Topic 4 Flashcards
Species Richness
Number of Species in a habitat/community
Speciation
Two or more species emerge from a species
How does Evolution occur?
When two species are reproductively isolated , natural selection separates species
Biodiversity
The complexity of a biological community
Habitat
Area where an organisms lives
Factors which effect Biodiversity?
- Human Population Growth
- Agriculture
- Climate Change
Evolution
Causes Reproductively isolated populations to evolve in different directions
Monoculture
Practise where farmers grow only one crop species in field
Adaptation definition
traits that have been selected for because they help increase an organisms chance of survival
Example of Behavioural Adaptations
- Evolved to increase survival
- Can be learnt or inherited
Example of Anatomical Adaptations
-Physical Structures to increase survival
Example of Physiological Adaptations
-Processes within the body that have evolved
Natural Selection
-Process that leads to evolution in a population
Four Key principles of Natural Selection
- Random Mutation
- Variation in Mutations
- Inheritance
- Change in allele frequency
What is Random Mutation
- Changes in gene sequence of DNA
- Can arise spontaneously
- Result in alleles of a gene
What is Variations in Mutations
- Most mutations are harmful
- Alter function of a gene
- If you have a beneficial allele you can survive and reproduce
How does Inheritance effect Natural Selection
- Individual Reproduces
- inherit half its genes
- Advantageous allele also passed on
Biological Definition of a Species
-A population of organisms that can interbreed to produce fertile offspring
Taxa
-A group of closely related organisms
Whats is Taxa dependent on?
-Phylogeny of organisms (evolutionary)
What is the Hierarchy divided to for classification
- Smaller taxa
- Organisms can only belong to one taxa
7 Stages in Linnaean Hierarchy
- Kingdom
- Phylum
- Class
- Order
- Family
- Genius
- Species
3 Groups Woese concluded
Archaea - primitive bacteria
Bacteria - true bacteria
Eukaryota - organisms possessing sub-cellular structures
Chloroplasts function
-Carry out photosynthesis
Cellulose
-main component of plant and algal cell walls
Chitin
-main component of fungal walls
What is Xylem responsible for
-transporting water and mineral ions
Structure of a Xylem
- Long tubes of cells
- No end of tubes (continuous flow of water)
- Lignin - provides structural support
What are cells of xylem vessels called
-vessel elements (dead)
How does water flow up the Xylem
-Cohesion-Tension Theory
4 steps of the Cohesion-Tension Theory
1) Transpiration
2) Tension
3) Cohesion
4) Diffusion in roots
Xylem flow of water - Transpiration
- Water leaves leaves via transpiration
- Some leaves as used in respiration
Xylem flow of water - Tension
- Formation of hydrogen bonds between water molecules and side of vessel elements
- Due to loss of water via leaves
- Pulls water upto leaves
Xylem flow of water - Cohesion
-Individual water molecules form hydrogen bonds with eachother
Xylem flow of water - Diffusion in Roots
- When water pulled up stem
- Water potential decreases
- Diffuses via osmosis
- Creates conc. gradient
Steps in Water transport in Xylem?
1) Water evaporated from leaves - transpiration
2) Loss of water creates tension in xylem
3) Water pulled upwards via xylem
4) Water molecules form Hydrogen bonds via cohesion
5) Water pulled upwards via cohesion
6) Water diffuses through roots to replace water lost in bottom
