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IB Biology > A4 > Flashcards

A4 Flashcards

1
Q

Biological evolution

A

Change in the heritable characteristics of a population. Heritable traits are rooted in DNA, refers to populations, not individuals or species.

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2
Q

Why is Lamark’s theory falsified?

A

Lamark’s theory- we adapt to our environment over our lifetime and get characteristics which are passed on. e.g giraffe’s neck stretches over its life due to use, and then this is passed on. We now know that offspring inherit DNA which cannot be altered over a lifetime- changes over lifetime cannot be passed on.

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3
Q

What is Darwin’s theory of natural selection?

A
  • Alterations in heritable material give rise to different traits in a population
  • Some of these aid in survival, organisms that survive longer are able to reproduce, thus more offspring are born each generation with the trait
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4
Q

What is falsification?

A
  • Falsification: when there is evidence that determines a theory to not be true
  • It is hard for scientific theories to be proven to be true, so we instead seek lack of falsification
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5
Q

What are the forms of molecular evidence for evolution

A
  • DNA
  • RNA
  • Proteins
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6
Q

What are Hox genes?

A

Hox genes are a gene family (group of related genes) that play a role in determining body plans of organisms during development.

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7
Q

How do Hox genes relate to evolution

A

If there is similarity in Hox genes across very different organisms, there could be common ancestors between them.

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8
Q

What is a phylogenetic tree and what does it show?

A
  • Phylogenetic trees are visual diagrams that show which organisms are most similar or related
  • Organisms on closer branches have more genetic similarity
    note: can be used for a whole genome or just a single common gene
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9
Q

What is our current understanding of evolution?

differences to Darwin’s theory

A

The heritable material is DNA- which does not change during an organisms lifetime

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10
Q

What are the steps involved in the process of natural selection?

in brackets= what we know now but darwin didn’t

A
  1. Differences exist in heritable material (changes in DNA due to mutation)
  2. (Genetic) variation in a population
  3. There is a survival pressure- threat to survival e.g abiotic factors, competition for resources, predators and disease
  4. In that environment some variations (adaptations) increase likelihood of survival
  5. Those with the desirable adaptation produce more offspring- SURVIVAL OF THE FITTEST
  6. Adaptation is passed onto their many offspring
  7. Increased frequency of the adaptation within population change in heritable trait= evolution!
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11
Q

DNA as a form of evidence for evolution

how and strengths/ weaknesses

A

How: comparison of the base sequences
Strengths:
- provides more information, including all differences detected and silent mutations
- This makes it good for closely related species

Weaknesses:
- Difficult to isolate and sequence DNA (but getting easier)
- Can be overly complex

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12
Q

RNA as a form of evidence for evolution

how and strengths/ weaknesses

A

How: comparison of the base sequences (same idea as DNA)
Strengths:
- Useful for viral evolution- viruses only have RNA

Weaknesses:
- Equally as difficult to sequence as DNA
- Harder to isolate than DNA

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13
Q

Proteins as a form of evidence for evolution

how and strengths/ weaknesses

A

How: comparison of amino acid sequences of a shared protein
Strengths:
- Much easier to sequence and obtain as it is an older technology

Weaknesses:
- It shows less differences and data- can be good as it is more simple

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14
Q

Selective breeding

A

Breeders choosing the males and females with the most desirable characteristics for agriculture and breed them together

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15
Q

Artificial selection

A

Is a result of selective breeding. Generations of selective breeding causes new traits aka evolution- but not natural

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16
Q

Homologous structures

A

Similar internal structures between organisms but can be used for different purposes. Suggests a common ancestory but over time have changed to suit specific functions. Evidence of divergent evolution

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17
Q

Pentadactyl limbs

A

Presence of 5 digits- fingers or toes- generally front or hind limb. Made up of the same set of bones across organisms- homologous structures

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18
Q

Analagous structures

A

Body parts that carry out similar functions but have different structures. Suggests a lack of common ancestry. Evidence of convergent evolution.

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19
Q

Convergent evolution definition

A

Species that develop similar adaptatioms on their own independent evolutionary journeys, but exist in similar environments, so have similar adaptations.

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20
Q

Examples of organisms that have undergone significant selective breeding

A
  1. Modern corn- selected for larger kernals and protective leaves
  2. Modern dogs- originate from grey wolf
  3. Cannabis- bred for high THC content, average THC has quadrupled in 23 years
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21
Q

Functional variations of pentadactyl limbs in animals

A
  • Walking on the limb (most animals)
  • Use as a hand (bipedal humans)
  • Use as a fin (aquatic mammals e.g whales and dolphins)
  • Use as a wing (bats)
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22
Q

Similarities and differences between artificial and natural selection

A

similarity acts as evidence of natural selection
Similarities:
- Both start with genetic variation
- Both end with one variation having more offspring causing it to increase in frequency
Differences:
- Natural selection results from pressures in the environment which determines who survives
- Selective breeding results from humans prefering some individuals and mating them more

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23
Q

Speciation

A

Formation of new species by the splitting of an existing species- population that could previously interbreed can’t now, therefore are different species

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24
Q

Reproductive isolation

A

2 populations that are unable to successfully interbreed, therefore preventing gene flow between groups. Could be due to geographical barriers, anatomical incapability or misalignment of mating behaviours.

