Biodiversity Flashcards
(271 cards)
1
Q
By counting the number of taxa what are you finding?
A
The species richness
2
Q
What percentage of the worlds biomass is accounted for by plants?
A
90%
3
Q
When do bryophytes start to invade the land?
A
The Ordovician - after the Cambrian explosion
4
Q
What type of group are the non vascular plants?
A
Paraphyletic
5
Q
Describe the alternation of generations in bryophytes
A
N haploid gametophyte dominant
- male and female sex organs
- sperm swims through film of water onto the egg and fertilises it
- egg becomes 2n diploid and grows into the sporophyte, produces the sporangia
- sporophyte is parasitic - cannot photosynthesise. Obtains its energy through the gametophyte
- sporophyte undergoes meiosis, single cells divide twice to form a tetrad - 4xn, these are released into the atmosphere. Drop onto the land and become a gametophyte
6
Q
What does homosporous mean?
A
All spores are the same size and are all both male and female
7
Q
Where are egg cells enclosed in bryophytes, describe this structure ?
A
Archegonium - single and flask shaped
8
Q
What is meant by referring to the spermatozoids as zooidogamous?
A
Zooidogamous means the male gametes swim in a path of water to the female gametes
9
Q
How many flagella do bryophyte sperm cells have
A
2
10
Q
What makes up the wall of a bryophytes isospores?
A
Sporopollenin
11
Q
What sort of size are bryophytes?
A
Generally very small
They have no lignin and hence they cannot have advanced water conducting cells
12
Q
Why have bryophytes been able to exist almost everywhere?
A
Small spores are widely dispersed by wind
Can lose most of their water and still survive
Colonise bare rock e.g. Surtsey
Have phenolic compounds that protect from UV which enables them to live in polar regions, deserts and mountainous regions
Can be epiphytic
13
Q
Although bryophytes have been found almost everywhere, what is the limitation to their invasion?
A
They must have a film of water over them to reproduce
14
Q
What is an endolithic community?
A
One that lives under rocks
15
Q
What are the big 5 problems for the movement of plants onto the terrestrial environment ?
A
Constant dehydration - xylem, cuticles, and stomata need to evolve
UV B radiation
Nutrient availability
Support - no longer supported by water, need lignin
Harder to reproduce - need to evolve ways of dispersing seeds
16
Q
Give the order of bryophytes from most to least basal
A
Liverworts
Mosses
Hornworts
17
Q
Give the main differences between bryophytes and tracheophytes
A
Bryophytes have no lignified tissues, and the gametophyte is dominant
Whilst tracheophytes have lignified conducting tissues, the sporophyte is dominant
18
Q
For each bryophyte division give the number of species and generas
A
8000 species of liverworts (hepatics) in 400 genera
2000 species of mosses (musci) in 400 genera
100 species of hornworts (anthrocerotes) in 11 genera
19
Q
What is meant by protonema?
A
The chain of cells that forms the earliest stage of the life cycle
20
Q
Define dorsiventral
A
Flattened leaves having a distinct upper and lower surfaces as most leaves do
21
Q
What is a thallus plant?
A
One in which the plant body is not differentiated into stem and leaves and lacks true roots and a vascular stem. E.g. Some liverworts
22
Q
Where may you find oil bodies in a liverwort gametophyte?
A
Cytoplasm
23
Q
On which side of a leafy liverwort are the leaves fully developed?
A
The dorsal side
24
Q
Archegonia and antheridia, which is male and which is female
A
Archegonia is female
Antheridia is male
25
When the sex organs of a plant become umbrella shaped as they do in some liver worts what are they called? How do these develop?
Antheridophores - males
Archegoniphores - females
Develop from dichotomy ( repeated branching )
26
Where do antheridia lie in leafy liverworts? And the archegonium?
Antheridia in axils of leaves
| Archegonium laterally or the tip of the shoot
27
What are elaters? And what isnt their purpose?
Elaters are made from cells undergoing meiosis, they are long cells that wiggle when dried to push all the spores out of the windpipe
28
What is true of all mosses gametophytes?
Leafy and multicellular rhizoids
29
What is meant by monoecious and dioecious?
```
Monoecious = plants that have sperm and eggs on the same gametophyte
Dioecious = plants that have sperm and eggs on different gametophytes
```
30
Moses dont have elaters, what do they do to aid spore dispersal?
Use a peristome on the sporangium, these dry up and allow spores to release
31
What happens to the antheridia of mosses at maturity?
Its distinct lid opens and releases the spermocytes
32
From where does the moss sporophyte always grow from?
The apical cell of the gametophyte (tip)
33
What is a key step in the evolution of land plants from liverworts to mosses?
Obtaining a stomata
34
Stomata in mosses are not for gas exchange, what three things have the been considered to be for?
1) method of allowing sporangium to open
2) let water into the sporophyte
3) dry out the sporophyte to let spores leave
35
Describe a method of spore dispersal in mosses that involves the operculum
Sporophyte grows through the gametophyte and rips off the calyptra (protective layer to the archegonium) it then rips off the operculum as well, small section exposed that allows spores to escape through
36
What structure do hornworts take?
Thalloid structure,much of thallus is undifferentiated
37
Describe the sporophyte in hornworts
Remains inserted within the gametophyte, basal part surrounded by thallus tissue. Sporophytic tissue continuously produced by the basal meristem
38
Describe the evolutionary history of bryophytes
Mid ordivician - 475 mya, they first evolved from green algae
Don't change for 40 million years
Early silurian (435mya) evolution of lignin, vascular plants dominant. Bryophytes moved to far corners
Mid Devonian 380 MYA
Trees evolve, epiphytes form and grow on trees
39
What is the most primitive form of living vascular plants?
