Understanding Organisms

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Understanding Organisms
(OCR Gateway)
W Richards The Weald School
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B1a Fitness and Health
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Modern diets and health problems
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The Circulatory system
The circulatory system is responsible for pumping
______ around the body. We need blood to be
taken around the body because blood contains
________ and _______. These are needed so that
all the ____ in our bodies can produce _____
through _________.
Words energy, blood, glucose, respiration,
oxygen, cells
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Arteries and veins
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Heart disease
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Heart disease and High Blood Pressure
Heart disease and high blood pressure are
conditions where the ______ and blood vessels
experience extra strain. They can be caused by

• Excess weight
• High stress levels
• _____
• Excess _______
• Diets that are high in saturated ___, sugar or
  salt

Long term high blood pressure can cause blood
vessels to weaken or even ______. To DECREASE
blood pressure regular exercise and a balanced
____ are a good start!
Words alcohol, burst, smoking, heart, fat, diet
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Measuring Blood Pressure
Blood pressure measurements are taken in terms of
Systolic pressure over diastolic pressure.
High blood pressure can cause heart attacks,
strokes, dementia, heart disease and kidney
disease. Low blood pressure can cause dizziness
or fainting.
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Fitness and Health
Having good health means being free from
disease Being fit means having an good
ability to do physical activity and can be
measured in terms of stamina, strength, agility
etc
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Smoking

• Cigarettes contain 3 harmful things
• NICOTINE, which is an ___________ drug that
  raises the heart beat, narrows the arteries and
  so causes ____ _____ _____. This leads to heart
  _________.
• TAR, which coats the lining of the _______ making
  them less able to take in oxygen. It also
  contains carcinogens which cause ______________.
• CARBON MONOXIDE, which is a _______ ____ which
  joins up with ____ blood cells making them
  incapable of transporting _____________ around
  the body. In pregnant women it can cause oxygen
  deprivation, leading to low birth ______.

Words high blood pressure, oxygen, red,
addictive, disease, poisonous gas, lungs, cancer,
mass
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Saturated Fat and Heart Disease
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B1b Human Health and Diet
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Balanced diet
A balanced diet should contain fats, proteins and
carbohydrates in roughly these amounts

• Carbohydrates are simple sugars such as glucose
• Fats are made up of fatty acids and glycerol
• Proteins are made up of amino acids

A good balanced diet should also contain water,
vitamins, minerals and fibre.
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Factors affecting choice of diet
Personal choice, e.g. vegetarianism
Age teenagers need more protein
What factors affect our choice of diet?
Religion some foods may be banned
Activity a sporty lifestyle will need more
energy
Allergies
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Protein
Proteins are long chains of amino acids.

• There are two classes of protein
• Essential amino acids (must be eaten)
• Non-essential amino acids (can be made in the
  body)

People who do not eat enough protein will not
grow properly. Protein deficiency can result in
a disease called kwashiorkor, where the muscles
waste away and the belly swells. This is common
in developing countries where overpopulation and
limited investment in agriculture can cause food
shortages. Proteins are used by the body as an
energy source if fats are not present.
How much protein should we eat?
EAR of protein (in g) 0.6 x body mass (in kg)
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Storing Food in our bodies
How do our bodies store food?
The liver converts glucose and other
carbohydrates into insoluble glycogen to be
stored in the liver
Fats are stored under the skin and around organs
as adipose tissue
Proteins are not stored in the body.
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Body-Mass Index
A commonly-used way to indicate is someone is
overweight or underweight is the Body Mass Index
(BMI)
BMI Meaning
lt18.5 Underweight
18.5-25 Ideal
25-30 Overweight
30-40 Obese obesity is linked to heart disease, diabetes and breast cancer
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Eating disorders
Anorexia nervosa this is a condition where
sufferers restrict what they eat and sometimes
starve themselves, leading to possible weight
loss, abdominal pains, discoloured skin,
irregular periods etc.
Bulimia nervosa this is when people vomit or
take laxatives straight after eating to get the
food out as quickly as possible. It can lead to
weight fluctuations, poor skin, hair loss,
irregular periods, tiredness etc.
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B1c Staying Healthy
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Pathogens
Pathogens are microbes (micro organisms) that can
cause diseases. They can enter the body in a
number of ways
or other natural openings
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Spreading of Pathogens
Diseases and pathogens can be spread by a number
of means, including
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Microbes our defence against them
Our bodies have defence mechanisms against
microbes
However, these mechanisms cant do anything about
non-infectious diseases (e.g. cancer) or
inherited diseases (e.g. cystic fibrosis)
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What pathogens do to us
Pathogens can cause the damage or death of cells,
e.g. in liver cirrhosis
They can also damage the body by producing toxins
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White blood cells
If microbes enter our body they need to be
neutralised or killed. This is done by WHITE
BLOOD CELLS

