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Biology Unit B3Biology Unit B3EdExcel Triple ScienceEdExcel Triple Science

N Smith

St Aidan’s

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Topic 1 – Control SystemsTopic 1 – Control Systems

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The Urinary SystemThe Urinary SystemMetabolism in cells causes us to produce waste products such as carbon dioxide and urea. Urea is formed by the breaking down of amino acids in the liver and kidneys are responsible for removing it.

Renal vein

Renal artery

Ureter (tube that takes urine down to bladder)

Bladder and urethra

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DialysisDialysisSometimes kidneys can fail due to infections, toxic substances or genetic reasons. One possible answer is to use a dialysis machine:

Dia

lysi

s flu

id

Blo

od

Dia

lysi

s flu

id

Partially permeable membranes

Urea and salt diffuse out of the blood into the dialysis fluid. Also, the dialysis fluid contains the same concentration of sugar and minerals as the blood so these don’t diffuse.

Urea

Urea

Sugar

Sugar

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Kidney transplantsKidney transplantsInstead of dialysis a kidney could be transplanted into the patient.

This option is cheaper than _____ but it requires a _______ (a normal person can still function with one kidney). This donor must have a similar ______ type to the patient. Also, the new kidney might be rejected by the body’s ______ system which will try to destroy the new organ by using _______ to attack the antigens on the surface of the kidney. To work around this problem the patient can take “immunosuppresant ___” which suppress the immune system.

Words – dialysis, donor, immune, tissue, drugs, antibodies

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KidneysKidneysKidneys work in 3 stages:

1. ULTRAFILTRATION - Lots of water and products of digestion are squeezed out of the blood and into tubules under pressure.

3. WASTE – excess water, excess ions and any urea are now removed through the ureter

2. SELECTIVE REABSORPTION – the blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient.

Blood vessel Tubule

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Kidney structureKidney structure

1) Ultrafiltration happens in the glomerulus and Bowman’s capsule

2) Selective reabsorption happens in the convoluted tubules

3) Excretion

21/04/23Controlling Water Content – “Negative Controlling Water Content – “Negative Feedback”Feedback”

Low blood water level causes a high salt concentration

Receptors in the hypothalamus detect the high salt content

More ADH is secreted into the blood

The kidney becomes more permeable to water so more is

absorbed.

The bladder fills with a small quantity of urine

Normal blood water level is achieved.

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Controlling Water Content 2Controlling Water Content 2High blood water level causes a

low salt concentration

Receptors in the hypothalamus detect the low salt content

Less ADH is secreted into the blood

The kidney becomes less permeable to water so more is

absorbed.

The bladder fills with a large quantity of urine

Normal blood water level is achieved.

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FertilityFertility

In normal circumstances natural hormones are responsible for releasing the egg and for thickening the lining of the womb. These hormones are produced by the pituitary gland in the brain and in the ovaries.

1) …stimulate the release of eggs

2) …inhibit the release of eggs

The amount of glucose in our blood is an example of a process controlled by hormones. Hormones are “chemical messengers”, produced by glands and transported by blood. Another example of a process controlled by hormones is the menstrual cycle, where hormones can...

21/04/23The 4 stages of the menstrual The 4 stages of the menstrual cycle:cycle:

Day 1: Bleeding starts when the lining of the uterus breaks down and passes out the vagina – “Having a period”

Day 4: The lining starts to build up again and thickens into a spongy layer of blood cells

Day 14 (approx): An egg is released and lasts for around 3 days

Day 28: The lining stays thick awaiting the arrival of a fertilised egg. If one doesn’t come then the lining breaks down again.