Lycopsids
40
What are the major changes when moving from non vascular bryophytes to vascular lycopsids?
The 2n diploid sporophyte becomes dominant
| Sporophyte has lignified conducting tissues enabling it to grow larger - explore more morphologies.
41
Are lycopsids hetro or homosporous?
Homo
42
Describe the alternation of generations in lycopsids
Sporophyte dominant
Cells in sporangia under go meiosis and form a tetrad that breaks apart to form spores.
Gametophyte grows from the spore and produces sex organs
43
Give features of the lycopsid order lycopodium
```
200 species in 3 genera
Eliguate leaves
Microphylls and sorophylls
Homosporous
Gametophyte can be surface or subterranean
Conspicuous neck on archegonia
```
44
There is an order of lycopsid that has only one species, what is it and what are its features?
Phylloglossum
Multiflagellate spermatozoids
Forms tubours
45
What is the key difference within selaginella to the other lycopsids?
Heterosporous
46
Describe the alternation of generations in selaginella
Produces fewer larger spores rather than many smaller ones, falls down and produces a female gametophyte. Small spores produced in numbers, land and produce a male gametophyte
47
Why is heterospory advantageous?
Heterospory encourages outbreeding hence increases genetic diversity
Female mega spore has a large energy supply and hence can stay in one place for a large amount of time, meaning the species can live through dry periods. Plants can now invade in periodically damp environments and invade more of the planet
48
Where are the male and female spores kept within a selaginella?
Microsporangium holds the male microspores
| Mega sporangium holds the female macrospores
49
When were lycopsids arborescent? How did this happen?
Carboniferous period
| Very high oxygen levels, planet started to dry out in the permian from here they started to go extinct
50
How many species of selaginella are there?
700 in predominantly tropical areas
51
Which order of lycopsids is aquatic?
Isoetes/ stylites
52
Give the features of isoetes (type of lycopsid)
Aquatic
Heterosporus
Mega or micro sporangia
53
How does isoetes reproduce?
Spores released onto the surface of the lake
| Male meets female, macrospore becomes denser and sink to the bottom
54
What is the only extant genus of sphenopsids?
Equistem - horsetail
55
In equisetum where is the sporangium found?
Top of the plant
56
Extant Sphenopsids are all homosporous. True or false
True but some fossil forms have been seen to be heterosporus
57
What is a spehnopsids epeltate?
The umbrella cone structure with the sporangia in the inside
58
Describe how sphenopsids attempt to encourage outbreeding
Gametophytes are released in flushes, females go first then males
59
What is the latin name for the plant group ferns?
Polypodiopsida
60
Describe the spermatoids in sphenopsids
Multiflagellate
61
Polypodiopsida are split into two groups what are these?
Eusporangiate - sporangium forms from two cells
| Leptosporangiate - is where the sporangium forms from one cell
62
How do trunks of tree ferns form?
Leaves gradually infurl, roots grow arpund each one of these leaves, upon death the leaf leaves behind its base which forms the trunk
63
All ferns are _____sporous and the sporangia are on the _______side of the leaf
Homosporous
| Underside
64
What is similar between the ferns and the bryophytes?
Both still need the film of water to reproduce
65
There is a very simple polypodiopsida that was mistaken for the most simple land plant what was it called? Why is it so basal?
Psilotales
| All it does is bifocate and produce sporangia and it can be epiphytic
66
How long does the heart shaped gametophyte of ferns last for?
Not very long at all
67
Are ferns gametophyte or sporophyte dominant?
Sporophyte
68
There is one type of fern that is heterosporous what is it called? Where does it exist and how does it reproduce?
Hydropteridales
Aquatic
Megaspores float on surface and have hooks microspores get hooked and become trapped
69
When did ferns and sphenopsids arise? What did they occur after?
Arose in the late devonian. They came after the lycopsids
70
What did the ferns and sphenopsids diverge from? Give a brief description of this species
Trimerophytes
| Bifurcating plant, sporangia occur on one sie
71
What is pseudomonopodial growth ?
Plants can bifocate but all stem grows in straight lines
72
What are the 5 major plant reproductive strategies
```
Bryophytes- gametophyte dominant homosporous
Then sporophyte dominant homosporous
Sporophyte dominant heterosporus
Seed plants
Flowering plants
```
73
Describe the alternation of generations in seed plants
Pollen grain is male and the megaspore - ovule - is female. The pollen grain lands in the ovule and forms a 2n zygote.
The ovule becomes a seed on fertilisation, gametophyte formed within the seed
74
Why is having seeds advantageous?
Removes the need for the film of water for reproduction, enables more invasions
Parents can look after daughters: when seed forms the tree can continue to provide food and water for the seed giving it more time to grow
75
When and from whom did the gymnosperms arise?
Trimerophytes in the devonian
| Trimerophytes gave rise to both the gymnosperms and the sphenopsids seperately
76
When and as what do progymosperms appear in the fossil record? Where these hetro or homosporous?
Devonian as trees
| Heterosporus plants
77
Give three examples of extinct seed plants (gymnosperms)
Pteridosperms - seed producing trees, evolves methods to keep the plant safe
Cordaites - carboniferohs forests similar to conifers
Glossopterids : seed plant in the permian
78
How many species of ginkgos are there? What is special about them?
1
| They are a living fossil, thought to have gone extinct but then found in china
79
Ginkgos are diesius which means what?
They have two "houses" seperate male and female plants
80
Which gender tree produces vomit smelling slime
Female
81
How many genera in how many species are there in cycads?
80 species in 12 genera
82
How long can cycads live? Where are they found? In what respect are they similar to ferns?
