DIVERSITY Flashcards
State the 3 ways in which biological differences can be reflected
1) Large No. Of different species of organisms leading to genetic differences
2) Within a species, variation in individual characteristics
3) Cell differentiation in single multicellular organisms where different genes are expressed leading to different proteins produced
Explain why there is genetic diversity within a species
This is due to genetic factors. Also, environmental factors can influence variation in the characteristics shown by individuals within a single species
Name the 5 causes for genetic variation
1) Meiosis - Crossing over leading to different combinations of maternal + paternal alleles on a chromosome.
2) Meiosis - Independent segregation of homologous chromosomes. Leads to different combinations of maternal and paternal chromosomes in gametes
3) Random fertilisation of genetically different gametes. 2 gametes fuse at fertilisation at random and there is variation in the offspring
4) Gene Mutation - Change in DNA base sequence leading to different sequence of amino acids in polypeptide chain. different hydrogen, disulphide and ionic bonds will form and protein will have tertiary structure. This could lead to new feature in offspring
5) Chromosome Mutation - This non - disjunction can lead to different No. of chromosomes in the gametes produced in Meiosis
Environmental Factors also cause variation. In animals, this is diet and disease And in plants it could be light intensity and nutrient availability
State the definition of Genetic Diversity
The No. of Alleles in a population
Explain what Directional Selection is
This will occur in a changing environment. If a mutation leads to a some organisms having a favourable allele (favourable characteristic), these individual are more likely to survive. This feature will be more common and the unfavourable characteristic becomes rare; Antibiotic Resistance in Bacteria
Explain what stabilising selection is
This occurs in an unchanging environment. Selection is against individuals at both extremes of the characteristics (birth weight in humans)
State the definition of Species
A group of organisms with similar features that can interbreed to produce fertile offspring
State the definition of Taxonomy
The study of the principles of classification. Classification is a means of putting organisms into groups
What does hierarchical mean?
Small groups are placed into larger groups with no overlap between groups
What does phylogenetic mean?
The classification reflects the evolutionary relationships between the organisms
Name the 8 groups in the Classification system
Domain Kingdom Phylum Class Order Family Genus Species
How to calculate the name of an organism
2 part Latin name
The first word is the genus (Capital Letter). The second word is the species (lower case)
Give 4 reasons why Courtship Behaviour is important
- Allows recognition of same species
- Allows recognition of different gender
- Allows recognition of sexually mature individuals
- Stimulates sexual behaviour (mating), release of gametes
State 3 genetic comparisons to clarify relationships between organisms
- Comparison of DNA base sequence, more similar base sequence, the more closely related the species are
- Comparison of the mRNA base sequence (more similar = more closely related)
- DNA Hybridisation
State the way protein comparisons can be used to clarify relationships between organisms
Consider the aminos acid sequences of proteins. The more similar, the more closely related the species are. Always use same protein that is found in different organisms
State the way immunological comparison are used to clarify relationships between organisms
It compares variations in a specific protein that different species process. Used when amino acid sequence unknown
What is a community?
All the different species in the havitatq
How to measure biodiversity?
Simplest way = species richness = Count No. of different species present in a community
How do Farming Techniques affect Biodiversity?
Reduces species diversity. In agriculture, farmers may only grow one cell or keep one type of animal reducing species diversity. They may use herbicides (weedkiller) to kill weeds competing with crop. They may use pesticides (to kill pests/insects). If only one plant in area, reduces variety of food so fewer species will be found in the area.
How does Deforestation affect Biodiversity?
This is clearing of forests for conversion of the land for agriculture, housing, roads etc. No. of species will decrease; biodiversity decreases.