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25
Q

Geographic isolation

A

Physical barrier that makes it impossible for males and females to come into contact, therefore mating is never able to be attempted. e.g mountain range, water

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26
Q

Sympatric speciation

A

Speciation occuring without a physical barrier. Mating does not occur due to incompatible mating times or rituals rather than physical separation.

27
Q

Allopatric speciation

A

Barrier to reproduction is a physical geographic barrier that leads to lack of contact and development of unique habitats

28
Q

Behavioural separation

A

Cause of sympatric speciation. Mate attracting actions of one group are different to that of another. Common in organisms with more elaborate courtship rituals. Can also be an adaptation to prevent unsuccessful mating attempts between organisms with different chromosome numbers.

29
Q

Temporal separation

A

Cause of sympatric speciation. Organisms have different mating times. Many organisms only produce gametes during mating seasons or times of day. Also can be to minimise unsuccessful mating attempts.

30
Q

Adaptive radiation

A

Many similar but distinct species evolve relatively quickly from one or a small number of species. Occurs when groups move into different niches and acquire different adaptations through natural selection, causing different species. Allows closely related species to coexist without competition (different niches) and increasing biodiversity.

31
Q

What is required for speciation to occur

A
  1. Reproductive isolation- causing no gene flow between the organisms (can be geographic, behavioural or temporal)
  2. Differential selection- different selection pressures on each group, causing them to develop differences.
32
Q

How do speciation and extinction interact to balance the number of species on earth?

A
  • Opposite forces that control the number of species on Earth
  • Speciation- only way new species are created
  • Extinction- causes species to no longer exist
  • When speciation is greater than extinction, biodiversity increases.
33
Q

Hybridisation

A

Fertilisation of gametes from one species by the gametes of another species. Unsuccessful offspring who either cannot survive or are sterile (cannot reproduce)

34
Q

Interspecific hybrids

A

The result of fertilisation between 2 different species. Usually formed artificially as species avoid through behavioral/ temporal strategies. Hybrids are not fertile as they have incompatible numbers of chromosomes or incompatible gene placement.

35
Q

Polyploidy

A

When a species has 3 or more copies of each chromosome. Can be due to an error in meiosis or hybridisation. Generally not compatible with life in animals, but many plants can survive.

36
Q

Autotetraploidy

A

Formation of a polyploidy organism from members of the same species. A whole genome duplication of a diploid cell then produces diploid gametes, offspring being autotetraploid

37
Q

Allotetraploidy

A

Combination of gametes from 2 different diploid species (often in pollinators). Hybrid is sterile, but if it duplicates, it can get homologous chromosomes and reproduce with other hybrids to create more tetraploids- considered a unique species.

38
Q

Abrupt speciation

A

When speciation occurs through tetraploidy, it can occur in just a few generations compared to natural selection which takes a long time.

39
Q

Why have species evolved barriers to prevent hybrid offspring and examples?

A

Hybrids are often sterile or create unhealthy offspring, so it is bad for both species to exert energy to not produce effective offspring. Beneficial to both species.

40
Q

What is reduced hybrid viability

A

Due to genetic differences, interspecific hybrids can miscarry or be born fragile/ diseased. This is known as reduced hybrid viability

41
Q

What is hybrid sterility and why does it occur?

A

Interspecific hybrids are often unable to produce viable offspring as gametes do not form in meiosis due to odd number of chromosomes. This is known as hybrid sterility.

42
Q

Biodiversity

A

The variety of living organisms in all its forms, levels and combinations. There are many different subcomponents.

43
Q

Species richness

A

A measure of biodiversity that specifically considers the number of different species in a community. Along with species evenness, is a good indicator of biodiversity.

44
Q

Species evenness

A

Measure of how balanced an ecosystem is. A healthy ecosystem has lots of each organism rather than one or two more dominant species.

45
Q

Gene pool

A

All different alleles in a population. This can be specific to a single gene/ trait or a whole genome. An increased gene pool means increased diversity.

46
Q

Three types of biodiversity that can be studied and what they are

A
  1. Ecosystem Diversity- the variety of the combination of species living together in communities. For example, in an area with forests, deserts and grasslands will be more diverse than one with just forests. It can also be considered in relation to the ecosystems within a biome.
  2. Species Diversity- How many unique species exist within a community, looking at one habitat or community. Healthier ecosystems have an even distribution of species as well.
  3. Genetic Diversity- Looking at the genetic differences within a single species. More alleles and genetic combinations means greater biodiversity for that species.
47
Q

What is anthropogenic species extinction?

A

Anthropogenic- due to humans. Anthropogenic species extinction is extinction where humans are a key causal factor. Scientists believe we are in the 6th mass extinction and the first to be anthropogenic in cause.

