PLANT BIODIVERSITY Flashcards
what adaptive traits do plants living on land need in order to survive
- presence or absence of water
- presence or absence of true roots, stems and leaves
- if they reproduce using spores or seeds
- presence or absence of fruit
- dependence of the plant on water for reproduction
what features are plants grouped into
divisions and sub-divisions
3 divisions of plants
- bryophytes
- ptedirophytes
- spermatophytes
two phases/generations to the life cycle of a moss plant
- a gametophyte generation that has male and femae organs which produce gametes(sexually) and water is needed
- a sporophyte generation where spores are produced(asexually)
function of calyptra
covers opening to capsule
function of capsule
produces spores
function of seta
- holds capsule in upright position allwing spores to be dispersed over a greater area
- conducts water and mineral salts to capsule
function of ‘‘leaf’’
is green so it manufactures food by photosynthesis
function of ‘‘stem’‘/axis
supports gametophyte
function of rhizoid(root)
- anchors plant to soil
2. absorbs water from soil
function of sporophyte
produces spores
function of leaf(frond)
- compound leaf with many pinnae
- cuticle and stomata are present
- sori present on the ventral surface of mature pinnae
function of root
- it is adventitious
- arises from rhizome
- functions as an anchorage and for absorption
function of young leaf
- tightly coiled and hairy whiich reduces transpiration
2. coiled leaf allows growing point to be produced
functon of stem
- underground horizontal stem known as a rhizome
- stores food
- covered by small, brown scale leaves which prevents water loss
two sub-groups spermatophytes are divided into
- gymnosperms
2. angiosperms
purpose of roots
gymnosperms have tap roots, stems and leaves as well as wel developed strengthening and conducting tissue is present and the plant itself can grow into a large tree(sporophyte)
purpose of leaves
it minimises transpiration by
- reduced SA of the needle shaped leaves
- thick cuticle
- sunken stomata
function of petals
- set of petals make a whorl called the corolla
2. brightly coloured to attract pollinating agents, namely, insects and birds
function of stamen
- the set of stamens makes up the androcecium, which is the male whorl
- a stamen is made up of an anther and a filament, anther produces pollen
function of sepal
- set of sepals forms the outermost whorl called the calyx
- sepals are green for photosynthesis
- protects the flower in the bud stage
function of pedicel
is the flower stalk so therefore it supports the flower
what does the stamen consist of
- anther
2. filament
what does the pistil consist of
- stigma
- style
- ovary
- ovule
function of pistil
- pistils make up the gynaecium(female whorl)
- ovules inside the ovary produce ova
- stigma is sticky or hairy to trapn pollen
why do plants reproduce
the reproduce so that the offspring can be produced ensuring that the species does not become extinct
2 types of reproduction
- asexual reproduction
2. sexual reproduction
asexual reproduction
involves reproduction without the formation of gametes(sex cells)
sexual reproduction
involves fusion of sex cells(gametes)
asexual reproduction in plants
offspringformed from asexual reproduction are genetically identical to the parent as the process involves producing new structures or growing parts of plants by mitosis
asexual reproduction by spores
plants like mosses and ferns dont form seeds and during their life cycle they reproduce both sexually and asexually. asexually by producing spores which germinate into gametophyte plants which matures and produces gametes. sexual reproduction then occursbbecause sperm fertilise ova
advantages of asexual reproduction in plants
- only one plant is needed
- new plants are produced relatively quickly
- agents of pollination and seed dispersal are not required
- one can select a plant with desireable characteristics
disadvantages of asexual reproduction in plants
- a weak parent plant will produce weak offspring since they’re alike genetically
- because of changes in the environment, the new plants may not survive since all offsprings are genetically alike
sexual reproduction in angiosperms(flowering plants)
it involves the fusion of a sperm cell with an egg cell to form a zygote and a zygote develops into an embryo and after repeated mitosis an individual is formed
advantages of sexual reproduction
- offspring are genetically different
- allows offspring to adapt to and evolve inn an ever-changing environment
- may lead to the formation of new species
disadvantages of sexual reproduction
- a relatively slow process
- mutations may occur
- adult male and female organisms are required in order to produce gametes
adaptation of flowers for pollination
pollination refers to the transfer of pollen grains from anther to stigma, when this occurs within the same flower its known as self-pollination and when it occurs between different flowers of the same species its known as cross pollination
insect pollinated flowers
- are brightly coloured to attract insects
- have large petals for landing area
- have a scent or nectar to attract insects
- pollen grains are sticky and become attached easily to insects
- anthers are firmly attached so that they cant be broken by visiting insects
bird pollinated flowers
- long and trumpet shaped
- usually red, orange or yellow
- are not scented
- produces nectar
characteristics of wind pollinated flowers
- dont have brightly colored petals
- dont have a scent or produce nectar
- produce large amounts of pollen, increasing the chances of pollination
- pollen grains are light and float easily
- anthers are large and hang out the flowers allowing pollen grains to be carried easily by wind
- stigmas are large and feathery which easily trap pollen grains
