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Plant Reproduction
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Thanks to www.clickbiology.com
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Asexual reproduction involves NO fertilisation between male and female gametes.
Offspring are genetically identical to their “parents”
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Examples of organisms that asexually reproduce
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Flowers are the reproductive organs of plants
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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stigma anther style stamen carpel filament ovary ovule petal sepal
Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Structure and function of the flower
stigma anther style stamen carpel filament ovary ovule petal sepal Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Flower Structure Quiz carpel sepal stamen peduncle
What is the name of the structure labelled X in the diagram? carpel sepal X stamen peduncle Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Flower Structure Quiz stigma sepal anther ovary Where is pollen made?
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Flower Structure Quiz petals style nectary ovary
Where is the ovule found in a flower? petals style nectary ovary Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Flower Structure Quiz X = style, Y = stigma X = filament, Y = anther
Which parts of the flower are labelled below: X = style, Y = stigma X X = filament, Y = anther Y X = stigma, Y = style X = anther, Y = filament Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Pollination is the transfer of pollen from the anther to the stigma
The pollen grain contains the male sex cell (gamete) Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Pollen can be carried between flowers by insects or by wind
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Insect-pollinated flowers are adapted to attract insects to them to enable transfer of pollen
Pollen has barbs for hooking onto insect fur nectar and a scent present Anthers positioned to rub pollen onto insects Sticky stigma to collect pollen Brightly coloured petals Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Wind-pollinated flowers are different in structure because they do not have to attract insects to them but do need to be exposed to the wind. Pollen grains are very small and light. They occur in very large numbers Anthers are exposed to the wind so that pollen can easily be blown away Stigma are feathery to catch pollen carried on wind Petals are small and green as there is no need to attract insects No scent or nectary Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Self-pollination occurs when pollen falls from the anther onto the stigma of the same flower
Self-pollination is not desirable as it reduces variation Is self pollination sexual or asexual? Many plants have male and female parts. Self pollination is sexual because it uses 2 gametes. Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Flowers will prevent self-pollination by either having stigma above stamen or…
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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…by having stamen and stigma mature at different times.
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Pollination is the transfer from….?
Pollination Quiz Pollination is the transfer from….? the stigma to anther style to stamen ovule to filament anther to stigma Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Two main mechanisms for pollination are?
Pollination Quiz Two main mechanisms for pollination are? Wind and water Insect and wind Insect and water Wind and birds Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Pollination Quiz Cross-pollination… Increases variation
Decreases variation Is only performed by insects Is only performed by wind Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
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Pollination Quiz Flowers are adapted for wind-pollination by…
Having bright petals and a scent Having a nectary Having feathery stigmas Having sticky stigmas Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Fertilisation and Fruit Development
Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Once pollination occurs a tube grows from the pollen grain down through the style to the ovule
stigma style carpel Not Covered in course… ovary ovule Note: Petals not shown in order to simplify diagram Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Fertilisation occurs when the male gamete fuses with the ovule (the female gamete)
Not Covered in course… Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Seed Dispersal Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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After fertilisation the petals, stamen and sepals fall off.
The ovule turns into a seed, the fertilised egg inside develops into an embryo plant. Not Covered in course… Cotyledon: Food store Testa: tough seed coat Plumule: Embryo shoot Micropyle: Hole made by pollen tube Embryo plant Radicle: Embryo root Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Water leaves the seed, it dehydrates and becomes dormant because metabolic reactions stop. The ovary develops to become a fruit. Fleshy wall of the ovary (yes, you are eating an adapted ovary when you crunch into an apple! seed Not Covered in course… Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Seeds can be dispersed by: Wind Water Mechanical Animals
Seeds need to be dispersed away from the parent plant in order to reduce competition for space, light, nutrients and water. Seeds can be dispersed by: Wind Water Mechanical Animals
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Germination Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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The seed contains the embryo plant and cotyledons (starch stores)
Testa Water enters the seed through the micropyle and activates enzymes. The water also softens the testa to allow it to split. Plumule (embryo shoot) Radicle (embryo root) Not Covered in course… Cotyledon Micropyle Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Enzymes are used in seed germination
Plumule The enzymes break starch down into maltose and then glucose. The glucose is used in respiration to provide energy for growth starch amylase secreted embryo plant absorbed maltose Not Covered in course… Radicle This is the first part to grow out of the seed as it needs to absorb more water Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Whilst germinating the plant uses food stores in the cotyledon to provide energy for growth
light The seedling can now photosynthesise and make its own food Not Covered in course… germination Plant growth and development soil Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Changes in dry mass of the germinating seed:
Seed loses weight as it uses up starch stores in the cotyledons as the seedling cannot photosynthesise yet Not Covered in course… Days Dry mass/g Weight increases as the seedling can photosynthesise and plant grows Dry mass is the mass of solid matter with all water removed Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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Conditions required for germination
4oC A moist dry Warm B C D E Oxygen present No oxygen No light Pyrogallol (absorbs oxygen) Flower Structure Pollination Fruit Development Seed Dispersal Germination Test
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