• White blood cells do 3 things
• They eat the microbe (these white blood cells are
  called phagocytes)
• They produce antibodies to neutralise the microbe
  (lymphocytes)
• The produce antitoxins to neutralise the poisons
  produced by microbes (lymphocytes again)

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Producing antibodies
Youre going down
Step 1 The lymphocyte sees the pathogen
(microbe)
Step 2 The cell produces antibodies to fit the
antigen
Step 3 The antibodies fit onto the antigens and
cause them to clump
Step 4 The pathogens are eaten by the white
blood cells
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Specific antibodies
Antibodies are specific for different antigens
they will only neutralise the microbe they have
been made for.
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Fighting disease
NATURAL IMMUNITY
This is when antibodies are produced by a person
when needed or they are passed on by the mother
during pregnancy.
ARTIFICIAL IMMUNITY

• Can be done in two ways
• A vaccine with dead microbes (which still carry
  the antigen) is injected the body is tricked
  into producing antibodies ready for the real
  thing. This is called PASSIVE IMMUNISATION and
  the body then remembers the microbe by
  producing memory cells that remember it
• The antibodies are injected directly into the
  body this is called ACTIVE IMMUNISATION.

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Vaccinations and Medicines
Vaccinations have eradicated some diseases
entirely but they can carry some side effects.
Health problems can also be treated using
antibiotics or antivirals

• Antibiotics are used to treat bacterial
  infections but they have to be used sparingly or
  the bacteria might become resistant (e.g. MRSA)
• Antivirals are used to treat a virus, such as
  HIV.

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The importance of testing drugs e.g. Thalidomide
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Developing new drugs
Before a new drug can be approved it has to go
through a strict testing process. Consider the
example of thalidomide
Date Event
Mid 1950s
Late 1950s
Early 1960s
Mid 1960s
Animal testing using thalidomide was undertaken.
Tests showed that it was safe but the tests were
inadequate no tests were done on pregnant
animals
Thalidomide prescribed to pregnant mothers to
help sleep and morning sickness problems
Babies are born with birth defects and the drug
was banned worldwide. Around 12,000 deformed
Thalidomide babies born, 4,000 die in first year.
Tests show that Thalidomide can help leprosy
sufferers and it is still used today for this
purpose.
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Researching new medicines
17/03/2017
Before new drugs can be approved they have to go
through three stages. What are the advantages
and disadvantages of each stage?
3. Is it safe for humans? Human volunteers are
tested on.
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Placebos
17/03/2017
Clinical trials can be done in different ways
1) Blind trials
Patients do not know which drugs they are taking
a real drug or a placebo
2) Double blind trial
Neither the doctors or the patients know if they
are taking the real drug
Placebos offer anethical dilemma as a patient
might be sick and still be given a dummy pill.
Also, you might notice if you had a placebo as
you wouldnt get the side effects of normal
drugs...
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Malaria

• The spread of malaria can be restricted by
• Sleeping under mosquito nets
• Taking malaria pills
• Avoiding being bitten

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Cancer
Cancer is a disease where cells show uncontrolled
growth.
Our diets can affect our chances of getting
cancer
Good foods Fruit Vegetables Fibre
Bad foods Salt Saturated fats Red meat
Exercise can play a key part as well Cancer
Research UK recommends 30 minutes a day of
moderate activity 5 days a week, such as
gardening, walking etc.
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Tumours
Tumours can be classed as malignant or benign
Malignant tumours are cancerous and will still
grow Benign tumours are not cancerous they may
still grow but wont spread
This graph shows the survival rates of different
types of cancer (source Cancer Research UK).
What conclusions can you draw from it?
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B1d The Nervous System
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The Eye
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Vision
What are the advantages and disadvantages of each?
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Seeing things
Rays of light are refracted (bent) first by the
cornea and then by the lens. They focus on the
retina.
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Focussing on different distances
For distant objects the ciliary muscles relax and
the suspensory ligaments pull tight making the
lens pull thin the light doesnt bend as much.
For close objects the ciliary muscles contract
allowing the lens to go fat, thus bending the
light more.
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Problems with vision
Short sighted
Long sighted
Colour blindness, caused by a lack of specialised
cells in the cornea
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Using lenses to correct vision
Short
Long
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The Nervous System
The CENTRAL NERVOUS SYSTEM (CNS) enables us to
react to our surroundings. It consists mainly of
the brain, the spinal chord, nerve cells
(neurones) and receptors.

