Chapter 3: Plant Growth and Reproduction 5 th grade Science Teacher Imarlys Cajigas Big Idea: Plants have a variety of structures to help them carry out life processes. plants/flower_anatomy.jsp

Lesson 2: How do plants reproduce?

Vocabulary  Spore- a single reproductive cell that can grow into a new plant.  Gymnosperm- a plant that produces naked seed.  Angiosperm- a flowering plant that has seeds protected by fruits.  Germinate- to sprout.

Plant Characteristics  Plants reproduce by spores or seeds.  there are two stages in a plants life:  Sporophyte (produces spores)  Gametophyte (produces gametes)

What is a Sporophyte?  A plant in the spore producing stage of life.  Spores can grow directly into an adult plant

What is a Gametophyte?  The stage in a plant’s life where it produces male and female sex cells.  Needs a moist environment for the sperm to swim and fertilize the eggs.

More on Gametophytes  Male and female sex cells must join in order to grow into a new plant. This is called Fertilization.

Fertilization  Gametes join to form a zygote.  A fertilize egg grows into a sporophyte,  Sporophyte grow from the gametophyte and live on its own.  Spores are produced in clusters called sori that toss spores several meters from the ground.

How are Plants Classified?  Vascular Plants  Have tissues that deliver needed materials throughout a plant - called vascular tissues.  Can be almost any size.  Are divided into gymnosperms and angiosperms

How are Plants Classified?  Gymnosperms -- non-flowering plants that produces naked seeds.  Angiosperms -- flowering plants that produces seeds protected by a fruit.

Gymnosperms Reproduction  Male pine cones produces pollen that contains sperm.  Females cones are larger and grow high on trees. Ovules contains the eggs and grow on the scales of female cones.  Mature male cones release millions of pollen grains that are blown by the wind.  Some pollen fertilize the eggs and a seed develops.  When the seeds are mature the cone scales separate and the seeds travel on the wind.  If the seed lands in a suitable habitat a new plant begins to grow. And the life cycle begins.

The Parts of a Flower  Most flowers parts:  sepals,  petals,  stamens,  stigma.

The parts of a flower  Petals attract insects.  Stamens make pollen.

Stamen (male)  Anther: pollen grains grow in the anther.  When the grains are fully grown, the anther splits open.  Petals – attracts insects for pollination. Sepals protect the bud until it opens.

Pistil (female)  Stigma collects pollen  Carpel (ovary) after fertilization it develops into a fruit.  Ovules (eggs) develop into a seed.

Pollination  Flowering plants use the wind, insects, bats, birds and mammals to transfer pollen from the male (stamen) part of the flower to the female (stigma) part of the flower.

Pollination  A flower is pollinated when a pollen grain lands on its stigma.  Each ovary grows into a fruit which contains the seeds.

Fertilization  Pollen grains germinate on the stigma, growing down the style to reach an ovule.  Fertilized ovules develop into seeds.  The ovary enlarges to form the flesh of the fruit and to protect the seed.

Wind pollination  Some flowers, such as grasses, do not have brightly coloured petals and nectar to attract insects.  They do have stamens and carpels.  These flowers are pollinated by the wind.

Seed dispersal Seeds are dispersed in many different ways:  Wind  Explosion  Water  Animals  Birds  Scatter

How birds and animals help seed dispersal?  Some seeds are hidden in the ground as a winter store.  Some fruits have hooks on them and cling to fur or clothes.

How birds and animals help seed dispersal?  Birds and animals eat the fruits and excrete the seeds away from the parent plant.

Seed Germination  Seeds are adapted to germinate when conditions are right for growth of the embryo.  A thick seed coat protects the embryo until it germinates.  Sometimes seeds stay in the ground for several years before they grow; the timing will depend on the needs of the plant.  When the time is right, a seed absorbs water and expands. This breaks the seed coat, and the embryo begins to grow.

 First, the root emerges from the seed and begins to anchor and take up nutrients.  Then a shoot pushes up. The leaves of an embryo cannot make food, the nutrients come from a structure called cotyledon, until the plant grow and makes its own food.  When the first leaves emerge from the ground, they turn green as chlorophyll for photosynthesis is produced.  Rapid growth begins and the embryo becomes a plant seedling.

Lesson Review  What is a gametophyte?  What happens during the sporophyte stage?  Male reproductive cells are called ____________.  Female reproductive cells are called_________.  Where do seeds of conifers develop?  How are angiosperm seeds and gymnosperm seeds different?  Which part of the flower eventually develops into a fruit?  Why are a flower’s petal so important in reproduction?  Where does the embryo obtains its food?  How do the leaves of an embryo differ from the leaves of a mature plant?

Practice  Answer workbook p  Make a diagram of the flower, identify each part and write its function.  Make a diagram of a moss life cycle and a fern life cycle.  Compare and contrast mosses and ferns.