Plants Part 7: Reproduction

Asexual Reproduction Plants use many structures to reproduce asexually. Rhizomes are modified stems such as stolons, eyes on tubers, etc. Modified leaves or shoots that can grow into new plants Usually occurs by the mitosis of diploid cells Makes genetically identical individuals (clones)

Asexual Benefits: If plant is successful in its environment, all offspring will get the same traits. Plant does not need reproductive structures, which require a lot of energy Only one plant needed Higher survival rate

Asexual Cost: Environment selects only individuals with traits that are favoured. Lack of variation can be dangerous for survival in environments that are not ideal.

Human Use of Asexual Reproduction Clone desirable plants by: Stem cutting and place in water and once the roots grow, transfer to the soil Grafting: cut a young branch of one plant and attach it to the stem of another plant of same or similar species

Seed Plant Sexual Reproduction Seed functions: protect and nourish the embryo and carry it to a new location. Seed dispersal by: Wind Animals eating fruit Animals spreading from fur Increases chance of survival

Seed Anatomy Monocots have one cotyledon with endosperm that feeds embryo. Dicots have two cotyledons that feed the embryo.

Gymnosperm Sexual Reproduction Conifers produce both male cones and female cones. Haploid cells called microspores are made in meiosis in the male cones that develops into a pollen grain containing the male gametophyte. Meiosis in female cones make megaspores that make egg-producing female gametophytes.

Seed Pollination and Fertilization Pollen grains have to move from the male cone to the female cone by pollination via the wind. The pollen grain grows a pollen tube that grows down to the ovule and releases two sperm nuclei. One fertilizes the egg, the other degrades Takes 13 months for the egg to be fertilized. Ovule then develops into a zygote, then an embryo. If the seed germinates, it becomes a sporophyte.

Sexual Reproduction in Angiosperms The products are seeds inside of a fruit Fruit is a mature ovary Flowers are the key organs in sexual reproduction Animal pollinated flowers are usually dramatic in order to attract bees, birds, insects. Cross pollination is when pollen is transferred from one plant to another. Self pollination is when pollen goes from one flower to another flower on the same plant.

Flower Anatomy CARPEL

Angiosperm Life Cycle