Large amount of time, up to 400 years
Tend to grow in the tropics
Leaves die and leave behind the trunk
83
Because cycads often produce _______ they have become endangered due to agriculture. However because they can __________ populations can be restored from relatively low numbers
Toxic seeds
| Change sex
84
Which gender of cycad holds the cones
Both
The male opens its cone to release pollen
The female opens its cone to enable pollen to swirl around within it
85
What is meant by conifer?
Cone plant
86
How is the pollen of the conifers adapted?
Air sacs enable it to fly and float
87
Describe the female cone in a conifer
Female opens up and exposes the ovule, pollen sucked in and fertilises. Cone seals up for upto 1 year to help the seed develop.
88
Conifer means cone plant but what is wrong with this name?
Some conifers produce berries e.g. The yew tree.
| Analysis of the berries ontogeny they seem to be modified cones with a single ovule
89
Gnetales have 3 genera which are?
Welwitshia
Ephedra
Gnetum
90
Give the extant orders of gymnosperms
Ginkgos
Cycads
Conifers
Gnetales
91
What is meant by mosaic evolution?
Different bits of the plant can evolve without effecting other parts
92
What are 9 important features of land plants?
Simple organisms with around 40 cell types
Essentially sedentary
Plants can regenerate
Reproductive propagules can last for a large amount of time
Can easily hybrize
Often form polyploids - rapid speciation
Asexual reproduction
Mosaic evolution
Small populations can exist successfully
93
Plants rarely go _______ . Liverworts have remained unchanged since ___________ lycopodium from _____MYA resemble ____________. And _______ have been around for 240mYA
```
Extinct
Mid ordovician
280mya
Lycopsids
Cycads and ginkgos
```
94
Why did Carboniferous forests last for much longer in china?
China didnt move as much due to tectonic movement
95
What three categories of changes drive plant evolution?
Environmental change - climate change, techtonic movement
Coevolution - mycorrhizal fungus, animals eating plants, plants eating insects
Freak events - polyploidy
96
Where are seeds held in angiosperms?
An ovary - fruit
97
Angisperms have __________ species which makes up ___ of the worlds plant species
250,000
| 90%
98
Describe the female sex organs of a angiosperm
Pistil or carpel
| Which is made of the pollen acceptor - the stigma and the style - the stigma supporter
99
Describe the male sex organ in angiosperms
Stamen with an anther - pollen producer
100
Darwin called the origin of angiosperm an _______________, because they suddenly appear in the fossil record in the ___________. They became the dominant vegetation by __________.
Abominable mystery
Mesozoic era
93.6 MYA
101
What are the best current guess for where angiosperms arose from?
Cycads or pteridosperms
102
What percentage of angiosperms are either monocots or eudicots?
98%
103
How many monocot species arw there? How many orchids ?
60,000 monocots, 20,000 of which are orchids
104
The cot part of monocot or eudicot means what?
Cotyledon = seed leaves, formed within the seeds and are identical to the maternal leaves
105
Describe the tissues differences between monocots and eudicots
Monocots have parallel tissues
| Eudicots have net tissue
106
Describe stomata in eudicots and monocots
Monocots have stomata in lines on both surfaces
| Eudicots have them scattered and only on the underside
107
Describe vascular bundles in monocots and eudicots and explain how this allows for eudicots larger size
Monocots - vascular bundle throughout the cell, prevents cambium production which means they cant produce wood
Eudicots have a vascular bundle in a continuous ring at the surface allows them to produce cambium and hence can support themselves at much greater heights
108
What are the different roots in monocots and eudicots? What are the pros pf each?
Monocts are fibrous - adventurous root system, explore more but near the surface
Dicots have taproots - less adventurous but goes much further down
109
Describe the flowers of monocots and eudicots
Monocots - have flowers in multiples of three parts
| Eudicots - have flowers in multiples of three or four
110
Describe the pollen of monocots and eudicots
Monocots have a monosculate structure in the pollen
| Eudicots have tricolpate pollen multiples of three with complex shapes
111
Where the dominant species of plant is not angiosperm it will always be what? Give examples
Gymnosperms
Boreal forests of canada
Juniper savanahas
112
Give the three key events in angiosperm life cycle (basic)
```
Seed dispesal (dispersal in space)
Seed dormancy (dispersal in time)
Germination
```
113
```
Define the following parts of the seed
Endosperm
Epicotyl
Hypocotyl
Radicle
Cotyledon
```
```
Endosperm = nutrient store
Epicotyl = joins leaf to plant
Hypocotyl =becomes stem
Radicle = becomes root
Cotyledon = becomes seed leaves
```
114
What are the four functions of angiosperm seeds
Muktiplication
Survivial
Dormancy
Dispersal
115
What two factors make fore succsessful angiosperm seed production?
Seed size - larger seed has more nutrients - coco de mur seed 10 orders of magnitude larger than the slipper orchids seeds
Seed number - huge numbers of seed or few seeds
116
Where parental investment is constant what does the graph of seed size vs number look like?
Increasing seed size sees decreasing seed number
117
Where would angiosperms with large seeds be advantageous? Why?
```
Hostile environments
More resources
Emergence from greater depths
Aggressive early growth
Greater tolerance for stress
```
118
Describe valivovian mimcry
Where a weed becomes like a domestic plant due to artificial selection
E.g. Weeds in flax fields, in Russia they are looking for oil plant seeds which are thick and large the weeds mimic this whilst in USA they are looking for fibre flax which is smaller and thinner again the weeds have mimicked this
119
Describe the experiment "the tragedy of the commons" in plants
Soybeans grown in individual pots and exposed it to competition.
