Biology AQA B -Module 8 - syllabus overview

**GJS** · 22-06-2006, 03:41 PM

More notes this time for biology, just finsihed these earlier -good luck tomorrow...

Patterns of Behaviour

Innate Behaviour

Innate - genetic - little influence from the environment - varies little within species - doesn’t need to be learnt
Learned - develops from animals interaction and experience from the environment - allows animals to adapt to an environment - not passed on genetically

Taxis & Kinesis

Innate behaviours

Taxis - orientating behaviour- directional - move towards or away from a stimulus
Kinesis - orientating behaviour - non directional - if environment is favourable, speed is decreased rate of turning is increased - allows organism to remain in favourable conditions

Reflex Actions

Reflex escape responses
Rapid, innate, automatic response to a stimulus
e.g. stimulus à receptor à sensory neurone à relay neurone à motor neurone à effectors à organism escapes/moves out of danger

Linking a number of reflexes too produce a more complicated behavioural response e.g. feeding a new born infant
Rooting Reflex - nipple seeking behaviour - as breast touches babies cheek baby turns its head, mouth open until it finds the nipple
Sucking Reflex - when lips touch nipple baby starts sucking
Let Down Reflex - Stimulation of nipple causes oxytocin to be released from the pituitary gland - oxytocin causes smooth muscles in the mammary glands to contract, releasing milk

Modified Reflexes

Learn to control a reflex of the ANS
Gain conscious control of the bladder
Stretch receptors in bladder send impulses along ANS, but also too the brain, motor areas send impulses to second sphincter too contract
Also inhibitory signals sent from CNS too inhibit normal reflex

Learned Behaviour

Habituation - when an animal becomes accustomed to something - e.g. when an animal learns too stop responding to a stimulus
Imprinting - e.g. goslings imprint on their mother - imprinted object used as a parent figure in times of distress - object of sexual desire

Conditioning
Classical - stimulus leads too a response - new stimulus given at same time as original stimulus - repeated many times - animal associates new stimulus with old stimulus - now animal has the same response for both stimulus
e.g. Pavlov with dogs - dogs salivate on sight and smell of food - Pavlov rang a bell every time before he served the food - repeated - after time the dog would salivate on just hearing the bell

Operant Conditioning - trial & reward learning - Skinners rats/box - rat presses leaver - food released (reward) - positive reinforcement - rat is then more likely to do it again, quicker

Similarities between humans e.g. parents give their children money if well behaved

Reproductive Behaviour

Courtship

Courtship is necessary for successful mating
Species Recognition - each species has their own courtship display too attract the opposite sex of the same species - this is important when two of the same species live close together to avoid aggression - aggression is a waste of energy and could possibly cause injury
Pair Bond Formation - synchronise breeding activities - pituitary glands secrete gonadotrophic hormones which stimulate production of sex hormones - oestrogen stimulates ovulation - so she is ready too mate
Sexual Selection - allows female too choose a healthy mate, who is going to be able to look after her and support their offspring

Sign Stimuli & Innate Releaser Mechanisms
Visual sign - usually coloured - triggers an innate reflex - communication between species - multiple sign stimuli can be strung together in courtship behaviour patterns

Territorial Behaviour

Reduces fighting and aggression between species
Advantageous because - reduced energy output - reduced risk - maintenance of a food source - defence of a nest site

Menstrual Cycle

Pituitary Hormones - FSH - follicle stimulating hormone - LH - lutenising hormone
Ovarian Hormones - Oestrogen - repair uterine endometrium - Progesterone - maintain uterine endometrium
The menstrual cycle uses negative feed back
Sequence - FSH stimulates growth of follicle - developing follicle produces oestrogen - rising oestrogen inhibits FSH production and promotes production of LH - LH stimulates follicle development into conversion of corpus luteum - rising oestrogen stimulates FSH production - surge in FSH & LH cause ovulation - LH stimulates progesterone production - progesterone inhibits FSH & LH

Contraception

Reliable methods - oral pill/ barrier contraceptive/ implant/ vasectomy/ IUD
Oestrogen/ Progestin Pill - oestrogen inhibits FSH - progestin inhibits LH which reduces chance of ovulation - also thickens cervical mucus so acts as a barrier to sperm

Infertility

Use extracted/ synthesised hormones e.g. clomiphene which stimulate hormone production
In vitro fertilisation - use fertility drugs too stimulate ovulation - collect mature eggs and incubate with sperm - insert embryo’s into the uterus

