THE ROLE OF CHROMOSOMES AND HORMONES

Question 1

• Is the role of chromosomes and hormones an example of nature or nurture

Answer 1

Nature

Question 2

Define chromosomes (2)

Answer 2

Found in the nucleus of living cells carrying information in the form of genes

the 23rd pair of chromosomes determines biological sex.

Question 3

Define hormones

Answer 3

chemical substance circulated in the blood that controls and regulates the activity of certain cells or organs.

Question 4

Define testosterones (3)

Answer 4

hormone from the androgen group that is produced mainly in the male testes.

and in smaller amounts in the female ovaries 

Associated with aggressiveness

Question 5

• Define oestrogen

Answer 5

primary female hormone playing an important role in the menstrual cycle and reproductive system.

Question 6

Define oxytocin

Answer 6

hormone which causes contraction of the uterus during labour and stimulates lactation.

Question 7

What does a Y gene do (3)

Answer 7

The Y chromosome carries a gene called the sex-determining region Y, or SRY for short

The SRY gene causes testes to develop in an XY embryo.

These produce androgens. male sex hormones Androgens cause the embryo to become a male; without them, the embryo develops into a female.

Question 8

How is the babies sex determined (2)

Answer 8

All normal egg cells produced by a human ovary have an X chromosome, Half of the sperms carry an X chromosome, and half a Y.

The baby's sex is determined by the sperm that fertilises the egg cell. The baby will be a girl if the fertilising sperm carries an X chromosome, the baby will be a boy if the sperm carries à Y chromosome.

Question 9

What is the role of chromosomes (3)

Answer 9

• Chromosomes are made from DNA (which stands for deoxyribonucleic acid - you knew that Genes are short sections of DNA that determine the characteristics of a living thing.
  
  • There are 46 chromosomes in the human body arranged into 23 pairs
  • last of the 23rd pair determining biological sex. The chromosomal structure for females is XX, and for males XY

Question 10

What is the role of hormones (5)

Answer 10

• Chromosomes initially determine a person’s sex but most gender development actually comes about through the influence of hormones.
  
  • Prenatally in the womb, hormones act upon brain development and cause development of the reproductive organs.
  • At puberty, during adolescence, a burst of hormonal activity triggers the development of secondary sexual characteristics such as pubic hair.
  • Males and females produce many of the same hormones but in different concentrations.
  • Of primary importance in male development are a number of hormones called androgens, the most widely known of which is testosterone.

Question 11

When is testosterone produced and what had research shown

Answer 11

begins to be produced at around eight weeks of foetal development.

Much research has focused on the behavioural effects of testosterone, most notably in terms of its link to aggression.

Question 12

What is the role of oestrogen

Answer 12

female hormone that determines female sexual characteristics and menstruation. Alongside the physical changes,

Question 13

What is PMS

Answer 13

oestrogen causes some women to experience heightened emotionality and irritability during their menstrual cycle. This is referred to as pre-menstrualtension (PMT) or pre-menstrual syndrome (PMS) when these effects become a diagnosable disorder.

Question 14

How has pms been used to defend crime

Answer 14

In extreme cases, PMS has been used (successfully) as a defence in cases of shoplifting and even murder! That said, some researchers dispute the existence of PMS as a viable medical category

Question 15

• Why do women produce more oxytocin then men

Answer 15

particularly as a result of giving birth.

Question 16

What is the role of oxytocin (3)

Answer 16

• The hormone stimulates lactation, making it possible for mothers to breastfeed their children.
  
  • reduces the stress hormone cortisol and facilitates bonding, for this reason it has been referred to as the ‘love hormone’.
  • is released in massive quantities during labour and after childbirth and makes new mothers feel ‘in love’ with their baby.

Question 17

What evidence fuels the stereotype of men in relation to oxytocin however how can this be argued

Answer 17

The fact that men produce, less of this hormone has, in the past, fuelled the popular stereotype that men are less interested in intimacy and closeness within a relationship.

However, evidence suggests that both sexes produce-oxytocin in roughly equal amounts during amorous activities such as kissing and sexual intercourse.

