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Biology HL > Topic 5 - Evolution and Biodiversity > Flashcards

Topic 5 - Evolution and Biodiversity Flashcards

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1
Q

evolution

A

the process of cumulative change in the heritable characteristics of a population

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2
Q

heritable traits

A

traits that can be passed genetically from one generation to the next

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3
Q

why do we use “cumulative change” when describing evolution?

A

just one change won’t have a significant impact on a species

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4
Q

why do we use “population” when describing evolution?

A

because the changes don’t affect just one individual

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5
Q

speciation

A
  • if enough changes occur in a population, a new species can arise
  • this process is called speciation
  • a species that came about from a pre-existing species cannot interbreed to produce fertile offspring
  • all species on Earth are a result of speciation from a common origin
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6
Q

evidences for evolution by natural selection

A
  • fossil records
  • homologous structures
  • animal breeding
  • DNA evidence
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7
Q

using fossil records to support the theory of evolution

A
  • life existing 500 mya is vastly different from life now
  • despite Earth having vast oceans for most of its 3.5 billion year existence, fish fossils have only been found in rocks dating back to 500 mya ago or less
  • none of the top predators of this time existed during the time of the dinosaurs
  • the majority of living organisms have no similar form in the fossil records
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8
Q

nuclear decay

A
  • the process of losing radioactivity

- a radioactive parent isotope changes into a stable daughter isotope

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9
Q

half-life

A
  • the rate at which nuclear decay occurs

- defined as the time it takes for half the isotope to decay into a stable daughter isotope

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10
Q

determining the age of fossils

A
  • carefully examining differences in isotopes
  • C-14 is radioactive but slowly decays and changes to N-14 over time
  • substances with a high quantity of C-14 are younger than substances with a low quantity of C-14
  • K-40 can also be used (it has a longer half-life than C-14)
  • minerals in rock contain a certain percentage of K-40, and when they crystallize it is impossible to add more
  • radiometric techniques with K-40 can measure the age of rocks formed from lava up to 4.6 bya
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11
Q

using artificial selection to support the theory of evolution

A
  • breeding domesticated animals provides a good record of recent changes in heritable characteristics
  • by watching mates, breeders can see which characteristics the offspring will have
  • over the years, breeders have learned to pair males and females with the most desirable genetic characteristics
  • after practicing selective breeding for many generations, certain breeds have unique combinations of characteristics that weren’t there before
  • this presents some evidence of evolution occurring as a result of small changes over time
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12
Q

homologous structures

A

features that are similar in form but found in dissimilar species

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13
Q

example of homologous structure

A
  • pendactyl limbs
  • the five-fingered limb found in very different species of animals (e.g. humans, whales, bats)
  • although the shape and number of bones may vary, the general format is the same
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14
Q

using homologous structures to support the theory of evolution

A
  • pendactyl limbs are not required in some animals (e.g. whales could probably swim just as well without them)
  • thus homologous structures are not a coincidence
  • they show that organisms have a common ancestor
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15
Q

species divergence

A
  • when speciation occurs, two populations of species have diverged
  • this process is called species divergence
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16
Q

niche

A

position or role in the community of an ecosystem

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17
Q

adaptive radiation

A
  • occurs when many similar but distinct species evolve rapidly from a single (or small number of) species
  • this happens as variations in a population and allow certain members to exploit different niches
  • this explains why places can only have either prosimians or anthropoids, not both
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18
Q

selective pressure

A
  • if a species has a wide geographical distribution, there will be changes in DNA
  • due to adaptations to the differing climate and soil conditions
  • thus, some genes are selected for and others selected against so populations are best adapted to their areas
  • this is called selective pressure
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19
Q

why does speciation occur?

A
  • selective pressure due to a wide geographical distribution
  • over a long period of time, the difference becomes so great that the two species begin to diverge
  • after a point, they will differ to the extent that they will no longer be able to interbreed
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20
Q

polymorphism

A
  • different versions of a species
  • within a population there is sometimes more than one common form
  • sometimes caused by mutations
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21
Q

why is there more variation in species that reproduce sexually than species that reproduce asexually?

A
  • asexual reproduction (e.g. binary fission of bacteria) produces genetically identical offspring
  • many future generations will be identical or show very minimal change
  • thus DNA is unlikely to be modified
  • however, with sexual reproduction, offspring are genetically variant
  • there can be any number of combinations of alleles from each parent
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22
Q

how does variation affect the chances of survival of a species?

A
  • fish with slightly different shaped mouth may be able to feed from parts of a coral reef that other fish may not be able to access
  • birds with more distinctive and conspicuous pigments to predators may have a decreased chance of survival
  • thus variations in traits can be either increase or decrease chances of survival
  • a sudden change in the environment will threaten some susceptible members but others may be unaffected
  • if there was no variation, all members would be equally susceptible to the threat
  • thus variation is a strength and not a weakness in a species
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23
Q

mechanisms that give species their variation

A
  • DNA mutations
  • meiosis
  • sexual reproduction
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24
Q

how do DNA mutations increase variation?

