Alevel Biology Topic 4 Flashcards
What is biodiversity?
Compromises every form of life, the genes that give them their specific characteristics, and the ecosystem of which they are part.
- Biodiversity is threatened as never before due to human activity
What is endemism?
Species that is uniquely found in only one part of the world and most commonly found in isolated areas.
Species richness
Number of different species in a particular area or region
Species evenness
Considers each population size in a habitat
Heterozygosity index?
Measures the proportion of genes in heterozygous form:
Number of heterozygous/Total population size
Diversity Index?
Used to measure diversity at the species level:
N(N-1) / Sum of n(n-1)
N= Number of all organisms in all species total
n= Total number of organisms of each species
The higher the value of D, the greater the biodiversity. Allows for comparison between habitats
What is a niche?
The way in which the species exploits it’s envoirnment and the role of an organism in its envoirnment. They become adapted to their environment by the process of natural selection.
What are the three forms of adaptations?
Behavioral: A change in behavior of an animal to increase the chance of survival e.g the use of tools to hunt for prey
Physiological: Changes in the internal biochemical functioning of the organism in response to environmental stimulus. E.g changes in metabolic rate for different seasons
Anatomical: Physical or structural adaptations. E.g Cactus plants have spines
How does natural selection lead to evolution?
- Natural occurring variation due to a mutation in alleles
- A change in environment results in a change in selection pressure
- Mutated allele may now be more favorable
- organisms will this allele are more likely to survive, reproduce and maybe pass it on to the next generation.
- Allele frequency increase over many generations
Evolution and rise of a different species
The change in allele frequency over time. In order for a new species to form, existing population must be reproductively isolated.
Hardy wienberg equation
P2 + 2PQ + Q2 = 1
Used to detect changes in allele frequency in a population. Cannot be used if there is a selection pressure, nonrandom mating, mutations, not if the population is small, no movement of organisms .
Speciation
Formation of a different species through reproductive isolation
What factors affect speciation?
Geographical ( Rivers or mountains)
Ecological (Preferences for habitats)
Seasonal (Mating times)
Mechanical (Changes in reproductive organ)
What is the order of classification?
-Three domain system
-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species
What are the three domains?
Bacteria, Archaea, Eukaryotes
What are the Kingdoms?
-Animalia
-Pantae
-Fungi
-Protoctista
-Prokaryotes
Define species
A group of organisms with similar morphology, physiology, and behavior, which can interbreed to produce fertile offspring, and which are reproductively isolated from other species.
What is molecular phylogeny and how does it change how we classify things?
It’s the analysis of genetic material to establish evolutionary relationships between organisms. The way in which we classify organisms is constantly changing, and this modern DNA analysis allows us to show relationships between organisms that have not yet been apparent.
The case for three domains
-For a long time, it was just accepted that life was either prokaryotes and eukaryotes
-Using molecular Phylogeny, a scientist named Woese found that bacteria (Prokaryotes) and eukaryotes has similarities and presented a new taxonomic group: three domain system called Archaea.
How is idea and evidence critically evaluated?
To ensure reliability and validity three keys aspect have to be ensured: Peer review, scientific conferences, dedicated scientific journals.
Before any research is published in must go under peer review where other scientists in the same area of work question is validity, significance, and originality. Then the paper can be published and speeches can be delivered at conferences. Scientists may also repeat the experiment to test for validity
All plant cells include the structures in animal cells except…
Centrioles
What features can be seen in a plant cell but not an animal cell?
Chloroplasts - Site of photosynthesis
Vacuole - Storage of water and minerals
Tonoplasts - The membrane round the vacuole ton control movement
Cell wall - For strength and support, and protection
Amyloplasts - To store starch
Middle lamella - To stick cells together
Plasmodesma and pits - To allow communication between one cell and other by allowing the connection of cytoplasm
What is the sugar polymer found in plant cells?
Cellulose
Explain the formation of cellulose and microfibrils? (+Diagram)
-B-Glucose vs A-Glucose
-Flipped over
-Glycosidic bonds
-Straight chain
—————-
-Hydrogen bonds between cellulose chains
