2.4 Variation and Evolution Flashcards
What is the difference between continuous and discontinuous variation?
Continuous- Something that can be measured
Discontinuous- Something that can be placed into categories
What is inherited variations (heritable) and what are environmental variations (non-heritable) ?
Inherited variations are things that you have from birth like eye colour, hair colour etc. Whereas, environmental factors that can change your phenotype include accent, hair dye, scars, tan etc.
What is a genotype?
The collection of alleles that determine characteristics and can be expressed as a phenotype.
What is a phenotype?
The visible characteristics of an organism which occur as a result of its genes
What are alleles?
Different variations of the same gene- eg different shaped ears, eye colours ect.
Explain homozygous dominant in terms of letters
AA
Explain homozygous recessive in terms of letters
aa
Explain heterozygous in terms of letters
Aa
Who were the two scientists who proposed the theory of natural selection?
Charles Darwin and Alfred Russel Wallace
What are the three words that best describe natural selection and what do they mean? (Describe the process of natural selection)
Variation, Competition and Selection
Variation- Individual organisms will have different genetic variations due to fluke mutations.
Competition- Sometimes, these random mutations will happen to be beneficial to the organism and help it to survive longer than other competition in the same species.
Selection - The longer an organism can survive, the higher the chance of it breeding and passing on their beneficial genes to offspring.
Over generations, these genes will pass onto the rest of the species and the species as a whole will become more adapted to its environment- they have evolved.
What are ‘superbugs’?
They are bacteria that have adapted to become resistant to anti-biotics.
Why is it that bacteria can evolve so quickly?
They reproduce very quickly (every 20 minutes) which results in the formation of many generations in a very short time.
It also increases the rate of mutation and natural selection.
What is gene therapy and what are the two treatments?
When faulty alleles/ DNA are replaced with normal Alleles/DNA.
The use of a section of DNA containing the normal allele/s as a way to treat genetic diseases like cystic fibrosis.
It’s the use of messenger RNA/DNA or vectors that are specialized viruses that sneak into body cells and fix the DNA makeup.
What are some of the ethical issues of gene therapy?
- Some religious groups believe we shouldn’t tamper or alter the genes of a living organism. (“Because god made us the way we should be”)
- The process is very expensive and time consuming and could take funding away from other types of health care that could help more people.
- This process could give the patient false hope of becoming healthy again when only 3.7% of cases were success full in 2015
What is genetic screening?
This is the process of looking at the genetic code in the DNA of a cell to identify abnormal genes/ alleles. A test is usually carried out before birth.
