Classification & evolution Flashcards

Question

what is anatomical adaptations

Answer 1

Physical features of an organism

Answer 2

The way an organism behaves in response to their environment learnt or inherited eg. migration herding

Answer 3

Biological processes within an organism process of productin of something - eg. pigmebt, enzymes, vasocnstriction, sweating, reproductive cycles

Answer 4

Convergent evolution occurs by natural selection as follows: two species live in different parts of the world with similar environments the species deal with the same selection pressures the same characteristics are advantageous in the two environments, so individuals with these characteristics are more likely to survive and reproduce over time the advantageous characteristics become widespread in both populations

Answer 5

Observation 1 : Organisms produce more offspring than are needed to replace parents Observation Populations tend to remain stable in size over time Deduction 1: There is competition for survival Observation 3: There is variation among the individuals of a given species Deduction 2: The best adapted variants will be selected for by the natural conditions operating at the time. The best variants have a selective advantage. Survival Of the fittest occurs

Answer 6

- variation caused by random mutation, produces a new allele - survival of the fittest - advantages allele is passed on - after many generations there is a shift in the population

Answer 7

differences in DNA base sequences between individual organisms within a species population transferred from one generation to the next and results in genetic diversity within a species

Answer 8

Random mutation can produce new alleles of a gene Many mutations are harmful or neutral but, under certain environmental conditions, the new alleles may benefit their possessor, leading to an increased chance of survival and increased reproductive success The advantageous allele is passed onto the next generation As a result, over several generations, the new allele will increase in frequency in the population

Answer 9

- directional selection - reduction in variation of range while favouring variants of one end - Stabilising selection - favours the most common phenotype as the best adapted. Selection removes the extremes at either end of the range. - disruptive selection - Occurs when environmental conditions are varied or when the environmental range Of an organism is large.

Answer 10

- variation caused by mutations - chance mutation might cause some bacteria to become resistant to an antibioti - When the population is treated with this antibiotic, the resistant bacteria do not die - resistant bacteria can continue to reproduce with less competition from the non-resistant bacteria - therefore the genes for antibiotic resistance are passed on with a much greater frequency to the next generation - Over time, the whole population of bacteria becomes antibiotic-resistant because the antibiotic-resistant bacteria are best suited to their environment -

Answer 11

Bacteria reproduce asexually by binary fission (the DNA of the bacterial chromosome is replicated and the bacterial cell divides in two, with each daughter cell receiving a copy of the chromosome) Bacteria reproduce like this very rapidly (on average, every 20 minutes) If one bacterium contains a mutant gene that gives it antibiotic resistance, all of its descendants (millions of which can be produced in a matter of hours) will also have the antibiotic resistance This form of transmission enables antibiotic resistance to spread within a bacterial population

Answer 12

Plasmids (the small rings of DNA present in bacterial cells) often contain antibiotic-resistant genes These plasmids are frequently transferred between bacteria (even from one species to another) This occurs during conjugation (when a thin tube forms between two bacteria to allow the exchange of DNA) – DNA from the bacterial chromosome can also be transferred in this way In this way, a bacterium containing a mutant gene that gives it antibiotic resistance could pass this gene on to other bacteria (even those from a different species). This is how ‘superbugs’ with multiple resistance have developed (e.g. methicillin-resistant Staphylococcus aureus – MRSA) This form of transmission enables antibiotic resistance to spread within or between bacterial populations

Answer 13

measures the spread of data around the mean value

Answer 14

- always give a null hypothesis - calculate mean for eahc data set - calculate tandard deviation for each data sheet - use standard deviaiton to cacluate t-test - calcuate degree of freedom (n1-1)+(n2-1) - write conclusion which should include: A reference to the t value, the critical value, the degrees of freedom and the probability level Whether or not there is a significant difference between the means of the two data sets Whether the null hypothesis is accepted or rejected - is calculated value less than qcriticla value null ypothesis accepted

Answer 15

- that which exists between individuals of different species - can be useful for classifying organisms into species groups

Answer 16

- that which exists between individuals of the same species - These differences are smaller than those found between individuals of different species - Variation within a species allows natural selection to occur

Answer 17

refers to differences that fall into discrete and distinguishable categories with no intermediates can be represented using a bar chart with bars that are clearly distinct from each other

Answer 18

efers to differences that show a range of values and can fall anywhere between two extremes can be represented on a histogram with bars that touch each other, and will often show a characteristic bell-shaped curve

Answer 19

- genetic - enviornmental - combination

Answer 20

- occurs solely due to genetic factors, environment has no effect, Phenotype = genotype - Different genes have different effects on the phenotype - Different alleles at a single gene locus have a large effect on the phenotype

