Transcript infectious disease

Biology warm up
Diet and exercise
Diet
A healthy diet contains
the right balance of
the
7 different food types
Carbohydrates
Fat
Protein
7 food
types
Fibre
Vitamins
Water
Minerals
7 food types
Food Type
What is it needed for?
Examples
Carbohydrates
Energy
Bread, Potatoes, Pasta
Proteins
Growth and Repair
Meat, Eggs, Fish Lentils
Fats
Energy Store, Insulation,
Protection
Butter, Oil, Cheese, Cream
Fibre
Helps get rid of undigested
food
Cereal, Potato Skin, Fruit
and Veg
Vitamins
Keep us healthy
A- carrots; B – cereals
C – Oranges; D - Milk
Minerals
Keep us healthy – strong bones Iron: Red Meat
and teeth etc
Calcium: Milk
Water
Chemical reactions take place
here, 70% of body
Most foods
A Poor diet can lead to:
• Obesity – being over weight
• Being underweight
• Diseases or conditions due to deficiency
Arthritis
(worn joints)
Diabetes
(high sugar
levels)
Obesity
High blood
pressure
Heart
disease
Exercise
• Exercise increases the amount of
energy used by the body
A person will lose weight when the
amount of energy used by the body is
more
than the amount of energy in the food
Cholesterol is a substance
• Made in the liver
• Found in the blood
The amount of cholesterol in your blood
depends on:
1. Diet &
2. Inherited factors
• Too much cholesterol can increase the
risk of heart disease
Metabolic rate is
The rate at which all the
chemical reactions in your
body’s cells are carried out
Metabolic rate is affected by:
- Amount of exercise you do
- Proportion of fat to muscle
- Inherited factors
Microbes and
disease
Pathogens are...
Micro-organisms
that cause
infectious disease
There are 2 pathogens that
you need to know about
&
Bacteria
Viruses
Why do bacteria and viruses
make us feel ill?
Produce toxins
Reproduce very quickly
White blood cells
1. Ingest/digest pathogens
2. Produce antibodies
3. Produce antitoxins
How do white blood cells help defend
against pathogens?
1. Ingest
pathogens
2. Produce
antibodies
White blood
cell changes
shape, engulfs
and ingests
the microbe
White blood cells
produce anti
bodies which
destroy particular
bacteria or viruses
3. Produce
Anti-toxins
White blood cells
produce antitoxins
which counteract
the toxins
released by the
pathogens
Immunisation and vaccines
Vaccines are used to
protect us from diseases,
making us immune (immunised)
• Inject small amounts of inactive/dead pathogen
into body
• White blood cells produce specific antibodies
to destroy the pathogen
• If the pathogen re-enters the body, our white
blood cells remember the specific antibody
required to destroy it quickly
MMR
MMR is an example of a vaccine used to
protect children from:
Measles
Mumps
Rubella
Preventing disease
• Semmelweiss recognised the
importance of good hygiene to prevent
spreading of infectious diseases
• He insisted doctors washed their hands
before examining patients
• This reduced the number of deaths
from infectious diseases
Treating disease
• Painkillers – relieve the symptoms of
infectious disease (less pain)
• Antibiotics - kill bacteria in the body
• Antibiotics DO NOT kill viruses.
Viruses live and reproduce inside cells.
Antibiotic resistance
• Many strains of bacteria have developed a
resistance to antibiotics (such as MRSA),
as a results of natural selection
• New antibiotics need to be developed all
of the time.
• It’s important not to overuse antibiotics
Investigating
microorganisms
Uncontaminated cultures of
microorganisms are required for
investigating the action of disinfectants
and antibiotics
Petri dishes containing agar are used by
to grow cells (microbiology)
Petri dishes must be sterilised
before use
Inoculating loops are used to
transfer microorganisms in the media
Inoculating loops must be sterilised by
passing them through a flame
The lid on the petri dish should be
secured with adhesive tape...
this is to prevent microorganisms from
the air contaminating the culture
In school and college laboratories, cultures
should be incubated at a maximum temperature
of 25°C, which greatly reduces the growth of
pathogens that might be harmful to humans
Nerves and
hormones
The nervous sytem
The nervous system enables humans to react
to their surroundings and coordinate their
behaviour
It consists of
•
•
•
•
The brain
The spinal cord
Neurones (nerves) and
Receptors
Electrical impulses travel
through neurones
There are 3 types of neurones
Sensory neurone
Relay Neurone
Motor Neurone
Synapse
A synapse is a gap found
between neurones
What happens at a synapse?
nerve impulse
receptor
• Chemical neurotransmitters
• Move across the gap by diffusion
• Between neurones
Stimulus
Receptor
Sensory neurone
Brain and spinal cord
(CNS)
Relay neurone
Motor neurone
Effector (muscle or gland)
Response
Reflex action
• Reflex actions are automatic and rapid responses.
