biological revision booklet

7/31/2019 Biological Revision Booklet

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Biological Revision booklet Jaspreet H

Key assumptions:

1. Our behaviour is determined by our genes andchromosomes e.g. intelligence is a gene which determines

how smart you are/intellect

e.g. species specific behaviour- rats cant vomit yet humans

can

e.g. some behaviours run in families like schizophrenia,

anorexia etc2. Our behaviour is directed by our Central Nervous System

(CNS) and hormones. E.g. movement and speech is

controlled by our brain

Central Nervous System:

- Brain + Spinal cord- Brain controls billions of neurones (nerve cells)- Brain then communicates with the rest of the body though

the nervous system telling the different parts what to do

- Neurones communicate with each other through synapsesSynapse:

- Small junctions between neurones where neurotransmittersare released

Neurotransmitter:

- A chemical that transmits electrical impulses within the bodyReceptor:

- A part of the receiving end of a neurone, this part receivesinformation

Genes:


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- They code for characteristics in a DNA moleculeHormones:

- A chemical in our bodies that causes certain behaviours e.g.moodiness when a girl is menstruating is caused by the

oestrogen hormone

Biological explanation for gender development:

1. Upto 6 weeks the embryos look the same although theycould have XX or XY sex chromosomes

2. AT 6 weeksGonads developand they look the same. TheyreBi-potential gonads at this moment in time.

3. The Y chromosome contains SRY gene which produces testisdetermining factorhormone. This stops production of ovaries

and the gonads develop into testes.

4. Then the testes make the anti-mullerian hormone whichprevents the growth of female sex organs

5. Testes produce testosterone which does 2 things: makes thewolffian system (male gonads) develop into FULL male sex

organs e.g. the penis

6. Testes also stimulate pituitary gland in the brain to producemore androgens (male hormones)

7. FEMALES: The mullerian system in XX embryos develops intofemale sex organs because of the ABSENCE of TESTOSTERONE

Brain lateralisation:

- One-sidedness of the brain- Left hemisphere = language + logic- Right hemisphere = spatial + creative- Males are said to be more lateralised than women


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How does information travel across a synapse?

1. In the terminal button of the sending neurone are vesicles.These vesicles contain chemicals called neurotransmitters

2. Electrical activity in the sending neurone triggers the releaseof these neurotransmitters into the synaptic gap

3. The neurotransmitter travels across the synaptic gap to thedendrite of the receiving neurone

4. There the neurotransmitter binds a special type of proteinmolecule called a neurotransmitter receptor. This receptor

changes its shape in response to binding with theneurotransmitter

5. This shape change results in a series of other changes in thereceiving neurone. These other changes result in alterations

in the electrical activity of the second cell.

6. If enough excitatory messages are received from otherdendrites of the receiving neurone it will fire and so the

electrical impulse is passed on.

7. Any neurotransmitter not used is taken up by the pre-synaptic (sending) neurone. This process is called re-uptake

Brain lateralisation:

If youre less lateralised i.e. women- then itll be easier to recover

from a stroke because the unaffected side can learn the functions

the affected side did more easily than in a male brain which is

usually more lateralised

KEY STUDIES:

Gottesman + Shields:

Aim: to see if there is a genetic component to schizophrenia

Procedure:


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- Researchers studied MZ + DZ twins- At leastone of the twins was diagnosed with schizophrenia- They used the data to calculate the concordance rates for

MZ + DZ twins i.e. if one twin had the disorder, what % of their

twin would also have it?

