1. The Biological explanation of gender

2. Lesson Objectives By the end of this lesson you will understand:
Typical sex chromosome patterns
Atypical sex chromosome patterns
Dabbs et al (1995)

3. Biological explanations
Biopsychologists assume that all gender differences are totally attributed to chromosomal differences, differences in brain structure & function and differences in hormonal activity.

4. Biological explanations
The normal human
body contains 23 pairs
of chromosomes.
Each pair of
chromosomes
carries genes that
control different
characteristics.
Biological sex is
determined by the
23rd pair. So females
have the genotype XX
and males the
genotype XY.

5. Atypical sex-chromosomes
Any combination of sex chromosomes other than XX or XY is seen as atypical.
Klinefelter’s and Turner’s syndrome are examples of conditions which result from atypical sex chromosome conditions.

6. Klinefelter Syndrome

7. Turner syndrome

8. Klinefelter Syndrome (XXY)
Atypcial Chromosomes
Klinefelter Syndrome (XXY)
Caused by the presence of an extra X chromosome
Biological male with a physical appearance of male
Affects between 1 in 500 and 1 in 1000 males
Psychological effects: poor language skills – which affects reading ability, passive temperament
Physical effects: less body hair than normal male, underdeveloped genitals, long legs in relation to torso, infertile
Turner Syndrome (XO)
Caused by the absence of an X chromosome
Biological female with the female external appearance
Affects 1 in 2500
Psychological effects; higher than average reading ability; lower than average spatial ability, visual memory and mathematical skills; difficulty is social adjustment
Physical effects; ovaries fail to develop, short squat body with webbed neck

9. Atypical Chromosomes
What does studying people with atypical sex chromosome patterns allow us to conclude what about gender?

10. Imperato mc Ginley et al (1979)
Atypical Chromosomes
It provides evidence that our biological makeup is responsible for gender-related behaviour.
For example, by comparing someone with typical chromosomes to someone with atypical chromosomes you can make clear comparisons what aspects of their behaviour have a genetic cause.
Studies to support:
Imperato mc Ginley et al (1979)
Money and Erhardt (1972)

11. Chromosomes Give the typical sex chromosome pattern for the following:
a male
a female
(2 marks)

12. Exam questions
Q. Identify one atypical sex chromosome pattern and outline how it might affect an individual.
(3 marks)

13. Past papers
Victoria is five years old and she is different from other girls of her age.
She is smaller in height and has a webbed neck. At school, her
teachers have commented that she has good verbal skills but her
mathematical skills are poor. Medical tests have revealed that Victoria
has a sex chromosome pattern XO.
Name the atypical sex chromosome syndrome described above.
(1 mark)
Q. Identify how Victoria’s sex chromosome pattern differs from that of most girls. (1 mark)
Explain how studying people like Victoria can contribute to our understanding Of gender.
(2 marks)

14. Summary What three things have you learned today….
Q Name one sex hormone and give an example of how this hormone might affect a person’s behaviour. (2 marks)
Discuss biological explanations of gender development. Refer to at least one study in your answer. (10 marks)

15. Study to support Dabbs et al (1995)
Aim: Researchers wanted to see if there was an association between prisoners’ behaviour, the types of crimes they had committed and their testosterone levels.
Method Saliva samples from 692 male offenders were used to measure for testosterone levels. The prisoners records were then coded by crimes committed and whether they followed prison rules.
Result They found that men with higher levels of testosterone were more likely to have carried out violent and sexual offences and were also more likely to have broken prison rules than men with lower testosterone levels.
Conclusion It was concluded that testosterone causes heightened arousal and aggressive behaviour