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OCR BIOLOGY (MODULE 4+6) > NATURAL AND ARTIFICIAL SELECTION > Flashcards

NATURAL AND ARTIFICIAL SELECTION Flashcards

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1
Q

What are Darwins four observations?

A

Species over reproduce
Populations tend to remain fairly constant
Variation within a species
Offspring often resemble their parents- characteristics are passed on

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2
Q

What are Darwins deductions?

A
  1. struggle for survival- individuals get eaten, diet disease or competition for resources
  2. individuals with best characteristics that best adapt them for their environment are most likely to survive and reproduce
  3. if characteristics can be inherited then organisms will pass them onto their offspring (passing of ALLELES)
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3
Q

Who was Wallace?

A

Independently came to the same conclusions as Darwin
Made collections in the Amazon and South East Asia
Darwin and Wallace both published joint papers on evolution and natural selection

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4
Q

How are fossil records evidence for evolution?

A

Show diff species were alive in the past
Become extinct and new species have arisen
Fossilised remains show species getting more and more complex (while retaining similarities)
Can be used on phylogenetic trees

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5
Q

What are problems with fossil records?

A

Often incomplete
Only hard parts fossilise and many organisms don’t have hard parts
Only form under certain circumstances
Can be damaged by movement of rocks

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6
Q

How are biological molecules evidence for evolution?

A

Many bio molecules found in all organisms- suggesting all species arose from one common ancestor
Closely related species have more similarities

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7
Q

How is protein variation evidence for evolution?

A

Vital proteins, DNA and RNA, four in all organisms
Higher organisms have added sub units that improve regulation
Cytochrome C (protein used in respiration) show patterns of changes
-more change= more evolutionary distance

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8
Q

How is DNA evidence for evolution?

A

Sequencing the bases in DNA allows for comparison, the more differences found means that there is greater evolutionary distance

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9
Q

How is mitochondrial DNA evidence for evolution?

A

Mitochondria passes to offspring by the egg (female) during sexual reproduction
Mutations more common in mitochondrial DNA than genomic DNA
Variations used to trace human evolution

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10
Q

Define an adaption

A

A feature that enhances survival and long-term reproductive success

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11
Q

Well adapted organisms should be able to..

A

Find enough food/photosynthesise at a fast enough rate
Defend against predators and disease
Survive physical conditions of environment, e.g. temp, water availability
Respond to changes in the environment
Reproduce successfully

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12
Q

Define behavioural adaption

A

Aspect of behaviour of the organism that allows it to survive where it lives

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13
Q

Examples of behavioural adaptions

A

Survival behaviour- opossum plays dead
Courtship- attract a mate
Seasonal behaviour- migration, hibernation

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14
Q

Define physiological adaption

A

Internal and biochemistry ical features that ensure the correct functioning of cell processes

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15
Q

Examples of physiological adaptions

A

Poison production to kill prey

Antibiotic production- some bacteria produces e antibiotics to kill other species

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16
Q

Define anatomical adaptions

A

Any structure that enhances survival of the organism (physical features)

17
Q

Examples of anatomical adaptions

A

Body covering- scales, hairs

Teeth- carnivores= sharp teeth, herbivores= continuously growing molars

18
Q

What is convergent evolution?

A

Adaptions controlled by the environment
Meaning evolutionary distinct species that live in similar habitats, or exploit similar ecological niche, often evolve similar adaptions

19
Q

What is an example of convergent evolution?

A

Marsupial and Placental moles

Powerful front claws, hairs on face, independently evolved

20
Q

Natural selection:

Explain genetic variation

A

Random mutations cause different alleles of genes
Instraspecific variation
Occasionally new alleles are beneficial, increase alleles frequency

21
Q

Natural selection:

Explain selection pressures

A 
Organisms have to compete for survival 
Environmental factors confer greater chance of survival and more reproduction 
examples:
-availability of food 
-predators 
-disease
22
Q

Natural selection:

Explain reproductive success

A

Best adaptions most likely to survive and reproduce

Pass on alleles that code for beneficial characteristics to their offspring

23
Q

Natural selection:

Repeated over many years

A

Repeated so beneficial alleles become more frequent in the population
Proportion of population with advantageous characteristics increase

24
Q

How is pesticide resistance an example of implication of evolution for human populations?

A

Creates a selection pressure for those with some form of resistance to insecticides
Problem because many insects carry disease therefore infection rates climb, pesticide become concentrated in the food chain

25
Q

What is stabilising selection?

A

If enviro stable, stabilising selection occurs
Same alleles selected in every successful generation and the gene pool of a population;ation remains roughly the same
Examples:
Coats of mice in forest best colour suited to enviro

26
Q

What is directional selection?

A

If enviro changes there will be a change in the selection pressure on the population
DS evolutionary force of natural selection
One extreme selected against another will have selective advantage
Over time allele frequency shifts towards an extreme
E.g. Londons peppered moths- industrial period, became black

27
Q

What is genetic drift?

A

Random fluctuations can occur in allele frequency within a population- purely by chance
Most likely in small populations
Occurs due to randomness of reproduction
Extreme cases alleles can be eradicated from population

28
Q

What is genetic bottleneck?

A

Population decreases which decreases allele frequency which decreases variation/genetic diversity

29
Q

What is the founder effect?

A

New population started from. a few individuals, may show loss of genetic variation
Amish people descended from small number of people and suffer from genetic disorders

30
Q

Formula for proportion of polymorphic gene loci

A

Number of polymorphic gene loci/total number of loci

31
Q

Define speciation

A

Large populations can be split into sub-groups by an isolating mechanism, geographical or reproductive barrier

32
Q

Explain geographical isolation

A

Physical barriers can separate population into two breeding groups
Diff selection pressures will act as diff populations
Selection, genetic drift and mutation will lead to diff gene frequencies in two populations
ALLOPATRIC SPECIATION

33
Q

Explain reproductive isolation

A 
Two groups of organism may be isolated from breeding together even if they live in the same place 
Reasons:
-mechanical problems (e.g. diff sizes)
-gamete incapability 
SYMPATRIC SPECIATION
34
Q

Explain ecological barriers as reproductive isolation

A

Two groups may live in the same area but rarely meet

35
Q

Explain temporal/seasonal barriers as reproductive isolation

A

Two groups may live in the same habitat but may not be active at the same time of year or day

36
Q

Differences between natural and artificial selection

A

Slow, fast
Benefits species, benefits humans
Whole genotype selected, few traits selected

37
Q

Explain a dairy cow as an example of artificial selection

A

Select cows with high milk yields to reproduce
Bulls which have progeny with high milk yields are used
Repeated over many generations
Artificial insemenation used to maximise no. of cows bulls can fertilise

38
Q

What are problems with artificial selection

A

Reduces genetic diversity/variation
Interbreeding often occurs increased chance of two recessive alleles coming together
Characteristics selected may cause health problems for organism

39
Q

What are solutions to artificial selection problems

A

Breeders may cross two different varieties to increase hybrid vigour
Gene banks created including ‘wild types’

OCR BIOLOGY (MODULE 4+6) (5 decks)

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