Answer 21

caused by an interaction between genetics and the environment, Phenotype = genotype + environment Different alleles at a single locus have a small effect on the phenotype Different genes can have the same effect on the phenotype and these add together to have an additive effect If a large number of genes have a combined effect on the phenotype they are known as polygenes

Answer 22

- a group of individuals that can reproduce to produce viable/fertile offspring

Answer 23

the process of which 2 new species form from a common ancestor

Answer 24

- single population of species - population is split and seperates so cant interact - each side subejcted to different seelction pressures - evolution by natural selection chang over many grrntations - if they meet they cna no longer breed

Answer 25

- physical seperation eg. River, road, lava, sea

Answer 26

Sympatric speciation takes place with no geographical barrier A group of the same species could be living in the same place but in order for speciation to take place there must exist two populations within that group and no gene flow occurs between them Something has to happen that splits or separates the two populations: This can occur via: Ecological separation Behavioural separation Ecological separation: Populations are separated because they live in different environments within the same area For example, soil pH can differ greatly in different areas. Soil pH has a major effect on plant growth and flowering, so a population growing in soil with a slightly different pH may flower at a different time from another population, leading to reproductive separation (and eventually genetic isolation) of the two populations Behavioural separation: Populations are separated because they have different behaviours For example differences in feeding, communication or social behaviours, such as courting behaviours to attract a matehappens at the same time in the same place eg: - ecolgical or behavioural isolation - temporal or seasonal isolation - behavioural isolation - mechanical isolation - soeciaiton by polyploidy, have extra chromosomes

Answer 27

he random changes in allele frequencies within a population's gene pool, due to chance events. Genetic drift does not occur as a result of natural selection. It is particularly influential in small, isolated populations, where it can accelerate the development of new species.random changes in allele frequencey taht occur in all populations decreases th egeentic variation in a species

Answer 28

occurs when a population's size reduces suddenly and drastically and this reduction lasts for at least one generation. - leads to a reduced gene pool and decreased genetic diversity compared to the original population. The decreased genetic diversity can cause issues related to inbreeding and reduced fertility. However, it may also allow a beneficial mutation to become more prevalent.

Answer 29

occurs when a small group splits from a larger population, and a small new population is established by this small number of individuals. leads to a reduced gene pool and decreased genetic diversity compared to the original population. Rare alleles from the original population may become more common in the new population, whether they are beneficial, harmful, or neutral (an extreme example of genetic drift).

Answer 30

the process by which humans choose organisms with desirable traits and selectively breed them together to enhance the expression of these desirable traits over time and over many generations

Answer 31

he population shows phenotypic variation - there are individuals with different phenotypes (i.e. different characteristics) A breeder (the person carrying out the artificial selection) selects an individual with the desired phenotype Another individual with the desired phenotype is selected. The two selected individuals should not be closely related to each other The two selected individuals are bred together The offspring produced reach maturity and are then tested for the desirable trait. Those that display the desired phenotype to the greatest degree are selected for further breeding The process continues for many generations: the best individuals from the offspring are chosen for breeding until all offspring display the desirable trait

Answer 32

Selective breeding can lead to ‘inbreeding’ This occurs when only the ‘best’ animals or plants (which are closely related to each other) are bred together This results in a reduction in the gene pool – this is a reduction in the number of alleles (different versions of genes) in a population This is known as inbreeding depression As inbreeding limits the size of the gene pool, there is an increased chance of: Organisms inheriting harmful genetic defects (as there is a higher chance of harmful recessive alleles combining in an individual and being expressed in the phenotype) Organisms being vulnerable to new diseases (as there is less chance of resistant alleles being present in the reduced gene pool) This means that some intensive artificial selection processes have resulted in conditions and diseases that are extremely damaging or deleterious for the animals involved, which is ethically questionable

Answer 33

In artificial selection, it is important to maintain a resource of genetic material that includes types that are close to the original wild type (of the organism you are selectively breeding) This is important as it ensures that the gene pool for a particular species doesn't become too small (which can weaken the population by reducing variation) An example of the importance of this can be seen in the artificial selection of maize Maize (also known as corn) is a staple crop in many countries around the world and is grown to feed both livestock and people Different hybrids of maize are constantly being created and tested for desirables traits such as resistance to pests/disease, higher yields and good growth in poor conditions In the past, maize plants have been heavily inbred (bred with plants with similar genotypes to their own) This has resulted in small and weaker maize plants that have less vigour This is due to inbreeding depression, which: Increases the chance of harmful recessive alleles combining in an individual and being expressed in the phenotype Leads to decreased growth and survivability A farmer can prevent inbreeding depression by outbreeding with wild type varieties of maize This involves breeding individuals that are not closely related Outbreeding produces taller and healthier maize plants It decreases the chance of harmful recessive alleles combining in an individual and being expressed in the phenotype and leads to increased growth and survivability (known as hybrid vigour) Crops of these plants have a greater yield