• Types of receptor
• Light receptors in the eyes
• Sound receptors in the ears
• Taste receptors on the tongue
• Smell receptors in the nose
• Touch, pressure and temperature receptors in the
  skin
• Changes of position receptors in the ears
  (balance)

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Nervous Reactions
When we react to a stimulus our bodies use the
following pattern
For example, consider a man and a camel
Oh No!
What are the stimulus, receptor, coordinator,
effector and response in this situation?
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Examples of reactions
Stimulus Receptor (i.e. the thing that detects the stimulus) Effector (i.e. the thing that will do the reaction) Response (i.e. action taken)
Bright light
Sour taste
Losing balance
Sit on a drawing pin
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Structure of a nerve cell
1) Motor neurone
2) Sensory neurone
3) Relay neurone
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Synapses
Neurones never ____ each other there is a small
gap between them called a _____. A signal is
sent from one _______ to the next by a _______
transmitter across the synapse. These
transmitters are then ________.
Words chemical, synapse, neurone, touch,
destroyed
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Conscious actions
A conscious action is one where the brain makes a
considered response. Heres what happens
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Reflex actions
Sometimes conscious action is too slow to prevent
harm, e.g
In situations like this the body bypasses the
brain to produce a quicker response. Heres how
it works
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Reflex actions
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B1e Drugs and You
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Cannabis Pros and cons
17/03/2017
In January 2004 cannabis was changed from a class
B drug to a class C drug. Some people think that
Cannabis should be made legal. What are the pros
and cons of cannabis?
Pros
Cons
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Drugs Research Project
17/03/2017
Explain and give examples for the following

1. Define the terms addiction, tolerance, withdrawal
   symptom and rehabilitation.
2. Why do people use legal drugs?
3. What are the drawbacks of legal drugs?
4. Alchohol is a legal drug. What does it do to
   the human body?
5. Why do people use illegal drugs?
6. What are the drawbacks of illegal drugs? What
   can they cause?
7. Choose one drug and discuss how it affects the
   human body

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Legal drugs
17/03/2017
Drug Effect on activities Abnormal behaviour caused
Caffeine/ other stimulants
Alcohol
Paracetamol/ other painkillers
Reactions could become faster
Highly strung, leads to exhaustion
May make you drowsy, you shouldnt drive
Leads to depressant effects on the nervous system
May make you drowsy, you shouldnt drive
Side effects include dizziness or itchiness
Overall, the effect of these legal drugs can be
greater than the effect of illegal drugs simply
because more people use them.
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Drugs
Drugs are classed as a substance that affects
the central nervous system, causing changes in
psychological behaviour and possibly addiction.
Some examples
Type of drug Effects Examples
Painkiller Block nervous impulses Morphine, aspirin, paracetamol
Hallucinogen Distort sense perception LSD
Stimulant Increase reactions Caffeine, nicotine, ecstasy
Depressant Slow down brain activity Alcohol, solvents, termazapam
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Synapses and drugs
Depressant drugs can bind with ______ molecules
in the membrane of adjacent _______ and block the
transmission of an ______. Stimulants can cause
more ___________ to cross the ________.
Words neurotransmitter, receptor, synapse,
neurones, impulse
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Investigating Reaction Times
Task Design an experiment that investigates the
affect of caffeine on reaction times.
Variables What are the independent, dependant
and control variables?
Results Draw your own results table
Conclusion What do your results show you?
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Steroids
17/03/2017
Steroids are drugs that are used to boost
athletic performance. Theyre banned and using
them will lead to disqualification from competing.
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Smoking revisited

• Cigarettes contain 4 harmful things
• NICOTINE, which is an ___________ drug that
  raises the heart beat, narrows the arteries and
  so causes ____ _____ _____. This leads to heart
  _________.
• TAR, which coats the lining of the _______ making
  them less able to take in oxygen. It also
  contains carcinogens which cause ______________.
• CARBON MONOXIDE, which is a _______ ____ which
  joins up with ____ blood cells making them
  incapable of transporting _____________ around
  the body. In pregnant women it can cause oxygen
  deprivation, leading to low birth ______.
• Particulates, which accumulate in the lungs.

