Please enable JavaScript.
Coggle requires JavaScript to display documents.
Sexual and Asexual reproduction, Coordination and responce, "Los…
Sexual and Asexual reproduction
Sexual reproduction
1. Fertilisation on plants
Gamete
A reproductive cell in animals and plants
In plants the gametes are
ovule
Female gamete
pollen
Male gamete
Gametes contain half the chromosomes of a normal cell ( in a plant 7) and (in a human 23
Fertilisation in plants
1.A pollen grain lands on the stigma of a flower, with help of canimals(pollinators) or wind
A pollen tube grows out of the stigma and down through the style to the ovary and into the ovule
The Nuclei from the male gamete moves down the pollen tube to the ovule, and then fuses with the egg nuclei to make a zygote (fertilised egg)
Each fertilised gamete forms a seed
The ovary develops int a fruit around the seed
https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=1920,w=1920/uploads/2022/05/pollination-and-fertilisation-1.png
Types of pollination
Wind pollinated
features of wind pollinated plants
small and dull pedals
stigma outside the flower to catch pollen
no nectar
long stames outside the flower so wind carries pollen
large amount of pollen with smooth , small and lighter pollen
large and feathery stigma
https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=1920,w=1920/uploads/2024/05/wind-pollinated-flower.png
Insect pollinated
Features of insect pollinated plants
sticky and flat stigma to grab pollen from insect
colourfull and big petals to atract insects
stigma inside the flower and flat
Produces nectar to atract insect
short stamen inside the flower
Small, spicky and sticky pollen to catch into insects
https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=1920,w=1920/uploads/2020/01/Flower-structure.png
Parts of a plant in sexual reproduction
Stamen
anther
The part where pollen is produced
filament
It holds the ancem up
The male part of the plant
Carpel
Style
A tube that conects the stigma and ivary to allow pollen to travel through
Ovary
The part where ovules are produced
Stigma
A flat and sticky surface where pollen gets stuck
Ovule
The female gamete in a plant
Female part of the plant
Petals
Colourful parts of the flower to atract insects
https://igcsebio.sciencesauceonline.com/wp-content/uploads/2021/09/Flower-Poster-Colour-1980x1400.jpeg
sepal
enclose a developing bud.
Receptacle
Supports the flower
Nectarie
produce nectar to atract insects
Only on insect pollianted plant
2. Germination
Factors for germination
Oxygen
necessary for respiration to provide energy
Warmth
boosts enzyme activity and improves germination until a certain temperature
Water
swells the seed, breaks the seed coat, and activates enzymes for growth
CO2 and sunlight have no effect on germination
parts of a seed
foodstore
a starch suply to use before the plant can do photosynthesis
seed coat
Tough protective cover for the seed
Embryo
root and shoot that will become the adult plant
The growth of the seed into a small plant called a
seedling
Germination is a exothermic reaction
Germination practical
Put 4 tubes withh wet wool and seeds
Tube 2 is the controll variant
Germination will happen
Tube 3 has hot water and a layer of oil
No germination as there is no oxygen
Tube 1 has no water
No germination as there is no water
Tube 4 has been put in a refrigerator
NO germination as there is no heat
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/Conditions-required-for-germination.png
3. seedling
After germination of the seed, the shoot grows upward and the roots grow downward
The first seed is called seed leaves or
cotyledon
There are 2 different seedlings
Monocotyledons
grasses and irises which only have one seed leaf/ cotyledon
Dicotyledons
plants such as roses or carrots with multiple cotyledons/ seed-leafs
Reproduction which involves 2 organisms
Asexual reproduction
Reproduction which only involves 1 organism
Asexual reproduction amkes an identical clone to the parent
Types of Asexual reproduction
Artificial asexual reproduction
cuttings
A branch of the plant is cut off
Then it is planted in compost and agar jelly which contqains routing powder to encourage new roots
Thye branch with new roots is planted in soil again
Most commonly seen in gardens
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/07/Taking-cuttings.png
Tissue culture
Tiny piece of plant is cut off and put in agar jelly with routing powder and plant hormones
Lots of nutrients are needed for this process
https://i0.wp.com/gokulamseekias.com/wp-content/uploads/2024/04/ptc1.png?w=664&ssl=1
Natural asexual rperoduction
Runners
When plants grow branches with plantlets(small plants) at the end of them
The plantlets then starts to grow roots and leafs and the runner shrivels away
Exp: strrawbery plants
Differences between sexual and asexual reproduction
Sexual reproduction
meiosis as a form of division of cells
The cells are divided twice, producing 4 cells and they only contain half of the genetical information
Genetically unique (different to the parent)
low number of offsprings produced
2 parents needed
Slow proces
genetic variation comes from 3 different factors
The production of gametes by meiosis (resulting in new combinations of alleles on the chromosomes)
The random assortment of chromosomes into gametes during meiosis
The contribution of 50% of their DNA from each of the two parents
Asexual reproduction
fast proces
mitosis as a form of cell division
The cells are divided and produce an identical clone
Geneticlly identical to the parent
large number of offspring produced
One parent needed
genetic variation sources comes from mutation
Coordination and responce
Auxins
Auxins are a type of hormones which regulate the growth of a plant
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/Positive-phototropism-in-plant-shoots.png
Auxins are made in the tips of growing shoots and stimulate elongation (geting larger) in the region
Auxins in phototropism
If light shines all around the tip, auxin is distributed evenly throughout and the cells in the shoot grow at the same rate
If light shines only comes from one side the auxins qill acumulate in the shaded zone
This will cause faster growth on the shinying part and cause the plant to bend towards the light
Auxins in Geotropism
IF the plant is places horizontally the auxins will go to the underside of the plant
This will cause the plant to start growing upwards
Controll of growth in different parts of the plant
In root
Auxins cause less growth
In stem
Auxins cause more growth
Stimuli
Plants need to be able to grow in response to certain stimuli
Growth responses to a stimuly are called tropisms
There ae 2 type of tropisms
Positive tropisms
growing towards the stimuli
Negative tropisms
Growing away of the stimuli
Tropisms in plants
Geotropism
When the growth of a plant is dictated by gravity
Geotropism in parts of the plant
Stem
Negative geotropism (grows away of gravity)
Root
Positive geotropism (grows towards gravity)
Phototropism
When the growth of the plant is dictatet by light
Phototropism in parts of the plant
Roots
Negative phototropism (away of light)
Stem
Possitive phototropism (towards light)
https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=1920,w=1920/uploads/2021/04/Parsley-phototropism.png
"Los españoles son muy españoles y mucho españoles" Rajoy
"Somos sentimientos y tenemos seres humanos"Rajoy