Test Flashcards
(23 cards)
State the order of taxa from highest to lowest
Diddy kings play chess on fancy gold squares. Domain kingdom phylum class order family genus species
What are selectional pressures?
Environmental factors that affect the chances of survival of an organism
What are the two different types of selection?
Stabilising and directional
Describe stabilising selection.
Natural selection that keeps allele frequencies relatively constant over generations. Things stay as they are unless there is a change in the environment.
Give an example of stabilising selection.
Human birth weights
Describe directional selection.
Natural selection that produces a gradual change in allele frequencies over several generations, usually when there is a change in selection pressures or a new advantageous allele has appeared in the population
Give and explain an example of directional selection.
Antibiotic strains of bacteria. The presence of antibiotics is the selection pressure, and a mutation arises that confers antibiotic resistance (a beneficial allele). Bacteria with this allele are more likely to survive and reproduce and bacteria without this allele are more likely to die. Over generations, this leads to an increase in the frequency of the beneficial allele that produces antibiotic resistance
Describe the phylogenetic classification system of taxonomy. (2 marks)
A hierarchy of groups with no overlaps
Grouped according to evolutionary relationships
Two organisms belong to the same species if…
They can produce fertile offspring
List the four ways that courtship behaviour helps achieve the maximum chance of survival.
- Recognising members of their own species
- Identifying a mate that is capable of breeding
- Synchronise mating
- Becoming able to breed/ pair bonding
What are binomials?
The scientific name of a species
Outline how to write in binomials
The organisms genus name, then species name (in Latin). The genus name should begin with a capital letter, and species with a lowercase letter. When hand written, the whole thing should be underlined.
What is genetic isolation?
Two populations of the same species become separated from each other and therefore are no longer reproducing with each other, so do not exchange genes in the production of offspring. They evolve independently of each other which leads to two groups that are unable to interbreed.
What is genetic diversity?
The number of different alleles of genes
Give the 4 ways of measuring genetic diversity.
-measurable characteristics
-the nucleotide base sequence of DNA
-the nucleotide base sequence of mRNA
-the amino acid sequence of proteins
State some measurable and observable characteristics
Number of legs, number of seeds
Colour, fur patterns, habitat
Evaluate using measurable and observable characteristics to determine genetic diversity.
Strengths: quick, can be useful if a species has unique features
Weaknesses: unreliable and genetic differences between individuals can only be implied
Describe the process of DNA extraction when investigating genetic diversity.
DNA is extracted from the nuclei of cells and is processed, analysed and the base sequence is obtained and compared to other organisms. The more similar base sequences, the more closely related the species
Evaluate using DNA analysis and comparison when investigating genetic diversity.
Strengths: most accurate method
Weaknesses: hard to extract and can be misleading due to introns
Describe mRNA analysis and comparison.
mRNA can be used to produce cDNA, and this strand of cDNA is used to produce a second cDNA strand which is the same as the coding strand but without introns
Evaluate mRNA analysis and comparison
Strengths: easier to isolate from cells than DNA as it is located in the cytoplasm, multiple copies of the same mRNA, no introns
Describe the procedure of amino acid sequence analysis and comparison
The sequence of amino acids of the same protein can be compared between individuals.
Evaluate amino acid sequence analysis and comparison.
Strengths: proteins are easier to isolate from the cells than DNA
Weaknesses: the protein used must be present in all individuals being compared. Amino acid sequences evolve much slower than DNA so it’s likely that closely related species will have the same amino acid sequence even though the species split from their ancestors millions of years ago.
