Transcript Knowledge PP - Science @ St John`s

B1
Topic 1 Influences on Life
B1.1 Classification
• Biologists classify living organisms
according to how closely they are
related to one another.
• Species – groups of organisms that
have many features in common
• Genus – contains several species with
similar characteristics
• Family – comprising of several genera
• Order – comprising of several families
• Class – comprising of several orders
• Phylum – comprising of several classes
B1.1 The Five Kingdoms
Kingdom
Characteristics
Animalia
multicellular, no cell walls, no
chlorophyll, feed heterotrophically
Plantae
multicellular, have cell walls, have
chlorophyll, feed autotrophically
Fungi
multicellular, have cell walls, no
chlorophyll, feed saprophytically
Protoctista
unicellular, have a nucleus
Prokaryota
unicellular, have no nucleus
VIRUSES are classified as NON LIVING because…
The virus does not show the characteristics of life such as growth and feeding,
B1.2 Phylum - Chordata
• Animals with a supporting rod running the length of their body.
• Example – a backbone in vertebrates.
How are vertebrates classified?
a Oxygen absorption methods – lungs, gills and skin
b Reproduction – internal or external fertilisation, oviparous or viviparous
c Thermoregulation – homeotherms and poikilotherms
Key words: Chordata – Animals with backbones , homeotherm –
can regulate temperature, poikilotherms – coldblooded, oviparous
– animals which lay eggs, viviparous – internal embryo
development
B1.3 Species
Definition: A group of similar individuals that can
interbreed to produce fertile offspring.
Limitations to this definition…
• Some organisms reproduce asexually.
• Some hybrids are fertile.
The Binomial System – uses two names e.g. Homo sapien
First name – tells us the organisms are closely related
Second name – species name
B1.2 & 1.6 Difficult Classification
• Some amphibians have gills as adults.
• Sharks use internal fertilisation unlike most other fish.
• Duck billed platypus…
•
and it lays eggs!
So…scientists use many characteristics to classify
organisms.
B1.2 & 1.6 Difficult Classification
• Hybridisation in Ducks – Mallard ducks can
hybridise with other closely related species. This
produces a range of hybrids that are all fertile.
• Ring Species – Neighbouring populations can still
interbreed. The two populations at either end of
the chain cannot
B1.2 & 1.6 Difficult Classification
• Classification is difficult because of variation within a
species.
• Variation – differences between individuals
• The binomial system is needed to identify, study and
conserve species and can be used to target
conservation efforts.
• Scientists must collaborate using journals, peer review
to agree new classifications.
B1.4 Can
you use
a key?
B1.4 Variation
e.g. height
Normal distribution
curve
Key words:
1. Continuous
Variation
2. Discontinuous
Variation
e.g. eye colour, blood
group
B1.6 Reasons for Variety
• Caused by GENES or ENVIRONMENT or BOTH
• Organisms adapt to their habitats
• Mutations increase genetic variation
Key words: Mutation – a change in an organisms DNA
B1.6 The Polar Bear – 6
adaptations
Feature
Reason
Small ears
Reduce heat loss
Thick fur
Insulation
Large feet
Spread weight, help swimming, stop it
sinking in the snow
Rough soles
Grip
Thick blubber
Insulation
White fur
Camouflage
B1.6 Pompeii Worms – 4
adaptations
• Lives in deep sea vents 2km below sea level
• Has no eyes but sensitive tentacles
• Covered in bacteria to survive temperature changes
• Lives inside a tube to avoid predators
• Can survive pressures of 200atm
Summarise to 6 words:
variation,
overproduction,
competition, survival,
reproduction, change
B1.7 Darwins theory of Evolution
– 6 stages
1.
2.
3.
4.
5.
6.
variation – most populations of organisms contain individuals which vary
slightly from one to another
over-production – most organisms produce more young than will survive to
adulthood
struggle for existence – because populations do not generally increase
rapidly in size there must therefore be considerable competition for survival
between the organisms
survival – those with advantageous characteristics are more likely to survive
this struggle
advantageous characteristics inherited – better adapted organisms are more
likely to reproduce successfully passing on the advantageous characteristics
to their offspring
gradual change – over a period of time the proportion of individuals with the
advantageous characteristics in the population will increase compared with
the proportion of individuals with poorly adapted characteristics, and the
poorly adapted characteristics may eventually be lost
• New evidence from DNA research and the emergence of resistant organisms
supports Darwin’s theory
B1.8 Genes – know the key words
Key words:
• The nucleus of the cell contains chromosomes, on which
genes are located.