48
Q

List and explain the 5 anthropogenic causes of the current 6th mass extinction and ecosystem loss

A

C- Climate Change
Rate of climate change is faster than rate of natural selection, meaning species cannot adapt to tolerate the abiotic conditions of their habitat
H- Habitat destruction
Destroying ecosystems e.g forests in order for use in agriculture or creation of homes and human infrastructure
I- Invasive species
Introduction of alien species who outcompete native species leading to their extinction
P-Pollution
Release of substances into environment- emissions into atmosphere or litter in oceans. Impact can be direct or indirect
O- Overharvesting
Humans removing plants and animals at a faster rate than a species can reproduce. Examples include overfishing, overhunting and poaching

49
Q

List some forms of data that can be used as evidence of a biodiversity crisis

A
  • Decrease in population size of species
  • Change in range of abiotic conditions a species can inhabit
  • Comparing Simpson’s Diversity Index from different times
  • Number of threatened species
  • Genetic diversity within species
50
Q

What is IPBES and what have they done

A

Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services
What have they done: Uses large amounts of data to publish report in 2019 with reliable scientific guidelines for policy makers

51
Q

What is IUCN and what have they done

A

International Union for Conservation of Nature
What have they done: Created red list that rated species for current level of threat. Currently, 40,000 species are listed as threatened with extinction.

52
Q

Extinction case study: North Island Giant Moa

who, when, where, why

A

Who: North Island Giant Moa
When: Became extinct as long ago as 500-1000 years ago
Where: New Zealand
Why: Hunting by Maori people

53
Q

Extinction case study: Carribean Monk Seal

who, when, where, why

A

Who: Carribean Monk Seal
When: last sighted in 1957
Where: Carribean
Why: Hunted for their blubber, which was used as a source of fuel for lamps

54
Q

Extinction case study: Mount Glorious Torrent Frog

who, when, where, why

A

Who: Mt Glorious Torrent Frog
When: By 1980
Where: Northeast Australia- Queensland
Why: Deforestation, feral pigs eating them (invasive species)

55
Q

Ecosystem loss case study: Mixed Dipterocarp Forest

who, when, where, why

A

Who: Mixed Dipterocarp Forest
When: Current- in the past 20 years
Where: Asia
Why: Logging and clearing to grow palm oil plantations

56
Q

Simpson’s diversity index equation

A

D= N(N-1)/sum of (n x (n-1))
Where D= diversity
N= total number of species
n= number of that species

57
Q

When was the current biodiversity crisis first identified?

A

1970

58
Q

List ways that increasing human population has contributed to current biodiversity crisis

A

human population has over quadrupled from 1920-2020
- Increased population means more overharvesting for resources and more deforestation and pollution
- Human travel and urbanisation has increased as a result of human population boom

59
Q

What is in situ conservation?

A

Conservation efforts and management within the natural habitat. First attempt to prevent further degradation to prevent need for ex situ measures

60
Q

List some examples of in situ conservation efforts

A
  1. Establishment of national parks and nature reserves- limits development and protects wildlife within
  2. Rewilding- introducing helpful species and removing human structures/ negative human interferences
  3. Reclaimation of degraded landscapes- active replanting and rebuilding of physical ecosystem- may require short term management
61
Q

What is ex situ conservation?

A

Management and conservation of species outside of their natural habitat. Done after the natural habitat is past recovery through in situ methods

62
Q

List some examples of ex situ conservation efforts

remember strengths and limitations of seed and animal tissue banks

A
  1. Establishment of botanic gardens- creation of artificial habitat for species and a living store of plant material
  2. Zoos who run breeding programs for endangered species- use of artificial insemination across different zoos increases genetic pool
  3. Seed banks and animal tissue banks- stores seeds and animal tissue (including gametes and embryos- Germoplasm banks) for use if a species becomes endangered
    Strengths of seed banks: easy and effective and can be used for gardens and reclaimation there are over 1000 seed banks
    Limitations of tissue banks: requires cryogenic care
    Strengths of tissue banks: somatic tissue can be used for cloning, embryonic stem cells can be harvested from placenta or umbilical cord and stored, gametes and embryos can be used for IVF
63
Q

What is the EDGE program and how does it identify animals needing conservation efforts?

A

EDGE- Evolutionary Distinct and Globally Endangered Species. Established in 2007 by Zoological Society of London to have a more targeted approach to conservation. Combines ICUN rating of endangered species with DNA sequencing to determine genetic uniqueness, which forms the EDGE score.

64
Q

Case study of reproductive isolation and differential selection: Chimpanzees and Bonobos

A
  • Both primates in the genus Pon
  • There is no overlap in their geographic range- separated by the Congo River.
  • At some point, the water level of the Congo river may have fallen so far that groups of chimpanzees were able to cross to the other side
  • When the water level rose, the chimpanzees became geographically isolated, therefore unable to reproduce with each other
  • The founding population (population on the other side) experienced different selection pressures to the original population
  • They gradually evolved to be smaller and display differend behaviours to chimpanzees

IB Biology (2 decks)

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