2.3 SEXUAL 2.3 SEXUAL REPRODUCTION IN PLANTSREPRODUCTION IN PLANTS

Recall: Many plants can reproduce Recall: Many plants can reproduce asexually.asexually.

Plants also reproduce sexually.Plants also reproduce sexually. The products of sexual reproduction in The products of sexual reproduction in

plants are seedsplants are seeds A seed contains: A seed contains:

an embryo, an embryo, a food supply a food supply and a seed coat to keep the embryo moist.and a seed coat to keep the embryo moist.

Plant TypesPlant Types

Robert Brown classified seed bearing Robert Brown classified seed bearing plants into two types based on the seeds:plants into two types based on the seeds: Angiosperms: flowering plants Angiosperms: flowering plants

• Over ½ of all known plant speciesOver ½ of all known plant species Gymnosperms: non-flowering plantsGymnosperms: non-flowering plants

• Most produce seeds inside conesMost produce seeds inside cones

AngiospermsAngiosperms

These plants have large These plants have large (chrysanthemums) or tiny (grass) flowers.(chrysanthemums) or tiny (grass) flowers.

Seeds form inside flowers.Seeds form inside flowers. A pod or shell forms around the seeds.A pod or shell forms around the seeds. Flowers contain the plant’s reproductive Flowers contain the plant’s reproductive

organs.organs.

There are males, females and There are males, females and hermaphrodites.hermaphrodites.

Females have Females have pistilspistils, males have , males have stamens.stamens.

Gametes are produced and must join to Gametes are produced and must join to form a zygote.form a zygote.

Zygotes grow into embryos.Zygotes grow into embryos.

AngiospermsAngiosperms

The Stamen (Male)The Stamen (Male)

Pollen Grains – the male gametes in a hard Pollen Grains – the male gametes in a hard shell.shell.

Anther – where pollen is made and stored.Anther – where pollen is made and stored. Filament – the stalk supports the anther.Filament – the stalk supports the anther.

The Pistil (Female)The Pistil (Female)

ovules – sacs containing the female gametes.ovules – sacs containing the female gametes. ovary – swollen base of the pistil containing ovary – swollen base of the pistil containing

ovules.ovules. Stigma – sticky “lip” of the top of the pistil Stigma – sticky “lip” of the top of the pistil

which catches pollen grains.which catches pollen grains. Style – the stalk that holds up the stigma.Style – the stalk that holds up the stigma.

Flower PartsFlower PartsAnimationAnimation

-scroll down for two animations-scroll down for two animations

Flower DissectionFlower Dissection

Ovary Cross SectionOvary Cross Section

Pollination in AngiospermsPollination in Angiosperms

Wind and insects carry pollen to the Wind and insects carry pollen to the stigma. Angiosperms often have stigma. Angiosperms often have bright colors, and strong odours to bright colors, and strong odours to help insects find it.help insects find it.

http://www.britannica.com/eb/article-9110808/pollination http://www.britannica.com/eb/article-9110808/pollination

Pollen: Shape, Color & SizePollen: Shape, Color & Sizepollen Tubepollen Tube Click on pollen and Life CyclesClick on pollen and Life Cycles

Watch second half of videoWatch second half of videoPollination – MovePollination – Move

-clip on pollen tube growth-clip on pollen tube growth

AngiospermsAngiosperms

Self Pollination – pollen from the same Self Pollination – pollen from the same plant lands on the stigma.plant lands on the stigma.

  

Cross Pollination – pollen from different Cross Pollination – pollen from different plants of the same species land on the plants of the same species land on the stigma.stigma.

Fertilization in AngiospermsFertilization in Angiosperms

When a pollen grain lands on the stigma:When a pollen grain lands on the stigma:

-     a pollen tube begins to grow through the style -     a pollen tube begins to grow through the style down to the ovary and into one ovule.down to the ovary and into one ovule.

-     a sperm is released from the pollen grain which -     a sperm is released from the pollen grain which swims down the pollen tube.swims down the pollen tube.

-     the sperm and egg unite forming a zygote.-     the sperm and egg unite forming a zygote.

