10.5 Types Of Variation

Question 1

Types of Variation

Answer 1

Interspecific - widest type; between different species. E.g. a mouse has 4 legs and teeth, a bird has 2 legs and a beak.

Intraspecific - different between organisms in the same species. Humans vary in height, weight, hair colour etc.

Question 2

Causes of Variation

Answer 2

1. an organisms genetic material - differences in genetic material an organism inherits from its parents leads to GENETIC VARIATION.
2. Environmental factors (where organism lives) causes ENVIRONMENTAL VARIATION.

Question 3

Genetic Causes of Variation

Answer 3

1. ALLELES - with a gene for a particular characteristic, different alleles produce different effects so individuals in a species popn. may inherit different alleles of a gene.
2. MUTATIONS - changes to DNA sequence and, therefore, to genes can lead to changes in the proteins that are coded for. These proteins can affect physical and metabolic characteristics; if a mutation occurs in somatic (body) cells, just the individual is affected but if it happens in the gametes, it will be passed on to offspring.
3. MEIOSIS - gametes are produced by meiosis in sexually reproducing organisms. The genetic material inherited form both parents is ‘mixed up’ by INDEPENDENT ASSORTMENT & CROSSING OVER’.
4. SEX - offspring received half from mum and half from dad leading to variation between generations and other offspring.
5. CHANCE - many different gametes are produced from the parental genome; it’s only by chance that a certain sperm fertilises and certain ovum (RANDOM FERILISATION).

Question 4

Environmental Causes

Answer 4

1. Affected by location (are they near sunlight)
   An example of a characteristic that is determined purely by environmental variation is scars on your body. They don’t have a genetic origin and can’t be inherited.

Question 5

Environmental and Genetic Causes

Answer 5

E.g. if you have tall parents, you’re likely to be tall, but if you have a poor diet, this could change your height/development.

E.g. skin colour is determined at birth but can change based on UV exposure.

As many characteristics are caused by a combination of both, it can be hard to determine what caused what, causing the ‘nature vs nurture’ argument.