Thickness of uterus lining

Day 0

Day 4

Day 14

Day 21

Day 28

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FertilityFertility4 hormones are involved in the menstrual cycle: oestrogen, progesterone, LH and FSH. Here’s how:

Step 3: LH stimulates the release of the mature egg at day 14. The remains of the follicle develop into a structure called a “corpus luteum” which then secretes progesterone

Step 1: FSH produced by the pituitary gland causes both a follicle (an egg and its surrounding cells) to mature and the ovaries to start producing oestrogen

Step 2: The rising levels of oestrogen cause the uterus lining to thicken and the pituitary gland to stop producing FSH and produce LH instead

Step 4: The progesterone then maintains the lining of the uterus and inhibits production of FSH and LH. When the level of progesterone falls (and there’s a low oestrogen level) the lining breaks down. This allows FSH to be produced and the process starts again. If the woman is pregnant then progesterone levels stay high.

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The Menstrual CycleThe Menstrual Cycle

Hormone concentration

Oestrogen – produced in the _______ and causes the lining of the uterus to ______

Progesterone – produced by the empty ________ and maintains the ______. If egg is _______ progesterone continues to be produced to maintain the lining for the fertilised egg

Words – follicle, lining, ovaries, thicken, fertilised

Thickness of uterus lining

Day 0

Day 7

Day 14

Day 21

Day 28

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EggsEggsThe female egg cell is an example of a gamete:

The egg cell is basically an enlarged cell with massive _______ reserves in the cytoplasm

Nucleus

Words – nutrients, sperm, fertilised, haploid, genetic

The nucleus in the egg cell is a “_______”, meaning it only contains one set of _______ material and isn’t complete until it is ______. When this happens the egg’s membrane changes its structure to stop any more _______ getting in.

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SpermSpermThe sperm cell is also specialised:

Words – swimming, energy, mitochondria, digest, membrane

The head has an acrosome packed with “enzymes” to ______ its way through the egg’s ________

Strong tail for ________

Haploid nucleus

A middle section with lots of ________ to produce a lot of _______

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IVFIVFSome couples cannot have children naturally. In-vitro fertilisation (IVF) can help. Here’s how it works:

1. Eggs are removed from the womb and placed in a solution of oxygen and water to keep them alive

2. Sperm is added 3. The fertlised egg is allowed to grow into an embryo (a group of 4-8 cells)4. Usually 3 of these embryos are transferred back into the uterus

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Other fertility treatmentsOther fertility treatmentsArtificial insemination – this is used when the sperm count is low or if a woman’s oviducts are blocked. Sperm is put directly into the uterus and oviducts to increase the chance of fertilisation.

Egg donation – if the woman cannot produce eggs herself eggs can be donated by another woman which are then fertilised using IVF treatment (see next slide)

Ovary transplants – these are used if a woman’s ovaries do not function

Surrogacy – this is when an embryo produced through IVF is implanted into a surrogate mother who then carries the baby. When the baby is born he/she is given to the biological parents.

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Boy or Girl?Boy or Girl?

X Y X

XX XYGirl Boy

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Father

Mother

Son

Daughter

Boy or Girl?Boy or Girl?

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Genetic DiagramsGenetic DiagramsHere’s what happens (genetically) when an egg is fertilised:

xx

xx xy xyxx

xy

x yx x

Equal (50%) chance of being a boy or a girl

Mother Father

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x y

x

x

Genetic DiagramsGenetic DiagramsHere’s another way of drawing it:

Father

Mother

21/04/23Inheriting colour blindness and Inheriting colour blindness and haemophiliahaemophilia

For example, here’s a female who carries the recessive allele for colour blindness crossed with a “normal” male:

XNXn XnYXParents:

Offspring: XNXn XNY XnYXnXn

Gametes: XN Xn YXn

(FOIL)

Colour blindness and haemophilia are two “sex-linked” genetic disorders - they are caused by faulty alleles located on sex

chromosomes.

XN = Normal colour vision allele

Xn = faulty colour vision allele

Carrier female

Normal male

Normal female

Colour blind male

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Bacteria revisionBacteria revisionIn unit B2 we met bacteria:

Bacteria – containing cytoplasm and a membrane surrounded by a cell wall. The genes are NOT in a distinct nucleus.

