no clue Flashcards
Which features of life cycle, structure and physiology are common to the
protist green algae and land plants, and which are unique to land plants?
common to the protist green algae and land plants
-alternation of sporophyte and gametophyte generations
-growth arising from specialised regions called apical meristems- (more
complex in land plants than in algae)
-photosynthesis in plastids with chlorophyll a, b and carotenoids, energy
stored as starch
-requirement for light, water, mineral nutrients CO2 and oxygen
-cell walls of cellulose
unique to land plants
-an embryo arising from the union of male and female gametes that is
protected and nourished by the female gametophyte/or endosperm
-the spores produced by the sporophytes are dispersed by air, not water.
-multicellular sex organs with cellular walls that do not develop into gametes.
- meiotic and mitotic nuclear divisions in which the nuclear membrane and
nucleoli breakdown in prophase, and centrioles are only seen at meiosis in
cells that develop into motile sperm
In which major phyla of the land plants is the sporophyte larger than the
gametophyte, and in which is it smaller?
Gametophyte larger than sporophyte –phyla – Hepatophyta, Bryophyta
Sporophyte larger than gametophyte- phyla- Filicophyta, Cycadophyta,
Coniferophyta, Anthophyta
Explain why bryophytes and ferns are mainly found in moist areas
These motile sperm of these groups requires free water to swim to fertilise the
egg in the archegonium. In addition Bryophytes lack roots and usually also
cuticle.
Describe which parts of the cycad life cycle are diploid and which are haploid.
The palm-like plant with its cones is the diploid sporophyte. In the cones
inside the ovules there is a haploid female gametophyte. On male plants the
pollen is haploid. The zygote formed from fertilisation of the egg by the sperm
is diploid.
List (i) the distinguishing characteristics of angiosperms,
(i) the distinguishing characteristics of angiosperms
Flowers
Double fertilisation and endosperm
Seed enclosed in an ovary
and (ii) the
distinguishing features of monocots and eudicots.
Monocots
One cotyledon
Fibrous root system
Main leaf vein linear
Floral parts in multiples of 3
Vascular bundles of the stem scattered
No secondary xylem
eudicots
two cotyledons
tap root
leaf veins a network
floral parts in multiples of 4 or 5
vascular bundles in a ring
secondary xylem (wood)
describe the structure and function of the xylem
Xylem has parenchyma, fibres, tracheids and (in almost all flowering plants)
vessels. Water transport is in tracheids and vessels, elongated cells with walls
strengthened with cellulose and lignin. Cells are dead at maturity and in
vessels the end walls are eliminated during development. Function -water and
nutrient transport in an upward direction from roots to leaves.
describe the structure and function of phloem
Phloem consists of parenchyma, fibres, sieve tubes and companion cells. The
sieve tubes lack a nucleus at maturity but have some cytoplasm and conduct
sugars and other metabolites both upwards and downwards in strands that run
through perforated sieve plates at the ends of the cells. Companion cells
function in the loading and unloading of the sieve tubes.
explain how water and CO2 enter leaves for photosynthesis
Water uptake by roots and transport in xylem, pulled to the leaves by the
transpiration stream
CO2 through stomata (very slow diffusion through epidermis when stomata
are closed)
explain how sugars produced by photosythesis are transported throughout the plant body
sugars are transported by the phloem in the sieve tubes, movement is in excess of diffusion and explained though the pressure flow hypothesis.
Why is the terrestrial environment described as the harshest of all
environments for life?
The need for animals to have a high moisture content of cells, and to have a
moist surface across which oxygen uptake can occur makes the terrestrial
environment more ‘harsh’ than a marine or aquatic one
In what ways is the cnidarian body plan more complex than that of the
poriferans?
In contrast to poriferans, cnidarians have distinct tissues in their bodies
What special problems are presented by a parasitic lifestyle and how do
parasitic flatworms and nematodes overcome them?
-reproduction and finding new host- /reproduction may involve a motile stage
that finds a new host, and or an intermediate host that is eventually eaten by
the final host
-attachment to the lining of the host gut-/ special mouthpiece adaptations such
as the scolex in tapeworms or the piercing mouth parts in nematodes
-avoiding being digested by the host- / a resistant cuticle
- A cephalopod and a snail look very different, but they are both classified in the
Phylum Mollusca. What features are shared by cephalopods and other
molluscs? What features are unique to cephalopods amongst the molluscs?
Common features
-main body cavity a haemocoel, (not a coelom)
-formation of a mantle from outgrowths from the dorsal surface
-radula- (although cephalopods also have beaks as well)
-trochophore larva that develops into a veliger larva
Differences
-muscular foot is modified into a ring of tentacles in cephalopods
-cephalopods have a beak as well as a radula
-cephalopods have a closed circulatory system whereas gastropods and other
molluscs have an open circulatory system
The arthropods make up the great majority of animal species and in turn most
of the arthropod species are insects. From your knowledge of the biology of
insects and the other invertebrates, suggest why there are so many insect
species
- diversity of habitats/food sources drives diversity of speciation. as they can utilise a wide array of habitats and huge numbers of food rescources
- flight = enables them to exploit temporary resources, escape predators and disperse widely.
