
spindles don’t form. By targeting the mitotic spindle
protein complex, an effective anti-cancer drug could be
produced.
Further your learning
New discoveries in meiosis
Meiosis is incredibly important for generating genetic
variation via crossing over and independent assortment.
However faults in these processes can lead to birth
defects.
A PhD student at Cornell University [12] have found a
protein, Mlh3, which checks the quality of cell’s DNA
during replication, repairing it if necessary. It also allows
communication between overlapping chromosomes
during crossing over. If this process goes wrong the
chromosomes won’t pull apart, causing birth defects.
Now that the protein controlling this is found research
can be aimed at reducing faults.
New York University [1] have also been researching
meiosis. During meiosis DNA replicates and is then
recombined to give genetic variation. Disruption to this
process causes birth defects. They have established two
enzymes necessary for meiosis, Mec1 and DDK.
Mec1 senses when chromosomes are being replicated
and sends a molecular “wait” signal to the second
enzyme DDK, which coordinates chromosome
reshuffling. Understanding this process is the first step to
establishing how to stop birth defects.
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Appendix references:
Amos, J., 2003. Fossil of Archaeopterix. [photograph] Available at:
<http://www.sciencephoto.com/media/172092/view> [Accessed 4 April 2015].
Boyle, M., and Senior, K., 2008. Biology. 3rd ed. London: Collins.
Campbell, N., and Reece, J., 2011. Campbell Biology. 9th ed. San Francisco: Benjamin Cummings.
Davidson, M., 2013. Human Immunodeficiency Virus (HIV) Anatomy. [image] Available at:
<http://micro.magnet.fsu.edu/cells/viruses/hivvirus.html> [Accessed 4 April 2015].
Fox, C., 1987. Cancer cells. [photograph] Available at:
<https://visualsonline.cancer.gov/details.cfm?imageid=2306> [Accessed 4 April 2015].
Gerber, G., 2011. Small Parasitic Wasp. [photograph]. Available
at:<http://bugguide.net/node/view/512635/bgimage> [Accessed 4 April 2015].
Meiosis interphase microscope. [Photograph] Available at: <http://imgkid.com/meiosis-
interphase-microscope.shtml> [Accessed 4 April 2015].
Mitosis under microscope. [Photograph] <Available at: http://imgkid.com/mitosis-under-
microscope.shtml> [Accessed 4 April 2015].
Novak, J., and Cañas, A., 2006. The Theory Underlying Concept Maps and How to Construct them
[pdf]. Institute for Human and Machine Cognition. Available at:
<http://cmap.ihmc.us/Publications/ResearchPapers/TheoryUnderlyingConceptMaps.pdf>
[Accessed 11 April 2015].
Figure 2. Sakurai, M., Koga, R., Tsuchida, T., Meng, X., and Fukatsu, T., 2005. Whole-mount in situ
hybridisation of aphid embryos targeting Rickettsia and Buchnera. [microscope image]. Applied
and Environmental Microbiology. 71(7), 4069 – 4075.
Timmer, J., 2014. The ebola virus, magnified 108,000 times. [photograph] Available at:
<http://arstechnica.com/science/2014/11/understanding-the-ebola-virus/> [Accessed 4 April
2015].
[1] Blitzblau, H., and Hochwagen, A., 2013. ATR/Mec1 prevents lethal meiotic recombination
initiation on partially replicated chromosomes in budding yeast. Elife. 2: e00844.
[2] Boyle, M., and Senior, K., 2008. Biology. 3rd ed. London: Collins.
[3] Campbell, N., and Reece, J., 2011. Campbell Biology. 9th ed. San Francisco: Benjamin
Cummings.
[4] Centers for Disease Control and Prevention, 2014. 2014 Ebola Outbreak in West Africa –
Case counts [online] Accessed at <http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-
africa/case-counts.html> [Accessed 4 April 2015].
[5] Douglas, A., 1998. Nutritional interactions in insect-microbial symbioses: aphids and their
symbiotic bacteria Buchnera. Annual Review of Entomology. 43, 17-37.
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[6] Franzen, J., 1985. Exceptional preservation of Eocene vertebrates in the lake deposit of
Grube Messel (West Germany). Philosophical Transactions of the Royal Society of London. 311,
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