A
  • mutations can sometimes produce genetic diseases
  • these harmful mutations are not favored by natural selection
  • however, useful mutations can provide advantageous characteristics such as a different camouflage that better matches a changing habitat
  • however, only a few genes mutate each generation
  • so compared to sexual reproduction, mutation is not a powerful source of variation in a speciees
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25
Q

how does meiosis increase variation?

A
  • at the end of meiosis, 4 genetically different haploid cells are produced
  • each only contain 50% of their parents’ genomes
  • since there are so many possible combinations of 50% of their genomes, it is nearly impossible for a woman to produce two genetically identical gametes in her lifetime
  • other sources of variation in meiosis include crossing-over and random orientation in metaphase I
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26
Q

consequence of having no variations in a population

A
  • all members of the population have the same weaknesses

- so their only choices are to survive or die

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27
Q

how does sexual reproduction increase variation?

A
  • in non-human species, when a female is fertile, many males may copulate with her to impregnate her
  • thus it is impossible to predict which male gamete may fertilize the egg
  • in flowering plants, which bee lands on which species of flower with what species of pollen from another flower is also left to chance
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28
Q

how does natural selection work?

A
  • overproduction of offspring
  • presence of natural variation
  • the existence of these two factors lead to struggle between competing varieties for survival
  • essentially survival of the fittest
  • so natural selection eliminates members of a population that are ill adapted to their surroundings
  • as they are less suited for survival, it is unlikely that they will live to reproduce, or find a mate to reproduce with
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29
Q

why do animals overproduce offspring?

A
  • it seems paradoxical because the energy used to produce those offspring could have been utilized for survival
  • and some of those offspring are unlikely to survive to reproduce
  • but the answer here is: to maximize the chances of their survival
  • too many offspring + finite resources = struggle for survival (i.e. competition of resources in order to stay alive)
  • many species are territorial and possessive of food supplies
  • trees have active compounds (e.g. tannins, alkaloids) in their trunks to ward off insects
  • so parents send out as many offspring as they can to maximise the probability of their genes being passed on
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30
Q

process of evolution & adaptation via natural selection

A
  1. Overproduction of offspring and natural variation due to genetic differences
    - some may acquire useful genetic traits
    - others may acquire harmful traits
  2. Individuals with genetic characteristics poorly adapted for their environment will be less successful in gaining resources and have less chances of survival
  3. Individuals with well-adapted characteristics will be more successful at survival (better fitness)
  4. As they are more likely to survive to maturity, they have a better chance of passing on their genes
  5. Over many generations, this accumulation of change in the heritable characteristics of a population results in evolution
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31
Q

how does antibiotic resistance in bacteria develop?

A

-

32
Q

plasmid transfer

A
  • involves one bacterium donating genetic information to another
  • by transferring a ring of nucleotides (plasmid)
  • they open their cell walls in order to pass genetic information
33
Q

how to counter antibiotic-resistant bacteria

A
  • there’s no way to use antibiotics to kill antibiotic-resistant bacteria
  • finding new antibiotics is only a temporary solution
  • the only way is through prevention
34
Q

chance in natural selection

A
  • the emergence of useful characteristics in a population is due to chance
  • but their continued presence is likely not due to chance
  • because natural adaptation favors useful adaptations and selects against harmful ones
35
Q

taxon (plural taxa)

A

categories used to group animals

36
Q

types of domains

A
  • archaea
  • eubacteria
  • eukaryote
37
Q

archaeans

A
  • single-celled organisms
  • very ancient
  • thrives in diverse conditions (e.g. hot springs)
38
Q

eubacteria

A
  • made up of bacteria
39
Q

eukaryote

A
  • all other life besides Archaea & bacteria
40
Q

types of taxa

A
  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species
41
Q

plant phyla

A
  • bryophyta
  • filicinophyta
  • coniferophyta
  • angiospermophyta
42
Q

bryophyta

A
  • plants of very short stature (e.g. mosses)
  • non-vascular – they don’t have true vascular transport tissue such as xylem or phloem tissue
  • reproduce via spores
  • spores are transported via rainwater and ground humidity
43
Q

filicinophyta

A
  • includes ferns, horsetails
  • vascular plants
  • no flowers
  • triangular fronds made up of many smaller long thin leaves
44
Q

coniferophyta

A
  • includes cedar, juniper, fir, pine trees
  • all produce woody stems
  • leaves in the form of needles/scales
  • relies on wind to
  • reproduce via pollination with the help of wind
  • many of them produce seed cones with seed scales
45
Q

angiospermophyta

A
  • includes all flowering plants and plants that have seeds surrounded by a fruit
  • they can be pollinated via wind, birds, and insects
  • the sexual reproductive organs of angiosperms are the flowers
46
Q

animal phyla

A
  • porifera
  • cnidaria
  • platyhelminthes
  • annelida
  • mollusca
  • arthropoda
  • chordata
47
Q