Pregnancy

Conception

Capacitation - ejaculation - sperm has a protective membrane of protein and lipoproteins - enzymes must remove the coating before fertilisation occurs
Acrosome Reaction - fertilisation occurs in the oviduct - contact between granulosa an occyte trigger the acrosome reaction - enzymes released from acrosome - enzymes create a gap too the zona pellucida - sperm binds too a ZP3 receptor protein on the zona pellucida - this forms a slit into the oocyte - the sperm enters the oocyte - its back fuses with the oocyte membrane - the tail keeps moving causing the oocyte too rotate inside the zona pellucida - enzymes cause cortical granules too thicken - ZP3 receptors destroyed
Cortical Reaction - only one sperm fertilises the oocyte - zona pellucida forms a barrier enzymes cause cortical granules too thicken - ZP3 receptors destroyed

Hormones In Pregnancy

Once an embryo is implanted on the endometrium it releases HCG
HCG - Human Chorionic Gonadotrophin
Acts on the corpus luteum so it continues too secrete progesterone - maintaining the endometrium - also inhibits FSH so no follicles develop

Pregnancy Test

Conformation of pregnancy by detection of HCG or higher levels of progesterone
HCG/Progesterone specific shapes, bind too complementary structures - binds too a tracer - makes a colour

Placenta

Supplies substances e.g. glucose, amino acids for growth
Removes nitrogenous waste/CO2
Placenta - blood never mixes - allows exchange of substances - hormone production
Many chorionic villi and microvilli to increases surface area for exchange of substances, large conc gradients due too counter current multiplier effect - foetal blood has a higher affinity for oxygen - active transport - pinocytosis of anti bodies

Physiological Changes

Body Mass - foetus/placenta - myo/endometrium - blood mass/haemoglobin - plasma - body fat
Cardiovascular - rich blood supply - larger heart - increase in plasma and blood cell mass - transport more substances - increased blood flow too maintain conc gradients for effective diffusion
Kidney Function - Increased blood flow through kidneys - larger kidneys - increased waste products - more conc urine due too amino acid metabolism in foetus

**GJS** · 22-06-2006, 03:41 PM

Human Growth & Development

Algometric growth - different parts of the body grow at different rates

Childhood

Pre-pubertal period - acquire the complex skills of life e.g. speech and language - large pre-pubertal period so when children are ready to live on their own they can interact successfully in a complex human society
Hormonal Control - steady growth rate due too endocrine glands growing at a proportional rate - endocrine glands control growth - large amounts of cell division require lots of energy and a high metabolic rate - pituitary gland is in control of growth - PGH - pituitary growth hormone - stimulates elongation of bones -PGH binds too specific receptors - assimilation of amino acids for protein synthesis - thyroxine stimulates metabolic rate and glucose metabolism - providing raw materials for growth

Adolescence

Growth of reproductive organs - puberty - pituitary gland produces LH & FSH - LH & FSH stimulate ovaries and testes to produce testosterone and oestrogen - develop secondary sexual characteristics - female growth spurt is small triggered by PGH - male growth spurt triggered by testosterone and hormones from adrenal gland - growth spurt later but larger - positive feedback of growth hormones and sex hormones
Many environmental factors inhibit growth e.g. nutrition

Ageing

Decline in physiological function
Degeneration in tissue - wear and tear - incorrect repair - reduced efficiency e.g. bronchioles/alveoli in the lungs or exposure of skin to UV
Malfunction of immune system - immune systems can distinguish between the bodies proteins and foreign proteins e.g. bacterial/viral - when our own body cells mutate e.g. cancerous cells the immune system destroys them - however when we get older the immune systems becomes less efficient in its ability to detect pathogens and cancerous cells/proteins

Human Population & Health

Population Size & Structure

Population - number of individual species in a specified area
Population growth = (births + immigration) - (deaths + emigration)
Growth rate = {population change / population at start} x 100
On an age pyramid comment on; angle of the sides - height - width of the base
On a survival curve half of deaths = average life expectancy
4 stages of growth - high stationary - early expanding - late expanding - low variable
High Stationary - high birth rate (BR) - high death rate (DR) - limited food supply - starvation - diseases - high fluctuating DR - infant mortality high - food shortages/ diseases/ primitive living conditions
Early Expanding - more reliable food sources - improved living conditions - reduction in disease - population expands
Late Expanding - significant fall in BR leads too social changes - industrialisation - families less dependant on income of children - birth control
Low Variable - stable population - low BR & DR - BR more variable - increase in percentage of older people

