Classification Flashcards
Domain and what are the three domains?
The highest taxonomic rank. Three domains are Archaea, Eubacteria and Eukaryote
What are the five kingdoms?
Plantae, Animalia, Fungi, Protoctista and prokaryote
What are the taxonomic ranks?
Kingdom Phylum Class Order Family Genus Species
What is the biological definition of a species?
A group of organisms that can freely interbreed to produce fertile offspring
What is the phylogenic definition of a species?
A group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics
Prokaryote
- have no nucleus
- loop of DNA not in chromosomes
- naked DNA
- no membrane bound organelles
- smaller ribosomes
- smaller cells
- free living or parasitic
Protoctista
- eukaryotic
- mostly single celled
- wide variety of forms
- plant-like or animal-like features
- autotrophic or heterotrophic nutrition
Fungi
- eukaryotic
- exist as single cells or have a mycelium which consists of hyphae
- chitin walls
- multinucleate cytoplasm
- mostly free living and saprophytic
Plantae
- eukaryotic
- multicellular
- cells surrounded by cellulose cell wall
- autotrophic
- contain chlorophyll
Animalia
- eukaryotic
- multicellular
- heterotrophic
- able to move around
What is phylogeny?
The study of evolutionary history of groups of organisms. Explains who is closely related to whom.
Biological molecules used as evidence in classification
DNA and proteins can be compared, the more similar the molecules the more closely related the organisms.
CYTOCHROME C is found in all living organisms as it is needed for respiration. However, it is not the same in everyone. The amino acid sequence of cytochrome c in two organisms can be compared, the more simialr the sequence, the more closely related they are.
DNA base sequence can be compared, more similar the sequence in a part of DNA, the more closely related the species.
Other evidence to show how similar organisms are
EMBRYOLOGICAL - similarities in the early stages of an organisms development
ANATOMICAL - similarities in structure and function of body parts
BEHAVIOURAL - similarities in behaviour and social organisation
How are archaebacteria different from eubacteria?
- different cell membrane structure
- flagella
- different enzymes for synthesising RNA
- no proteins bound to genetic material
- different mechanisms for DNA replication and for synthesising RNA
How are archaea similar to eukaryotes?
- similar enzymes for synthesising RNA
- similar mechanisms for DNA replication and synthesising RNA
- production of some proteins that bind to their DNA
What is an artificial classification?
- done for convenience
- based on a few characteristics
- does not reflect evolutionary relationships
- provides limited information
- is stable
What is a natural classification?
- uses many characteristics
- reflects evolutionary relationships
- provides a lot of useful information
- may change with advancing knowledge
A well adapted organism will be able to…
- find enough food or photosynthesise well
- find enough water
- gather enough nutrients
- defend itself from predators/disease
- survive physical conditions of its environment
- respond to changes in environment
- have sufficient energy to allow successful reproduction
Anatomical adaptations of marram grass
- Long roots to reach water deep underground
- roots spread over wide area to absorb lots of water when available
- Curled leaves reduces the surface area exposed to wind. It traps air inside so moisture builds up in an enclosed space
- Lower epidermis covered in hairs t trap moisture and reduces air movement
- Lower epidermis folded to create pits where stomata are to reduce loss of water vapour
- Low density of stomata
- Thick waxy cuticle reduces evaporation of water
Behavioural adaptations of marram grass
Responds to shortage of water by rolling leaf more tightly and closing stomata. This helps reduce transpiration. When covered by sand, marram will grow more quickly to reach sunlight.
Physiological/biochemical adaptations of marram
- ability to roll leaf due to hinge cells in lower epidermis. When water is scarce the cells lose tugidity and leaves roll more tightly.
- guard cells work in similar way to open and close stomata. Turgid cells open stomata.
- Marram maintains a lower cell water potential to survive the salty conditions by the sea.
- Leaves contain lignified cells that provide support when turgidity is lost
Behavioural adaptations
- possums ‘play dead’ to escape attack from predators, this increases chances of survival
- scopions dance before mating, to increase chances they attract a mate of the same species to increase chances of sucessful reproduction.
Physiological adaptations
- Brown bears hibernate and lower their rate of metabolism over winter. This conserves energy so so they don’t need for when it is scarce, increasing their chance of survival
- some bacteria produce antibiotics to kill other bacteria in the surrounding area so there is less competition
Anatomical adaptations
- Otters have a streamlined shape to swim through water so they can more easily catch prey and escape predators
- Whales have a thick layer of blubber to keep them warm in the cold sea
What features do the marsupial mole and the placental mole share?
- cylindrical body
- small eyes
- strong front legs
- large claws on front legs
- short fur
- short tail
- nose with tough skin for protection
Darwin’s observations
- offspring generally appear similar to their parents
- no two individuals are identical
- organisms can produce large numbers of offspring
- populations in nature tend to remain a fairly stable size
Darwin’s theory
- individuals in a population show variation
- selection pressures (predation, disease, competition) create a struggle for survival
- Individuals with better adaptations are more likely to survive and pass on these adaptations to their offspring
- over time, the proportion of the population possessing this advantageous adaptation increases
- over generations this leads to evolution
What evidence can be used for evolution
fossils
DNA
other biological molecules
Using fossils as evidence for evolution
Fossils are the remains of organisms preserved in rocks. Fossils can be arranged in chronological order and gradual changes in organisms can be seen.
Using DNA as evidence for evolution
Evolution is caused by gradual changes in the base sequence of DNA. Organisms that diverged away from each other more recently will have more similar DNA. Scientists can compare nuclear or mitochondrial DNA.
Using other biological molecules as evidence for evolution
Amino acid sequence of proteins can be compared
Antibodies can be compared
Organisms with more similar molecules diverged more recently
Natural selection
- mutation creates different versions of a genes (alleles)
- This creates intraspecific variation (within a species)
- Selection pressures will give some individuals with certain mutations an advantage.
- Individuals with an advantageous characteristic will survive and reproduce and pass on advantageous characteristic
- Over time, proportion of population with advantageous characteristic increases so the group of organisms becomes better adapted
Pesticide resistance
- genetic mutations make some insects naturally resistant to pesticides
- if the population of insects is exposed to the pesticide, only the insects with resistance will survive
- These alleles will be passed on to next generation
Pesticide resistance implications on humans
- crop infestations with pesticide resistant insects are harder to control
- if disease carrying insects become resistant, the spread of disease could increase
- A population of insects could become resistant to all pesticides so new ones need to be made which takes time and money