Control has 10g of nitrogen in 2 pots with 2 seperate beans
Experiment cuts tap root of two soybeans and split them into two pots (half of each tap root in each pot)
- shoot mass didnt change
- root mass changed - sharers had to put more energy into the roots.
- seed mass reduced since it has less energy
If it didnt grow out its roots as much as possible it would get none of the 20g
120
Give four methods of seed dispersal
Anemochory - wind dispersal (many pioneer species)
Hydrochrory - by water - needs to be bouyant
Zoochory - by animals
Autochory - seed dispersal by plants
121
Give all the differenet types of zoochory
```
Endo - inside or epizoochory - outside
Synzoochory - deliberate e.g. Squirrels
Orithochory - bird dispersal
Mymecochory - by ants
Chiropterochory - bats
Saurochory - lizards
```
122
Define iteroparity and semelparity
Iteroparoty is where they reproduce many times
| Semelparity is where reproduction is fatal hence they only reproduce once
123
What are the potential reasons for semelparity?
Predation satiation - large numbers of predators, making huge amount of seeds the predators will be full
Increases recruitment after a fire - seeds left in seed bank so after a fire they can grow without competition
124
Give two examples of plamts that can be dormant for large periods of time
Sacred lotus is dormant for 1400 years
| Silene stenophylla dormant for 32,000 years
125
What is masting?
Where semelpatric plants synchronise their flowering over vast areas
126
What controls dormancy in plants?
Hormones e.g. Auxins promote and gibberelins break
After ripening - i.e. A set time
Abiotic factors - light or temperature dependant
Physical dormancy - seed coat needs to crack
127
In angiosperms the gametophyte is _______ large
One cell
128
Describe the process of making female gametes in an angiosperm
Ovary produces ovules (aka the mega gametophyte)
Single diploid nucleus, splits by meiosis into four haploid nuclei. 3 of the fpur die. Other matures by mitosis
8 haploid nuclei within 7 cells.
One cell becomes the egg some become polar nuclei
The rest become either synergid or antipodal sacs that reside on either side of the embryo
129
Describe the production of male gametes in angiosperms
Single diploid nucleus splits by meiosis to produce four haploid nuclei
Each nuclei becomes a pollen grain which occurs by mitosis
Each pollen has two nuclei:
1) generative nuclei which forms two male gametes
2) tube cell
130
What is pseudocopulation?
Plant looks like an animal, other animals of same species try to mate with it. In doing ao they pollinate them
131
Describe how the fertilisation occurs in an angiosperm
Cell nucleus produces a pollen tube
| Generative cell splits and produces two sperm cells whic follow down the polen tube into the embryo sac
132
Describe the double ferilisation in angiosperms
One pollen nucleus fuses with two polar nuclei to form the endosperm 2/3 maternal 1/3 paternal
Other two fuse with an egg to form the zygote 1/2 paternal 1/2 maternal
133
Give two methods of self fertilisation can be done
Imperfect flowers have male and female parts, either on different plants (diocious) or different flowers (monoecious)
Self incompatiable - through use of S genes 50 types of s gene if s gene in pollen is the same as the stigma thenpollen tube is aborted
134
The animals are a _____phyletic group
Monophyletic
135
How many described species are there and how many estimated species are there?
1 million described
| 10 million estimated
136
What are the six features of animals?
Eukaryotes
Multicellular and held together by collagen
Heterotrophic- must take in preformed molecules
No other groups have Muscle and nervous systems (not all animals do)
No cell wall
Unique cell junctions (tight gap and desmosomes)
137
Define the three types of junction
Tight junctions - continuous belt that seal layers of epithelium
Desmosomes - anchoring junction formed from keratin, glues cells together
Gap junctions - communicating junctions that allow molecules to pass through
138
Describe animal development from a zygote
Zygote is cleaved to an 8 cell ball and again to a blastula
Inside the hollow blastula is the blastocoel
Blastula evaginates this is gastrulation and forms the gastrula
Point of evagination is the blastopore
139
The number of hox genes is associated with what?
Body plan complexity
140
What are hox genes?
Genes expressed during embryonic development that form the basis of the diversity of life
141
What is the monophyletic ancestor of all animals? What evidence is there for this?
Colonial heterotrophic flagellate similar to current choanoflagellate
- have flagellum surronded by microvilli used for filter feeding
- single flagella like cilia
- similar mitochondria structure
- DNA evidence
142
Describe how ontogeny reflects phylogeny in animal evolution
The protist evolved into a hollow ball of cells of which some become specialised, some gastulate
This is similar to how animals today develop, hence ontogeny reflects phylogeny
143
How do we infer evolutionary relationships?