Words high blood pressure, oxygen, red,
addictive, disease, poisonous gas, lungs, cancer,
mass
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Diffusion in the lungs
O2
Oxygen diffuses in and carbon dioxide diffuses
out of blood in the lungs
CO2
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Damaging the lings (emphysema)
Another way smoking can damage the body is
through destroying the shape of alveoli
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More damage by smoking smokers cough
The pink hairs in this photo show cilia, small
hairs lining the windpipe that clear dust and
other particles away from the air we breathe.
Regular smoking causes the cilia to become
paralysed and excess mucous and tar build up in
the lungs, causing smokers cough.
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Tobacco and Lung Cancer
Smoking has existed in Western culture since the
16th Century. However, scientists only proved
the link between it and various diseases shortly
after the Second World War.
Over 50 years I proved the link between smoking
and lung cancer. I published my first findings in
1950, based on patients in London hospitals, and
then studied 40,000 doctors and proved a link in
a paper published in 1954.
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Cancer Research UK statistics
What do these statistics imply?
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The Effects of Alcohol
17/03/2017
Time Effects
Short term
Long term
Blurred vision, lowering of inhibitions, slowing
of reactions (hence why there is a limit on
drink-driving)
Liver cirrhosis, brain damage
Alcohol content is measured in ABV. Wine is
typically 12 while beer is 4-6. 40 of
hospital AE incidents are alcohol-related. When
the liver removes alcohol it turns it into toxic
chemicals that cause liver damage or liver
cirrhosis
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B1f Staying in Balance
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Homeostasis
Homeostasis means controlling internal
conditions
Waste products that need to be removed how Waste products that need to be removed how
CO2

Internal conditions that need controlling how Internal conditions that need controlling how
Temperature
Water content
Produced by respiration, removed via lungs
Increased by shivering, lost by sweating
Increased and decreased by hormones
Some of these mechanisms are controlled by
negative feedback systems, i.e. the absence of
a particular hormone causes the reaction to
change.
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Measuring Body Temperature
Some possible methods
Common places to measure temperature are in the
armpit, the mouth, the fingers, the ears or the
anus.
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Controlling Body Temperature
Wow its hot! My body temperature needs to stay
at 37OC as its the best temperature for the
enzymes in my body. How does my body keep the
temperature right?
The thermoregulatory centre in the brain detects
warm blood.
Also, temperature sensors in the skin detect the
heat and send information to the brain.
When the brain detects the high temperature it
takes two main steps....
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Maintaining Body Temperature
Cold
Hot
Vasoconstriction
Vasodilation increases heat transfer to the
surroundings and heat is also lost through the
evaporation of sweat.
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Heat stroke and hypothermia
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Body Temperature and the Nervous System
Effectors (muscles and sweat glands) carry out
the response
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Controlling Blood Sugar levels
We need glucose in our bodies to help our cells
to respire and produce energy. What happens if
we have too much glucose?
If glucose levels fall too low then the hormone
glucagon is released from the pancreas which
causes liver to turn glycogen back into glucose.
The trouble with hormones is that they are slower
than nervous reactions.
If blood sugar is too high the pancreas releases
insulin, which travels in the blood stream.
Insulin lowers blood glucose levels by converting
glucose into insoluble glycogen.
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Diabetes
What is diabetes? What do the pens (above right)
do? What does an insulin injection (above left)
do? What is the difference between Type 1 and
Type 2 Diabetes? How does physical activity
affect Type 1 and Type 2 Diabetics?
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Diabetes
Type 1 Diabetes is a ________ in which a persons
blood sugar (i.e. glucose) level may rise to a
_______ level. This is because the ______
doesnt produce enough _________. Physical
activity will _______ the amount of glucose
needed by the body. Diabetes can be treated by
__________ carefully or by injecting extra
insulin when needed. Diabetics have to test
their blood sugar level before they decide how
much insulin to _______ themselves with. Type 2
Diabetes occurs when the patient becomes _______
to insulin so the patient will have to be careful
regarding physical activity.
Words insulin, disease, inject, dangerous,
eating, pancreas, increase, resistant
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B1g Controlling Plant Growth
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Plant Growth Introduction
Plants grow due to their cells dividing through
mitosis. The cells then specialise into root
hair cells, palisade cells etc. Unlike animals,
plants continue to grow for the rest of their
lives.
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Plant Hormones
The growth of roots and shoots is controlled by
hormones called auxins that move through the
plant in solution
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Some Definitions
Shoots grow towards light (positive phototropism)
and against gravity (negative geotropism). This
is caused by cell elongation on the underside of
the shoot and this happens because auxin is made
in the tip and is unevenly distributed through
the shoot. Roots grow away from light (negative
phototropism) and in the direction of gravity
(positive geotropism). This is caused by cell
elongation on the upper side of the root.
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Artificial Plant Hormones
Hormones can be used to help plant growth and the
development of fruit
1) Auxin
2) Ethene
This hormone helps fruit to develop
This hormone helps fruit to ripen
Other uses include rooting powders (to help root
development), control of dormancy and weedkilling.
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B1h Variation and Inheritance
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Variation
Variation is the name given to differences
between individuals of the SAME
species. Variation is due to GENETIC or
ENVIRONMENTAL causes. For example, consider dogs