porifera

A
  • sponges (sessile marine animals)
  • no mouth/digestive tract
  • feed by pumping water through their tissues to filter food
  • no muscle/nerve tissue
  • no distinct internal organs
48
Q

sessile

A

stuck in place

49
Q

cnidaria

A
  • diverse phylum: sea jellies, coral polyps, etc
  • all have stinging cells (nematocysts)
  • some are sessile, others are free-swimming, some are both depending on their life cycle
  • they have a mouth and a gastric pouch to digest food caught in their tentacles
  • no anus
50
Q

platyhelminthes

A
  • flatworms (e.g. tapeworm)
  • only one opening used as both mouth & anus
  • no heart or lungs
  • they’re flat because cells need to be close to the surface to exchange gases via diffusion
  • unsegmented bodies
51
Q

annelida

A
  • segmented worms: earthworms, leeches, etc
  • their bodies are divided into sections separated by rings
  • bristles on their bodies (though not always easily visible)
  • mouth and anus in separate cavities
52
Q

mollusca

A
  • includes snails, clams, octopi
  • mostly aquatic
  • many produce a CaCO3 shell
  • mouth and anus in separate cavities
53
Q

arthropoda

A
  • includes spiders, insects, crustaceans
  • hard exoskeleton made of chitin
  • segmented bodies
  • limbs can bend because they are jointed
  • mouth and anus in separate cavities
54
Q

chordata

A
  • organisms that have a notochord (spine) at some point in their development
  • also known as vertebrates
  • can be made of bone, cartilage, etc
55
Q

notochord

A

a line of cartilage going down the back to provide support to the animal

56
Q

classes of chordata

A
  • fish
  • birds
  • amphibians
  • reptiles
  • mammals
57
Q

fish

A
  • have gills to absorb oxygen
  • skulls made of bone/cartilage
  • vast majority of fish have jaws and teeth
  • fish have fingerless limbs in the form of fins
58
Q

amphibians

A
  • they start their lives in water
  • have gills to breathe underwater
  • develop lungs to breathe air
  • most can also absorb oxygen through their skin
  • most have 4 legs
  • ectothermic (cold-blooded)
  • lay eggs with no membrane around the embryo
59
Q

reptiles

A
  • lay amniote eggs
  • scales
  • ectothermic
60
Q

amniote eggs

A

eggs with a membrane around the developing embryo to protect it

61
Q

birds

A
  • bipedal (2 legs)
  • wings (most of which are adapted for flight)
  • have feathers
  • lay eggs with hardened shells
  • lightweight skeletons due to bones being hollow
  • their low density is well adapted for flight
  • have beaks, with no teeth
  • comparatively higher metabolism (thus higher heart and respiration rates)
62
Q

characteristics used for classification

A
  • morphology
  • anatomy
  • cytology
  • phytochemistry
  • chromosome number
  • molecular differences
63
Q

morphology

A

shapes (e.g. of a plant’s seed coat or a bird’s bill)

64
Q

anatomy

A

structure of an organism (e.g. type of digestive system in an invertebrate, or number of petals on a flower)

65
Q

cytology

A

structure of cells and their functions

66
Q

phytochemistry

A
  • special organic compounds that only plants can make

- often used to protect themselves from attacks by insects

67
Q

significance of chromosome number in classification

A

species with closer chromosome numbers are likely to be more closer related than species with vastly differing chromosome numbers

68
Q

significance of molecular differences in classification

A

proteins and DNA sequences differ between species

69
Q

cladistics

A
  • system of classification
  • groups taxa together according to their most recent evolved characteristic
  • to decide how close a common ancestor is, researchers look at primitive and derived traits
70
Q

plesiomorphic traits

A
  • AKA primitive traits
  • they’re traits that have remained with the same structure and function
  • they evolved early on in the history of an organism
71
Q

apomorphic traits

A
  • AKA derived traits
  • traits that have the same structure and function but evolved recently as a result of modifications to a previous trait
  • e.g. flowers are an adaption of vascular leaves
72
Q

clades

A
  • monophyletic group
  • form when a group can be split in two parts (one or both having derived traits that the other doesn’t have)
  • usually made up of more than one species
73
Q

biochemical evidence of clades

A
  • every known living organism on Earth uses DNA as its main source of genetic info
  • any gene from any organism can be mixed and matched with DNA from other organisms to produce a specific protein
  • the easiest way to explain this: all known species have a common ancestor
  • amino acids can be left-handed or right-handed
  • the vast majority of living organisms uses right-handed amino acids
  • only several small organisms use left-handed amino acids
  • this implies a common ancestry that utilizes left-handed amino acids to build proteins
74
Q

phylogeny

A

the study of the evolutionary path of a species

75
Q

analogous characteristics

A
  • characteristics with the same function but not necessarily the same structure
  • they are not derived from a common ancestor

Biology HL (12 decks)

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