Bacteria grow VERY fast. For example, if a certain bacteria doubles itself every 5 minutes calculate how many bacteria you would have after one hour.No. of bacteria

Time

21/04/23How our bodies fight How our bodies fight bacteriabacteria

Step 1: The lymphocyte “sees” the pathogen (bacteria)

Step 2: The cell produces antibodies to “fit” the pathogen

Step 3: The antibodies fit onto the pathogens and cause them to “clump”

Step 4: The pathogens are “eaten” by the white blood cells

You’re going down

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VaccinationsVaccinationsVaccinations work by doing the following:

1) A harmless ________ or antigenic material is introduced

2) The antigens trigger an ________ response which causes the production of _________

3) The antigens also trigger the production of “_______ lymphocytes” that “_______” the illness in case your body is exposed to the real pathogen in the future.

Words – remember, pathogen, immune, MMR, memory, antibodies

Vaccinations can also cause concerns, such as the recent controversy over the _____ vaccine.

21/04/23The Development of The Development of VaccinationsVaccinations

Edward Jenner, 1749-1823

Hi. I was a doctor in England and in the late 18th Century I discovered that you can vaccinate people against smallpox:

In 1796 Jenner took bits of scab from a girl who had ______ (a less deadly disease than smallpox). He then put them into a cut in the arm of a boy and then exposed the boy to ________ and discovered that the boy was ______ to it.

The vaccination worked because the cowpox _____ triggered the boy’s B-lymphocytes to produce _______. Smallpox has the same antigens as cowpox so when the boy was exposed to smallpox his body quickly made antibodies for it.

Words – smallpox, cowpox, antibodies, antigens, immune

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Specific antibodiesSpecific antibodies

Antibodies are specific – they will neutralise the microbe they have been made for. They do this by

recognising the antigen on the surface of the microbe.

Microbe

Antigen

Once the body has made the antibody “memory cells” can make it again very quickly if needed,

which protects you from catching the disease again.

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Immunity to later infectionsImmunity to later infections

Concentration of antibody in the blood

TimeWhen this person first catches a disease the response takes time

When the person catches the disease again at a later time

the body responds much quicker

Memory lymphocytes then stay in the body

for a long time

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VaccinationsVaccinationsSome people argue that the MMR vaccine is a good idea, others think it is a bad idea. Briefly summarise each side of the argument:

MMR vaccine

For Against

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Vaccination PoliciesVaccination Policies

Factors to consider about vaccinations

Is the infection a big risk?

Who is at risk?

Is the vaccine safe?

How much does it cost?

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Monoclonal AntibodiesMonoclonal AntibodiesMonoclonal antibodies are basically “identical antibodies” that can be made to bind to anything you want. They are the same because they are made from the same parent cell. Here’s how:

Step 1: Take an animal (e.g. mouse) and inject it with an antigen

Step 2: Extract the B-lymphocytes that the mouse makes in reaction to the antigen

Step 3: Fuse this lymphocyte with fast-growing tumour cells to make a “hybridoma” (a cell that produces lots of antibodies)

Step 4: The hybridoma then divides really quickly (due to it being made from a tumour cell) which gives you lots of identical antibodies called monoclonal antibodies

Eek!

21/04/23Uses of Monoclonal Uses of Monoclonal AntibodiesAntibodies

What are monoclonalantibodies used for?

Diagnosis of cancer and the location of cancerous

cells

Pregnancy testing

Treating cancer by targeting

specific cancerous cells

Task: Find out how monoclonal antibodies are used in each of

the above uses.

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Louis PasteurLouis Pasteur

Pasteur, 1822 - 1895

I did a lot of work on germs in the 1850s. The process of “pasteurising

milk” is named after me.

Pasteur took two flasks and put some boiled broth in each one. One of the flasks had a curve in it, the other one didn’t. He observed the fact that the broth in the non-curved flask went bad but the one with the curved neck didn’t – what was his conclusion?