• They DO NOT involve the brain
• They often involve sensory, relay and motor neurones
Control in the human body
Conditions controlled inside the
body:
•Temperature
• Blood glucose (sugar)
levels
•Water content
• Ion (salts) content
Waste products removed from the
body:
•Carbon dioxide
- produced by respiration leaves the body via the lungs when
we breathe out
• Urea
- produced in the liver by
breakdown of excess amino acids
- temporarily stored in the bladder
- removed by kidneys in the urine
Hormones
•
•
•
•
Hormones are chemical messengers
There are produced by glands
They travel in the blood stream
They travel to target organs
Gland
Bloodstream
Organ
There are 4 hormones you need to
know about in the menstrual cycle:
•
•
•
•
Follicle stimulating hormone (FSH)
Oestrogen
Luteinising hormone (LH)
Progesterone
Hormones and the menstrual cycle
Hormone
Secreted
by
Function
FSH
Pituitary
gland
Causes ovaries to produce an egg
Stimulates ovaries to produce oestrogen
Oestrogen
Ovaries
Stops FSH production
Starts LH production
LH
Pituitary
gland
Stimulates egg release
Progesterone
Ovaries
Maintains uterus lining
Controlling fertility
If a woman:
She should:
Because:
Does not want
a baby
Take the
contraceptive
pill
Stops ovaries
releasing eggs
Wants a baby
Take FSH as a
‘fertility drug’
Stimulates eggs
in the ovary to
mature and be
released
IVF is given to women who have
difficulty getting pregnant:
1. Mother given FSH and LH to mature eggs
2. Eggs collected from mother
3. Eggs fertilised in a lab using father’s
sperm
4. Fertilised eggs develop into embryos
5. One or two embryos are inserted into
mother’s uterus/womb to develop
Plant hormones
Plants are sensitive to
light,
moisture and gravity:
Phototropism
Plant shoots grow towards light and against
the force of gravity
Gravitropism
Plant roots grow towards moisture and in the
direction of the force of gravity
Control in plants
• Auxins are hormones which cause
growth responses in plants
• Gardeners may use plant hormones as:
weed killers and as rooting powders
Drugs
Drugs are chemical substances
that alter the way the body
works
Types of drugs
Type of Drug
painkiller
sedative
stimulant
antibiotic
antiseptic
Effect
Examples
Stops nerve
impulses
Paracetamol,
Heroin, aspirin
Alcohol, sleeping
tablets
Caffeine
Slows down nerve
impulses
Speeds up nerve
impulses
Kills bacteria in the
body
Kills bacteria on a
cut
Penicillin
TCP
(trichlorophenol)
Legal and illegal drugs
• Recreational drugs – for leisure
• Legal drugs eg, alcohol or tobacco
• Illegal drugs eg, heroin, cocaine are very
addictive
Developing drugs
Drugs are tested and trialled in a series
of stages to find out:
- If they are toxic
- If they are efficient (efficacy/do they
work?)
- What dose/strength is needed
Placebo = fake or dummy drug
Double blind trial = neither
doctor or patient knows who has
received a placebo to reduce
bias
Thalidomide
Original use in
1950’s:
Used as a sleeping aid
For pregnant women to combat morning
sickness, nausea and other symptoms
The problem with
Thalidomide:
Many babies born with severe
What happened to
Thalidomide at the
time?:
Use for
Thalidomide now:
limb abnormalities
It was banned
Used to treat leprosy
Adaptation and
competition
Why do organisms
compete?
For survival
What do animals compete for?
Food
Water
Animals
compete
for:
Territory
Mates
What do plants compete for?
