reproduction (topic 16) Flashcards
define assexual reproduction
a process resulting in the production of genetically identical offspring from one parent
outline process of assexual reproduction
1.bacteria dna copied
2. continued growth of cell
3.division of cell into two
name examples of organsims that reproduce assexually
bacteria, starfish, yeast, ferns, strawberry plants
what are advantages of assexual reproduction
only one parent needed (meaning faster, and saves energy)
quick reproduction
individuals offsprings are identical (good for crops, if they possess a desireable trait)
what are disadvtanges of assexual reproduction
produces identical offsprings, species is more vulnerable to changes in enviornment or diseases
define sexual reproduction
a 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 are gametes
sex cells needed for sexual reproduction
sperm- male
egg- female
fertilisation
the fusion of the nuclei of
gametes
how do the nuclei of gametes compare to the nucleus of a zygote
gametes are haploid and zygotes are diploid
what is meant by diploid and haploid
diploid- Describes a nucleus containing two sets of chromosomes, for example in body cells. 46 chromosomes
haploid-Describes a nucleus containing a single set of unpaired chromosomes. 23 chromosomes
advantages of sexual reproduction
introduces variation, more resistant to changes in environment or to diseases
good for selective breeding
disadvantages of sexual reproduction
takes more time and energy to find a mate, more than one parent needed
much slower
pollination
The transfer of pollen grains from the anther to the stigma.
insect pollination what is meaning
Flowers that transfer their pollen by way of insect pollinators.
pollinators
Insects that transfer pollen from flower to flower in pollination.
name structures found in an insect pollinated flower
stigma, style, ovary, anther, filament, ovule, sepal, petal
stamen
male parts of the flower composed of anther and filament
to produce male gametes (pollen) and provide the correct structures and conditions necessary for the transfer of pollen
carpel
female parts of the flower composed of ovary style and stigma
sepal
green part at the top of the stem, protect the growing flower and help to stop it drying out
petal
bright coloured part, to attract insects, birds or mammals to carry out pollination
filament
stalk that supports anther, hold the anther in a position where it is able to transfer its pollen to an insect, mammal or bird
anther
powdery appearance, coloured, produce pollen grains, which contain the plant’s male gametes
stigma
usually green tallest part of the flower sticky and waxy layer, to trap pollen from other flowers
style
strucutre that supports stigma, above the ovary, to support and present the stigma in a position where it can receive pollen from an insect, bird or mammal