Reproduction in Flowering Plants Objective: 1. Describe the reproductive organs of the plant 2. Explain the process of sexual reproduction in angiosperms 3. Describe the structure and function and structure of seeds Homework: Learn about and describe different methods of seed dispersal Quiz 1. Why are the palisade and the spongy mesophyll called the ‘working layers’ of the leaf? 2. What is cambium and what does it do? 3. How does the arrangement of the stomata leading into the spongy mesophyll (filled with air spaces) ensure chlorophyll containing cells have a constant supply of carbon dioxide for photosynthesis? 4. On board 9Ad Parts of a flower Sexual Reproduction in Angiosperms • Plants reproduce sexually • The products of this sexual reproduction are seeds. • These seeds are contained inside an ovary. Which develops into a fruit. Reproductive Parts Male reproductive organs (stamen): • Anther: produces pollen grains • Filament: supports anther above female reproductive organs Female reproductive organs (carpel): • Stigma: sticky landing site for pollen grains • Style: tube that leads down to ovary • Ovary: contains ovules that develop into seeds 9Ad Reproductive Mechanisms Pollen (male gamete) from one plant lands on the stigma of another plant. This is called pollination. stigma pollen Methods of Pollination • Natural Reproduction • Pollination in angiosperms can happen by wind or animals. • Animals can transfer pollen (bees) from one plant to the other. – They are called pollinators • Pollen can be blown from one plant to another. – Wind dispersal Reproduction 9Ad Selective breeding in plants texture taste size Selective breeding and cross-breeding are carried out on plants to produce flowers and crops with desirable characteristics… colour 9A Plant-breeding techniques Anne the plant breeder chooses two parent plants with useful characteristics. One plant will be the female parent. Anne removes the anthers and covers the flower with a bag. Why? female parent The other plant is the male parent. Its anthers develop as normal. Anne collects its pollen and brushes it onto the female plant. collected pollen anthers removed She puts the bag over the flower again. Later she collects the seeds and grows them to produce the new plant. 9Ad From Pollen to Ovary The pollen grain grows a pollen tube towards the ovary, which contains the ovule and egg cell (female gamete). pollen tube ovary containing ovule 9Ad Fertilization Fertilisation takes place when the ‘sperm’ nucleus from the pollen grain enters the egg cell. The resulting zygote eventually turns into a seed. pollen tube with pollen grain nucleus ovule Embryo grows inside the ovule. egg cell Compare • With your neighbour, discuss how the reproductive system in plants is similar to the reproductive system in humans. Quiz 1. Name three different methods of seed dispersal. 2. Chose one method and explain how it effectively disperses seeds away from plant. 3. What are the male parts of the plant called? 4. What is it called when pollen from one plant lands on the stigma of another plant. Comparing Plant and Human Reproductive Systems • • • • • • • • Plant Male and Female organs Male Gamete is pollen Female Gamete is egg produced in ovule Pollen nuclei fuses with egg nuclei (fertiliation) Diploid zygote Zygote grows into embryo Embryo grows inside protective seed coat Cotyledons provide nourishment • • • • • • • • Human Male or Female organs Male Gamete is sperm Female Gamete is egg produced in ovary Sperm nuclei fuses with egg nuclei (fertilization) Diploid zygote Zygote grows into embryo Embryo grows inside protective womb Placenta provides nourishment Zygote to Embryo The zygote will grow through the process of mitosis to form an embryo (The ovule is now called a seed and is covered by a protective seed coat.) seed seed coat food supply (cotyledon) embryo Fruit Formation • Some plants produce fruit containing seeds. • Fruit: Mature ovary • Tissue surrounding the embryo develops into fruit. • When the fruit is fully developed it drops off the plant, or is carried away by an animal. • When fruit decomposes it releases the seed and germination can occur. Germination • A seed requires moisture (water) to germinate. • The as the embryo grows, the root and shoot break through the seed coat. • Nutrients stored in the cotyledon provide nourishment and support early development Life cycle of an angiosperm Plenary.. 1. What is the function of the flower? 2. What is a seed? 3. What basic condition is required for a seed to germinate? 4. Describe two methods of pollination.