Unit 2: The Biological Approach


The Central Nervous System

The central nervous system (CNS) consists of two main parts: the brain and the spinal cord. Nerves in our body send information via the spinal cord to the brain, which the brain then processes, sending a message to the body through the spinal cord.

Genetics & Behvaiour

Describe the role of genes in sex assignment. (4 marks)

Most human cells have 23 pairs of chromosomes, but in sperm and egg cells the 23 chromosomes are unpaired and are paired up to form a new organism. A male baby gets an X chromosome from the mother and a Y from the father and a female baby has two X chromosomes. Genes are a blueprint and set certain actions in motion in the individual so this difference in the sex chromosomes (females having XX and males having XY) makes a difference as the foetus develops. A main difference is the secretion of hormones. Studies of mice show that there are 54 genes where activity levels vary according to gender — and this is what is known now. A male foetus has one of the X chromosomes turned off and you can think of a new organism as female until becoming male — female is the basic form. Genes trigger certain processes through RNA and proteins.

Hormones & Gender

Brain Lateralisation

Generally, it is thought that females tend to use both sides of the brain equally, and males seem to use the right side of the brain more. This is because it is said that the corpus callosum (a large network of fibres connecting the two hemispheres) is larger in female brains.

Because males use one size more efficiently than the other, male brains are said to be lateralised. Brain lateralisation occurs in males, and not females. This is one difference between male and female brains.

There is also said to be a gender difference in visuospatial ability. Visuospatial tasks require the use of the right hemisphere, which is the one that male brains are thought to have preference towards. Studies have shown that males do use this side more than the left, a quality females do not share. This means that generally males should be better at visuospatial tasks and maths.

Nature vs Nurture

We say that what we inherit is the ‘nature’ aspect, and that which is learned from the environment is ‘nurture’. Nature concerns the influence of genes, among other biological structures, on an individual. This includes the effects of neurotransmitter functioning, brain structure and function, genetic makeup and other similar biological structures.

Nurture is more concerned with environment, so anything other than the biological aspects. This includes the style and environment of upbringing and growing up, schooling experience, social influences, position within a family and other similar issues.

Brain Scanning Techniques

Twin & Adoption Studies

Animal Studies

Cost-Benefit Analysis

It is said that a decision cube should be used to see whether a study should be carried out or not. It weighs up the potential benefits from running the experiment, and measures them up against the costs of doing so. This is particularly important when deciding whether or not to do an animal study, as these are among the most controversial (ethically).

Key Study: Money (1975)

Key Study: Gottesman & Shields (1966)

Key Issue: Are Transgender Operations Ethical?

Comparing the Biological & Learning Approach to Gender

Hypotheses/Variables/Levels of Measurement

Inferential Statistics: Mann-Whitney U

You would use a Mann-Whitney U Test when you are/have...

1. Looking for a difference
2. At least ordinal data
An independent groups design

If you had a calculated value, could you interpret this table?

Biological Practical

Past Paper Questions