Variation Flashcards
What are the advantages of asexual reproduction?
Only on parent needed
More time and energy efficient as no mate is needed
Faster than sexual reproduction
Many identical offspring can be produced if conditions are favorable
What are the advantages of sexual reproduction?
Produces variation in the offspring
If environmental change occurs, variation provides species with a survival advantage by natural selection
Natural selection can be sped up in selective breeding to increase food production
What organisms produce via both asexual and sexual reproduction?
Malaria parasites: asexual in human host, sexual in mosquito
Fungi: asexual via spores, sexual to produce variation
Plants: seeds made sexually, runners and bulb division are asexual
What is the difference between meiosis and mitosis?
Mitosis forms two genetically identical daughter cells whereas meiosis forms four not genetically identical cells
What does sexual reproduction involve?
The fusion of male and female gametes; egg and sperm in animals and an egg and pollen in plants.
What are the features of sexual reproduction?
Two parents
Fusion of gametes
Mixing of genetic information
Results in Variation
Involves Meiosis and Mitosis
What are the features of asexual reproduction?
One parent
No fusion of gametes
No mixing of genetic information
No variation
Involves ONLY Mitosis
What happens with the number of chromosomes in reproduction?
Meiosis forms gametes with half the number of chromosomes of normal cells and during fertilization two gametes fuse and return to having the full number of chromosomes.
What two things cause differences in the characteristics of individuals in a species?
Genes and Environment
How does genetic variation occur?
Via genetic mutation and this can be extensive
What is the impact of a mutation on a phenotype?
Most commonly it has no impact
Few times it can influence the phenotype
Rarely it can determine the phenotype
What happens if a mutation determines the phenotype?
If this change in the phenotype provides a species with a better chance for survival due to an environmental change it can lead to a relatively rapid change in species
What is evolution?
The change in inherited characteristics of a population over time through the process of natural selection which may result in the formation of a new species
What does the theory of evolution via natural selection state?
That all species of living things have evolved from simple life forms that first developed more than three billion years ago.
What leads to evolution?
Natural Selection of variants that gives rise to phenotypes best suited to their environment
What is speciation?
When species become especially different in phenotype they can no longer reproduce together to form fertile offspring forming two separate species.
What book was published by Charles Darwin?
On the Origin of Species 1859 containing Darwin’s theory of evolution via natural selection.
What was Darwin’s evidence for evolution via natural selection?
Observations from around the world
Years of experimentation
Developing knowledge of geology and fossils
What is the theory of evolution via natural selection?
- Individual organisms within a particular species show a variation for a characteristic
- Individuals with the characteristic are most suited to the environment are more likely to survive and breed successfully
- The characteristic that enabled these individuals to survive are then passed on to the next generation
Why was Darwin’s theory of evolution only gradually accepted?
- Theory challenged the idea that God created all the animals and plants on Earth
- There was insufficient evidence at the time to convince many scientists
- The mechanism of inheritance and variation was not known until 50 years later
What was John Baptiste Lamarck’s theory?
Based on the idea that changes that occur in an organism during its lifetime can be inherited.
What was discovered about Lamarck’s theory?
In the vast majority of evolution cases this is not correct
Who proposed the theory of evolution via natural selection independently to Darwin?
Alfred Wallace, in 1858
What are the two modern day pieces of evidence evolution via natural selection?
Fossil Records and Antibiotic Resistant Bacteria
Why is Darwin’s theory of evolution now widely accepted?
Now proven that characteristics are transferred via genes
What is extinction?
When there are no remaining individuals of a species still alive
What are the reasons for extinction?
New predators
Competition for food
Environment change
New diseases
What are fossils?
The ancient remains of organisms from millions of years ago which are found in rocks
