plant repro Flashcards
what is asexual repro
a process resulting in the production of genetically
identical offspring from one parent
what is an example of binary fission
Bacteria produce exact genetic copies of themselves in a type of asexual reproduction called binary fission
what are the adv of asexual reproduction?
POPULATION CAN BE INCREASED RAPIDLY WHEN CONDITIONS ARE RIGHT
CAN EXPLOIT SUITABLE ENVIRONMENTS QUICKLY
MORE TIME AND ENERGY EFFICIENT
MUCH FASTER THAN SEXUAL REPRODUCTION
what are the disadv of asexual reproduction?
LIMITED GENETIC VARIATION IN THE POPULATION - OFFSPRING ARE GENETICALLY IDENTICAL TO THEIR PARENTS
POPULATION IS VULNERABLE TO CHANGES IN CONDITIONS AND MAY ONLY BE SUITED FOR ONE HABITAT
DISEASE IS LIKELY TO AFFECT THE WHOLE POPULATION AS THERE IS NO GENETIC VARIATION
adv of asexual repro in crop plants
a plant that has good characteristics (high yield, disease-resistant, hardy) can be made to reproduce asexually and the entire crop will show the same characteristics.
what is sexual repro
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 is fertilization
the fusion of the nuclei of gametes, when a pollen nucleus fuses with an ovum nucleus in the ovule
what is a gamete
in plants
in animals
gamete is a sex cell
in animals, sperm for male, ovum for female
in plants, the pollen nucleus for male, ovule for female
what type of nucleus do gametes have and why
haploid nucleus as it has half the number of chromosomes
what are the adv of sexual repro
INCREASES GENETIC VARIATION
THE SPECIES CAN ADAPT TO NEW ENVIRONMENTS DUE TO VARIATION, GIVING THEM A SURVIVAL ADV
DISEASE IS LESS LIKELY TO AFFECT POPULATION (DUE TO VARIATION)
what are the disadv of sexual repro
TAKES TIME AND ENERGY TO FIND MATES
DIFFICULT FOR ISOLATED MEMBERS OF THE SPECIES TO REPRODUCE
adv of sexual repro in crop plants
variation is increased and a genetic variant may be produced which is better able to cope with weather changes, or produces a significantly higher yield
disadv of sexual repro in crop plants
variation may lead to offspring that are less successful than
the parent plant at growing well or producing a good harvest
what is the sexual organ of the plant
the flower
what is the male gamete of the plant
pollen
diff between sperm and pollen
pollen isnt locomotive sperm is
what is pollination
the transfer of pollen grains from an anther to a stigma
what are the 2 main methods of pollination in plants
wind
insect
what does the sepal do and where is it
protects the unopened flower
bottom of the flower looks like a leaf
what are petals
brightly coloured in insect-pollinated flowers to attract insects
what is the anther
produces and releases the male sex gamete (pollen)
essentially the male sex organ
plant equivalent to the penis
what is the stigma
top of the female part of the flower which collects pollen grain
what is the style
the connector between the stigma and ovary, part of the female part of the flower.
what is the ovary
produces the female sex cell (ovum)
what is the ovule
contains the female sex cells (found in the ovary)
what are the features of an insect-pollinated flower
-large and brightly coloured petals to attract insects
-scent and nectar are present and entices the insects to visit the flower and push past stamen to get nectar
-moderate pollen grains to allow insects to efficiently transfer pollen grains from stamen to stigma with a high chance of successful pollination
-sticky pollen grains to stick to insects
-anthers inside the flower, stiff and firmly attached to brush against insects
-inside flower, sticky so pollen grains stick to it when an insect brushes past
what are the features of a wind-pollinated flower
- petals small, dull and often green or brown in colour
- no nectar or scent
- large amounts of pollen to increase chance of successful fertilization
- smooth, small and light pollen grains so they can be blown by the wind easily
- stigma outside the flower, feathery to catch drifting pollen grains
how is the pollen made by wind and insect-pollinated flowers different from each other
Insect-pollinated flowers produce smaller amounts of larger, heavier pollen grains that often contain spikes or hooks on the outside so they are better able to stick to insects
Wind-pollinated flowers produce large amounts of small, lightweight pollen grains that are usually smooth
what is self-pollination
the transfer of pollen grains from the anther of a flower to the stigma
of the same flower or a different flower on the same plant
what is cross-pollination
the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
disadv of self-pollination
reduces genetic variety of the offspring as all the gametes come from the same parent (and are therefore genetically identical)
Lack of variation in the offspring is a disadvantage if environmental conditions change, as it is less likely that any offspring will have adaptations that suit the new conditions well
dis adv of cross-pollination by insect pollination
cross-pollination relies completely on the presence of pollinators and
this can be a problem if those pollinators are missing
process of fertilization in plants
- if the pollen grain has landed on the right kind of stigma, pollen tube is grown
- nucleus inside the pollen grain slips down the tube as it grows down the style towards the ovary
- ovary contains one or more ovules which each contain an ovum with a female nucleus that a male pollen nucleus can fuse with
- once the nuclei fuse, the ovule has been fertilized and a zygote is formed
-The zygote will start to divide and eventually form a seed within the ovule
what is germination
start of growth in the seed
what factors affect germination
water
oxygen
warmth
how does water affect germination
allows the seed to swell up and the enzymes in the embryo to start working so that growth can occur
how does oxygen affect germination
so that energy can be released for germination
what do germinating seeds need to germinate
water
oxygen
describe how growers selectively breed plants
1 cross parent plant with desired features
2 chose offspring for desired features
3 cross offspring plants showing desired features
4 keep many generations of crossing and selecting
5 transfer of pollen between desired plants
what part of the flower that develops into the seed
ovule
what part of the flower that develops into the fruit
ovary wall
state and advantage of seed dispersal
reduce competition
what are the roles of enzymes in germination
stored food in seed is broken down
enzymes required/control process of respiration
