Extra Flashcards
Bacterium resistance
Mutation causes variation in levels of resistance/some are individuals more resistant; antibiotic is selective pressure; resistance allows survival/confers advantage; slightly resistant individuals survive; resistance allele passed to next generation; further variation each generation increases level of resistance.
Darwin Observation
Offspring look like their parents; no two individuals are identical; populations have the capacity to overproduce; in nature populations tend to be stable
Convergent evolution
A mutation occurs; produces variation; new feature may confer an advantage on the individual; that individual is successful; passes allele on to next generation; a similar feature in an unrelated group living in same environment will also be successful; so similar features develop in unrelated species living in similar environment.
Why does selection happen in short bursts
Selection occurs when the environment changes and the organisms are not well adapted – through selection they become adapted to the environment. Selection (and so evolution) slows or stops when the organisms are well adapted to the environment, until the environment changes again.
Anatomical adaptions of Marram Grass
Long roots – enables plant to reach water deep underground
Roots spread over a wide area – enables Maram to absorb a lot of water when its available, also helps to stabilise plant in the sand dune where it lives
Leaves are curled – Reduces SA exposed to the wind. Also traps air inside, against the lower epidermis. So that moisture can build up in the exposed space
Lower epidermis is covered in hairs – Reduces air movement so water is retained close to the lower epidermis
Lower epidermis is folded to create pits in which the stomata are positioned – Water vapour build up in the pits further reducing the loss of water vapour from inside the leaf
Low density of stomata – Fewer stomata means less water vapour is lost
Leaf covered in thick waxy cuticle – Reduces evaporation of water from the cells of the leaf
Behavioural Adaptions to Marram Grass
Marram grass responds to shortage of water by rolling its leaf more tightly and closing the stomata – reduces the rate of transpiration/ when covered with sand Marram will grow more quickly to reach the sunlight
Physiological adaptions to Marram Grass
- Ability to roll its leaf due to specialised hinge cells in the lower epidermis – when turgid the hinge cells unroll the leaf to allow easier access to CO2
- Guard cells – non turgid close, turgid open
- Mantains cell water potential lower than most plants
- Leaves contain many lignified cells that provide support when turgidity is lost
Anatomical/Behavioural/ Physiological
- structural
- way the behaviour has been modified for survival
- affects the way that processes work
Adaption
Characteristic that enhances survival in a habitat
3) Why are half our genes are half in a species in a banana:
-Many of the processes of life require similar structures and similar enzymes in all living things, so many cell organelles, membrane structure and protein structures are shared. For example, the enzymes and proteins associated with respiration, DNA synthesis and protein synthesis could all be the same
Monophyletic
all members of the group arose from the same ancestor
Differences between plants and fungi
Plants have chloroplasts and chlorophyll, they photosynthesise, use autotrophic nutrition, have cell walls made of cellulose/ Fungi have no chlorophyll and do not photosynthesise, use heterotrophic nutrition, have cell walls of chitin.