Social Conditions

Food Supply - growth depends on food - lack of food results in malnutrition - more susceptible too infection - BR drops due too decrease in fertility in woman
Sewage Disposal - needed too reduce water born diseases - must be treated otherwise organisms can develop
Drinking Water - taken from deep under ground or reservoirs - specially treated

Infectious Disease

Pathogens - virus/ bacteria/ fungi
Virus - smallest - acellular - uses host cells materials
Bacteria - middle - prokaryotic - asexual - heterotrophic
Fungi - cell walls of chitin - eucharistic - spore reproduction

Transmission

Droplet/ Contact/ Food & Water
Droplet - coughing - micro organisms passed out in droplets of water - small droplets remain air borne - larger droplets fall and dry releasing micro organisms into the air - can then be inhaled
Water - sewage contamination with drinking water
Food - microbial growth - raw materials for growth I food - warm conditions for reproduction
Contact - Blown nose - micro organisms on hand - sexual diseases

Natural Immunity

Antigen enters body - B-lymphocytes produce a specific anti-bodies too destroy pathogen - this antigen is remembered and corresponding anti-body - next time antigen detected anti-bodies produced much quicker
Artificial Immunity - vaccinations
Limitations - Antigens are proteins - immune system recognises specific antigens - due too quick reproduction of viruses there is a large chance of mutation - a mutation cause shape of the antigen to change - it will no longer be recognised by the immune system - therefore a new strain has been created - antigenic drift - viruses can also combine too form new strains
Herd Immunity - if large enough percentage of people are vaccinated the incidence of the disease is reduced - as there is less chance of a person coming into contact with the disease

Effects On Lifestyle & Health

Carbohydrate/ lipids/ proteins/vitamins/ minerals/ water

Deficiencies of minerals
Calcium - milk - bones/ nerves/ muscles - rickets
Iron - red meat - haemoglobin - anaemia
Iodine - sea food - thyroxin - goitre

Deficiencies of vitamins
Vit A - dairy/ fish oil - membranes/ rhodopsin - dry skin/ night blindness
Vit D - milk/ fish oil - absorption of calcium/ calcification of bones - rickets
Vit C - citrus fruit - collagen formation - scurvy

Water - chemical reactions - surface of lungs for gas exchange - transport systems - heat absorption/ sweat

Effects of excess fat/ salt intake
Build of fatty deposits in inner lining of artery - antheroma
High blood pressure

Antheroma - restricts blood flow - increases chances of a blood clot - thrombus is stationary - embolism is moving
Antheroma in coronary - CHD - blood clots may form - causing blocked artery - deprives cardiac muscle of oxygen - part of cardiac muscle dies - MI myocardial infarction

Aneurysm - artery walls become weakened from elasticity loss - swells like a balloon - can burst and cause internal bleeding

Cerebrovascular Accident - lack of oxygen too brain - cause death of brain tissue - maybe a blood clot or aneurysm

Diseases Of The Lung

Chronic Bronchitis - smoking and pollution paralyse cilia cells which would usually move mucous up the bronchia tubules - mucous builds up - bronchial tubes become irritated by coughing - excess mucous production occurs - more likely to catch diseases e.g. pneumonia - smoking also damages bronchioles & alveoli - reduced surface area for gas exchange - gets better if smoking stops
Emphysema - further irritation by coughing - irreversible damage - less elasticity - ineffective gas exchanges - reduced SA and excess fluid in lungs
Lung Cancer - carcinogens in smoke - alter DNA - switches on oncogene - oncogene missed by the immune system -rapid, uncontrolled growth of unspecialised cell occurs - tumour made - secondary tumours can grow if tumour is malignant - metastasis - benign tumours stop growing
Skin Cancer - UV light is a carcinogen
Reducing Risks - diet - low fat/salt intake - exercise - low stress - no smoking - avoid sun at peak times - sun cream

Screening Programmes

Genetic Analysis
Chorionic villus sampling - sample of placenta - DNA analysed for anomalies
Aminocentesis - sample of amniotic fluid - DNA analysed - done later than chorionic villus sampling
Ethical Issues - Who has a right to the information - should parents make an unborn child’s decision about a genetically inherited disease - should insurance companies know
X-ray - shows damage to bones and abnormalities in soft tissue - can cause mutations
Ultrasound -high frequency sound waves - does not damage DNA
Endoscopy - looking inside the body - key hole surgery