Water
Sunlight
Plants
compete
for:
Space
Nutrients/
minerals
Adaptation
Adaptations are features
that make an organism
well-suited to their
environment in order to
increase their chance of
survival
Adaptations helping animals to
survive in arctic or dry conditions:
• Thickness of coat (insulation)
• Amount of body fat
• Camouflage
• Size of feet/paws
• Body shape
• Surface area : volume ratio
Adaptations helping plants to survive
in dry conditions:
• Extensive root system to
absorb water (deep and
shallow roots)
• Thick stem to store water
• Needles instead of leaves to
reduce water loss
• Prickles - protection
Extremophiles
- Some organisms live in environments that are very extreme
- Extremophiles may be tolerant to high levels of salt, high
temperatures or high pressures
Pollution indicators
Living organisms can
be used as
indicators of pollution
Lichen can be used as air pollution
indicators, particularly of the
concentration of sulphur dioxide in
the atmosphere
Invertebrate animals can be used as water pollution
indicators and are used as indicators of the
concentration of dissolved oxygen in water
Energy and biomass
Food chains represent energy
transfer
Pyramids of biomass
A Pyramid of Biomass
Grass
Rabbit
Fox
Fleas
Fleas
Fox
Rabbit
Grass
Biomass = The mass of living material
(Mass = the amount)
(Bio/Biology = living thing)
The mass of living material (biomass) at each stage in
a food chain is less than it was at the previous stage.
The biomass can be drawn to scale and shown as a
pyramid of biomass
Fleas
Fox
Rabbit
Grass
Pyramid of biomass – what do
you get marked for?
1 mark = correct order of blocks/levels going up
1 mark = labelled correctly
1 mark = correct scaling
Where does the energy go?
• Respiration
• Growth
• Movement
• Excretion/waste
• Keeping warm
How can the efficiency of food
production be improved?
1000J
100J
10J
1.Reducing the number of stages in food chains
2.Restricting energy loss from food animals by
limiting their movement and controlling the
temperature of their surroundings
Decay and the
carbon cycle
What is decay?
Decay is a process whereby
dead organisms are
broken down by
decomposers such as
bacteria and fungi
Materials decay because they are broken
down (digested) by microorganisms
What are the best conditions
for decay?
• Warm
• Moist
• Oxygen rich (for
aerobic respiration)
• Food
The carbon cycle
Genetics
Genes and chromosomes
Genes and chromosomes
Reproduction
Sexual reproduction
– Involves joining of male and female gametes.
- The mixture of the genetic information from two parents
leads to variety in the offspring
Asexual reproduction
– No fusion of gametes and only one individual is needed as
the parent
- There is no mixing of genetic information and so no
genetic variation in he offspring.
- These genetically identical individuals are known as clones
Cloning techniques
1. A skin cell from a sheep’s udder is removed
POP
2. The udder cell is starved of nutrients to make it stop dividing
3. An unfertilised egg cell is removed from a donor sheep
4. The nucleus of the egg cell is removed so the cell no longer contains
any DNA from ewe 2
5. The 2 cells are fused by an electric current so that the egg cell from
ewe 2 now contains DNA from the udder cell of ewe 1
6. The new egg cell begins dividing. It is implanted into a surrogate
mother, ewe 3 and allowed to develop
7. The surrogate mother gives birth to a lamb which is a clone of sheep
Genetic engineering
Basically...
Gene is cut out from chromosome
using enzyme
Gene is transferred to cells of
other organisms
Genetic engineering
Evolution
Fossil record
• Fossils provide evidence of how much (or how
little) different organisms have changed since life
developed on Earth.
Theory of evolution
living
billion
simple
evolved
species
The theory of evolution states that...
all ______of ______things have
_______from _____life-forms
which first developed more than
three ______years ago
Darwin
• Natural variation between
organisms causes them to
differ in ability to survive
and reproduce
• Natural selection
• Survival of the fittest
• Small changes taking place
over a long time
• Organisms that do survive
carry genes on to the next
generation
Lamarck
• Acquired
characteristics passed
onto the next
generation
• Inherited traits
acquired through
over/under-use of body
parts
Evolution by natural selection
Some final tips...
• Read the whole Q – 33% of the Qs can be
answered from information given to you in
text, diagrams, graphs & tables
• Follow instructions – “tick one box” “tick two
boxes” “use info from the table”
• Don’t write “it” – “the concentration
increases” NOT “it increases”
• What is the Q asking you to do?
Don’t forget...
Describe a graph
Refer to the pattern e.g.
as……...increases………increases etc
Explain
Describe & give a reason “because…….”
Evaluate
For & against
Compare
What is the same & what is different
Calculate
Show calculations & give units
Suggest a reason
This should be scientific
Remember...
• 1 mark per minute – you have 60
minutes to answer 60 marks
• Use bullet points – 3 marks should
mean 3 bullet points
• Use good grammar and spellings in the
long 6 mark question
Good luck