Results:

- MZ twins concordance rate: 48%- DZ twins concordance rate: 17%- Incidence in general population: 1%

Conclusion:

Study shows that the closer the people are genetically, the more

likely it is they will develop schizophrenia (genetic component)

EVALUATION:

- The fact that the concordance rate is not 100% suggests thatthe onset of the disorder being developed is not purely down

to genes- environmental factors also play a part too e.g.

stress, loss of job, a death in the family

Ethics:

- Consent gained from pps - Standardisation = high (experimental validity) - Twins share the same pre-natal environment, this may affect

behaviour e.g. if the mother smokes cannabis whenpregnant

- Twins share the same post-natal environment, this may alsoaffect their behaviour e.g. if they are raised in the same

household, same upbringing

- Influential to schizophrenia research = led to our modernunderstanding of the disorder and led to treatments e.g. drug

treatments


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- High population validity = results can be applied to widerschizophrenia population

- High experimental validity = accurate, standardised,replicable and reliable

- Study has been replicated = findings show same trend i.e. MZtwins C-rates always higher than DZ twins and both are

higher than general population significantly

- Biased sample = volunteer sampling MONEY (1975)

Aim: To test his theory of gender neutrality

(he theorised that kids were born genderless and gender was

determined by upbringing; he was the nurture side of the

nature-nurture debate)

Procedure:

- In 1965 identical twins Bruce and Brian were born (MZ twins)- They were sent for a circumcision at 10 months due to a

problem in urinating- There was a mistake during the procedure which caused

Bruces penis to be completely removed

- They saw Dr Money on TV about intersex children beingbrought up as either male or female

- He argued that the sex of a child is determined by theprocess of their upbringing outside of the pre-natal

environment

- After contacting Dr Money, a decision was made to bring upBruce as a girl, as it would be too difficult for him dealing with

the absence of his penis in later life

- Bruce was castrated surgically and his name was changedto Brenda (removal of testicles, can no longer produce

testosterone)

- He was dressed in dresses and was given dolls to play with,,and his hair was grown long


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- Did feminine activities such as baking- At age 12 he was given oestrogen- to induce female pubertyResults:

- Brenda had masculine traits- Liked boys toys, was a tomboy, used to fight in playground- Urinated standing up without a penis- Behavioural and emotional difficulties- At 15 was so unhappy, was permitted to live as a boy- Changed name to David- phalloplasty to create a penis- Was happy as a manand in his 20s married- In his30s Brian commits suicide due to childhood trauma of

this

- David- unhappy and depression worsened- 2004 David commits suicide

Conclusion:

This case suggests that GENES + BIOLOGY heavily determine a

childs gender rather than upbringing

EVALUATION:

Ethics: POOR

- Stress caused, traumatic experiences, drastic change inidentity = caused stress to David/Bruce Brian and parents

- Suicide = both brothers committed suicide, other people whoalso had a sex change also did the same. Some people

have also criticized this study and said it influenced both

Reimer twins into their suicides due to the trauma caused by

it

- Why make a vagina? Because it was easier (only basicsurgery was available then) but this does not mean it was

best for Bruce

- Sexually explicit materialshown to a child = A woman givingbirth in graphic detail


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Data highly valid:

Case study, data gathered from more than one source,

qualitative data, in-depth and rich

Data highly reliable:

Data comes from more than one person e.g. Parents, Bruce,

Brian

Ecological validity:

HIGH procedure + study took place in natural environment of

the twins

Replicability:

LOW hard to test for reliability, unique case + circumstances,

cant be generalised to the general population

PFEIFFER (1936)support for gender development

- Removed sex organs of genetic male and female newbornrats and found that they all developed into adults withfemale hormone release patterns from the pituitary gland.

- Some rats who had their gonads removed and had testestransplanted onto them (even female rats) there was also a

steady release of male sex hormones from the pituitary

gland.

- Suggests that the presence or absence of testosterone fromthe testes accounts for sex differences in the hypothalamus

(the part of the brain which controls the release of sex

hormones from the pituitary gland)

- Conclusion: this provides support for the biologicalexplanation of gender development


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METHODOLOGY:

Lab experiments D&E:

Description:

- Experiment conducted in a controlled environment with highcontrol over extraneous variables.