Paleontological evidence
- fossil record earliest animal 600mya, diversification occured in cambrian
Anatomical - shared derived homologus structures
Developmental similarity - patterns of cell division
Biochemical similarities- DNA etc
144
Give the four basic body plan diversifications that are used to build phylogenies
True tissue formed by gastrula
Symmetry
Presence of body cavity
Pattern of coelom development
145
Gastrulation is the first step in our phylogency, describe how it is used to split up the animal kingdom
Development of tissues in at least two layers - endoderm and ectoderm
Seperates the parazoa no true tissue e.g. Sponges from eumetazoa which are everything else
146
After gastrulation the next determinant in our phylogency is ________
Radial or bilateral symmetry
147
Describe the differences between radial and bilateral symmetry and what groups they split up
Radial symmetry have a top and bottom whilst bilateral have anterior (front) and posteria (back) as well as dorsal (upper side) and ventral (bottom)
Radiata are diploblastic whilst bilateria are triploblastic
Radiata are the jellyfish bilateria are everything else
148
Via the evolution of body cavities seperate acoelomates, pseudocoelomates and coelomates
Acoelomates - solid body between digestive tract and outerbody, no anus. E.g. Flatworms
Pseudocoelomate - gut that runs from anus to mouth but it isnt completely lined with mesoderm e.g. Nematoda
True coelomate - coelum lined with mesoderm e.g. Earthworm
149
What is the function of the body cavity
Protection
Enables organs to grow independently of the body
Allows movement
150
In four points seperate protostomes from Deuterostomes
Early embryo - spiral cleavage in protostome radial cleavage in Deuterostomes
Cell fate - determinate growth in P indeterminate growth in
Coelom development- schizocoelous: solid masses of mesoderm split in P
enterocoelous in D : out pocketing of endoderm (archenteron)
Blastopore fate: Protostomes blastopore becomes mouth and anus forms seperately, deuterostomes blastpore become anus and mouth forms sepertely
151
When looking at DNA phylogenies rather than body plans the protostomes are split into clades which are? Where does it put acoelomates
Lophotrochozoa- annelids and molluscs
Ecdysozoa - arthropods and nematodes
Aceomates once had a coelom and lost it, puts them into Lophotrochozoa
152
Parazoa are the most basal animal how so? What phylum do they contain? Describe this phylum
No symmetry or gastrulation
Sponges (porifera) of which there are 5000-10000 species
- have a simple body plan
- lack nervous system muscles and organs
- rigid sessile perforated sack
153
How do sponges feed ?
Water drawn into the spongocoel through porocytes by action of flagella
Passed out of the osculum
Water moved over chanocytes by flagella, food particles caught on the collar of cillia
Amoebocytes pick up food from chanocyte and distribute it to other cells
154
Describe how sponges can reproduce asexually and sexually
They are hermaphrodites - but only male OR female at any one time
They can bud off from parent sponges and grow
155
Which phyla contains jellyfish, hydra and corals? What sort of symmetry do these show?
Cnidara - around 10,000 species
| Radial and diploblastic
156
Describe digestion in radiata
Ingest food in the gastrovascular cavity and the mouth is the same as the anus
157
There are two forms of cnidaria what are they?
Polyp form - mouth up
| Medusa form - mouth down
158
Radiata are diploblastic what is between there inner and outer layers?
Mesoglea - jelly like substance
159
Describe cnidocytes
Parts of tenticles that sting
Contain nematocysts = organelles containg threads capable of stinging threads have spike that puncture skin and inject toxins
160
What are the four classes of cnidarian?
Anthozoa - sea anemones and corals
Scyphozoan- medusa dominant jellyfish
Cubozoan- predatory jellyfish
Hydrozoans - polyp dominant
161
What are the features of protostomia?
```
Spiral cell division
Determinate growth
Coelom forms from mesoderm
Mouth forms first
Triploblastic
```
162
What are the three phyla of Lophotrochozoa?
Platyhelminthes
Annelids
Molluscs
163
What are the Platyhelminthes? How many species ?
Flatworms with a simple body plan, no coelom but seems they had one and lost. True muscles and organs with cephalisation. No gas exchange or circulatory system.
20,000 species
164
What are the three classes of Platyhelminthes
Tubellaria - free moving marine animals. Predators with a blind ending. Twin ventral nerve cords.
Trematoda - parasitic flukes e.g. Blood fluke (human primary host in which it produces eggs, enter secondary host and secondsry type or larvae emerges which moves back to humans)
Cestoidea - paraistic with hooks and suckers for attachment
165
Describe annelids
12,000 species
Linear bodies
Septa divides coelom making it segmented
Each segment has a circular blood vessel and a metanephrida fo deal with waste
Body has inner longitudinal muscles and outer circular muscles
Closed circulatory system
166
What are the three classes of annelid?
Oligochatea - earthworms
Polychaeta - marine segmented worms
Hirudinea - leeches, blood sucking parasites
167
What are two important evolutionary features of the annelids ?
Well developed coelom giving a hydrostatic. Gives space for organ systems
Metamerism - specialisation of body regions
168
Describe mollusca phyla of protostomes
50,000 species
- trochophore larval stage - completely different to adult stage
- not segmented
Foot for locomotion
Visceral mass where internal organs are kept
Mantle - fold tissue responsable for creating a shell
Many have a radula (tounge)
169
What are the three classes of molluscs ?
Gastropods 40,000 species
Bivalivia 7,000 species
Cephalopod - 600
170
Describe the gastropods
Typical mollusc body plan
Coiled shell
Mantle acts as a lung in terrestrial gasteopods but most are marine
Mantle cavity is moved over the head and visceral mass rotates 180 degrees. This is torsion.
171
Describe bivalvia
```
7000 species
- shell in two halves
Laterally compressed body and foot
Mantle has gills for filter feeding
No head or radula
```
172
Describe cephalopods
600 species
Beak like jaws often have venom
Muscular siphon is a heavily adapted foot used for propulsion, tendtacles derived from foot
Mantle is used as a below to push water out of the siphon
E.g. Octopus
173
Why are the ecdysozoa so called?
Ecdysis is the shedding of an exoskeleton
174
What are the two main phyla of ecdysozoa?
Nematodes
| Arthropods
175
Describe nematodes
90,000 species
Coelom is not fully bound by the mesoderm, - pseudocoelom
Cylindrical unsegmented body tapering at the tail
Outer cuticle which is shed as they grow
Complete digestive tract
No circulatory system
Free living or parasitic
176
What is the density of nematodes in soil
1 cubic meter contains over 4 million
177
Describe the arthropods
1 million described species
Body covered by jointed exoskeleton made of chitin and protein making them water proof - allows land exploration
Inekastic cuticle requires shedding
Cephalisation and sensory organs
178
Describe the circulatory system in arthropods
Haemolymph - combines blood and lymph pumped through a tubular heart into an open circulatory system.
