Genetics Flashcards
What is biodiversity
variety of organisms in an ecosystem
What is species diversity
number of different species within an area
Benefits of high species diversity
- stable ecosystem
- each species is less likely to become extinct
How to measure species diversity for an area
- species diversity index
- considers the number of different species and how many individuals there are for each species
- larger species diversity index = larger species diversity
How does deforestation lower species diversity
- decreases plant species diversity
- less variety of habitats
- less variety of food sources
- decreases animal species diversity
How does agriculture/farming reduce species diversity
- deforestation to make space for farm
- selectively breed plants and animals
- use pesticides to kill other species
What is classification
placing organisms into groups
What is hierarchical classification
large groups divided into smaller groups without overlap
What is a species
a group of individuals with similar characteristics that can interbreed to produce fertile offspring
Why are the offspring from 2 different species infertile
offspring will have an odd number of chromosomes so can’t perform meiosis, so cant’t produce gametes
What is phylogenetic classification
species arranged into groups based on their evolutionary origins and relationships
What are 3 ways of comparing relationships between different species
- DNA hybridisation; comparing DNA base sequence
- A A sequence; comparing A A sequence for the same protein
- Protein shape; comparing shape of same protein using immunological technique
What is variation
difference in characteristics between organisms
Two types of variation
- intraspecific; differences between organisms of the same species
- interspecific; differences between organisms of different species
Causes of intraspecific variation
- genetic factors; same genes but different alleles
- environmental factors
Causes of interspecific variation
- genetic; different genes and different alleles
- environmental factors
Name two types of characteristics
- discontinuous
- continuous
Properties of discontinuous characteristics
characteristics fall into certain groups with no overlap based on genetics only
Properties of continuous characteristics
characteristics show a range determined by genetics and environment
What is genetic diversity
number of different alleles of genes in a population
Benefit of high genetic diversity
species able to adapt with changes in the environment
What can reduce genetic diversity
small population size
Describe the principles of natural selection
- random mutation can produce new alleles of a gene
- the new alleles may benefit the possessor, leading to an increased chance of survival and increased reproductive success
- the advantageous allele is passed onto the next generation
- over several generations, the new allele will increase in frequency in the population
Name 2 types of selection
- stabilising
- directional
What is stabilising selection
when the environment favours those with the most common characteristic, so those on the extreme die out; common characteristic increases in proportion