• Genes exist in alternative forms called alleles which give rise
to differences in inherited characteristics
• Dominant – will always be expressed if present
• Recessive – will only be expressed in the absence of
dominant allele
• Homozygous – two alleles the same e.g. hh, HH
• Heterozygous – two different alleles e.g. Hh
• Phenotype – the outward appearance e.g. brown eyes
• Genotype – the description of the genes e.g. BB, Bb, bb
B1.9 Punnett Squares
• You must be able to draw these and identify
genotype and phenotype of offspring.
• You must work out % of offspring with each
characteristic.
• T – tall
• t – short
• What % of the offspring will be short?
B1.10 Inherited Diseases – 4
symptoms for each
Sickle Cell
• Become tired easily
• Shortness of breath
• Joint pain
• Blocked blood vessels
Cystic Fibrosis
• Lungs clogged with mucus
• Difficulty breathing
• Repeated infections
• Weight loss due to blocked ducts in digestive system
B1.10 Pedigree Analysis
• Cystic Fibrosis is caused by a recessive allele. What is the genotype of
person Z? The first generation parents? What are the chances of person
X and Z having a baby with CF if they mated?
B1
Topic 2 Responses to a changing
environment
Factors controlled by homeostasis:
A.
B.
C.
B1.11 Homeostasis
Blood glucose
Water
Temperature
Keywords
• Homeostasis – maintenance of a constant/stable internal environment
• Osmoregulation – Control of body water levels (involved the
• Thermoregulation – control of body temperature (human body temp - 37°C)
• Hypothalamus – part of the brain that monitors temperature and coordinates all the responses
• Vasodilation – Blood vessels widen (to increase heat loss by radiation)
• Vasoconstriction – blood vessels narrow (to reduce heat loss by radiation)
• Negative feedback – a control mechanism that occurs when a change in one direction (e.g. getting hot)
causes a response to bring the level back to normal (i.e. cooling down)
Thermoregulation
Responses to increased body temperature include:
1.
2.
3.
Vasodilation - widening of blood vessels. Blood flow is increased and more heat is lost through the skin. Nerve
impulses pass along the nerves from the thermoregulatory centre to the muscles in the walls of blood cells,
stimulating contraction and causing them to narrow. When the muscles relax the blood vessels widen.
Sweat is produced. Heat from the body evaporates the water in sweat.
Body hair lies flat against the skin, preventing air becoming trapped next to it.
Responses to decreased body temperature include:
1. Vasoconstriction - narrowing of blood vessels in the skin. Blood flow through the skin is reduced, therefore heat loss
is decreased. Body temperature increases.
2. Shivering - tiny muscles under the skin contracting and relaxing very quickly. The muscle cells release heat.
3. Body hair rises away from the skin, trapping a layer of air next to it, insulating the body. Erector muscles contracting.
B1.12, 1.13 – Sensitivity, Skin sensitivity
Keywords
•
Neurone – a cell that transmits electrical impulses in the nervous system.
•
Central Nervous system (CNS) – Brain and Spinal cord
•
Peripheral Nervous system (PNS) - nerves connecting the sense organs and effectors to the CNS
•
Sense organs – detect changes both in and outside your body. They contain receptor cells
– Eye; Ear; Skin; Mouth; Nose
•
Stimulus – Anything your body is sensitive to e.g. noise, heat, light
•
Impulses – Electrical signals in the nervous system that travel through neurones. This is called neurotransmission.
•
Dendron – extension of a neurone that carries the impulse to the cell body. It ends in many dendrites and is
usually shorter than the axon.
•
Dendrite – many fine extension of a dendron that collect impulses from other neurones or receptors.
•
Axon – the long extension of a neurone that carries an impulse away from the cell body towards other neurones
Types of Neurone :
1. Sensory neurones send impulses from
receptors in the sense organs to the CNS.
2. Motor neurones send impulses from the
CNS to muscles and glands.
3. Relay neurones found in the spinal
cord/brain. The link sensory and motor
neurones. They have no dendron, just
dendrites on the cell body.