- the possibility of 2 life stages (egg and pupa) besing resistanct to environmental extremes such as heat, cold or drought enabling many habitats to be exploited
Early biologists classified cnidarians and echinoderms together in one phylum,
the Radiata, because they all had radial symmetry. On what basis are they now
placed in two distinct phyla?
Cnidarians have a very simple body structure lacking the deuterostome
development seen in the echinoderms. Echinoderms also have bilaterally
symmetrical larvae.
List the major distinguishing characteristics of (a) chordates and (b) vertebrates
Chordate characteristics:
a notochord, a ventral nerve chord, pharynx pouches
at some stage of development, an endostyle, metameric organisation and a postanal tail.
Vertebrate characteristics:
a body plan with head, trunk and post-anal tail all
supported by an endoskeleton; organ systems including a well-developed brain
and paired sense organs, a complete digestive system, an endocrine system, a
closed circulatory system and excretion by paired kidneys; a body covering with
many different adaptations and a neural crest in the embryo.
List the milestones in vertebrate evolution. How were these associated with the
movement of vertebrates from aquatic to terrestrial environments?
development of jaws/ enabled use of a much wider array of food sources
growth of legs/associated with movement on land of water,
development of the amniotic egg/ allows embryonic development within a
protective shell that still allows oxygen transfer and provides the embryo with
an ‘aquatic’ environment
respiration using lungs /internal lungs mean that the moist oxygen uptake
surface is protected from dehydration compared to exposed gills.
increases in the number of heart chambers/ enables efficient use of lungs with
separation of deoxygenated blood to be pumped to the lungs, and oxygenated
blood for circulation to tissues
describe breifly the major applications of population ecology
- biological control- predicting the fall in a population resultant from the introduction of a disease or pest
- sustainable harvesting - predicting the population numbers that result from different intensity of harvesting or harvesting cohorts of different ages
- recovery of endangered species- in situ or on translocated populations
What are the common characteristics of all communities?
Interactions between different species of organisms,level of species richness
and diversity, presence of dominant/keystone species, trophic relationships
(=feeding relationships)/energy flow
Distinguish between species richness and species diversity
Species richness is the number of different species in a community
Species diversity expresses the number of different species and their relative
abundance
List the six main types of interactions between organisms in a community and
indicate which of the participants benefit, are harmed or are unaffected
Neutralism = neither species affected
Commensalism =one species benefits, no effect on the other
Amensalism = one species harmed, no effect on the other
Mutualism = both species benefit
Predation = one species benefits, the other harmed
Competition = both species disadvantaged
Explain the difference between primary and secondary succession.
Primary succession is a sequence of communities that replace one another
until a climax community is reached
Secondary succession occurs when a climax community is altered by a
disturbance and the community changes to re-establish the climax community
or an alternative stable state
list the main physical and chemical parameters that determins the water quality in a wetland
light, temp, oxygen, pH, salinity and nutrients
what facactors in the aquatic environment reduce the depth light penetrates into the water
dissolved substances such as tannins, silt and phytoplankton
What human activities are likely to cause an increase in the salinity of a water
body in an area with saline ground water at depth?
activities that casue a rise in the ground water level such as excessive irrigation or removal of trees/perennial vedgetation and its replacement with annual crops
Why is the availability of phosphorus often of more interest than the
availability of nitrogen in freshwaters subject to eutrophication?
eutrophic water bodies usually have populations of N-fixing cyanobacteria and are thus more likely to be phosphorus limited than nitrogen limited
What is meant by the thermal stratification of a water body and what factors
might disrupt such stratification?
thermal stratification is the separation of lake waters into layers of different temperature and thus density
disruption is caused by wind and change of season.
explain the difference between lotic and lentic waters
Lentic (standing water: lakes and wetlands) and lotic (flowing water: rivers and
streams).
why are macrophytes important to wetland function? what functions do they perform?
They photosynthesise thereby oxygenating the water during daylight hours,
recycle nutrients, stabilise sediments, reduce scouring and providing a
habitats for aquatic organisms.
list the components of a detritus based food chain
dead organic matter and feces. vertebrates and invertebrates that eat dead and decaying organic matter and microbes (fungi and bacteria) that break it down.
As you move from the surface waters to the bottom of a deep lake what
environmental factors will change, and what kinds of organisms might be
present.
Decrease in light, change in wavelengths present, decrease in temperature,
decrease in daily and seasonal fluctuations in temperature. Photosynthetic
organisms only to the compensation depth, carnivores, detritivores and
decomposers below this depth.
