Presentation on theme: "Chapter 24 Reproduction of Seed Plants"— Presentation transcript:
1 Chapter 24 Reproduction of Seed Plants SporophytesGametophytes are the gametes (egg and sperm)Sporophytes are the plantsGametophytes
2 Life Cycle of Gymnosperms Turn to page 611, Figure 24-4Cone scaleLife cycle of gymnosperms takes place in cones which are produced by the mature sporophyte plant.OvulePollen cones – produce male gametophytesSeed cones – produce female gametophytesOvules – found at the base ofeach scale, this is where thefemale gametophyte developsOvules
3 Fertilization and Development Text page 611Pollen tube – structure containing two haploid sperm nucleiZygote – new diploid sporophyte plantGenerally takes 2 years to completeZygote grows into an embryo, and becomes encased in a what will soon become a seed.Pollen grain has 2 nuclei!
4 Structure of flowers Specialized leaves: NOT involved in reproduction...Sepals – outermost circle of floral parts; protects flower bud2. Petals – found just inside the sepal; often brightly colored; attract insectsText page 612
5 Structure in Flowers: Reproduction Specialized leaves:ARE involved in reproduction...3. Stamen – contains the male parts of the flowerAnther – oval sac producing pollen grainsFilament – stalk that supports the anther
6 Structure in Flowers Reproduction Specialized leaves:ARE involved in reproduction...Carpel (Pistils) – makes up the female part of the flower; stigma, style, and ovaryOvary – contains ovules where the female gametophyte are producedStyle – stalk leading to the ovaryStigma – top of the style; sticky
7 Flower varietyFlowers vary greatly in shape, color, and size.
8 Flower VarietyThe typical flower produces both male and female gametophytes.But, sometimes, male and female gametophytes are produced in separate flowers on the same plant... Like on corn!Tassel = flower that produces male gametophytesSilk = style of a flower that contains the female gametophyte
9 Composite Flowers A simple flower has one reproductive system... Often called compound flowersA simple flower has one reproductive system...A compound flower is a whole colony of flowers with their own petals, and multiple reproductive systems.A sunflower is not a single flower, but arow of outer petals around many small flowersIncomplete flower = missing sepalsPerfect flower = has both stamen and pistilComplete flower = has pistil, sepal and stamenImperfect flower = staminate or pistillate..
10 Life Cycle of Angiosperms Reproduction takes place within the flowerSeeds develop inside protectivestructures.4 haploid cells are produced in the antherEach cell becomes a pollen grainIn the ovary, 4 haploid cells form, but three disintegrate.Remaining cell divides into 8 nuclei within a membrane called a embryo sac. One of the 8 nuclei is the egg nucleus.This is the gametophyte of the flowering plant
11 Pollination Most angiosperms are pollinated by animals, not wind... Advantage?Animals carry pollen from one flower to another.What is the advantage to the animal?
12 Double FertilizationText page 616A pollen grain lands on the stigma and begins to grow a pollen tube.The pollen tube grows into the style, eventually reaching the ovary and entering the ovule.Two distinct fertilizations take place:sperm and egg nuclei fuse together new plant embryoother nuclei form endosperm, a rich food supply for plant
14 24-2: Seed Development & Germination Development of the seed was a major factor in the success of plants on landA seed enclosed within a fruit offers something else...A better start to its new life!
15 Seed & Fruit Development Fruit – applies to any seed that is enclosed within its embryo wallsWhich of these foods are fruits?As Angiosperm seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds.
16 Plant Ovary (fruit) Lab Assignment:Bring in a plant ovary for our lab.You may choose any ovary, from the grocery store or out of your yard.We will dissect the plant ovaries...and possibly eat a few
17 Seed Dispersal Dispersal by Animals: Seeds are covered with a tough coating enabling them to pass through the digestive system unharmedSeeds dispersed by animals are typically contained in fleshy, nutritious fruits
18 Dispersal by Wind and Water Seeds dispersed by wind or water are typically lightweight, allowing them to be carried in the air or to float on the surface of the water
19 Seed DormancyDormancy – time in which an embryo is alive, but not growingEnvironmental factors such as temperature, and moisture can cause a seed to end dormancy and germinate
20 Seed GerminationGermination – the early growth stage of the plant embryoMonocotsUsually, the single cotyledon remains undergroundDicots (one of two ways)cotyledons emerge above ground and protect early leavescotyledons remain below the soil,providing food for the growing seedling
21 24-3: Plant Propagation & Agriculture Seed plants are essential to human lifeThe earliest humans gathered plants for food, shelter, and medicine
22 Vegetative Reproduction Vegetative reproduction - the production of new plants from horizontal stems, plantlets, or underground rootsOccurs when plants are well adapted to an areaPlantletsStolen – long, trailing horizontal stems that produce rootsCan reproduce very quickly!
23 Plant PropagationWhen a plant has a desired characteristic, we want copies.There are a variety of methods...Text p. 622Cuttings – cut a length of stem that includes buds (meristematic tissue)
24 Plant Propagation Other methods... Text p. 623To reproduce seedless or woody plants without strong root systems, we use grafting or budding.Grafts – stems are usedBudding – buds are usedScion – the stem or bud of a plantStock – root plant to which scion is attached
25 Agriculture Agriculture - the systematic cultivation of plants Worldwide Patterns of AgricultureNorth America has some of the richest, most productive cropland in the world.Most of the people in the world depend on a few crop plants for the bulk of their food supply...WheatRiceCorn
26 Changes in Agriculture Increases in crop yields has lowered prices, and fed more people on less land.As our population on Earth increases,what else can we do?