- Artificial setting- Researchers usually manipulate the IV and measure it

against DV to see a cause and effect relationship

Evaluation:

- Strength is can be highly controlled which makes itstandardised so highly replicable

- Weakness is that its a lab so unnatural environment whichreduces ecological validity

- High control which means low chance of extraneousvariables affecting results which increases experimental

validity

- Usually made to perform unnatural tasks, could result indemand characteristics (likely to guess aim) and therefore

display behaviour they believe is required for the

experiment. This is not their true behaviour

Scans:

PET scans:

- Show the function of the brain, like the brain doing a task e.g.adding up numbers

- The patient lies in a scanner and is injected with water orglucose containing a radioactive tracer

- When the brain uses oxygen in the water or glucose solutionthe tracer starts to decay, emitting positrons

- These positrons collide with electrons forming gamma rays,forming a picture of the working brain


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Key words: function, glucose, radioactive, oxygen, electron,

positron, gamma rays, water, colours, tracer, decay

MRI scans:

- Scans that show the structure of the brain, like brain tissuecontaining tumours; the scans are usually black, white + grey

- The patient lies in the scanner and a strong electromagneticwave is passed through their head

- These waves cause the nuclei in the patients hydrogenatoms to spin a certain way emitting radio waves

- Different types of tissue have different hydrogenconcentrations and so, the scanner can make a picture ofwhat the inside of the brain looks like

Key words: structure, electromagnetic, radio waves,

hydrogen atom, spin, nuclei, concentrations, black white +

grey

Twin studies & Adoption studies D&E:

Twin studies: Adoption studies

Description:

Adoption studies- Adoption studies are when children who were

adopted are assessed in later life, on certain characteristics.

The information on these characteristics is compared with their

adoptive parents and their biological parents.

If the adopted children are more like their adoptive parents then

nurture/the environment is important to the development of that

characteristic.

If the adopted children are more like their biological parents then

nature/genes is important to the development of that

characteristic.


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Twin studies- twin studies are used to see if behaviours are shared

by those who are genetically similar, in this case twins are 100%

genetically identical (MZ twins)

Psychologists look at twins to see what traits they shareby lookingat concordance rates between them (the likelihood that if one

twin has a certain trait, the other twin will also have the same trait)

e.g. gottesman + shields schizophrenia

If there is a high concordance rate between MZ twins there may

be a genetic cause for the trait they share. If the concordance

rate is higher for MZthan DZ then it is likely that genes play a

strong part in the behaviour being studied.

NATURE VS NURTURE

Evaluation:

- Both methods are good for testing genetic causes ofbehaviour: for twin studies the twins are compared with one

another so if the researcher gets similar results, then they can

assume it is due to their genes, and if results are different it islikely to be due to their environment. In adoption studies the

child is compared with their biological parents and adoptive

parents allowing the researcher to conclude that behaviours

shared with B parents (and not with A parents) are genetic,

and behaviours shared with A parents (and not B parents)

are due to nurture + their environment

- There is a problem studying MZ twins in the same homebecause you cannot decide if similar traits are due to their

genes or the environment that they share, as they are

already 100% genetically identical

- Studying MZ twins raised in the same environment however ismore beneficial to researchers because they are more able

to observe differencesand similarities between both twins, as

you can see if similarities are due to genes and differences

due to environment


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- Concordance rates for behaviours between MZ twins arerarely 100% e.g. schizophrenia is 48%. This suggests our

behaviour is due to BOTH our nature (genes) and nurture

(upbringing)

- One problem with these types of studies is twins share a pre-natal environment together, and also like adoptive children

they share their pre-natal environment with their biological

mother.The behaviour of the mother could affect the

development of the child such as; drug use, smoking,

alcohol, sex hormones e.g. taking testosterone, stress,

medication, food/diet etc

- Adoption agencies placing twins with different familiesusually try to place them with similar couples, so they will be

brought up similar and share similar experiences and

environments. This could affect results of studying the

genetics of MZ twins because if the researcher finds

similarities its hard to determine whether they are due to the

genes or the similar environments.

- There is a minimal amount of twins raised separately. This canaffect sample size and results found because it reduces the

sample sizeand its hard to test for reliability because there

may not be enough pps to replicate the studies.

- Many of the pps for twin + adoption studies are gatheredusing ads. The researcher is likely to gain a bias result

because it will be biased towards people who have the time

and interest to volunteer, so the results may not be

generalisable to all twins. Demand characteristics mayoccur, reducing validity where the twins may act more

similarly than usual because they think that is what is

required.