1. Ways in which they are the same
2. Ways in which they are different

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Variation
Variation means differences within a species.
For example, consider some of the people in your
class
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Environmental differences
Some of this variation is due to our parents, but
some of it is due to our upbringing and the
environment in which we live this is called
Environmental variation.
Variation due to inheritance only Variation due to environment only Variation due to a bit of both

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Genes, Chromosomes and DNA
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Sexual Reproduction
We have similar characteristics to our parents
due to genetic information being passed down in
genes through gametes
The human egg and sperm cell (GAMETES) contain
23 chromosomes each.
When fertilisation happens the gametes fuse
together to make a single cell called a ZYGOTE.
The zygote has 46 chromosomes (23 pairs) and
contains information from each parent.
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Sexual vs. Asexual reproduction

• Sexual reproduction
• 2 parents are needed
• Offspring will have pairs of chromosomes
• This will cause genetic variation
• Asexual reproduction
• Only 1 parent needed
• Offspring are GENETICALLY IDENTICAL to parent
  (clones)

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Boy or Girl?
Girl
Boy
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Boy or Girl?
Mother
Son
Father
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Key words
17/03/2017
Genotype Phenotype Allele Dominant Recessive
Homozygous Heterozygous

• This allele determines the development of a
  characteristic
• The characteristic caused by the genotype
• This allele will determine a characteristic only
  if there are no dominant ones
• This word refers to a pair of chromosomes being
  made of two different alleles of a gene
• The genetic make up in a nucleus
• This word refers to a pair of chromosomes being
  made of two of the same alleles of a gene
• An alternative form of a gene

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Eye colour
In eye colour the brown eye allele is dominant,
so we call it B, and the blue eye is recessive,
so we call it b
bb
BB
Bb
Homozygous brown-eyed parent
Heterozygous brown-eyed parent
Blue-eyed parent
What would the offspring have?
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Eye colour
Example 1 A homozygous brown-eyed parent and a
blue-eyed parent
Example 2 2 heterozygous brown-eyed parents
X
X
Parents
Gametes
(FOIL)
Offspring
All offspring have brown eyes
25 chance of blue eyes
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Eye colour
Example 3 A heterozygous brown-eyed father and a
blue-eyed mother
Equal (50) chance of being either brown eyed or
blue eyed.
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Another method the Punnett square
Example 3 A heterozygous brown-eyed father and a
blue-eyed mother
B b
b
b
B b
b Bb bb
b Bb bb
Father
Mother
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Example questions
1) In mice, white fur is dominant. What type of
offspring would you expect from a cross between a
heterozygous individual and one with grey fur?
Explain your answer with a genetic diagram.
2) A homozygous long-tailed cat is crossed with
a homozygous short-tailed cat and produces a
litter of 9 long-tailed kittens. Show the
probable offspring which would be produced if two
of these kittens were mated and describe the
characteristics of the offspring (hint work out
the kittens genotype first).
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Inherited diseases
1) Cystic fibrosis a disease that causes thick
and sticky mucus to coat the lungs, gut and
pancreas, making breathing and digestion
difficult. Its caused by faulty recessive
alleles
2) Huntingdon's disease a disease of the
nervous system that causes shaking, memory loss,
mood changes and eventually dementia. Its
caused by a faulty dominant allele
3) Sickle cell anaemia a disease that alters
the shape of red blood cells, thereby reducing
their oxygen capacity, causing weakness and
anaemia. Its caused by recessive alleles
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Family Pedigree Charts
17/03/2017
Consider the following chart of the offspring and
grandchildren between two sickle-cell anaemia
carriers
Q. Describe the genotype and the phenotype of
each of the grandchildren. Also, which member of
this family has got sickle-cell anaemia?
98
The debate over genes
The Nature vs Nurture debate is all about
whether or not certain attributes or abilities
are down to genetic reasons or through
upbringing, e.g.