B1.14 –Responding to stimuli
Keywords – (all from previous slide B1.12 and 1.13 also needed)
•
Reflex – a response to a stimulus that does NOT require processing by the brain. The response is automatic.
–
•
•
•
•
Examples: Blinking/ removing hand from hot surface/ knee jerk reflex/ covering ear to loud noise
Reflex Arc – Connection of a sensory neurone to a motor neurone (usually via a relay neurone) that allows reflex
actions to occur.
Neurotransmitter – Substance that diffuse across the synapse between two neurones and triggers an impulse to be
generated in the neurone on the other side of the synapse.
Synapse - Point at which 2 neurones meet. There is a tiny gap which cannot transmit an impulse without a
neurotransmitter.
Myelin Sheath – fatty covering around the axons of many neurones. It speeds up transmission of impulses and help
to insulate them from one another.
3
e
e
2
5
e
4
6
1
1. Stimulus
2. Receptor
3. Sensory neurone
4. Relay neurone
5. Motor neurone
6. Effector
B1.14 Hormones and B1.15 Diabetes
Keywords
•
•
•
•
•
•
Hormone – Chemical messengers that cause certain parts of the body to respond to their presence. E.g. Human
Growth Hormone causes bones and muscles to grow at a faster rate during puberty.
Endocrine glands – Glands that produce and release hormones.
Target organ – an organ on which a hormone has an effect. (e.g. Insulin has an effect on the Liver)
Pancreas- organ that produces digestive enzymes and the hormones insulin and glucagon.
Insulin – hormone that decreases blood glucose concentration by causing liver cells to convert glucose into glycogen for
storage.
Glucagon – hormone that causes liver cells to convert glucagon back into glucose to increase
blood glucose
concentration
Examples of hormones and their effects
Hormone
Released from
Effect
Anti-Diuretic
Hormone
Pituitary gland
Causes the kidney to make more concentrated urine
Oestrogen
Ovaries
Development of the female reproductive system during
puberty
Adrenaline
Adrenal Gland
Speeds up the heatbeat
Testosterone
Testes
Development of the male reproductive system during
puberty
B1.15 Diabetes
Keywords - See previous page (B1.14)
Type 1 Diabetes
1. Pancreas does NOT produce insulin
2. Inject insulin daily (into the fat layer beneath
the skin)
3. Exercise and diet are used to help lower blood
glucose levels too
Type 2 Diabetes
1. Cells respond less well to insulin (they become
resistant)
2. Control by changes in diet and exercise .
3. Risk factors of developing it are:
1.
2.
3.
4.
High-fat diets
Lack of exercise
Getting older
Obesity
Body Mass Index (BMI) – used to determine
obesity.
The diagram shows normal blood sugar
control (without diabetes)
B1.18 Plant Hormones
Keywords:
Tropism – plant growth response to a stimulus.
Phototropism – A plant growth response to light.
Geotropism –A plant growth response to gravity.
Positive Tropism – towards the stimulus.
Negative Tropism – away from the stimulus.
Auxin – Plant growth hormone.
B1.18 Plant Hormones
• Auxin produced in the tip of the shoot
• Auxin moves to shaded side of the stem
• Auxin causes cell elongation
B1.18 Plant Hormones
• Auxin produced in the tip of the root
• Auxins have opposite effect in the root
• Auxins stop elongation and root grows down geotropism
1.8 Plant Hormones
• Experiments with hormones.
• Why do the plants respond this way?
Keywords:
Auxin, tip,
shoot, cell
elongation,
bend,
light,
stimulus
B1.19 Uses of plant Hormones
1. Selective Weedkillers – Auxin makes broad leaved
plants grow out of control and die.
2. Rooting Powder – Auxin makes cuttings develop
roots quickly.
3. Seedless Fruit – Flowers sprayed with hormones
to make fruit develop but not seeds.
4. Fruit Ripening – Farmers use hormones to control
fruit ripening.
B1
Topic 3 Problems of and solutions to
a changing environment
B1.20 and 1.21 – Effects of drugs and reaction time
Keywords
Narcotic – Drug that makes you feel sleepy
Addictive –people can become dependent on the drug and feel they NEED it to function
Recreational drug – a drug used to change to way people feel e.g. alcohol
Medicine – a drug that helps to limit the damage caused by disease or injury
Drug Types
1. Halluginogen – changes the way the brain works (distorts senses)

LSD/ cannabis
2. Stimulants – INCREASE the speed of neurotransmission which speeds up (decreases) your reaction
time.

