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Flower structure Learning objectives: • Describe the structures of a flower and explain the function of each part Task 1: Why do plants have flowers?
Sexual reproduction Flowers are the organs of sexual reproduction in plants. Sexual reproduction is the production of a new individual resulting from the fusion of two gametes (sex cells). This fusion is called fertilisation. In plants, the male sex cell is called pollen and the female sex cell is called an ovule.
Flower structure Flowers have important structures. Task 2: Use the diagram below and your textbooks to complete ‘Structure of a flower worksheet’ stigma anther style carpel stamen filament ovary ovule petal sepal receptacle peduncle
Ranunculus bulbosus (Bulbous buttercup) Visible Ultra-Violet Infra-red
Ranunculus acris (Meadow buttercup) Visible Ultra-Violet Infra-red
Yellow Day lily (Hemerocallis lilioasphodelus) Visible Ultra-Violet Infra-red
Pollination The first process in sexual reproduction of plants is pollination. Pollination is the transfer of pollen from the anther to the stigma of a plant. (Task 3: This is not fertilisation – why?) EXTENSION: What is the difference between self-pollination and cross pollination? Within same flower = self-pollination Between different flowers = cross pollination
Pollination We will cover more on this in next lesson Some plants are adapted for insect pollination, whereas others are adapted for wind pollination.
Insect pollination Insect pollination is the transfer of pollen (by means of sticking to an insect) from the anther to the stigma of a plant. Task 1: Discuss how these plants are adapted for insect pollination
Insect pollination Pollen often sticky or has spikes to attach to insects Nectar and a scent present to attract insects Sticky stigma to collect pollen Anthers are firm and positioned inside the flower; ideal location to rub pollen onto insects Stigma located inside flower; ideal location for insect to deposit pollen onto. Large brightly coloured petals to attract insects
Wind pollination Wind pollination is the transfer of pollen (by means of being blown in the wind) from the anther to the stigma of a plant. Task 2: Discuss how these plants are adapted for wind pollination
Wind pollination Pollen grains are very small and light so they can be carried easily by the wind. Pollen produced in very large numbers – to maximise chances of landing on a stigma. Anthers are exposed to the wind so that pollen can easily be blown away Stigma hang outside the flower and 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 as there is no need to attract insects
Pollination Task 3: Complete pollination worksheet. Try not to use your notes.
Pollination Task 4: Study the photographs provided, and for each, decide whether you think it is wind- or insect-pollinated. Make a table and justify your answers. EXTENSION: Design a new flower adapted for either wind or insect pollination.
Flower structure quiz • What is the name of the structure labelled X in the diagram? carpel sepal X stamen peduncle
Where is pollen made? stigma sepal anther ovary
Where is the ovule found in a flower? petals style nectary ovary
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
Where does pollination occur? stigma sepal anther ovary
Fertilisation in plants Learning objectives: • Define fertilisation • Describe the role of a pollen tube in plant fertilisation
Fertilisation Task 1: Define fertilisation
Fertilisation Task 1: Define fertilisation Fertilisation is the fusion of a male (pollen in plants) and female (ovule in plants) gamete to produce a zygote that undergoes cell division and develops into an embryo. It is part of sexual reproduction.
Fertilisation in plants Step 1: Pollination occurs – either by wind or insects.
Fertilisation in plants Step 2: Pollen lands on stigma and grows a pollen tube down the style using digestive enzymes. The pollen tube grows towards the ovary and enters the ovule via an opening known as a micropyle.
Fertilisation in plants Step 3: The nucleus of the pollen grain passes down the pollen tube to fertilise the egg cell inside the ovule.
Fertilisation in plants Step 4: The fertilised egg develops into an embryo. The ovule becomes the seed and the ovary becomes the fruit.
Fertilisation in plants Task 2: Draw a cycle diagram to summarise fertilisation in plants.
Seed dispersal Learning objectives: • Describe, using named examples, seed and fruit dispersal by wind and by animals. • State the importance of seed and fruit dispersal
Life of a plant POEM Task 1: Class reading of poem Task 2: Complete questions concerning the poem on worksheet A plant, with space, will grow from a tiny seed, Some water and sun is what they need. First the roots reach underground, They suck up minerals from all around. Some roots grow, deep, deep down. Others are shallow, but spread around Then come stems, some tall, some stout, And next the branches spread about. Leaves grow in all shapes and sizes, Based on, for them, if the sun rises. Flowers bloom from buds on stems, They are as pretty as precious gems. Some bloom early spring, others late. Avoiding each other, they avoid debate, By wind or water, or a juicy gift, The next generation are given a lift, The new seeds travel, they’re on the go! The further from Mum, the better they grow On and on the cycle keeps going, Soon new stems and leaves are showing.
Seed dispersal Sir David Attenborough tells us the different ways seeds are dispersed. Task 3: Watch the video and write down the different methods of seed dispersal and at least one example of each.
Seed dispersal Wind: dandelion, liana, sycamore Water: seabean Animals: burdock (hooks), rhino apple (eaten fruit) Explosive: squirting cucumber, Himalayan balsam
Seed dispersal Task 4: Discuss and write one amazing sentence to explain why Seeds must be dispersed away from the parent plant.
Seed dispersal Task 4: Discuss and write one amazing sentence to explain why Seeds must be dispersed away from the parent plant. Dispersal avoids the new plants growing near the plants. This reduces overcrowding and competition for resources such water, light and minerals.
Seed dispersal Task 5: In pairs on your table, design & make your own seed. Criteria: • It must be clear which method the seed is dispersed by. • You must be able to explain the workings of your seed. • It must work • It must look good. When you’ve finished, TEST it!
Thumbs up or down Learning objectives: • Describe, using named examples, seed and fruit dispersal by wind and by animals. • State the importance of seed and fruit dispersal
Germination Learning objectives: • Describe the conditions needed for seed germination • Describe how germinating seeds utilise food reserves until the seedling can carry out photosynthesis
Where does pollination occur? B A C D
Where does fertilisation occur? B A C D
The pollen tube grows down the… A Stigma B Filament C Style D Ovule
The pollen enters the ovule via the… A Micropyle B Micropole C Minipyle D Minihole
Which part of the pollen moves down the pollen tube into the ovule? A All of it B Cytoplasm C Mitochondria D Nucleus
The ovule becomes a A Fruit B Seed C Embryo D Plant
The ovary becomes a A Fruit B Seed C Embryo D Plant
RECAP: Fertilisation After fertilisation the petals, stamen and sepals fall off.The ovary turns into a fruit, the ovule turns into a seed, the fertilised egg inside develops into an embryo plant. Fleshy wall of the ovary (yes, you are eating an adapted ovary when you crunch into an apple!) seed
Seed structure Task 1: Complete first page of germination worksheet Testa: tough seed coat 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) Cotyledon (seed leaves): starch store Micropyle: hole made by pollen tube
Germination Germination: is the process by which plants grows from a seedling in to new fruit or a flower
Germination and energy 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 germination Plant growth and development soil
Conditions required for germination Task 4: Summarise the findings of the experiment shown below on the second page of your worksheet Pyrogallol (absorbs oxygen) No light Oxygen present Oxygen present Oxygen present Oxygen present No oxygen moist moist moist moist dry 4oC A Warm B Warm C Warm E Warm D Click to listen to an explanation
Conditions required for germination Seeds need WOW to germinate: Water to activate enzymes which digest stored food Oxygen Needed for the production of energy for germination Warmth Needed for the enzymes to work effectively.
