Topic 4 Flashcards
What is a habitat?
- The place an organism lives
What is a species?
- A group of organisms which can interbreed to produce fertile offspring.
What is a population?
- A group of interbreeding individuals in an area
What is a community?
- All the populations within a habitat
What is a niche and what does it include?
- It is the way an organism exploits its environment.
- Includes interactions with other organisms and interactions with non living environment.
What is biodiversity?
- It is the variety of species in an area
What is species diversity?
- The number of species and number of individuals in a species within an area
What is genetic diversity?
- Measure of all alleles in the gene pool of a species
What can you look at to measure genetic diversity?
- Genotype, genetics of an organism
- Phenotype, observable characteristics of an organism
What is species richness?
- Refers to different number of species present in an area
What is species evenness?
- Measures the relative abundance of different species in an area
What is Simpsons biodiversity index?
- Quantitative measure of diversity in a habitat to give a comparable score.
- d = N(N - 1)/sum of n(n - 1)
- N = total number of all species, n = number of organisms in a species
What are polymorphic genes?
- Genes that exist in three or more different versions or alleles.
- Greater number of genes have greater genetic diversity.
What does the Heterozygosity Index measure?
- Genetic diversity within a species
What is the equation for the Heterozygosity Index?
H = no of heterozygous/number within population
What is a heterozygous?
- One with a different allele on each chromosome.
Where does genetic diversity come from?
- Mutations
- Random selection
- Meiosis
What are adaptations?
- They enhance survival in a habitat
What are anatomical adaptations?
- Change to structural features of an organism for survival
- eg. otter is streamlined to glide through water
What are behavioural adaptations?
- Actions and behaviour is modified for survival
- eg. earthworm burrows on vibrations to avoid predators
What are physiological adaptations?
- Changes to internal workings and processes for survival
- eg. stomata close during dry conditions to avoid water loss
What is evolution?
- A change in allele frequency over time
What is convergent evolution?
- Evolution in common traits between two phylogenetically distinct species due to similar selection pressures.
How does natural selection occur?
- New alleles created through mutation
- A selection pressure occurs in the environment
- Organisms with advantageous allele are more likely to survive, reproduce and produce offspring
- Their offspring are more likely to have the allele, so it becomes more common in the population
What is a gene pool?
- All the alleles of all the genes present in a population of a species.
What is the benefit of having a bigger gene pool?
- Having more genetic diversity.
- Possess alleles which allow them to survive.
What is the frequency of an allele?
- Proportion of individuals that have one copy of an allele
When do allele frequencies change?
- Change in response to selection pressures by natural selection.
What are the three types of genotypes?
- Homozygous dominant (FF)
- Heterozygous (Ff)
- Homozygous recessive (ff)
What is the Hardy Weinburg equation?
p^2 (freq of homozygous dominant) + 2pq (freq of heterozygous) + q^2 (freq of homozygous recessive) = 1
What are the assumptions of the Hardy Weinberg equation?
- Large population
- No mutations
- No natural selection
- Random mating
- Isolated population
What factors must be needed to adapt to new conditions?
- Strength of selection pressure
- Size of gene pool
- Reproductive rate
What is speciation?
- Formation of a new species from an existing one
What must happen for speciation to occur?
- Become reproductively isolated and unable to produce fertile offspring.
What is allopatric speciation?
- Isolation due to geographical isolation
- Eg. mountain range
What is sympatric speciation?
- Isolation due to reproductive isolation
- Eg. seasonal changes or behavioural changes
How does allopatric isolation lead to speciation?
- Isolation prevents individuals breeding with rest of population
- The two groups respond to different selection pressures which causes random mutations
- They then cannot interbreed to produce fertile offspring.
What is endemism?
- A species only found in one geographical location
What information should you collect for studies of biodiversity?
- Presence of endemic species
- Use of a diversity index
- Genetic diversity of populations
- Species richness
What is the order of the hierarchy of classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
What is phylogeny?
- The study of evolutionary relationships between organisms.
What is molecular phylogeny?
- Study of molecular differences in DNA of proteins to show evolutionary relationships
What are phylogenetic trees?
- Show the relationships between species
- Branches represent common ancestors and show relatedness.
What are the 3 domains?
- Eukaryote
- Archea
- Prokaryotes
What are the 5 kingdoms?
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
What does climate change cause in animals?
- Causes migration or death
- Creating low genetic diversity
What are the human impacts on the earth?
- Alters ecosystems
- Uses biological resources
- Mines resources eg. fossil fuels
What is the function of the plant cell wall?
