plant reproduction Flashcards
What is the process called where plants transfer the male gametes (pollen) from the anther to the stigma?
Pollination
What are the two different methods of pollination flowers will use?
- Insect pollination
- Wind pollination
What is the function of the sepal?
To protect the flower when it was an unopened flower
What are the functions of the petals?
In insect pollinated plants, these are brightly coloured to attract insects
What is the male reproductive system in a flower called?
The stamen
What is the part of the male reproductive system in a flower called which produces and releases the male sex cell?
The anther
What is the structure which holds the anther up called?
The filament
What is the female reproductive system in a flower called?
The carpel
What is the function of the style?
To support and connect the stigma and the ovary, allowing for a pollen tube to grow between them inside of the style
What is the part of the female reproductive system in a flower called which collects the pollen grains?
The stigma
What is the function of the ovary?
It produces the female sex cell (the ovum)
What is the function of the ovule?
The ovules are found inside the ovary, and contain the female sex cells (the ova)
How does the process of insect pollination work?
Insects visit the flowers attracted by the nectar, scent and petals. The insects body may brush with the anther when looking for nectar, and the pollen will stick to its body. When it then visits another flower (or the same one), it may brush up against the stigma in search for nectar, depositing pollen in the stigma, leading to fertilisation.
How are insect pollinated flowers adapted for pollination?
- Large and brightly coloured petals to attract insects
- Nectar and scent to attract insects and make them brush past the anther and stigma in search of it
- Large, sticky/spiky pollen grains in order to attach to insects
- The stigma is inside the flower and is sticky so pollen grains stick to it when an insect brushes past
- The anthers are inside the flower and are firmly attached to the flower as insects brush past them
- The number of pollen grains produced are moderate as this type of pollination is efficient
How does the process of wind pollination work?
When ready, the anthers open and shed their pollen into the wind. It then, by chance, lands on the stigma of a plant of the same species.
How are wind pollinated flowers adapted for pollination?
- The petals are small and dull as there is no need to attract insects
- The flower has no nectar and scent as there is no need to attract insects
- The pollen grains are smooth, small and light so they are easily blown in the wind
- The anthers are outside the flower and swing loosely due to the long and hinged filament in order to release pollen grains easily
- The stigma is the outside the flower, and is feathery in order to catch drifting pollen grains
- A large number of pollen grains are produced to increase the chances of pollination
What triggers the growth of a pollen tube inside of a style?
When a pollen grain of the same species lands on the stigma
What happens following the growth of a pollen tube?
The pollen moves down the pollen tube, and enters an ovum through an opening. Fertilisation occurs, and a zygote is formed inside of an ovum.
How are seeds and fruits formed following fertilisation?
- The zygote formed by fertilisation develops into a seed
- The ovule wall develops into a seed coat (testa)
- The parts of the flower surrounding the seed (the ovary walls) develop into the fruit, which contains the seed(s)
- The fruit provides a means for seed dispersal by animals
- Not all plants form fruit, although if they do this is how it is done
What are the factors required for seed germination?
- Water - Allows the seed to swell and the testa to burst allowing the embryo plant to exit the seed. It also enables enzymes to start working
- Oxygen - Required for respiration
- Warmth - Allows enzymes to work effectively
Outline an investigation of the factors required for seed germination
Set up four test tubes, each containing 10 cress seeds on cotton wool. Leave test tube A completely dry at room temperature. Leave test tube B moist at -4 degrees C. Leave test tube C submerged in water with a layer of oil on top at room temperature. Leave test tube D moist at room temperature. You should find that only the seeds in test tube D germinated because it is the only one with all 3 conditions present.
How do germinating seeds acquire nutrients and energy before they are able to grow their own leaves?
Through food reserves known as cotyledons which surround the embryo
What are the two methods of asexual reproduction in plants?
- Naturally by runners
- Artificially by cuttings
How do runners work in plants?
Side branches called runners with small plantlets at the end will sprout sideways out of a plant. Once these runners touch the soil a good distance away from the parent, roots will start to grow and the plantlet will become independent. The plants that grow from runners are genetically identical to the parent plant.
How are cuttings used for plant asexual reproduction?
A section of the parent plant with favourable traits with a new bud on it is cut off. It is often dipped into hormones which encourage root growth. The cuttings are planted, and will eventually grow into adult plants. The plants that grow from cuttings are genetically identical to the parent plant.
what’s a cotyledons function?
Cotyledons surround the embryo, storing food for the seedling
Some plants have one cotyledon, others have two
Cotyledons provide energy until the plant can photosynthesize
describe what water is needed for germination in detail
Water absorption splits the seed coat (testa), allowing the plumule (first emerging shoot) and radicle (first emerging root) to emerge