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Drugs from PlantsDrugs from PlantsPlants produce chemicals to defend themselves against pests:

Back off

Some of these chemicals can be used as drugs to treat human diseases or to relieve pain symptoms. Some examples:

1) Aspirin – made from a chemical found in the leaves and bark of a willow tree

2) Taxol – an anti-cancer drug from the bark of the Pacific yew tree

3) Quinine – used for treating malaria, it comes from the South American cinchona tree

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Plant Diseases and PestsPlant Diseases and Pests

How might these factorsaffect the availability

and price of food?

Plant diseaseDamage by pests

WeedsBad weather

21/04/23Periodicity in Plants and Periodicity in Plants and AnimalsAnimals

Many plants and animals show various forms of periodicity. For example:1) Plants show “photoperiodicity” – this

means that they respond to changes in the length of a day. For example, many plants only flower at the start of the summer season whereas other plants only flower in autumn. Doing this means that they flower when the right insects for pollination are around.

2) Animals, plants and microorganisms show “Circadian Rhythms” – rhythms that follow a 24-hour cycle. For example, sleep patterns are affected by hormonal reaction to light and the body’s production of urine also slows down overnight. Plants control their stomata using similar rhythms.

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Topic 2 - BehaviourTopic 2 - Behaviour

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Mating PatternsMating PatternsHere’s a random selection of animals:

Animals have many different mating strategies – some will have one mate for life, others will have one mate for each mating season while others have many mates.

This is my harem!

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Behavioural StrategiesBehavioural StrategiesMost animals engage in some sort of display that advertises their qualities…

Some animals, particularly birds and mammals, have developed special behaviours for looking after their young (which can sometimes endanger the parents):These behavioural adaptations can increase the chances of survival and increase the chance of the parental genes being passed on.

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Types of Animal BehaviourTypes of Animal Behaviour1) Innate behaviour – this is when an animal does something almost by instinct, e.g. feeding from a bottle.

3) Imprinting – this is when an animal recognises its parents and instinctively follows them around, a combination of learned behaviour and innate behaviour.

2) Learned behaviour – this is when an animal learns from a previous experience and changes its behaviour accordingly. Having a lot of learned behaviour can lead to “habituation” – the animal learns not to respond to something.

Whatever

Classical Conditioning - Pavlov’s Dog

Ivan Pavlov, 1849-1936

I won the Nobel Prize in 1904 and am most famous for investigating

“conditioned responses”:

1) Steak + dog = saliva

2) Steak + bell + dog = saliva

3) Bell + dog = saliva

Operant Conditioning – Skinner’s Operant Conditioning – Skinner’s BoxBox

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Conditioning is a form of learned behaviour and there are two main types:

Burrhus Skinner, 1904-1990

Operant conditioning is when an animal learns a behaviour by trial

and error, i.e. by learning that some behaviours give a reward whereas

others don’t. For example, consider my Skinner Box:

Combinations of classical and operant conditioning are used to train animals such as police horses, sniffer dogs and dolphins. How?

Signals in AnimalsSignals in Animals21/04/23

Animals use a variety of ways to communicate with each other, such as:

Sound signals:

Squawk

Chemical signals (pheromones):

Visual signals (e.g. gestures and body language):

Studying Behaviour in Studying Behaviour in AnimalsAnimals

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Task: summarise the work of the following ethologists:

1) Tinbergen, who studied innate behaviour in gulls2) Fossey, who studied social behaviour in gorillas3) Goodall, who studied social behaviour in chimpanzees4) Lorenz, who studied imprinting in geese

For each of these people find out how they studied this behaviour and some of their main observations and conclusions.

Signals in PlantsSignals in Plants21/04/23

Back offAs we’ve said before, plants can use chemicals to warn off unwanted insects:

They can also use chemicals to attract insects, such as bees to help them pollinate.

Plants can also release chemicals to warn other plants of predators:

YumMy friend is in danger – I’m going to harden my

leaves

Co-Evolution in Plants and Co-Evolution in Plants and AnimalsAnimals

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Co-evolution is when two organisms evolve in ________ to each other. For example, consider an orchid:Orchids have a very deep store of _____ so only certain types of ____ can reach it. This may mean that this type of moth will probably only pollinate other ______.

