Chapter 3: Plant Growth and Reproduction

5th grade Science

Teacher Imarlys Cajigas

Big Idea: Plants have a variety of structures to help them carry out life processes.

http://www.softschools.com/science/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 PlantsHave 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:

WindExplosionWaterAnimalsBirdsScatter

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. 19-20

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.