Chromosomes & Hormones

Question 1

Role of Chromos

Answer 1

1) Chromosomes are made from DNA - genes are short sections of DNA.
2) Humans have 23 pairs of chromos - 23rd pair determines biological sex.
3) Under a microscope these chromosomes are either X or Y shape. Female sex chromos are XX and male are XY.
4) A baby’s sex is determined by whether the sperm that fertilises the egg is an X or a Y chromosome.

Question 2

Y Chromosome - SRY gene

Answer 2

The Y chromosome carries a gene called the sex-determining region Y (SRY). This causes androgens to be produced in a male embryo.

Question 3

Gender Development Governed by Hormones

Answer 3

1) Prenatally hormones act upon brain development & cause development of the reproductive organs.
2) At puberty a burst of hormonal activity triggers secondary sexual characteristics e.g. pubic hair.
3) Males and females produce the same hormones but in different concentrations.

Question 4

Sexual Differentiation - Male

Answer 4

1) Before 6 weeks, embryo is female.
2) After 6w, window for sexual differentiation opens.
3) If sperm that fertilises egg has Y chromo it stimulates body to produce androgens —> embryo develops along ‘male path’.

XY —> Androgens —> Dev of Testes —> Testosterone —> Dev of Penis; Changes to Brain

Question 5

Sexual Differentiation - Female

Answer 5

1) If a sperm with an X chromosome fertilises the egg then X chromosome will stimulate development of ovaries.

XX —> Dev of Ovaries —> Oestrogen —> Uterus & Vag; Changes to Brain

Question 6

Testosterone

Answer 6

Key Role in Male Development and Aggression

1) Testosterone controls the development of male sex organs before birth.
2) If a genetic male produces no testosterone, then no male sex organs appear.
3) If a genetic female produces high levels of testosterone then male sex organs may appear.
4) High levels of testosterone are linked to aggression because such behaviour is adaptive for males, e.g. for competing with other males to mate with a fertile female and also for hunting (while females tend children).
5) ~ 95%. produced in testes, rest from adrenal glands
- Has anabolic (musile building) effects bath and androgenic (masculinizing) effects
- Anabolic steroids used medically to treat male patients with Iow testosterone asw as muscle- wasting diseases.

Question 7

Oestrogen

Answer 7

Key Role in Female Development and Behaviour

1) Oestrogen controls female sexual characteristics including menstruation.
2) During the menstrual cycle some women experience heightened emotionality and irritability - premenstrual tension or premenstrual syndrome (a diagnosable disorder).
3) In extreme cases PMS has been used (controversially) as a defence for violent behaviour in women.

Question 8

Oxytocin

Answer 8

Implicated in Lactating and Bonding

1) Women typically produce oxytocin in larger amounts than men.
- Stimulates lactation post-birth.
- Reduces the stress hormone cortisol.
- Facilitates bonding.
- May explain why females are more interested in intimacy in relationships than men - though amounts are the same in men and women when kissing & during sex.

Question 9

Strength of Role of Testosterone

Answer 9

RESEARCH SUPPORT

1) Wang et al. (2000) gave 227 hypogonadal men (men with low levels of testosterone) testosterone therapy for 180 days.
2) Testosterone replacement improved sexual function, libido and mood, and significantly increased muscle strength in the sample.
—> Study suggests testosterone exerts powerful and direct influence on male sexual & physician behaviour even in adult males.

Question 10

Limitation of Biological Accounts

Answer 10

BIOLOGICAL ACCOUNTS IGNORE SOCIAL FACTORS

1) Hofstede et al. (2010)
claim that gender roles are more about social factors than biology.
2) Countries that value competition and independence above community (individualist cultures), e.g. US and UK, are more masculine, and masculine traits more valued than in collectivist cultures.
—> This challenges biological explanations of gender behaviour and suggests social factors may ultimately be more important in shaping gender behaviour and attitudes.

Question 11

Limitation of Bio Explanations

Answer 11

REDUCTIONIST

1) Accounts that reduce gender to the level of chromosomes and hormones exclude alternative explanations.
2) Cognitive explanations include the influence of, for example, schema. Psychodynamic explanations include the importance of childhood experiences.
—> suggests gender is more complex than its biological influences alone.