Plant Asexual Reproduction• Above ground Stems arch over and take root at the tips, forming new plants (Forsythia, Raspberry and Strawberry)• Horizontal above ground stems are called stolons
Plant Asexual Reproduction• Underground stems that serve for food storage and reproduction. Rhizomes, bulbs, corms and tubers
Plant Asexual Reproduction• Leaves—Mitosis along the meristems at the leaf margins produce tiny plantlets that fall off and can take up an independent existence.
Advantages Of Vegetative Propagation• The young plant uses the food resources of the parent plant, while it is developing.• Only one parent plant is involved.• Good and desirable parental characters are retained in the offspring.• The new plant formed matures more rapidly than the plant which grows from seeds.• A large number of desired varieties of plant are produced in a very short time.
Disadvantages Of Vegetative Propagation• No new varieties are produced.• Over crowding of the vegetative produced plants leads to severe competition for survival among them.• Lack of variety leads to reduce resistance to disease and changes in the environment.• Colonization of the new localities is unlikely. Thus the plants are not widely distributed.
The life cycle of a flowering plant 4. Pollination 3. Flower blossom 5. Fertilization 2. Plantdevelopment & maturation 6. Seed/Fruit formation 1. Germination 7. Seed dispersal
Seed Structure Seed coat / Testa Forms a tough Plumule protective layer Embryo shoot Embryo – grows into seedlingsCotyledon / Food storeProvides the embryo Radicleplant with food. Embryo root
Development of the seed and fruit There are many kinds of fruits Carpels Flower Stigma Stamen Ovule Carpel Each (fruitlet) Stigma segment develops Seed from the carpel of Stamen one flower Pea Raspberry PineappleSimple fruit - single carpel of Aggregate fruit - many separate Multiple fruit - many carpelsone flower carpels of one flower of many flowers
What are fruits like?The fruits can be: - soft & fleshy - hard & dry• What fruits can you think of?• What are their seeds like?
Seed Dispersal- why?Seeds must be carried away (dispersed /scattered) from the parent plant to:• Reduce overcrowding• Reduce competition for: - Water - Light - Nutrients
How birds and animals help seed dispersal• Birds and animals eat the fruits and excrete the seeds away from the parent plant.
Development of the seed and fruit Fruits aid seed dispersalMany dry fruits are wind dispersed
Development of the seed and fruit Fruits aid seed dispersalSome dry fruits are animal dispersed
Development of the seed and fruit Fruits aid seed dispersalMany fleshy fruits are animal dispersed
Development of the seed and fruit Fruits aid seed dispersalSome fruits disperse seeds explosively (e.g., some mistletoes)
Development of the seed and fruit Fruits aid seed dispersalSome fruits make seeds buoyant, to aid dispersal by water
Seed DispersalDispersal Description Seeds/method Fruits Wind Seeds are designed to travel as far as possible. May have extensions which act as parachutes or wings. Fruits may be shaken like a pepper pot.
Seed DispersalDispersal Description Seeds/method Fruits Animal Some have little hooks(external) or sticky substances so they stick onto the animal’s fur, are carried away and rubbed off later. Some carried away by animals and dropped.
Stages of Seed Germination Absorption of Testa Radicle Grows water through Ruptures downwards micropyle Cotyledons is Hypocotyl Lateral roots pulled above lengthens formed ground Plumule Hypocotyl 1st foliage exposed to straighten leaves exposed sunlight Second leaves Photosynthesis
Advantages of GM foods(1) Pesticide alternative Crop loss due to pests can be financially crippling for farmerswhich is the reason most farmers use pesticides. As an alternative to pesticides, cropssuch as corn and soybeans can be genetically altered to resist pests - making the farmer,the consumer and the environmentalist happy.(2) Disease resistance There are many diseases - including fungi, viruses and bacteria -that can attack crops. With new GM technology, scientists can create crops that aregenetically resistant to these attackers.(3) Cold tolerance In order to prevent cold temperatures from killing crops, scientists cantake a gene that causes cold water fish to produce "antifreeze", and place it into certainplants that are susceptible to frost.(4) Drought resistance Genetically altering crops to resist drought and grow in otherwisenon-ideal conditions (like poor soil quality), farmers are able to grow crops in areas thatwere previously unsuitable for agriculture.(5) Adding nutritional value Scientists are able to identify nutritional deficiencies inspecific parts of the world, and genetically enhance the corn in order to satisfy thenutritional need.