9.4: Reproduction in Plants

Jasmine Wells
Flashcards by Jasmine Wells, updated more than 1 year ago
Jasmine Wells
Created by Jasmine Wells over 5 years ago
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International Baccalaureate Biology (9. Plant Biology) Flashcards on 9.4: Reproduction in Plants , created by Jasmine Wells on 01/05/2016.

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Question Answer
What is the vegetative stage of a plant? The phase when a seed germinate and a young plant is formed that grows roots, stems and leaves.
When does the vegetative stage end? When the meristems in the shoot start to produce parts of flowers instead of leaves. I.e. Reproductive stage.
Why are flowers useful? Flowers are structures that allow for sexual reproduction - thereby to increase variety.
What factor(s) play a role in transforming leave producing shoot to a flower producing shoot? -Temperature - Dark period (main trigger).
What are short day plants? Are plants that flowers when the days are short and the nights are long. (Longer than critical day length). E.g. Chrysanthemums during autumn
What are long day plants? Plants that flowers when days are long and the nights are short. E.g. Irises during the summer.
How can growers force flowering? By manipulating the length of day/night to force flowering to occur.
How to force flowering for long day plants during the winter/autumn? By providing additional light in the middle of the night may lead to flowering.
How to induce flowering for short day plants during summer/spring? Blinds can be closed to extend nights artificially.
What are the 2 kinds of pigments found in leaves that is used to measure the length of dark periods? - Phytochrome red - Phytochrome far-red.
What happens to phytochrome red in normal sunlight? When Pr absorbs red light of wavelength 660nm, it is converted into phytochrome far-red
What happens to phytochrome far red in darkness? When pFR absorbs far-red light, (730nm), it converts it back into pR.
Which of the 2 phytochromes are more stable? pR is more stable than pFR.
Which of the 2 phytochromes is the more 'active' one? pFR is the active form of phytochrome, and receptor proteins are present in cytoplasm to which pFR binds.
In long day plants, which of the 2 phytochromes cause gene expression? pFR.
In short day plants, which of the 2 phytochrome causes gene expression? pR.
What does successful reproduction of plants depend on? Transfer of pollen from anthers on one plant to a stigma of another, of the same species.
What are the three most common animal pollinators? - birds - bats - bees
Describe the mutualism between pollinators and flowers. Mutualism of pollinators and flowers involve close association of the 2 organisms where both organisms benefit from the relationship. E.g. Pollinators benefit by gaining food in the form of nectar, and on the other hand, plants gains a means to transfer pollen to another plant.
Why should we strive to protect entire ecosystems rather than individual species? Because more than 85% of the worlds 250,000 species of flowering plants depend on insects or other animal pollinators for survival.
What is pollination? Pollination is the transfer of pollen from one anther to a stigma.
Define fertilisation. The fusion of the male gamete (pollen) with the female gamete (ovule), to form a zygote.
leWhat happens after pollen is transferred to a stigma? A pollen tube containing male gametes grow down the style to the ovary and then to ovule, where the gametes fertilise.
What is seed dispersal? The spreading of seeds away from the parent plant.
Why are seeds dispersed? this allows the seed to germinate and grow without competing with parent for nutrients, water, and sunlight and also to spread the species.
What does the fertilised ovule and ovary turn into? The fertilised ovule turns into a seed and the ovary develops into a fruit.
What is a seed? It is an embryo plant and food reserve.
What does the embryo plant consist of? - Embryo shoot - Embryo root - One or two cotyledons. (leaves containing food reserve)
1) Radicle (Embryo root) 2) Micropyle 3) Plumule (Embryo shoot) 4) Seed coat (testa) 5) Cotyledon.
What are the three factors needed for successful germination? - Water (to hydrate seed) - Oxygen ( cell respiration) - Warmth (Enzyme activity)
What are the functions of anthers? Produce pollen and contain pollen sacs containing male gametes.
What is the function of the nectary? Attracts insects.
What are the functions of the petals? Brightly coloured to attract pollinators.
What is the function of the sepal? Protects the flower bud.
What is the function of the filament? The filament holds the anthers upright so that insects are likely to pass by.
What is the function of stigma? Sticky so that pollen can stick to it - so that pollen grain is able to grow a tube down the style.
What is the job of the style? Separates the ovary from the stigma.
What is the function of the ovary? Contains the female gametes. After fertilisation occurs, the ovary develops into a fruit.
What is the function of the ovules? They are the female gametes which fertilise with pollen to produce a seed.
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