- Made of cellulose and provides support for the cell
What is the function of the middle lamella?
- Sticks plant cells together to provide stability.
What is the function of the plasmodesmata?
- Narrow channels of cytoplasm between two plant cells to transport substances between them and communicate.
What is the function of a pit?
- Allows plant cells to exchange substances.
What is the function of chloroplasts?
- Where photosynthesis occurs.
What is the function of an amyloplast?
- Plant storage granules containing starch, which convert back to glucose when the plant needs it for respiration.
What is the function of the vacuole?
- Stores cell sap which keeps the cell turgid and to digest molecules
When is plant cell turgid or flaccid?
- When there is high water potential, water rushes into the cell but cell wall stops from bursting appearing turgid.
- When there is low water potential, water leaves the cell appearing flaccid.
What is cellulose?
- Unbranched polysaccharide
- Long chain of beta-glucose with 1,4 glycosidic bonds.
What is a microfibril?
- Bundle of cellulose chains formed by hydrogen bonds
- Beta glucose joined in condensation reaction
- Unbranched chain
What holds microfibrils together?
- Polysaccharides known as hemicelluloses and pectins
What is the xylem and how is it adapted for its function?
- Transport water and mineral ions from roots to plant.
- Dead, hollow cells, thickened with lignin.
- One continuous tube for transport
- Pits for movement in and out of cells.
What is the phloem and how is it adapted to it’s function?
- Transport organic solutes and sugars from where they are made (source) and where they are used (sinks)
- Sieve tube elements to transfer material between adjacent cells.
- Companion cells control transport of sap.
What is the sclerenchyma and how is it adapted to it’s function?
- Stiffened, hollow cells with lignin deposited in walls.
- Provide structure for the cells
Why are plant fibres so strong?
- Strong arrangement of microfibrils in mesh type pattern
- Secondary cell wall containing lignin
What is the transpiration stream?
- Constant movement of water from roots to leaves
- Water is pulled up as it evaporates out of the stomata due to tension of H bonds and cohesive forces
What is the cohesion-tension theory?
- Forces of water molecules movement through xylem (cohesion)
- Water adheres to lining of the walls (adhesion)
What is translocation?
- Movement of sugars through phloem
- Sugars are actively loaded into sieve tube + water potential source decreases
What is the process of active loading?
- Sucrose into sieve tube elements
- H+ ions pumped from companion cells to surrounding lead creating a diffusion gradient
- H+ ions diffusion back into companion cell with sucrose by cotransporter protein
- Sucrose diffuses into sieve tube elements
How are plant fibres useful for humans?
- Very strong for ropes and fibres
Why are plant fibres sustainable?
- Less fossil fuels
- Replanted for next generation
- Biodegradable
- Cheaper and easier to grow
What is lignin?
- Tough, waterproof substance which is found in xylem and sclerenchyma cell wall to provide strength
What is the cohesion-tension theory?
- Shows pulling forces of water molecules through xylem (cohesion)
- And water adhering to lining of the cell (adhesion)
What happens if plants don’t get nitrate ions?
- They can’t produce amino acids
- They become yellow (chlorosis)
What happens if plants don’t get magnesium ions?
- They have insufficient chlorophyll
- Leaves turn brown in patches
What happens if plants don’t get calcium ions?
- They have weakened cell walls and cell membranes
- Plant will have stunted growth
What are sources vs sinks?
- Sources load material into transport systems
- Sinks removes material from transport systems
What did Withering do?
- Tested fox glove leaves to cure heart and muscle problems.
- Made digitalis soup to test doses.
What is pre-clinical testing?
- Testing on cultures and then animals before humans.
What are the phases of drug testing?
- Phase I - healthy volunteers + low dose to see effectiveness and safe dosage
- Phase II - people who has the disease + uses a placebo to measure psychological effects
- Phase III - large groups of people + double blind trial where neither the patient nor doctor know who is receiving the treatment.
What is needed for bacterial growth?
- Ideal nutrients
- Optimum temperature
- Oxygen for aerobic respiration
What are the uses of starch?
- Extracted from plants to make bioplastics and biofuel
- It is absorbent so when rehydrated the particles take up water.
- Gelatinisation at high temperatures.
What is the roles of zoos?
- Captive breeding programmes
- Increase numbers within a species
- Maintain genetic diversity
- Reintroduce animals to the wild.
How is genetic variation lost?
- Genetic drift - allele may not be passed on
- Interbreeding depression - harmful alleles so less fit to survive
How is genetic diversity conserved?
- Through zoos, using stud books for interbreeding
- Through seed banks, testing germination
