The Role of Chromosomes and Hormones

Question 1

Outline typical chromosome patterns

Answer 1

• Each person has 23 pairs of chromosomes in each cell of their body, which carry genetic information (DNA)
• The 23rd pair determines sex. The male chromosome pattern is XY while the female chromosome pattern is XX

Question 2

Describe the link between sex and chromosomes

Answer 2

• There’s a link between chromosomal sex and external and internal genitalia.
• During prenatal development, both male and female embryos have external genitalia that appear feminine. But when the foetus is 3 months old, if it’s to develop as a male, the testes normally produce testosterone, causing the external genitalia to develop.
• So genetic transmission explains how individuals acquire their sex and some aspects of gender due to link between chromosomes and genitalia

Question 3

What are 2 atypical sex chromosome patterns?

Answer 3

• Klinefelter’s syndrome
• Turner’s syndrome

Question 4

Describe Klinefelter’s syndrome

Answer 4

• This is due to the XXY configuration
• Affects around 1 in 600 males
• Physical characteristics: taller than average, have less muscular coordination than average, may look less masculine due to reduced levels of testosterone e.g. less facial hair, broader hips and breast tissue.
• Psychological characteristics: Poorly developed language and reading skills, passive, shy and uninterested in sex, don’t respond well to stressful situations

Question 5

Describe Turner’s syndrome

Answer 5

• This is due to the XO configuration (2nd sex chromosome is partly or completely missing)
• Affects around 1 in 2,000 females
• Physical characteristics: shorter than average, a lack of monthly periods due to underdeveloped ovaries, small lower jaw, webbed jaw, narrow hips.
• Psychological characteristics: higher than average reading ability, performance on spatial, visual memory and maths tasks are lower than average, socially immature and trouble relating to peers

Question 6

Describe the role of testosterone

Answer 6

• It’s produced prenatally and affects the development of genitalia.
• However, some XY individuals have an insensitivity to such hormones (their bodies’ tissues don’t respond to the effects of the hormone). In extreme cases, no external male genitalia develops and are identified as females at birth and raised as girls
• Testosterone may affect brain development both prenatally and in childhood
• The surge of testosterone during puberty is responsible for secondary sexual characteristics like facial hair and deepening voice

Question 7

Describe a study that supports the role of testosterone

Answer 7

Berenbaum and Bailey found that XX females exposed prenatally to large doses of male hormones (as the pregnant mother had been given drugs containing male hormones) later showed boyish behaviour and greater interest in male-type activities

Question 8

Describe the role of oestrogen

Answer 8

• It has prenatal effects
• Plays a major role from puberty onwards promoting secondary sexual characteristics (breast development) and directing the menstrual cycle (increasing blood supply to the uterus in preparation for pregnancy)

Question 9

Describe a study that supports the role of oestrogen

Answer 9

Shi et al found that oestrogen may lead to smaller brain size

Question 10

Describe the role of oxytocin

Answer 10

• Has been called the ‘love’ hormone as it promotes feelings of bonding in men and women.
• It’s produced in the pituitary gland and encourages feelings of calmness and contentment
• It’s important in breastfeeding as it causes milk to flow in a lactating mother.
• In men and women, oxytocin is related to orgasm and faster wound healing

Question 11

Describe a study that supports the role of oxytocin

Answer 11

• At times of stress, oxytocin dampens flight-or-fight response
• Taylor et al found that in females the alternative tend and befriend response is triggered
• This evolved response ensures that females protect their young (tending) and form protective alliances with other women (befriending)
• The same doesn’t happen in men as testosterone dampens the effects of oxytocin

Question 12

Give evaluation for the role of chromosomes and hormones (research support)

Answer 12

• In the case of David Reimer, after his botched circumcision when he was 6 months old, he was raised a girl ‘Brenda’, due to Dr Money’s advice.
• Money claimed the gender reassignment was a success but this wasn’t true. David was told his true sex later and said ‘it all made sense’ as he felt like he never fitted in and later lived as a man
• Therefore, this shows that sex hormones may have more influence than environmental factors on gender-related behaviours

Question 13

Give evaluation for the role of chromones and hormones (no consistent effect on gender)

Answer 13

• There’s contradictory evidence that shows that hormones have no consistent effect on gender-related behaviours
• In Tricker’s double-blind study, men were given either a weekly injection of testosterone or a placebo. It was found that there was no significant differences in aggression (a gender-related behaviour) after the 10-week period between the 2 groups
• Therefore, if the biological approach was accurate, we would expect more differences due to hormones but as there wasn’t, it shows how sex hormones aren’t the only influence on behaviour

Question 14

Give evaluation for the role of chromosomes and hormones (reductionist)

Answer 14

• Reducing behavior to the level of chromosomes and hormones means it ignores alternative explanations
• e.g. the cognitive approach would focus on the influence of thought processes (schemas), which isn’t adequately explained by the biological approach.
• In addition, the psychodynamic approach points to the importance of childhood experiences (interaction with the family) which isn’t acknowledged by the biological model.
• This shows that a behaviour, like gender, involves so many complex factors that biology may not accurately explain.

Question 15

Give evaluation for the role of chromosomes and hormones (real-world applications)

Answer 15

• In the past, surgery was the norm for intersex conditions (such as CAH) to make them more ‘normal’
• Now, the Intersex Society of North America recommends that babies with such conditions should be assigned a gender, but no surgery should be done until they make an informed decision.
• Furthermore, genetic testing enables certain individuals, like those with Turner’s syndrome, to be identified early. They can be given hormone supplement to help them develop secondary sexual characteristics and improve their health
• This shows how the implication for treatment as a result of psychological research can contribute to improving people’s lives