Caffeine/ cocaine/ nicotine
3. Depressants – slows down the activity of neurones which causes relaxation. INCREASES reaction time

Alcohol/ solvents
4. Painkillers – blocks some of the impulses to reduce the pain felt.

Morphine/heroin/ asprin
5. Performance enhancer – improves muscle development

Anabolic steroids
B1.22 – The damage caused by smoking
Keywords
Tar – sticky chemical in smoke that contains carcinogens
Nicotine – addictive stimulant in tobacco smoke
Carcinogen – something that causes cancer
Carbon Monoxide – toxic gas found in cigarette smoke
Health issues
1. Tar
a) Increased risk of developing cancers
b) Reduced surface area in the lung as it coats them in sticky tar
2. Carbon Monoxide
a) Less oxygen in blood causing pain in active muscles
b) Blood vessel narrow reducing blood flow
c) Emphysema and chronic bronchitis
3. Nicotine
a) Highly addictive to hard to give up
Long term studies – evidence links smoking to many diseases including all cancers,
respiratory diseases and circulatory diseases.
B1.23 – The effects of alcohol
Short term effects
1. Affects all organs as absorbed quickly
2. Slows down brain activity resulting in longer reaction times
3. Reduced negative feelings so feel happier
4. Lower inhibitions so take risks
5. Vomiting
6. Large quantities can cause unconsciousness and death (stops breathing)
Long term effects
1. Cirrhosis of liver – cells die and liver function fails
2. Brain damage
–
–
Memory loss
Blood clots
3. Addictive
Cost to society
1. Violence when drunk
2. Accidents increase
3. Treatment of drink related illness
B1.24 – Ethics and
transplants
Keywords
Transplant – Healthy organ taken from a donor and given to a
recipient
Ethical decision - uses ethical criteria to make a decision that is right
or fair.
Ethical criteria
1. Similar tissue (closer match give greater chance of survival)
2. Similar age (increased success)
3. Geographically close (quicker transplant = increased success rate)
4. Degree of illness (the more ill a patient the less likely they will survive)
Organ donors can be:
• Living: live donors can donate tissues such as bone marrow or an organ such as a kidney, where there
are two doing the same job.
• Dead: people can give permission for their organs to used if they are killed in an accident. Most organ
donors are victims of accidents.
Rejection of the organ is less likely to happen if the donor is related to the recipient.
Need is far greater that supply so alternatives looked at:
1. Xenotranplantation (animal donors)
2. Genetic engineering (modified animal organs)
3. Transplant tourism (looking abroad)
Morals are what people think is right or wrong.
Ethics are the actions people take as a result of their moral judgement.
B1.25 – Pathogens and infection
Keywords
Pathogen – microorganism that causes disease
Bacteria – microscopic organism (some are pathogens)
• Salmonella/ Cholera/ E.coli
Fungi – organisms that feeds of dead or decaying material
• Athlete’s foot/ ring worm
Viruses – a particle that can infect cells and cause them to make new copies of the virus
• Influenza/ chicken pox/ HIV/ HPV
Protozoan – a single celled protoctist
• Malaria
How are pathogens spread? (6 ways)
1. Water - Cholera
2. Vectors (animals that spread disease) – Malaria (mosquitoes)
3. Food - Salmonella
4. Contact – Athlete’s foot
5. Airborne – Influenza, colds or TB
6. Body fluid - HIV
B1.26 – Antiseptics and Antibiotics
Keywords
Antiseptics – kill microbes outside the body to reduce the spread of infection
Antibiotics – chemicals that kill or prevent growth of bacteria and some fungi
Antifungals – antibiotics that only affect fungi
Defence against invasion
1. Physical barriers – prevent pathogens getting in
2. Chemical defences – kill pathogens before they harm us
Resistance
Some bacteria develop natural resistance to antibiotics
During antibiotic treatment
1. Less resistant bacteria killed first
2. More resistant ones remain and will re-infect if full course not taken
3. Overuse of antibiotics can cause more resistance to develop
MRSA – multi resistant to many antibiotics therefore very difficult to treat
B1.28 – Interdependence and food webs
Keywords
Trophic level – organisms that feed at the same level
Interdependence – organisms in an area that depend on each other
Dynamic relationship – constantly changing populations
Carnivores, top
predators
Carnivores, both
predator and prey
Herbivores
Plants that
photosynthesize
Energy is • used in metabolic processes (respiration)
• transferred into ‘waste’ energy forms e.g. heat which is lost to the environment
• transferred into BIOMASS as the organism grows
• moved to the next organism when it is eaten
B1.29 – Parasites and Mutualists
Parasites
One organism feeds off another while it is
alive.
