Classifications and evolution and variation

Question 1

what is evolution

Answer 1

theory in which animals evolve as a result of natural selection

Question 2

what is the evidence for evolution?

Answer 2

-palaeontology: study of fossils and the fossil record
-comparative anatomy:
-comparative biochemistry

Question 3

How do fossils provide evidence for evolution?

Answer 3

-fossils of simple organisms (algae, bacteria) are found in early rocks while complex organisms are found in recent rocks.
-sequence in which organisms are found matches ecological links (e.g plants found before animals so plants are required for animals to live)
-by studying similarities in the anatomy of fossil organisms, common ancestors and links can be found

Question 4

why is the fossil record not complete?

Answer 4

-many organisms are soft-bodied and decompose quickly before fossilising
-conditions for fossils to occur are not met
-fossils destroyed by earth movements (e.g volcanoes)

Question 5

What is a homologous structure in comparative anatomy?

Answer 5

-structure that appears superficially in different organisms but has the same underlying structure (e.g polydactyl limb of invertebrates)
-it provides evidence for divergent evolution

Question 6

how do embryos show evidence for evolution?

Answer 6

animals all look the same when an embryo so there is a common origin but they have evolved different traits

Question 7

what does the hypothesis of neutral evolution state?

Answer 7

most of the variability in the structure of a molecule does not affect its function as most of the variability occurs outside of the molecules functional region. Changes that don’t affect region are called ‘neutral’. This does not affect natural selection.

Question 8

How is the molecular sequence of a particular molecule compared?

Answer 8

-scientists look at DNA or order of amino acids in protein
-the number of differences is plotted against rate the molecule undergoes neutral base pair substitutions
-scientists can estimate the last common ancestor

Question 9

what is interspecific variation?

Answer 9

variation between different species

Question 10

what is intraspecific variation?

Answer 10

difference between organisms within a species

Question 11

what are the causes of variation?

Answer 11

-genetics
-environment

Question 12

what are the genetic causes of variation?

Answer 12

-alleles (dependent on parental combination)
-mutations
-meiosis (independent assortment and crossing over)
-sexual reproduction (each individual produced differs from parents)
-chance (many different gametes, unique combination of genetic material)

Question 13

What is discontinuous variation?

Answer 13

no in-between values, controlled by one gene

Question 14

what is continuous variation?

Answer 14

graduation in values, controlled by many genes

Question 15

what is the bell shaped curve in a continuous variation data called?

Answer 15

normal distribution curve

Question 16

what are the characteristics of a normal distribution?

Answer 16

-mean, mode and median is the same
-bell shape
-50% values less than mean, 50% above the mean
-most values lie at the mean

Question 17

what is standard deviation?

Answer 17

measure of how spread out the data is. The greater the standard deviation, the greater the spread of data, larger variation

Question 18

when you calculate standard deviation of data that display a normal distribution, what will you generally find?

Answer 18

-68% of values are within 1 standard deviation of the mean
-95% of the values are within 2 standard deviations of the mean
-99.7% of the values are within 3 standard deviations of the mean

Question 19

what statistical tests can be done to determine the significance of the data collected?

Answer 19

-student’s t test: this can be used to compare the means of data values of two populations
-spearman’s rank correlation coefficient: this can be used to consider the relationship between two sets of data

Question 20

Describe student’s t test?

Answer 20

used to compare the mean values of two sets of data. To use this test, the data collected must be normally distributed and enough data should be collected to calculate the mean. Different sample sizes may be used.

Question 21

what are adaptations?

Answer 21

characteristics that increase an organisms chance of survival and reproduction in its environment

Question 22

What are the different types of adaptations?

Answer 22

-anatomical adaptations: physical features (internal and external)
-behavioural adaptations: can be learned from parents or inherited
-physiological adaptations: processes that take place within an organism

Question 23

what are some anatomical adaptations?

Answer 23

-body covering
-camouflage
-teeth (related to diet)
-mimicry

Question 24

how is body covering an anatomical adaptation?

Answer 24

-e.g hair, scales, spines, feathers
-they can help with flight, warmth, protection, prevent water loss (waxy layer)

Question 25

how is mimicry an anatomical adaptation?

Answer 25

harmless organism appearing harmful or dangerous to fool predators

Question 26

what adaptations do marram grass have to reduce transpiration as a xerophyte?

Answer 26

-curled to minimise surface area
-hair inside surface to trap moist air and reduce diffusion gradient
-stomata into sunken pits
-thick waxy cuticle

Question 27

what are some behavioural adaptations?

Answer 27

-survival adaptations (e.g playing dead or freezing)
-courtship (to attract a mate)
-seasonal behaviours (migration and hibernation)

Question 28

what is migration?

Answer 28

moving from one region to another, then back again when conditions are more favourable for food or a better climate

Question 29

what is hibernation?

Answer 29

-a period of inactivity when body temperature, heart rate and breathing rate slows down to conserve energy, reducing animals requirement for food.

Question 30

what are the two main categories in which behavioural adaptations fall into?

Answer 30

-innate (instinctive) behaviour: genetic (e.g webs)
-learned behaviour (e.g the use of tools)

Question 31

Give some physiological adaptations?

Answer 31

-poison production (poison from reptiles and leaves kill)
-antibiotic production (some bacteria produce antibiotics to kill other species of bacteria in the surrounding area)
-water holding (storing water within body e.g water holding frog and cacti)

Question 32

what are analogous structures?

Answer 32

features of different species which have the same function but different genetic origin

Question 33

Describe convergent evolution

Answer 33

takes place when unrelated species begin to share similar traits. Similarities evolve because organisms adapt to similar environments or other selection pressure

Question 34

what are some examples of convergent evolution?

Answer 34

-marsupial and placental mice (both small agile climbers)
-flying phalangers and flying squirrels (both are gliders that eat insects and plants, their skin is stretched)
-marsupial and placental moles (both burrow through soil to find worms, streamlined body shape, velvet fur for smooth movements)

Question 35

what are selection pressures?

Answer 35

factors that affect the organisms chance of survival or reproductive success

Question 36

what are the steps of natural selection?

Answer 36

-organisms within a species show variation in their characteristics (genetic variation), new alleles arise by mutations
-organisms whose characteristics are best adapted to a selection pressure have an increased chance of survival and successfully reproducing while less adapted organisms die-survival of the fittest
-successful organisms pass on advantageous allele to offspring
-over generations, the frequency of allele that codes for this particular characteristic increases in its populations gene pool
-over time, many generations and often involving multiple genes will lead to the evolution of a new species.

Question 37

give an example of an antibiotic-resistant bacteria?

Answer 37

methicillin- resistant bacteria (MRSA)

Question 38

How have peppered moths evolved?

Answer 38

due to the industrial revolution trees became darker so darker moths were better camouflaged. The allele frequency changed

Question 39

Explain how a specific molecule is used to show that two different species have evolved from a recent common ancestor?

Answer 39

In the sequence of amino acids, the smaller the number of differences, the more closely related they are