16: 1.2.3 Flashcards
what is assexual reproduction?
process resulting in the production of genetically identical offspring from one parent
advantages and disadvantages of assexual reproduction
advantages- only one parent is needed, saving energy
-quicker reproduction
-easier reproduction
disadvantages- as all parents and offsprings are the same, they become more vulnerable to environmental changes
examples of things that reproduce assexually.
starfish, bacteria, many plants
what is sexual reproduction
process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other
what is fertilisation
the fusion of the nuclei of gametes
advantages and disadvantages of sexual reproduction
advantages- introduces variation in population
-in wild variation makes it more resistent to environmental changes and to disease
-farmers can chose best characteristics from two different stains to produce new varities of plants, selective breeding
disadvantages- time and energy needed
-much slower than assexual
function and description of sepal
green part at the top of the stem, underneath the petals
to protect the growing flower and help to stop it drying out
function and description of petal
brightly coloured part of the flower
to attract insects, birds or mammals to carry out pollination
function and description of stamen
the male part of the flower consisting of the filament and the anther
to produce male gametes (pollen) and provide the correct structures and conditions necessary for the transfer of pollen
function and description of filament
the stalk that supports the anther
to hold the anther in a position where it is able to transfer its pollen to an insect, mammal or bird
function and description of anther
coloured, usually with a powdery appearance
to produce pollen grains, which contain the plant’s male gametes
function and description of stigma
usually green and the tallest part of the inside of the flower, and with a sticky, waxy layer
to trap pollen from other flowers
function and description of style
the thin structure that supports the stigma and is above the ovary
to support and present the stigma in a position where it can receive pollen from an insect, bird or mammal
function and description of carpel
the female part of the flower that contains the stigma, style and ovary
to produce female gametes and provide the correct structures and conditions necessary for fertilisation
function and description of ovary
green, bulb-shaped part near the bottom of the flower
contains ovules (which contain the female gametes) which will develop into seeds after fertilisation
function and description of ovule
structures within the ovary
female gametes are produced and contained within the ovules. Upon fertilisation, these ovules will develop into seeds
function and description of petal (wind pollination)
small and usually dull in colour because they do not need to attract insects
function and description of anther (wind pollination)
loosely attached and dangle outside the flower so its pollen can be blown easily by the wind
function and description of stigma (wind pollination)
loosely attached and dangle outside the flower so they can catch wind-borne pollen from other plants; often appear feathery
what is pollination?
transfer of pollen grains from the anther to the stigma.
description for pollen transported by insects
has a spiky outer layer, which hooks onto insects so that the pollen can be transported from one flower to another
description for pollen transported by wind
smaller, lighter, and smoother allows flower grain to be blown from one flower to another
what is self pollination?
transfer of pollen grains from the anther of a flower to the stigma of the same flower, or to a different flower on the same plant
what is cross pollination?
transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
advantage and disadvantage of self pollination
do not need to rely on pollinators, can grow in areas which pollinators dont live
reduces variation, and ability for plants to respond to changes in enviorment eg disease and change in climate
advantage and disadvantage of cross pollination
variation increases within a population of plants
relies on pollinators to transport pollen
when does fertilisation occur
when a pollen nucleus fuses with a nucleus in an ovule
describe the growth of the pollen tube and fertilisation
after pollination, pollen tube grows through the style towards the ovary, male gametes move through this tube eventually this tube reaches ovule. Nucleus of one of the sperm cells fuses with egg cell nucleus (fertilisation), forming a zygote, develops into an embryo which then develops into a plant.
what is germination
seeds will be dispersed away from the parent plant. In the right conditions, they will begin to open
what is needed for germination (conditions)
right temperature, warmth
right amount of water
and oxygen
