Chromosomes and hormones

• What topic is the video going to cover?

  Biology’s role in sex and gender development
• According to the video, are masculinity and femininity solely determined by hormone levels?

  The video explores this relationship, asking whether this is true
• What are the two atypical chromosome combinations mentioned in the introduction?

  XXY and X
• What two biological aspects are considered to play a role in sex and gender?

  Chromosomes and hormones
• How are chromosomes and hormones connected?

  Genes code for hormone levels
• How many chromosomes do most people have?

  46
• How are chromosomes arranged?

  In 23 pairs
• Where are chromosomes located?

  In the nucleus of cells
• What do chromosomes contain?

  DNA
• What information do chromosomes hold?

  Genetic information, genotypes
• What do genotypes code for?

  Physical and behavioural characteristics (phenotypes)
• What chromosomal combination is typically biologically female?

  XX
• What chromosomal combination is typically biologically male?

  XY
• What triggers testes development in males?

  Sex-determining region on the Y chromosome
• What do testes produce?

  High levels of testosterone
• What do genetic differences between biologically male and female chromosomes create?

  Hormonal and neural differences
• What are hormones?

  Biochemical messengers in the bloodstream
• How do organs respond to hormones?

  By altering their function
• What is testosterone known as?

  An androgen, a male sex hormone
• How do testosterone levels differ between males and females?

  Females have about ten times less
• What gene triggers testis development at seven weeks?

  SRY gene
• What does the SRY gene prevent?

  Development of ovaries
• What are secondary sexual characteristics in males?

  Larger muscles
• What behavioral traits is testosterone thought to be linked to?

  Aggression and competition
• What is the female sex hormone?

  Oestrogen
• What is one role of oestrogen in sex?

  Regulation of the menstrual cycle
• What is one role of oestrogen in sex?

  Development of female secondary sexual characteristics
• What behavioural traits is oestrogen thought to influence?

  Irritability and cooperative behaviour
• Which hormone is generally produced in higher quantities in females?

  Oxytocin
• What does oxytocin stimulate in females?

  Lactation
• What feelings is oxytocin thought to produce?

  Caring and attachment
• What is considered atypical gender development?

  Gender identity not matching sex assigned at birth
• What purpose do caring and attachment feelings serve?

  Caring behaviours towards infants and attachment in couples
• What sample size did Van Beijsterveldt use in their twin study?

  Over 8000 twin pairs
• Where was Van Beijsterveldt's twin study conducted?

  The Netherlands
• What were the two types of twins in Van Beijsterveldt's study?

  Dizygotic and monozygotic
• What percentage of variance in gender identity was accounted for by genetic differences in Van Beijsterveldt's study?

  70%
• What does Van Beijsterveldt's study support?

  Gender is heritable
• What did Van Beijsterveldt find regarding girls with female co-twins?

  They were more likely to show cross gender behaviour
• What theory does Van Beijsterveldt's finding contradict?

  Social learning theory