Identify, describe and apply:

Levels of significance: it needs to be shown that it is 95%

certain that the behaviour predicted by the hypothesis is NOT

due to chance. If there already is a lot of supporting evidence,


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then the level of significance acceptable rises to 99% or 1%

likelihood that the hypothesis is down to chance, 99% it is not.

Usually P


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IV + DV:

IV = the independent variable is the causal variable; the one

being tested by the researcher

DV = the dependent variable is the measured variable, the one

that is changed by the independent variable.

Use of control groups: The control group is a comparison group

of participants/subjects that do not experience the

independent variable but are as similar as possible to the

experimental group.

Experimental procedures, including allocating groups to

conditions (e.g. randomising) and sampling

Nominal- categorised data e.g. hair colour/eye colour

Ordinal- ranking (high to low) e.g. scores in a test, positions in a

race

Interval- equal spacing between interval points but NO true

zero e.g. temperature

Ratio- Like interval measurements but have a TRUE ZERO e.g.

height or weight

D&E use of animals in lab experiments, including strengths and

weaknesses, validity, reliability, generalisability, credibility, ethical

and practical issues

Description:

- Animals are used in many ways in research and veryfrequently

- E.g. lesion studies = cutting or burning away areas of thebrain, or using drugs to shut parts of the brain off temporarily

- Normally observe difference in behaviour- Area damaged can be linked to behaviour change


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- damage = independent variable- change in behaviour = dependent variable- normally compared with control group = normally

functioning

Evaluation:

- Animals are easier to house and monitor because they aresmaller and have simpler needs

- Rats for example, are genetically similar enough to humanswith similar body plans etc. So some generalisations from

animals to humans can be made

- This enables researchers to conduct studies on animals thatwould be unethical on humans e.g. lesion studies

- Animals are naive pps, so they wont guess the aim orchange their behaviour, so the researcher wont get DCs

- Animals like rats breed quickly (22 days gestation) so aready supplyof pps can be produced easily and quickly

HOWEVER

- Animals are not 100% genetically similar to humans;therefore we cant always assume that results you get using

an animal pp would be the same as if you used a human pp.

This reduces generalisability

- Animal exps are criticized of being speciesist- the idea thathuman life is more valuable than animal life. Some see this

as immoral

- May be more expensive than humans (must have highestlevel of care) 24 hours a day!

Ethics:

- Legislation = laws regarding animal welfare- Choice of species = animals chosen should be most suited to

research and least likely to suffer adverse effects from taking

part in the study


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- No. Of animals = must be kept to the minimum amount thatneeds to be used so results are gathered with the least

possible effect

- Procedures = researchers should avoid causing pain,discomfort or death to animals. If it is unavoidable and

necessary a license must be in place and must be done

under controlled supervision. All potential suffering is kept to

a minimum

- Procurement of animals = acquired from reputable suppliers- Housing and animal care = should be housed in

environments similar to natural habitats

- Final disposal of animals = animals may be re-used as longas care is maintained

PRACTICAL- SPATIAL ROTATION TASK

Aim: To see if there is a difference between genders in terms of

performance on spatial rotation tasks

Null Hypotheses: There will be NO difference between males

and females in terms of performance on spatial rotation tasks

Alternative/Experimental Hypotheses: There WILL BE a

difference between males and females in terms of performance

on spatial rotation tasks (2 tailed)

Males will be better than females at spatial rotation tasks in

terms of performance (1 tailed) (choose any just know the

difference)

VARIABLES:

- Variables were operationalised- IV was changed or manipulated thus 1 group males + 1

group females

- DV was measured thus test score was out of 9Research method: quqsi experiment b/c gender is naturally

occurring


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Best environment for this exp= lab/classroom, provides higher

control over extraneous variables e.g. noise, temperature

Fairly easy task= so all pps were able to attempt it and

understand what they are required to do

QUANTITATIVE/ORDINAL DATA

PROCEDURE:

