Seeds and Sustainability Topic 4.4f

 Describe how the uses of plant fibres and starch may contribute to sustainability, e.g. plant-based products to replace oil-based plastics. Specification

 What is a seed?  Embryo with food inside a protective coat  What is the function of a seed?  Protects the embryo  Aids dispersal  Provides nutrition  How is a seed formed?  Double fertilisation occurs  A diploid zygote is formed: how?  The first male nucleus fuses with the ovum Activity 4.21a- Seeds

 What does this develop into?  the embryonic plant  What happens to the second male nucleus?  it fuses with the two polar nuclei  What is formed?  the Triploid endosperm which is the plant’s food  What does the ovary become?  Fruit  What does the ovule wall become?  seed coat Activity 4.21a- Seeds

Internal structure of an endospermic seed

Watch these videos and list the different ways of seed dispersal #p00lxv9z

 How are seeds dispersed?  Wind, animals, water or self  What adaptations might they have to aid dispersal? Activity 4.21a- Seed dispersal

 What factors trigger germination of the seed?  Water, correct temperature, presence of O2  What happens when a seed germinates? which triggers cause the Activity 4.21a- Seed dispersal Water goes through micropyle The switching on of plant growth factor genes Production of plant growth factors Secretion of amylase, maltase, lipases and proteases These enzymes catalyse the breakdown of polymers to monomers which can to transported (mobilised) to where they are needed (radicle and plumule)

 Which enzymes break down starch?  Amylase and maltase (think about malted grains...)  Which class of enzymes break down proteins and lipids?  Proteases and lipases  What are they broken down into?  Amino acids and fatty acids and glycerol  What is glucose made into so that it can be transported to the plumule and radicle?  Sucrose Activity 4.21a- Seed dispersal

 Starch  Oil What do we use from seeds?

 Thickening  Starch granules absorb water and swell when heated in water. This makes the liquid thicken. Called gelatinisation  Examples: Custard and wall paper paste   Stiffening fabrics  Starch is gelatinised and cooled allowing bonds to form between the starch molecules- called sizing  Adding water can reverse the stiffening  Examples: stiffening cloth and paper Starch

 Super- absorbents  Starch is chemically cross-linked BEFORE it is gelatined. Particles are formed which can be dried. These particles can absorb large amount of water.  Examples: nappies  Starch foam  Gelatinisation with a water content of less 10%, at temperatures above 100 degrees Celsius, and high pressure. The pressure is then suddenly released (by the sead coat bursting or by a machine) and the water turns into steam causing the starch to puff up into a foam.  Examples: puffed cereals, starch based foam packaging  Starch

 Oils in cooking  Examples- sunflower oil, corn oil, olive oil  Fuels  Like fossil fuels, oils from seeds can also burn releasing heat energy. The oils can be blended with diesel (from fossil fuels). The advantage is that when oils burn they produce less sulphur dioxide than diesel. They are also carbon neutral (more later)  Examples- Castor bean oil, peanut oil, rapeseed oil  Vegetable Oil

 Read pages  Define Sustainable:  A resource or system that meets present needs without compromising those of future generations-  without using up a limited source- renewable  Without producing pollutants  Example:  A continuously maintained forest where mature trees are harvested and new trees are replanted to absorb carbon dioxide and provide continued resources and products for future generations. Sustainability

 Why is it not sustainable to use fuels and plastics from fossil fuels?  Running out, pollution, leading to global warning, non biodegradable  Using biofuels is carbon neutral: what is meant by this term?  Carbon footprint is zero, any carbon dioxide produced by the burning of biofuels is roughly equal to the amount of carbon dioxide used by the plants in photosynthesis RECENTLY.  What other factors have to be considered when using biofuels?  Cost of growing- ploughing, harvesting, fertilising cost energy and money (this may involve using fossil fuels)  Finding land to grow the crops- less land for food, more land is deforested, more species lose their habitat  Transport to where they are used in terms of energy used and pollution- this may involve using fossil fuels Sustainability

 What are the advantages of a biodegradable material?  It is broken down relatively quickly into harmless products- less pollution. Also renewable sources are used  Is biodegradable packaging always a good solution for our waste problem?  No, it might not get broken down in anaerobic conditions, like land fill sites,  Also methane is sometimes released when it is broken down. Methane is a green house gas  What are some of the problems that need to be considered when switching to plant derived materials?  Source, energy used and pollution created during the production and transport of the product, paper bags can more easily break

 Do you think your lifestyle is sustainable?  What is our footprint?   What changes could you make to contribute to more sustainability?

Practical Review Practical 4.17 – Mineral Ion Deficiencies in Plants Practical 4.18 – Extracting Plant Fibres and Measuring the tensile strength of Plant Fibres. Practical 4.19 – Investigating the antibacterial properties of plants – Mint and Garlic Hmwk- For each of the above practicals write down the following in your notes: – dependent variables – independent variables – variables to control – procedure summary – safety/ethical concerns – Sketch of a graph for results