List the major physical features of marine environments important in
controlling the abundance and distribution of organisms.
water salinity, temperature, light intensity, substrate, tides and wave velocity
what are the main physical andbiotic fatures of seagrass habitats
seagrass habitats- physical: soft substrates, calm areas, depth dependent on
water turbidity. Biotic : leaves are substrate for epiphytes and epizoa, swards
form habitat, shelter, breeding areas for many fish and invertebrates.
what are te main physical and biotic features of mangrove habitats
mangrove habitats- physical: soft marginal substrates that are sheltered and
gently sloping and subjected to at least a 1m tidal range, generally restricted
to above 24o
C isotherm. Biotic: high primary production, nursery area for
many fish, habitat for birds, bats and insects
salt marsh habitats
salt marsh habitats- physical: under the 24°C isotherm, a tidal range of 0.5 m
or more, a soft substrate and protected shores. Biotic : primary productivity
important to invertebrates and birds, detritus also important in food webs.
Compare and contrast the temperature regulation mechanisms of a
poikilotherm such as marine jellyfish with those of a homeotherm such as a
dolphin, a marine mammal. What are the advantages and disadvantages of
each method?
Poikilotherms cannot regulate their body temperature so their internal
temperature is the same as the external environment.
Homeotherms, regulate their body temperature through metabolic activity,
muscular activity and/or altered blood flow.
Explain, using marine examples, the differences between osmoregulators and
osmoconformers.
Osmoregulators maintaining concentrations of dissolved substances inside
their bodies different from those of the environment (marine birds, reptiles,
mammals and fish)
An osmoconformer has cell contents at the same osmolality as the
surroundings (most marine invertebrates, echinoderms, cephalopods,
coelenterates, polychaetes, and most marine molluscs and crustaceans).
What dispersal strategies are used by marine animals and how are these
accommodated when designing marine reserves?
dispersal strategies -mobile adults, crawl away larvae, planktonic larvae
dependent on ocean currents or larvae that are strong swimmers.
Marine reserves should conserve the habitats of all stages of the life cycle of
key organisms, should also be a source of propagules to populate adjacent
areas.
Describe, with examples, how (a) animals and (b) plants may be adapted to
cold environments
(a) animals, thick fur/ fat layers (arctic wolves, polar bears) , torpor
(Leadbeaters possum), hibernation (Burramys), behavioral patterns (penguins
huddling)
(b) plants- low streamlined shape (cushion plants), hairy leaves ( ), deciduous
leaves (oak)
Describe, with examples, how (a) animals and (b) plants may be adapted to
hot, dry environments
(a) animals aestivation (desert frogs), life cycle with resistant stages during
the dry season (many insects), burrowing (frogs, lung fish, bilby), migration
(Bogong ) nocturnal activity, crepuscular activity and day time torpor
(kangaroos), concentrated urine (reptiles),
(b) plants, annual life cycle ( everlasings), small leaves, leaves with thick
cuticle and rolled edges (Triodia), hairy leaves (Banksia), succulence
(Crassula, Sarcocornia), C4 photosynthesis (Portulacca), thick cuticle
(Hakea), stomata in grooves (Casuarina, resurrection properties (moss)
How can population viability analysis be used to assist in the management of a
threatened species?
PVA is a modeling system that integrate demographic, genetic and
environmental data to predict the likely future population size under different
management options. In setting up the model often gaps in knowledge are
identified.
What limitations are there to using only a threatened species approach to
conservation?
Critical components or interactions in the community may be missed such as
pollinators or seed dispersal agents for plants. The same conservation effort
might be more usefully applied to conserving a community with acceptance
that loss of some species may occur.
What issues must be considered in setting the size and shape of conservation
reserves?
Only large reserves can support sufficient numbers of large, wide-ranging, lowdensity species to maintain long-term populations and that they can also support
large numbers of species. Large reserves also minimise the ratio of edge to total
habitat. Species averse to conditions at the edge will have more habitat available
to them in large reserves. On the other hand, the rate at which the number of new
species is added to a reserve tends to decline as total area increases. The
optimum shape is rounded, rather than a long, linear reserve because this
maximises the ratio of the area of the reserve to its perimeter and minimises edge
effects.
How does the conservation of Leadbeater’s Possum illustrate (i) the need to
understand thoroughly an organism’s basic biology before recommending
conservation measures, and (ii) the importance of legislation to encourage and
enforce conservation action?
It was incorrectly assumed that possums would recolonise regenerated logged
areas as their food was available in those regions. It was found that nesting
hollows in old trees are essential so areas must be protected from logging to
provide suitable hollows. Similarly post fire logging should be restricted as fires
help create hollows. Corridors of undisturbed vegetation are necessary to link
sites together.
(ii) Legislation was necessary to protect the areas needed from logging.
What evidence is now available that outbreaks of crown-of-thorns starfish on
the Great Barrier Reef are encouraged by human activities?
High nutrient load in runoff from agricultural areas encourages algal growth
on coral reefs which in turn supports higher survival of starfish larvae
