A3.1 Diversity of Organisms Flashcards
(15 cards)
Define variation
Differences between organisms
Things that can vary: visual appearance, behaviour, biochemistry
Define species (morphologically)
A group of organisms with shared traits based on morphology and external features.
How does the binomial naming system work?
Genus species
- Genus: initial capital letter
- Species: lowercase
What is the biological species concept?
A biological species is a group of organisms that can interbreed to produce fertile offspring.
What are limitations of the biological species concept?
- Does not apply to organisms that reproduce asexually all or most of the time (eg. prokaryotes).
- Does not apply to extinct organisms
- Does not account for animals of different species that breed together and produce fertile offspring.
Define speciation
When the splitting of one species results in two or more new species.
What causes speciation?
- When a population becomes isolated from other populations of the same species due to living in a different area
- If the environmental conditions affecting each population are different, then NATURAL SELECTION can lead to speciation.
- Random changes in allele frequencies in a population due to chance ( genetic drift) can also lead to speciation
Why is it difficult to distinguish between populations and species?
- The ability of two populations to interbreed successfully declines gradually hence, it is difficult to pinpoint the stage at which two separate populations have become two new species.
- Therefore, the decision as to when to assign separate species status to two populations can therefore seem arbitrary.
Why do diploid cells always have an EVEN number of chromosomes?
Because it must always be divisible by two to produce a whole haploid number.
How many chromosomes do humans and chimpanzees have?
Humans: 46
Chimpanzees: 48
What is a karyogram?
An image that shows all of the chromosomes in a cell arranged by size, shape and banding pattern, and placed with their homologous pairs.
What is a karyotype?
The appearance of a complete set of an individual’s chromosomes, including their number, size, shape, and banding
(basically what is being shown in a karyogram)
How were the extra chromosomes in humans lost during evolution? (clue: hypothesis)
Chromosomes in pairs 12 and 13 in a common ancestor fused to form the human pair in chromosome 2.
Define genome
- All of the genetic information in an organism
– Genome size is determined by total amount of DNA.
– Vary in base sequence.
– Variation between species is much larger than variation within a species.
What are current and potential future uses of human genome sequencing?
- Continuously advancing to become faster and cheaper
- Current use: research into evolutionary relationships
- Future use: personalised medicine
