Biodiversity Flashcards
Gene pool
All of the alleles of all the genes in a population
Gene pool constant
Population is not evolving
Gene pool changing
There are selection pressures and population is evolving
Species
A class of similar organisms that can interbreed freely, producing fertile offspring
Morphologically similar
Look similar
Homologous chromosomes
Have the same genes in the same places (different alleles)
Karyotypes
The number and appearance or chromosomes in a cell nucleus
Ecosystem
An area in which organisms interact with each other and their environment
Community
Entire set of organisms which coexist in a particular ecosystem at a particular time
Environment
The physical and biotic surroundings
Population
The total number of individuals of a species within a community in a particular ecosystem at a particular time
Habitat
An area within an ecosystem in which a particular organism lives
Niche
The way an organism uses its environment and its role in the community
Fundamental niche
Largest niche an organism could occupy if there was no competition
Realised niche
The niche that is actually occupied by the organism
Adaptation
When an organism involves its behavioural, physiological, anatomical features for survival in their habitat
Behavioural adaptations
Actions that help an organism survive within a habitat eg penguins huddle
Physiological adaptations
Features of the cells, tissues, or systems in the body in order for an organism to suit its habitat for survival eh whales thick blubber warm
Anatomical adaptations
Visible, physical features that enable an organism to survive better in their habitat eg Arctic hare small ears lose less heat
Co-adaptation
Mutual benefit of two or more organisms as a result of a mutual survival adaptation
Microevolution
A change in allele frequency in a population over time (which results in a change behaviour, psyiology, and/or anatomy)
What three factors determine the ability of a population to adapt to environmental change?
- Strength of selection pressure
- size of the gene pool
- reproductive rate of organism
Why is it unlikely that a population would be perfectly adapted to their environment?
- Environments change continually
- There is always a selection pressure
- Time lag for populations (allele frequencies) to adapt
- mutations occur (alleles making populations less well adapted)
Why is it a problem to be perfectly adapted to an environment?
- Dependence on other species- vulnerable if other species die out
- Less likely to survive environmental change
How can a new species form? (Speciation)
- some individuals migrate to nearby islands
- reproductive isolation of island communities
- random mutations, some advantageous
- different selection pressures experienced on each islands
- some mutations are selected (in reproduction)
- the island species are no longer able to produce fertile offspring with mainland population
What causes allele frequencies to change?
Mutations Emigration/immigration Small populations (genetic drift) Non-random mating Natural selection
Gene flow
The movement of genes from one population to another
Genetic drift
Change in allele frequency that happens due to chance or random events
What can cause genetic drift?
Founder effect, bottleneck effect
What is the bottleneck effect?
When population rapidly reduces eg due to disease of natural disaster
What is the founder effect?
New population is established with a different allele frequency
Biodiversity
The number of different species and the genetic variation within species
Endemics
Species that are unique to a geographic area (they provide much of the biodiversity on earth because of founder effects, isolation, bottle necks, other selection pressures)
Species richness
The simplest measure of biodiversity (the number of species in a defined area)
Species evenness
When species (at the same trophy level) have similar abundances
Diversity index
A measure of biodiversity that takes into account both species richness and species evenness (can be used to compare habitats)
Directional selection
Selection pressure favouring one extreme of a characteristic (other extreme selected against)
Stabilising selection
Selection pressure that favours the mean (both extremes selected against)
Disruptive selection
Selection pressure that favours both extremes (mean is selected against)
Classification: taxonomic levels
Kingdom, phylum, class, order, family, genus, species
Chloroplasts structure and function
Double membrane and grana (singular granum)
Function: photosynthesis
Amyloplasts
Store starch (potato cells have a lot of Amyloplasts)
Vacuole
Stores water, plant pigments
The vacuole membrane is called tonoplast
Plasmodesmata
Cytoplasmic streams between plant cells for the transport of molecules between cells
Formed by the ER getting stuck in cell wall as it forms and fills
Pits
Pores in cell walls that allow movement of fluid between plant cells, especially xylem for transport of water
Middle lamella
The layer between cell walls that helps to keep the cells together for stability (acts as a blue between plant cells)
Made of pectin
Microfibrils
Each Microfibril has 60-70 cellulose chains
How are microfibrils arranged
Microfibrils are laid down in different directions.
They make cell walls strong and flexible.
Cross-linking molecules also help to hold the cell wall together, while allowing a little stretch when the cell becomes turgid
Epidermis
Single layer of cells on outside of plant
Vascular tissue
For transport and support
Ground tissue
Cells for photosynthesis, storage or support
Parenchyma
(Big white cells in the middle)
Packing tissue, thin cellulose walls, provide support (eg palisade or spongy cells)
Collenchyma
Below epidermis, tightly packed, thick cellulose walls, provides flexible support
Sclerenchyma
(Small on outside of vascular bundle)
Dead cells when mature
Rigid, thick, lignified walls
Support plant - very strong
(Made up of sclereids and fibres)
