Variation And Evolution Flashcards
(12 cards)
Variation
Differences between the members of same species
Types of variation
1
Acquired variation
-not genetically controlled
-learned or developed during life
-eg ability to walk
Types of variation
2
Inherited variation
-passed from parents to offspring using genes
-controlled by genes
-eg eye hair colour
Mutation
Change in the amount or structure of dna
Can occur anywhere on chromosome
Mutagens
Agents that cause mutations
Eg radiation and tabocco smoke
Types of mutation
1 gene mutation
-gene point or mutation are changes in a simple gene
-caused by changes in a single base pair
Eg haemophilia sickle cell anaemia
Sickle cell anaemia
Is inherited blood disorder caused by mutations in the haemoglobin gene
Produces incorrect amino acid -forms insoluble form of haemoglobin caused red blood cells to take curved shape
Symptoms - paleness weakness
Treatment - bone marrow transplant and blood transfusions
Cure - no cure
Types of mutations
2
Chromosome mutation
Large changes in structure or number of one or more chromosomes
Normally humans have 46 chromosomes in each somatic cell
Eg Down syndrome
Down syndrome
Caused by presence of extra chromosome
Physical and mental changes arise due to extra chromosome
More common in children born to older woman
Evolution
Genetic chnages in population in response to environmental changes
Charles Darwin and Alfred Wallace formed theories based on concepts of evolution eg theory of natural selection
Theory of natural selection
-high reproductive rates ; large numbers of offspring leads to competition for scarce resciurces
-organisms that have variations that enable them to adapt better to their environment are more likely to survive and reproduce
-populations become adapted to their environment with survive and reproduce
-less adapted die out
Evidence of evolution
Fossils - structure changes over time