Mutualists
Both organisms benefit from either food,
shelter or protection.
• Examples
1. Tape worm (inside the body)
• Examples
1. Oxpecker and wild cows
–
They take food from the intestine causing weight
loss.
2. Headlice (outside the body)
3. Fleas
4. Mistletoe
–
Roots grow into other plants to take their water
and minerals
–
Oxpecker eats insects that are parasites to the
cow
2. Cleaner fish and sharks
–
Cleaner eats the dead skin to clean sharks
3. Legumes and nitrogen fixing bacteria
–
The bacteria help the plant to get nitrates while
they get food from the plant and protection.
4. Chemosynthetic bacteria in tube worms
5. Intestinal bacteria in humans
–
Bacteria provide protection against pathogen and
get food and place to live in return
B1.30 – Pollution
Why did the human population
grow so quickly?
1. Better food
2. Improved sanitation and living
conditions
3. More medicines available
Increased populations mean bigger
demand on resources. More people
means more…
Keywords
• Pollutants - a substance that harms living organisms when
released into the environment.
• Eutrophication – The addition of chemicals, like fertilizers, to
water which encourages plant growth
• Fertiliser – chemical compounds added to soil to increase the
growth rate of crops
Eutrophication stages
1
2
3
1. food needed (increased
4
pressure to grow crops)
2. housing and transport that
uses fossil fuels (more gases
pollute the air)
Eutrophication
• Phosphate and nitrates increase
plant and algae growth
• Can destroy the ecosystem as it
kills plants and animals.
5
6
7
B 1.31 - pollution indicators
Keywords
Indicator species- an organism that is particularly sensitive to or tolerant of pollution so it can be used to
measure pollution levels.
Lichen – Mutualistic relationship between a fungus and an algae.
Air Pollution Indicators
1. Blackspot fungus (disease of roses) is killed by sulfur dioxide
2. Lichen – different species tolerate different pollutant levels. Feathery ones need clean air, crusty
flatter ones can tolerate higher levels of supfur dioxide
Water Pollution Indicators
Different animals need varying amounts of oxygen.
1. Stonefly larvae and freshwater shrimps needs
2. Bloodworms and Sludgeworms can live with low
lots of oxygen (clean rivers)
oxygen (polluted rivers)
Recycling
Taking materials out of waste so they can be converted in new products. This means we need less of the
raw materials that could be difficult to find or expensive.
1. Metal cans
Car parts, new cans
2. Paper
New paper, cardboard
3. Plastic bottles
Fleece clothing
B1.33 – The Carbon Cycle
Carbon is recycled as carbon dioxide
(CO2) through respiration and
photosynthesis.
1. Plants absorb CO2 to produce
sugars - photosynthesis.
2. Animals and plants release CO2
when they respire
3. Burning of fossil fuels releases
CO2
4. Chalk and other sedimentary
rocks is formed from the fossilised
remains of sea creatures.
5. When these rocks are exposed to
rain (which is slightly acid), the
rock dissolves and more CO2 is
released.
Keywords
Detritivores – worms and maggots that feed on dead
material
Decomposer – organisms (bacteria and fungi) that
feeds on dead material starting the process of decay
B1.34 – The Nitrogen
Cycle
Nitrogen is needed to make
biological molecules like
proteins and DNA.
•
Plants absorb nitrates from the
soil
•
Animals get nitrogen from their
food.
Bacteria in the Nitrogen Cycle
1. Nitrogen fixing bacteria- bacteria living in root nodules of legumes and soil. They
convert:
• Nitrogen gas
Ammonia
2. Nitrifying bacteria– converts
• Ammonia
Nitrates
3. Denitrifying bacteria– converts
• Nitrates
Nitrites
• Nitrites
Nitrogen gas