Evolution Flashcards
Define evolution
The change in characteristics of a population over several generations
Define variation
The differences within a population of organisms
Define independent assortment
The process by which chromosomes are randomly separated before the cell splits in meiotic division
Define recombination
An event in which two homologous chromosomes ‘swap’ sections with one another in meiosis
Define selection pressure
A factor that will impact an organisms ability to survive or reproduce
Define abiotic
Non-living
Define biotic
Living
Define natural selection
Survival of the fittest or the process in which organisms with favorable characteristics have better chance of surviving in a particular environment than others
Define fitness
How well suited an organism is to survive and reproduce in its environment or an organisms ability go survive
Define artificial selection
The process in which organisms with desirable characteristics are selectively bred
Define adaptation
A characteristic or trait that helps an organism survive
Define progeny/or offspring
Descendants or children
Define mutation
A change in the sequence or type of DNA bases in a gene
Define phenotype
The physical appearance of an organism or a characteristic that is expressed
Define genotype
The pair of alleles an organism has, for example Gg or gg
Define speciation
The evolutionary process by which populations evolve into a distinct species
Define organism
A living thing
Define gene pool
All of the genes in a population of organisms
Define population
All of the organisms of a particular species living in the same place
Define competition
Organisms fighting over a resource eg food/place / water or a mate
Define meiosis
Cell division of gametes (sperm and ova) that produces 4 genetically different haploid cells
Natural selection can only occur if:
- Variability
- Trait of interest must be inheritable (heritable)
- Trait convers advantage (adaptive)
There has to be —- for evolution to occur
Variation
3 things that lead to variation
- Independent assortment - random chromosome assortment in cell during meiosis
- Genetic recombination - an event in which 2 homologous chromosomes ‘ swap’ sections with one another during meiosis
- Mutations - A change in the sequence or type of DNA bases in a gene which leads to different proteins
All of which leads to genetic diversity
What causes mutations?
Errors in DNA replication or from the damaging effects of mutagens, such as radiation and carcinogens and gene editing
Describe the process in which identical twins are formed
One fertilised egg (ovum) splits and develops into two babies with exactly the same genetic information
Define epigenetics and how they can make identical twins different
When environment plays a role in expression of DNA. May trigger different genes. E.g cold or hot environment. For example, if a twin were to grow up in a cold environment they may look different from their twin who grew up in a hot environment.
Draw a diagram on how identical twins are formed during meiosis
Check book for diagram
Define homologous structures
Related species with the same basic structure and genetics
Through a shared ancestor
For example, cats and lions both have similar paw structures and they share an ancestor
Define analogous structures
Not similar genetically but similar structures due to similar environment
E.g dolphins and sharks
Methods of artificial selection
Cross breeding desirable traits
Interbreeding
Examples of selective pressures
Predators
Environmental conditions
Availability of food
Diseases
Process of speciation in 3 words
- Variation
- Isolation
- Selection
Explain how mutations can be advantageous
Mutations can alter genes which can result in advantageous traits to be produced
For example, white fur for bears was a result of a mutation which advantageous helping polar bears blend into the snow
Explain the difference between natural selection and evolution
Natural selection is when individual species have a higher level of fitness, bettering the chances of surviving to pass on their genes
Evolution is when inherited traits of a population change over many generations
2 types of gene selection:
Natural and artificial selection
Result of gene selection
Specific DNA sequence becomes more prevalent via gene selection
Artificial selection benefits
Think about GM foods and things humans have genetically modified
Selection of preferred genes (traits)
Can make food more nutritious– higher levels of vitamins such as vitamin-A
Making crops, cotton pest, disease resistant
Making foods bigger proportions
Artificial selection issues/ concerns
Inbreeding - increases the risk of recessive gene diseases and disorders since closely related organisms are more likely to carry a copy of the same recessive gene.
Cloning process via somatic cell nuclear transfer
Donor cells planted into surrogate mother’s egg
Nucleus from somatic cells transferred to the cytoplasm of an enucleated egg - egg becomes zygote (fertilised)
Cloning benefits
Prevents extinction of endangered animals
Aids the replacement of organs
Increase agricultural production
Enables same-gender couples to have offspring
Can solve infertility
Cloning cons
Reduced genetic diversity
If there were genes which coded for diseases it’ll be passed onto the offspring
Ethical concerns - “playing God “
identity fraud
Which is better: pure bred or mut
Mut because they are genetically healthier
Gm food concerns
Can be cross bred with wild plants for example, a pest resistant crop was cross bred with a wild plant the offspring of the wild plant would be also pest resistant
Gene transfer
Concerns about potential allergies
Define recombining genes
Selected gene from one organism placed into another organism
Human gene therapy pros
Modifies genes to treat, cure diseases or issues - modified to carry therapeutic genes
Potential to cure or treat genetic issues or diseases
Gene therapy issues/ concerns
Unwanted immune system reaction- immune system may see the newly introduced viruses as intruders and attack them
Introduction to wrong cell-chance of a tumor formation
Potential allergic reaction