179
Describe the subgroups of arthropods
Trilobites
Chelicerates - spiders, horseshoe crabs and ticks. No antennae have a cephalothorax and an abdomen
Crustacea - 40,000 species two pairs of antennae 3+ mouth parts thorax has branched legs
Uniramia - unbranched appendages chilopoda - centipedes and diplopoda - milipedes and hexapodia
180
Describe hexapodia
```
The insects
3 tagmata, bead thorax and abdomen
One antenna
Efficient gas exchange thriugh trachea
Spircales regulate air flow
Complex sophisticated sensory organs
```
181
What are feature of the Deuterostomes? (Over protostomes)
Radial cleavage
Indeterminate cell fate
Coelom forms from archenteron (endoderm)
Blastopore becomes anus
182
What two phyla do the deuterostomes divide into?
Echinodermata and the chordates
183
Give features of the echinoderms
Starfish, sea urchins and brittle stars 7000 species
Sessile or slow moving
Radial symmetry in adulthood but bilateral larvae
They are pentamerous (radiate from a disk as five spokes
Thin skin over an internal endo skeleton
Anus in top mouth on bottom
No cephalisation
184
Describe the three main systems in starfish
Digestive - connected to stomach, within each arm there are digestive glands. 2 stomachs one can move out of the mouth to absorb nutrients.
Reproductive- either male or female, gametes released into the water
Water vascular - ring cannal runs out of central disc.
Madreporite which is an opening to let water enter the body.
Radial cannals come of the ring into each arm that connects to each tube feet. Ampulla is near each tube foot acts like top of pippette.
185
What is a madreporite? (Echinoderms)
Opening to allow water into the body
186
What is a radial cannal?
Come of the main ring into each arm
187
What is an ampulla? (Exhinoderms)
Ampulla near each tube foot
| Acts like a pippete enables feet to move
188
```
The five classes of echinoderm are:
Asteroidea
Ophiuroidea
Echinoidea
Crinoidea
Holothruoidea
Give examples of species in these groups
```
Asteroidia - starfish - prey on molluscs, everts stomach into prey. They are totipotent - can regenerate whole arms
Ophiuridea - brittle stars. Distinct central disc
Echinoidea - sea urchins and sand dollars. No arms, slow movers and often are grazers
Crinoidea - seal lillies and feather stars. Very ancient organisms
Holothuridea - sea cucumers - tube feet act as tenticles
189
There are five accepted classes of echinoderms but there is a potential 6th class, what is this?
Concentricycloidea - sea daisies
| They have pentamerous symmery so could be placed in those group
190
When did the chordata diverge from the echinoderms?
500 million years ago
191
What are the key features of the chordata ?
Notochord - long flexible rod running the length of the body, prevides
Pharyngeal slits- slits in throat region of digestive tract allow water to pass through front end becomes a brain
Dorsal hollow nerve chord - rolled up plate of dorsal ectoderm
Muscular post anal tail
Many have a ventral heart
192
What are the three subphyla of chordates?
Urochordates
Cephalochordates
Vertebrates
193
Describe the urochordates
Sea squirts
Adult form sessile filter feeder
But larvae have all four chordate features, once it metamorphoses into adult form it loses chordate characteristics (other than pharyngeal slits)
194
Describe cephalochordates
Live in sand
All four chordate features in adulthood
Similar to fish in swimming movements
E.g. Brachiostoma
195
All chordates except the ________ have muscle segmentation . How do the segments devleop?
Urochordates
| Segments develop from blocks of mesoderm arranged along a notochord
196
3 hypothesis for evolution of segmentation
Three separate evolutionary events (annelids arthropods and chordates)
Evolved twice once in chordates and once in the Lophotrochozoa, lost by urochordates and non segmented Lophotrochozoa
Evolved once and lost many times
197
What is a theory of Cephalochordate evolution from urochordates?
Evolved from larval urochordates via paedogenesis
| Sexual maturity in larva
198
How many vertebrate species are there? What makes them vertebrates?
```
40,000
Formation of neural crest during development
Cephalisation
Developed sesnory organs
Segmented vertebral column
Closed circulatory system
```
199
When did vertebrates first appear in the fossil record?
550mya
| In late precambrian
200
What are the two major vertebrate groups?
Gnathostjomes - with jaws
| Agnathastomes - without jaws
201
Describe the Agnatha
Most are extinct known as ostracoderms (shell skinned)
Heavily armoured jawless fish, dominanted silurian and devonian
Pectroal fins are absent
202
Why did the agnatha mostly go extinct?
Outcompeted by the jawed fish
203
How many species of modern agnatha are there?
60
204
Describe the agnatha type hagfish
No vertebrate
Cartilaginous skull
Often scavengers (go through anus and eat there way out)
Isotonic with sea water
205
Describe the type of agntha lampreys
Predators or parasites of fish
Marine or freshwater
Convergent evolution means they are similar to tapeworms
Cartilaginous vertebral column
206
What is key evolutionary about the Gnathostoma?
Two pairs of appendages
207
What are the 3 classes of jawed fish?