Some plants are also poisonous to most insects. This means that the ones who can eat it have an evolutionary ________ over other insects while the plant in question has evolved a defence mechanism to help it protect itself.

Words – advantage, response, orchids, moth, nectar

Human EvolutionHuman Evolution21/04/23

Task: Find out how the following famous fossil hominids have provided evidence for human evolution:

1) Ardi (4.4 million years old)

2) Lucy (3.2 million years old)

3) Various fossil hominids found by Leakey (1.6 million years old)

For each fossil find suitable images and explain how these images show human development over the last few million years.

Then find images to show the development of tools over the last 2 million years and how these tools show human evolution.

Mitochondrial DNAMitochondrial DNA21/04/23

Recall our basic animal cell:

Mitochondrial DNA is only inherited from your mother. Everyone on Earth has similar mitochondrial DNA but it also has a high mutation rate. Scientists have used the mutation rate and the fact that it is only passed down by the mother to come to this conclusion:

Everyone on Earth has descended from ONE WOMAN – scientists call her “Mitochondrial Eve” or “African Eve” and she lived in Africa

around 200,000 years ago.

These are mitochondria and they have a small piece of DNA inside them

Scientists can also use Nuclear DNA to study human evolution and migration. However, mitochondrial DNA is more useful as there are lots of mitochondria in one cell and mitochondrial DNA degrades less over time.

Climate Change and Human Climate Change and Human BehaviourBehaviour

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As humans migrated out of Africa they would have moved to a different climate. How would they have had to adapt their behaviour to this new climate?

Changes in human behaviour due to a different climate

Hunting methods

Changes in diet

Getting food from trees/fish Use of

tools/clothes

The Effect of the Ice AgeThe Effect of the Ice Age21/04/23

Ice ages are very long periods of time where the climate goes very cold and ice sheets and glaciers spread across most of the Earth. To survive the last ice age what would early humans have had to do? Think about the following:

1) Where they would live

2) What they would do for heating

3) How their clothing would change

4) How their hunting patterns changed

5) Use of tools

6) How their cooperation and communication might have had to change

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Topic 3 - BiotechnologyTopic 3 - Biotechnology

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Growing micro organismsGrowing micro organismsMethod:

1) Sterilise the inoculating loop

2) Dip the loop in the bacteria and spread it across the agar

3) Secure (but don’t seal) the lid with tape

Questions:

1) Why are you sterilising the loop?

2) What does the agar do?

3) Why is the lid not sealed all the way around?

4) Why would you not want to culture your bacteria at 37OC?

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FermentersFermentersA fermenter is a controlled environment (i.e. a large device) that provides ideal conditions for micro organisms to grow and feed.

Temperature sensor

pH sensor

Sterile air supply

Outlet tap

Water cooled jacket

Micro organisms

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More about FermentersMore about FermentersUsing your knowledge of microbe growth explain why the following features of a fermenter are important:

1) Aseptic precautions

2) The use of nutrients

3) An optimum temperature

4) The right pH

5) A good air supply

6) Agitation

21/04/23Fusarium fungus and Fusarium fungus and MycoproteinMycoprotein

Fusarium sp is a fungus used to make mycoprotein (a _______-rich food suitable for _________). The fungus is grown on glucose ______ under ________ conditions and the biomass is harvested and ________.

Words – aerobic, protein, vegetarian, syrup, purified

21/04/23Using Microorganisms for Using Microorganisms for foodfood

The human population is growing exponentially:

Population

Time

Microorganisms are a useful way to feed the population.

Other advantages of

using microorganis

ms

Ease of manipulation

Food can be produced regardless of climate

The process can use waste products from

other industrial processes

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Micro organismsMicro organismsMicro organisms are tiny living organisms such as bacteria, viruses and fungi.

