- storage of unwanted products.
- plant structure - cell
- plant colour and smell.
- defence against physical factors e.g. cold,
salinity, UV light.
- defence against herbivores.
- number of species increases with increase in island area.
an island of a given size number of species decreases with distance from source
- continual turnover of species where colonizations are balanced by
- Reduces chance of offspring/sibling/parent competition.
- Reduces inbreeding. 3) Increases chance of finding "safe" site.
competition i.e. competition between individuals of same species.
competition makes resources e.g. food unavailable to others.
competition occupying space, defending territory preventing others reaching
- Interspecific competition i.e. competition between different species.
- Abundant in soil seed bank.
- Small seeds.
intolerant. Germination only in open sites. Dormancy broken or germination
enhanced by high light intensity, high R/FR ratio light, fluctuating or high
temp. and/or moisture, high NO3
- Rapid growth.
- Large investment of resources in reproduction (r-selected).
- Reproduction continuous or frequent.
- Mechanisms for distant seed dispersal
(birds, insects, wind).
- Short lived.
- Genetically diverse.
- Phenotypically plastic.
- Low density wood, in trees.
- Leaves not robust
and short lived.
- Continental islands usually
have more species for their size
- Continental islands usually have a subset of mainland species; oceanic islands have a subset of those that are good at dispersal
- Oceanic islands contain a greater
number of endemic species.
islands rarely have freshwater fish.
- Oceanic island species often lose their powers of
- Oceanic island species may
differ remarkable in size from mainland species.
- nitrogen - young leaves, seeds, nectar and some
- carbohydrate - phloem and nectar, wood (structural carbohydrates)
- Lynx, 10 years
- Red grouse, 4-6 years
- Larch budmoth, 8-10 years.
Plant animal interactions. Illustrate the main benefits
plants receive from interacting with animals.
- Dispersal by attachment,
frugivory and granivory.
- Pollination, thereby increasing genetic variation and
- Both species
must have a common resource e.g., food.
- There must be intraspecific competition
between individuals of the same species.
- The performance of each species should
be better when they are separate than when they are together.
- Removal of one
species should increase the performance of the remaining species.
- The addition
of the common resource should increase the performance of both species, thereby
showing it is the limiting factor.
Plant apparancy. List features of plants which
contribute to their apparency to insects.
- geographical extent
- common abundance
- predictable and perennial
- length of time
- no. of niches, island size.
Soil condition. List 3 differences in soil conditions
between young mobile sand dunes and old fixed sand dunes.
- Low organic
content in young, higher in old.
- Higher pH in young, lower in old.
- High mineral
content in young, lower in old.
- storage of
- structural support e.g. cell walls, lignin
- plant colour
- defence against cold, salinity, UV light
- defence against
herbivores e.g. alkaloids
Social insects - 3 major traits.
- Individuals of the same species co-operate in caring for the young.
- There is a reproductive division of labour.
- There is an overlap of at least 2 generations in life stages capable of contributing to colony behaviour.
- Specialization: Low pollen/ovule ration, economic
and efficient, environmentally sensitive.
- Reduction of pollen, fusion of
parts, enclosure of nectar, special odours. Wind: High pollen/ovule ratio,
independent of animals, but very wasteful of pollen and plants.
of floral parts, separation of sexes, loss of nectar.
intermediate pollen/ovule ratio, buffered against environmental disturbances.
Reproductive barriers between species
- Ecological isolation. Populations live in different habitats and do not meet.
- Temporal isolation. Mating or flowering occur at different seasons or times of the day.
- Behavioural isolation. Males and females of the different species are not attracted to each other.
- Mechanical isolation. Structural differences in genitalia or flower prevent copulation or pollen transfer.
- Gametic isolation. Female and male gametes fail to attract each other, or are inviable.
- Hybrid inviability. Hybrid zygotes fail to develop, of fail to reach sexual maturity.
- Hybrid sterility. Hybrids fail to produce functional gametes.
- Hybrid breakdown. The offspring of hybrids have reduced viability or fertility.
- specialization, e.g. odours, reduction of pollen, fusion of parts, enclosure of
nectar, e.g., hammer orchid, yucca
- wind, e.g., reduction of floral parts, loss of nectar, separation of sexes,
e.g. festuca rubra
- non-specialisation, e.g.- formation of groups of flowers with more or less
exposed nectar, e.g., bellis perennis
The main parts of a flowering plant and their function.
- Flower. Generation and reproduction. Can be hermaphrodite or bisexual, producing the pollen grain or containing the ovule, or both. Female and bisexual flowers produce the seed when they are fertilised.
- Stem. Carries solutes from roots to leaves. Carries flood from leaves to other parts of the plant. Bears the leaves in a position for photosynthesis. Displays the flower for pollination. Exposes the seeds for dispersal.
- Leaf. Respiration - taking in oxygen and giving out carbon dioxide and water. Transpiration - giving off excess water in the for of vapour. Photosynthesis - making food from light.
- Roots. Anchor the plant to the substrate. Absorb inorganic salts in solution. Transports nutrients to leaves.
4 basic types of animal tissue
- Epithelial - a sheet of cells that covers an internal or external surface, e.g. lining the lungs, skin
- Connective tissue - binds and supports, e.g. bone, cartilage
- Muscular tissue - specialises in contraction, e.g. smooth muscle tissue in the intestinal wall, cardiac muscle tissue
- Nervous tissue - specialised to receive stimuli and conduct inputs from one region to another, e.g. neurons