Placodermi - plate skinned, now all extinct. Heavily armoured with cleaver plates adapted to biting
Chondrichthyes - cartilaginous fishes - 750 species rays and sharks
Osteichthyes - bony fishes 30,000 species. Calcium based endo skeleton. Has a gas sac organ - lung or swim bladder
208
describe the chondrichthyes (cartilaginous fish)
includes sharks and rays
flexible endoskeleton made from cartilage
covered in placoid scales very similar to teeth
well developed jaw and paired fins
five pairs of gill pouches
209
what ada[potations do condrichthyes have for being predators?
sharp vision (no colour)
good sense of smell
lateral line system
detect electric fields through electroreceptive organs
210
give defintions to do with the following (all to do with egg laying)
- oviparous - lays eggs
- ovoviviparous - young hatch internally and feed on egg yolk
- viviparious - young mature internally fed by mothers blood
211
why is Important that condrichthyes keep swimming?
heterocercal tail and wing like pectoral fins. must keep swimming or they sink. must keep swimming to move water over gills.
212
describe squalamine in the condrithyes species of dogfish
cholesterol like substance squalamine make sharks resistant to a lot of viruses
combat hepatitis
positively charged, on entrance to cell it remomves any positive proteins needed for viral attachment
213
describe osteichthyes
the bony fish (30,000 species)
endoskeleton made of calcium phosphate, skin has a flattened bony scale more like armoured fish
have a gas sac organ used for either a lung or swim bladder
214
what is meant by a fusiform shape?
tapered at both ends for hydrodynamics in fish
215
what are the three classes of osterichthyes?
lobe finned fish - actinistia, heavy pectoral and pelvic fins. bottom dwellers.
dipnoi - lungfish, has lungs
ray finned fish - Actinopterygii, reduced scales for increased mobility. increased buoyancy due to swim bladder.
216
when and why was there a pressure for organisms to move out of the water onto land?
during Devonian there was a lot of cyclic weather = drying out therefore less habitat for fish.
insects had evolved so abundant prey
no predators on land yet, many marine predators
217
describe the first tetrapods
tiktaalik alive 375mya
- are the transitional form between terrestrial and marine organisms
- flattened head similar to crocodiles
- heavy skeletal structure of the fin
- lungs and nostrils
218
there were some more transitional forms of tetrapod found. what are their names going from spending most time in water to being semi aquatic to be a land organism. with each give the number of fingers it had, why is this significant?
acanthostega - 8 thin fingers
ichthyostega - 6 and 1/2
eryops - 5
shows the evolution of the pentadactyl limb
219
give arguments for lobed finned and lungfish being the closest ancestor to amphibians.
lobe finned fish - teeth, skeleton, braincase, and fin structure. no breathing apparatus
lungfish - lungs and nostrils for breathing but appendanges aren't the same. mtDNA backed
220
how many species of amphibian are there?
4800
221
give 7 challenges to moving on land as an animal
```
UV light
physical body support
sense modification
deal with variable senses
water loss through breathing air
water loss through skin and excretion
desiccation of sperm and egg cells
```
222
what are the five adaptations of the amphibians?
lungs
epidermis with UV attenuating chromatophores
skeleton with paired appendages
sensory adaptations - tear ducts and basic ears
metabolism - 3 chambered heart
223
what are the three orders of amphibian ? give brief descriptions of each
urodela - newts and salamanders 400 species
aquatic or terrestrial, most basal, long tail
Anura - frogs and toads - 3500 species
tailless, v diverse in the tropics
apoda - legless 150 species
often subterranean, blind, some look like earthworms via convergent evolution
224
what is a key reason why amphibian diversity has reduced even in pristine habitats?
chytrid fungus
225
what does paedomorphic mean
slowed development in larval form when sexual maturity is reached = neoteny. salamanders will remain neotenous until there is enough iodine
226
describe the amniotic egg
self contained, water proof chamber for development.
227
describe the structute of the amniote egg (6 layers)
shell - waterproof
albumin - contains some nutrients and an air sac
chorion - regulates gas exchange
yolk sac - surrounds embryo which regulates gas exchange
allantois - grows out from embryo stores nitrogenous waste
amnion - filled with fluid to protect the egg (this is water breaking)
228
there are three types of amniote linage what are they based on?
number of windows into the skull (fenestra)
1) anapsids - no fenestra e.g. turtles
2) diapsids - two fenestra reptiles and some birds
3) synapsids - one fenestra all mammals
229
what is the purpose of skull fenestra ?
jaw muscles can attach to the skull
230
describe the reptiles
7000 species
paraphyletic group
lack a single characterising feature
basically amniotes that aren't mammals or birds.
231
reptiles, being ectotherms need ______ the heat as an endotherm would.
10%
232
when was the first radiation of amniotes ? what groups were formed
early Permian
- anapsids diapsids synapsids
- diapsids split again to get lepidosauria (snakes lizards) and archosauria (dinosaurs and crocodiles)
233
when was the second radiation of amniotes? what groups did it form
Triassic
- crocos
- pterosaurs
- dinosaurs
234
give evidence to support both sides of the debate as to wether the dinosaurs were ecto or endothermic.
endothermic
legs beneath body - increases stride so needs lots of energy
vascularised bones and predator prey ratios - similar to current
ectothermy - Mesozoic was very warm. large body so heat could have been stored since there was a low surface area for the heat to escape
235
what are the three modern day orders of reptile?
chelonia - turtles ( marine), terrapins (freshwater), terrestrial (torotoises) 250 species
squamata - lizards and snakes 4000 lizards, 2500 snakes.
crocodilia - 22 species
236
describe the reptile order chelonia
marine turtles, freshwater terrapins, terrestrial torotoises
teeth replaced with sharp horny plates
can retract limbs and neck
237
describe the reptile order squamata
4000 lizards and 2500 snakes
- snakes have lost limbs
- lost eyelids
- jacobsons organ allows for very good sense of smell
- pit organs to sense heat
238
describe the reptile order crocodilia
22 species
- extant adapted to water living
- broad flattened rail
239
the birds are a _______phyletic group
monophyletic
240
birds don't have teeth to hep keep their centre of mass central. what do they have instead
gizzard near their centre of gravity
241
describe the structure of wings
aerofoil shape
supported by pentadactyl limb
feathers made of central shaft with barbs and barbules.