Bacteria is used for making yoghurts and cheese.

Yeast is a single-celled organism used in making alcoholic drinks and bread.

The difference between these two processes is whether the yeast respires aerobically or anaerobically:

Sugar Alcohol + carbon dioxide

Anaerobic respiration (fermentation):

Sugar Water + carbon dioxide

Aerobic respiration:

Cell wall

Cytoplasm

Nucleus

21/04/23Using micro organisms to Using micro organisms to make foodmake food

Words – clot, milk, bacteria, lactic acid

In yoghurt production bacteria is added to warm ____. The _____ ferments the sugar in the milk (lactose) to produce ______ ____. The lactic acid causes the milk to ___ and turn into yoghurt.

21/04/23Industrial uses of Industrial uses of enzymesenzymes

1) Enzymes are used in washing powders to help digest fats and proteins in food stains. Biological washing powders will only work on 400C or lower.

2) Chymosin is an enzyme produced by genetically modified microorganisms, used in the manufacture of vegetarian cheese.

3) Invertase (sucrase) is produced by yeast and used in the manufacture of sweets

21/04/23Genetic engineering - Genetic engineering - InsulinInsulin

Step 1: Using RESTRICTION ENZYMES “cut out” the part of the human chromosome that is responsible for producing insulin.

Step 2: Using another restriction enzyme cut open a ring of bacterial DNA (a “plasmid”). The enzyme ligase is then used to insert the piece of human DNA into the plasmid.

Step 3: Place the plasmid into a bacterium which will start to divide rapidly. As it divides it will replicate the plasmid and make millions of them, each with the instruction to produce insulin. Commercial quantities of insulin can then be produced.

“Sticky ends”

21/04/23Feeding a Growing Feeding a Growing PopulationPopulation

As we’ve said before, the human population is growing exponentially:

Population

Time

This population (and a lot of other factors) can cause a lack of “food security” (where people go without food).

Ways to increase food

security

Using selective breeding to select and reproduce the

best plants

Genetically modifying plants to be insect-resistant

Using crop rotation

Reducing the number of pests by introducing insects that eat pests

but not plants

21/04/23Genetically Modified Genetically Modified PlantsPlants

Here’s a cotton plant:

Plants like cotton and corn can be genetically modified by using a bacterium called bacillus thuringiensis (Bt). Bt produces a toxin that kills insect larvae so scientists can insert the gene for the Bt toxin into crops like corn and cotton. However, there are two problems with this:

1) Although Bt is considered harmless to humans, its long term effects haven’t yet been discovered

2) Insects may develop resistance to it

Scientists have also used genetic modification to introduce “flavonoids” (molecules that have antioxidant effects and are useful in protecting against cancer) into “purple tomatoes”.

21/04/23How plants are genetically How plants are genetically modifiedmodified

Plants are genetically modified using the bacterium agrobacterium tumefaciens. This is basically a pathogen that invades plant cells and puts its genes into the plant’s DNA. The bacterium acts as a “vector” (a carrier that’s used to transfer DNA into other organisms):

Step 1: Take the genes you want (e.g. herbicide resistance) from the plant’s nucleus

Step 2: Cut open part of the bacteria’s DNA and insert the desired gene:

Step 3: Allow the GM bacteria to infect the target plant:

Step 4: The bacteria will insert their GM genes into the plant’s DNA. Put these cells into a medium containing the herbicide – the non-resistant cells will die, leaving the GM cells behind.

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BiofuelsBiofuelsOne of the reasons deforestation happens is so that crops can be used to grow biofuels. Biofuels are fuels that are “made” biologically. For example:

• Manure or other waste that can be used to release _______ (biogas)

• Corn or sugar cane that can undergo anaerobic respiration in a fermenter and then distilled to produce ______ like bio-ethanol.

Biofuels have two main advantages over traditional fuels – they are ______ and ________ but growing crops can also take up valuable land.

Words – alcohols, cleaner, burnt, renewable, methane