- Each student collected a PP from the common room(opportunity sampling)

- We had 10 boys and 10 girls- Read out standardised script w/ consent form (they ticked for

consent)

- Given a test paper regarding spatial rotation tasks (9 Qs)- Gave 5 mins to complete the test- Debriefed and then collected papers- Papers were marked by invigilators (in this case researchers-

being us)

Target population: Males + Females sixth form students agedbetween 16-18

Experimental design= independent measures- each pp only

takes part in one experimental condition

APPARATUS

Each pp receives test paper, pen, consent form

ANALYSIS:

Why Mann Whitney U test?

- Was a test of difference- Ordinal data (ranking- because youre deciding who is

better)

- Independent measures design. (Each group does one taskonce)


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RESULTS:

- Not significant enough so we rejected our alternativehypotheses and accepted the null.

EVALUATION POINTS:

High ecological validity: conducted in school, natural

environment for tasks like these to be conducted.

Not generalisable: 6 form students, cant apply to different ages

Biased sample: opportunity sampling, may have got one type

of pps who were on a free lesson at the time, e.g. physics

students/art students

Standardised: so replicable and can be tested for reliability

Population validity: do not represent whole population (LOW)

PROBLEMS: more than one pp sat per table- could cause

cheating/distractions

Improvements: next time assign one pp per table in an

individual room to avoid cheating and distractions

ETHICS: all you need to know is-

- Consent (not fully informed to not reveal true aim and avoidDCs)

- Debriefing- Remind them RTW and at the end reveal aim- Right to withdraw- told at start and finish- Right to destroy information- at own will, given option to do

so

How we avoided extraneous variables:

Student invigilatorsincrease in validity

Teacher prepared test papers


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CONTROLS:

- Having more controls would mean higher experimentalvalidity. More controls mean that there is less influence from

extraneous variables such as noise or temperature on the DV- To introduce controls we ensured:- PP age= 16-18yr olds- Tasks undertaken= all pps do same task- Environments= all pps in same environment- Time given= 5 mins- Seating per table= 3 per table facing the front- Instructions given= scripted therefore standardised

Other stuff which might come up:

- OVERT observation- pps know they are being watched- COVERT- pps dont know they are being watched e.g. one

way mirror (could be unethical)

- PARTICIPANT- observer is a part of pp group- NON-PARTICIPANT- observer is separate from pp group- NATURALISTIC- observing people in natural environment

naturally. Not doing anything but observing (no manipulation

of IV or DV)

- STRUCTURED- researcher will have a set list of behaviours theyare looking for and may have set the room up in a certain

way or task in a certain way. (controlled- easier to replicate)

KEY ISSUE: is autism an extreme male brain condition?

Autism: a developmental disorder, child has trouble building

relationships with others (inc parents)

Who came up with this idea? Simon Baron Cohen

Ratio of male to females w/ autism =3:1

So.. 75% of autistic people are male


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Why?males have much larger amounts of male hormones

than females produced by the pituitary gland, Low level of

male hormones are produced in female adrenal glands, could

amount to females developing autism

Structural differences between male/male/autistic brain:

1. Male brain is heavier than female brain, autistic brain isheavier still

2. Male brains grow more quickly in early development, autisticbrains grow quicker still

3. Male brains have a smaller corpus collosum, autistic brainshave a smaller one still

4. Males have a larger amygdale (negative emotions likeaggression are controlled here), autistic people have a

larger one still

Functional differences between male/male/autistic brain

1. Male brain is better at spatial tasks e.g. map reading, autisticbrains are even better at this

2. Male brain shows more brain lateralisation of brain function,HOWEVER autistic people do not show stronger than normal

brain lateralisation

Could autism be genetic?

- There is a high concordance rate of 60-90% for autism in MZtwins

- Only 5% in DZ twins- Suggests there is a STRONG genetic link

EXTRAS

Make sure you know all the sampling methods

Make sure you know all the experimental designs and how to

evaluate them

Make sure to know your results and what they mean


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Problems you encountered and overcame

Improvements

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