242
four different types of feather
contour - over lie the body to give bird their outer shape
down - underneath contour, trap air for insulation
flight - posterior trailing edge
filo plumes - very small with some sensory function
243
from whom did the birds arise from?
bipedal dinosaur e.g. velociraptor
244
why is it hard to say when a reptile became a bird? give two possibilities for the first bird.
reptile to bird evolution Is a continuum since birds still share some reptilian features
archaeopteryx or auroronis 10MYA earlier.
245
give the three theories for how flight in birds evolved
hypothesis 1: ancestor chasing insect prey, feathers aided running jumping and gliding.
hypothesis 2: feathers aided running up inclines then gliding. wing assisted incline running hypothesis
hypothesis 3: arboreal ancestors - feathers adapted to enable gliding to the ground or from tree to tree
246
describe the bird sub phylum ratites
flat chested
wide sternum stuggests they once had flight but they have now lost it. four separate groups: rheas S.america ostrichets Africa, emu and cassowary Australia, kiwi new Zealand
247
describe the bird sub phylum carinates
24 orders with 10,000 species
fying birds
great variety.
248
from what major radiation did the mammals arise?
end Mesozoic
249
how many species of mammal are there?
4500
250
what are the features of the mammals
```
endothermic
hair made from keratin
skin glands - the mammary gland
efficient respiratory system
limbs beneath body
synapsid skull
single bone jaw
```
251
describe the mammalian ear
three bones (as opposed to reptiles that only have a staples). staples incus and malleus. derived from bones in the amniote jaw
252
describe mammalian teeth
```
heterodont - different teeth types
incisors for cutting
canines for piercing and ripping
premolars for crushing
molars for grinding
```
253
give the dental formula for humans placental mammals and marsupials
humans: 2-1-2-3
placental mammals: 3-1-4-3
marsupials: 5-1-3-4/4-1-3-4 (upper/lower)
254
what are the three main groups of mammal
protheria - monotremes (the weird ones egg laying with mammary glands e.g. platypus and echidna)
marsupials - pouched mammals
eutheria - placental mammals
255
what are the four lineages of mammal based on dna evidence
afrotheria - evolved in Africa. includes elephants, manatees hydraxes and aardvarks
xenarthra - south American, e.g. sloths anteaters and armadillos
Laurasiatheria - the carnivores, hooved and the whales
boreoeutheria - rodents, rabbits, tree shrews, primates
256
manatees and elephants are in the mammalian lineage afrotheria. what is there latin names?
proboscidea - elephants
| sirenians - manatees
257
the mammalian group of the laurasiatherians is very large. break it down into smaller groups
insectivores - 375 species
chiropterans - bats 925
carnivores
artidactyls - 220 species the even toed mammals e.g. sheep.
perissodactyl - horses and rhinos - odd toed organisms.
cetaceans - whales, adapted for aquatic life, monphyletic with artodactyls
258
what is the difference between horns and antlers
antlers branch and are shed annually, horns don't branch and aren't shed.
259
what is the most likely ancestor to the primates?
small cretaceous insectivore
260
give evidence to suggest the closest relative to the primates was arboreal (7 features)
supple (bendy) shoulder joints allowing for brachiation (swinging from tree to tree)
hands adapted for climbing
nails replace fingers
front facing eyes - binocular vision allows depth of field
larger skull and braincase - optic lobe
long parental care
omnivores
261
what are the two major groups of primate?
prosimians (pre monkeys) and anthropoids (monkeys apes and hominids)
262
give features of the primate group, prosimians
two major lineages
lemurs from Madagascar: nocturnal, with small non binocular eyes. small brain and a pronounced nose
tarsier: mostly nocturnal. larger eyes but smaller olfactory regions
263
describe the primate group anthropoids
```
monkeys apes and humans
monphyletic
reduced nose and sense of smell
colour vision
social groupings develop
large brain
```
264
how is the primate group the anthropoids further subdivided?
platyrrhini - new world monkeys. wide spread nostrils. arboreal with a prehensile (gripping) tail. 3 premolars
catarrhini - old world monkeys, apes and humans. have a drop nose which is narrower and points downwards
265
the old world monkeys or the catarrhini can be further subdivided into?
Cercopithecoidea - old world monkeys, have sitting pads (ischial callosities). coated in colourful skin. e.g. babbons
no prehensile tails
2 premolars
hominoidea - hylobatidae (gibbons) and the pondidae ( apes) very large brains
266
what specialisations do hominids gain when they diverge from apes?
```
elaborated brain enables speech,
larger brain capacity
prolonged post natal development (parenting behaviour)
erect posture
strong thumb
```
267
what are the modifications to the skull when humans diverge from apes
```
enlarged frontal regions
shortened face and snout
recedeing jaws
fewer teeth which become rounded
chin develops
```
268
describe the first bipedal hominid
Australopithecus
4.5 to 1.5 million years
1/3 brain size of modern humans
heavy jaw
269
what period did homo erectus live for
1.5 mya to 25kya
270
when where Neanderthals present? describe them
130kya to 35kya
evidence to suggest they had cultural rituals e.g. burying the dead
skilled toolmakers
271
once homo sapiens arise they undergo a cultural evolution. give three key steps in this
2.5 mya division of labour - tribes
15 kya - agricultural revolution enables cities to form
1800s industrial revolution
