1. Topic 1 Influences on LifeB1
Topic 1 Influences on Life

2. 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

3. 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,

4. 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

5. 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

6. 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.

7. 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

8. 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.

9. B1.4 Can you use a key?

10. B1.4 Variation e.g. height e.g. eye colour, blood group Key words:
Continuous Variation
Discontinuous Variation
B1.4 Variation
Normal distribution curve
e.g. height e.g. eye colour, blood group

11. Key words: Mutation – a change in an organisms DNA
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

12. 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
White fur
Camouflage

13. 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

14. B1.7 Darwins theory of Evolution – 6 stages
Summarise to 6 words: variation, overproduction, competition, survival, reproduction, change
B1.7 Darwins theory of Evolution – 6 stages
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

15. B1.8 Genes – know the 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

16. 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?

17. 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

18. 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?

19. Topic 2 Responses to a changing environmentB1
Topic 2 Responses to a changing environment

20. B1.11 Homeostasis Thermoregulation Factors controlled by homeostasis:
Blood glucose
Water
Temperature
B1.11 Homeostasis
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:
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:
Vasoconstriction - narrowing of blood vessels in the skin. Blood flow through the skin is reduced, therefore heat loss is decreased. Body temperature increases.
Shivering - tiny muscles under the skin contracting and relaxing very quickly. The muscle cells release heat.
Body hair rises away from the skin, trapping a layer of air next to it, insulating the body. Erector muscles contracting.

21. 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 :
Sensory neurones send impulses from receptors in the sense organs to the CNS.
Motor neurones send impulses from the CNS to muscles and glands.
Relay neurones found in the spinal cord/brain. The link sensory and motor neurones. They have no dendron, just dendrites on the cell body.

22. 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.
1. Stimulus Receptor Sensory neurone Relay neurone Motor neurone Effector 6 5 4 3 2 1 e

23. 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

24. B1.15 Diabetes Keywords - See previous page (B1.14)
Type 1 Diabetes
Pancreas does NOT produce insulin
Inject insulin daily (into the fat layer beneath the skin)
Exercise and diet are used to help lower blood glucose levels too
Type 2 Diabetes
Cells respond less well to insulin (they become resistant)
Control by changes in diet and exercise .
Risk factors of developing it are:
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)

25. 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.

26. B1.18 Plant Hormones Auxin produced in the tip of the shoot
Auxin moves to shaded side of the stem
Auxin causes cell elongation

27. 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

28. Keywords: Auxin, tip, shoot, cell elongation, bend, light, stimulus
1.8 Plant Hormones
Keywords: Auxin, tip, shoot, cell elongation, bend, light, stimulus
Experiments with hormones.
Why do the plants respond this way?

29. B1.19 Uses of plant Hormones
Selective Weedkillers – Auxin makes broad leaved plants grow out of control and die.
Rooting Powder – Auxin makes cuttings develop roots quickly.
Seedless Fruit – Flowers sprayed with hormones to make fruit develop but not seeds.
Fruit Ripening – Farmers use hormones to control fruit ripening.

30. Topic 3 Problems of and solutions to a changing environment

31. 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
Halluginogen – changes the way the brain works (distorts senses)
LSD/ cannabis
Stimulants – INCREASE the speed of neurotransmission which speeds up (decreases) your reaction time.
Caffeine/ cocaine/ nicotine
Depressants – slows down the activity of neurones which causes relaxation. INCREASES reaction time
Alcohol/ solvents
Painkillers – blocks some of the impulses to reduce the pain felt.
Morphine/heroin/ asprin
Performance enhancer – improves muscle development
Anabolic steroids

32. 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
Tar
Increased risk of developing cancers
Reduced surface area in the lung as it coats them in sticky tar
Carbon Monoxide
Less oxygen in blood causing pain in active muscles
Blood vessel narrow reducing blood flow
Emphysema and chronic bronchitis
Nicotine
Highly addictive to hard to give up
Long term studies – evidence links smoking to many diseases including all cancers, respiratory diseases and circulatory diseases.

33. B1.23 – The effects of alcohol
Short term effects
Affects all organs as absorbed quickly
Slows down brain activity resulting in longer reaction times
Reduced negative feelings so feel happier
Lower inhibitions so take risks
Vomiting
Large quantities can cause unconsciousness and death (stops breathing)
Long term effects
Cirrhosis of liver – cells die and liver function fails
Brain damage
Memory loss
Blood clots
Addictive
Cost to society
Violence when drunk
Accidents increase
Treatment of drink related illness

34. 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
Similar tissue (closer match give greater chance of survival)
Similar age (increased success)
Geographically close (quicker transplant = increased success rate)
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:
Xenotranplantation (animal donors)
Genetic engineering (modified animal organs)
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.

35. 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)
Water - Cholera
Vectors (animals that spread disease) – Malaria (mosquitoes)
Food - Salmonella
Contact – Athlete’s foot
Airborne – Influenza, colds or TB
Body fluid - HIV

36. 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
Physical barriers – prevent pathogens getting in
Chemical defences – kill pathogens before they harm us
Resistance
Some bacteria develop natural resistance to antibiotics
During antibiotic treatment
Less resistant bacteria killed first
More resistant ones remain and will re-infect if full course not taken
Overuse of antibiotics can cause more resistance to develop
MRSA – multi resistant to many antibiotics therefore very difficult to treat

37. B1.28 – Interdependence and food webs
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
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
Plants that photosynthesize
Herbivores
Carnivores, both predator and prey

38. B1.29 – Parasites and Mutualists
One organism feeds off another while it is alive.
Examples
Tape worm (inside the body)
They take food from the intestine causing weight loss.
Headlice (outside the body)
Fleas
Mistletoe
Roots grow into other plants to take their water and minerals
Mutualists
Both organisms benefit from either food, shelter or protection.
Examples
Oxpecker and wild cows
Oxpecker eats insects that are parasites to the cow
Cleaner fish and sharks
Cleaner eats the dead skin to clean sharks
Legumes and nitrogen fixing bacteria
The bacteria help the plant to get nitrates while they get food from the plant and protection.
Chemosynthetic bacteria in tube worms
Intestinal bacteria in humans
Bacteria provide protection against pathogen and get food and place to live in return

39. B1.30 – Pollution food needed (increased pressure to grow crops)
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
Why did the human population grow so quickly?
Better food
Improved sanitation and living conditions
More medicines available
Increased populations mean bigger demand on resources. More people means more…
food needed (increased pressure to grow crops)
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.
Eutrophication stages 1 5 4 3 2 6 7

40. 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
Blackspot fungus (disease of roses) is killed by sulfur dioxide
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.
Stonefly larvae and freshwater shrimps needs lots of oxygen (clean rivers)
Bloodworms and Sludgeworms can live with low 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.
Metal cans Car parts, new cans
Paper New paper, cardboard
Plastic bottles Fleece clothing

41. B1.33 – The Carbon Cycle
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
Carbon is recycled as carbon dioxide (CO2) through respiration and photosynthesis.
Plants absorb CO2 to produce sugars - photosynthesis.
Animals and plants release CO2 when they respire
Burning of fossil fuels releases CO2
Chalk and other sedimentary rocks is formed from the fossilised remains of sea creatures.
When these rocks are exposed to rain (which is slightly acid), the rock dissolves and more CO2 is released.

42. 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
Nitrogen fixing bacteria- bacteria living in root nodules of legumes and soil. They convert:
Nitrogen gas Ammonia
Nitrifying bacteria– converts
Ammonia Nitrates
Denitrifying bacteria– converts
Nitrates Nitrites
Nitrites Nitrogen gas