Question 18

Evaluate contradictory evidence by Tricker et al (2) (-ve) for the biological factors in gender

Answer 18

• double-blind study conducted by Tricker et al: 43 males were given either a weekly injection of testosterone or a placebo. No significant differences in aggression were found after the ten-week period between the two groups.
  
  • many studies of biological factors in gender involve small samples of unusual people, or are conducted on animals, limiting the extent to which meaningful generalisations can be made.

Question 19

Evaluate overemphasis on nature in the chromosomes,hormones explanation in gender development (2 + study) (-ve)

Answer 19

• gender identity is purely down to biology then we would expect to find many more differences in male and female behaviour than there actually are⇒ In a major review of research in this area Jacklin et Al found significantly more differences in behaviour within the sexes than between them.
  
  • Alternative explanations such as social learning theory would point to the importance of social context in the learning of our gender identity and gender role. The influence of social norms would explain cross-cultural differences in gender-role behaviour, and the fact that, in Western society at least, males and females are gradually becoming more androgynous in their behaviour.

Question 20

What’s was the case study on Bruce reimer (6)

Answer 20

• Twin boys Bruce and Brian Reimer.→ Following a horrifically botched circumcision operation at six months of age, one of the twins - Bruce - was left without a penis.
  
  • traumatised parents were made aware of the up-and-coming psychologist who was developing his theory of ‘gender neutrality’ - that biological sex is less important than environmental influence in establishing gender identity. In other words, a biological male or female could be encouraged to develop the gender identity of the opposite sex if they
    were brought up in such a way→ this is what instructed the Reimers to do with their son.
  • Bruce was raised in a stereotypically
    feminine way, dressed in girls’ clothes and given dolls to play with.
    As he grew up, Bruce’s progress was monitored
  • never advised Bruce of the truth of his gender re-assignment.
  • By the time Bruce (or Brenda as she was now known) was in her teens⇒ written extensively of the success of the case
    dramatic proof of theory of neutrality.
  • Brenda had never adjusted to
    life as a female and was suffering from severe psychological and emotional problems. When she was eventually told the truth about her childhood by her parents, she immediately went back to living as a man (‘David’)

Question 21

What did diamond et Al find in case study of Bruce reimer (2)

Answer 21

• Aged 14 Brenda changed back to being a boy. In 2001 committed suicide.
  
  • Theory of Gender Neutrality refuted. Provides evidence that chromosomal influence is more powerful than environment in determining gender development.

Question 22

what was the case study on the Batista boys (7)

Answer 22

• unique family who lived in the Dominican Republic. Four of the children within the family were identified as girls at birth and raised as such until puberty, when they changed’ into males - each of the children’s vaginas closed over, testicles appeared and they grew normal-sized penises.
  
  • The four girls (now boys) were all affected by a very rare genetic disorder, which meant their male genitalia were not external at birth but were concealed inside (they were normal XY males).
  • During prenatal development, a crucial chemical step (the introduction of
    dihydrotestosterone) was missed, which would normally externalise the male genitalia.
  • As such, although their biological sex was male (unbeknown to their family), they had the external appearance of girls at birth. Because of this the four boys were raised as girls and adopted a
    female gender identity until the change at puberty.
  • Due to the onset of hormonal changes at puberty, the dihydrotestosterone that was absent in the womb was produced and the boys’ true biological sex was revealed.
  • the boys abandoned their female gender identity with very few problems of adjustment, and quickly adapted to their
    new roles as boys and men
  • suggesting that gender identity may be flexible rather than fixed.

Question 23

Evaluate CAH and the CAH study for biological factors determining gender (2 + example + study )

Answer 23

• Despite evidence pointing towards biological factors being of prime importance in determining gender, genes and hormones do not produce a simple formula for determining gender.
• Social, cultural and parental influences during socialisation also have a part to play.
• For example, congenital adrenal hyperplasia (CAH) occurs when XX females are exposed to unnaturally high levels of testosterone in the womb which results in rudimentary male genitalia at birth.
• Dessens (’05) study of 250 CAH females who were raised as females found that 95% were content with the female gender assigned to them.