Seed Development in Seed Development in AngiospermsAngiosperms

- As soon as the pollen lands on the stigma the - As soon as the pollen lands on the stigma the female’s ovule begins to form into a seed.female’s ovule begins to form into a seed.

- The food for the growing embryo is called the - The food for the growing embryo is called the cotyledon. The sac around the ovule forms the cotyledon. The sac around the ovule forms the

seed coat.seed coat.- the embryo forms a leaf, a stem, and a root.- the embryo forms a leaf, a stem, and a root.

- the ovary begins to mature turning into a fruit.- the ovary begins to mature turning into a fruit.

Lily MeiosisLily Meiosis

HowStuffWorks Videos "Plant Biology: Making Pollen“HowStuffWorks Videos "Plant Biology: Making Pollen“ HowStuffWorks Videos "Plant Biology: Making Eggs"HowStuffWorks Videos "Plant Biology: Making Eggs" HowStuffWorks Videos "Plant Biology: Pollination and HowStuffWorks Videos "Plant Biology: Pollination and

Fertilization“Fertilization“ HowStuffWorks Videos "Plant Biology: Germination HowStuffWorks Videos "Plant Biology: Germination

and Growth"and Growth" http://samson.kean.edu/~breid/flower_lab/angi_lab.hthttp://samson.kean.edu/~breid/flower_lab/angi_lab.ht

ml#LILYml#LILY• Excellent pictures Excellent pictures

GymnospermsGymnosperms

- seeds form inside cones.- seeds form inside cones.

- Cones open to let out the tiny seeds- Cones open to let out the tiny seeds

- The seed coat protects the seed from - The seed coat protects the seed from drying out.drying out.

- Some plants reproduce sexually without - Some plants reproduce sexually without bearing seeds. Examples include ferns bearing seeds. Examples include ferns and mosses.and mosses.

Seed Dispersal in AngiospermsSeed Dispersal in Angiosperms

Fruit aids in dispersal of seeds.Fruit aids in dispersal of seeds. All About SeedsAll About Seeds Name and briefly describe 4 methods of Name and briefly describe 4 methods of

seed dispersal from page 67.seed dispersal from page 67.

Why is seed dispersal important?Why is seed dispersal important?

Flower DissectionFlower Dissection

ObjectivesObjectives To identify the major parts of a plant and To identify the major parts of a plant and

flower and describe the function of each flower and describe the function of each part.part.

To thoughtfully, safely and respectfully To thoughtfully, safely and respectfully complete an anatomical dissection.complete an anatomical dissection.

MaterialsMaterials

Lily bloomLily bloom Paper plates/plastic trayPaper plates/plastic tray Scissors or razor blade (to open the ovary)Scissors or razor blade (to open the ovary) Hand lensHand lens TweezersTweezers Dissecting scope (One for the class)Dissecting scope (One for the class)

ProcedureProcedure

Tomato Plant Tomato Plant InvestigationInvestigation

Tomato Seedling Tomato Seedling

Growth ChartGrowth Chart

Graphing ProcedureGraphing Procedure

1.1. Title – put a descriptive title at the top of the Title – put a descriptive title at the top of the pagepage

Tomato Plant GrowthTomato Plant Growth

2.2. VariablesVariables Independent variable on x-axis – Time (days)Independent variable on x-axis – Time (days) Dependent variable on y-axis – Plant Height (cm)Dependent variable on y-axis – Plant Height (cm)

3.3. Range (subtract smallest # from largest #)Range (subtract smallest # from largest #) X-axis – 35 daysX-axis – 35 days Y-axix – 15 cm or 30 cmY-axix – 15 cm or 30 cm

Graphing ProcedureGraphing Procedure

4.4. LabellingLabelling Label the independent variable on the X-axisLabel the independent variable on the X-axis Label the dependent variable on the Y-axisLabel the dependent variable on the Y-axis

5.5. IncrementsIncrements Mark the incrementsMark the increments

• Each line is one day, mark every fifth dayEach line is one day, mark every fifth day• Every second line is one cmEvery second line is one cm

6.6. Plotting DataPlotting Data Represent each entry with a dotRepresent each entry with a dot Join the dots with a lineJoin the dots with a line