2.3 SEXUAL REPRODUCTION IN PLANTS

Recall: Many plants can reproduce asexually.  Plants also reproduce sexually.  The products of sexual reproduction in plants are seeds  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 Types  Robert Brown classified seed bearing 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 plants Gymnosperms: non-flowering plants Most produce seeds inside conesMost produce seeds inside cones

Angiosperms  These plants have large (chrysanthemums) or tiny (grass) flowers.  Seeds form inside flowers.  A pod or shell forms around the seeds.  Flowers contain the plant’s reproductive organs.

 There are males, females and hermaphrodites.  Females have pistils, males have stamens.  Gametes are produced and must join to form a zygote.  Zygotes grow into embryos. Angiosperms

The Stamen (Male)  Pollen Grains – the male gametes in a hard shell.  Anther – where pollen is made and stored.  Filament – the stalk supports the anther.

The Pistil (Female)  ovules – sacs containing the female gametes.  ovary – swollen base of the pistil containing ovules.  Stigma – sticky “lip” of the top of the pistil which catches pollen grains.  Style – the stalk that holds up the stigma.

Flower Parts Animation -scroll down for two animations Animation

Flower Dissection

Ovary Cross Section

Pollination in Angiosperms  Wind and insects carry pollen to the stigma. Angiosperms often have bright colors, and strong odours to help insects find it. Pollen: Shape, Color & Size pollen Tube pollen Tube  Click on pollen and Life Cycles Watch second half of video Watch second half of video Pollination – Move Pollination – Move -clip on pollen tube growth Angiosperms

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

Fertilization in Angiosperms

When a pollen grain lands on the stigma: - a pollen tube begins to grow through the style down to the ovary and into one ovule. - a sperm is released from the pollen grain which swims down the pollen tube. - the sperm and egg unite forming a zygote.

Seed Development in Angiosperms

- As soon as the pollen lands on the stigma the female’s ovule begins to form into a seed. - The food for the growing embryo is called the cotyledon. The sac around the ovule forms the seed coat. - the embryo forms a leaf, a stem, and a root. - the ovary begins to mature turning into a fruit.

Lily Meiosis HowStuffWorks Videos "Plant Biology: Making Pollen“ HowStuffWorks Videos "Plant Biology: Making Pollen“ 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: Making Eggs" HowStuffWorks Videos "Plant Biology: Making Eggs" HowStuffWorks Videos "Plant Biology: Pollination and Fertilization“ HowStuffWorks Videos "Plant Biology: Pollination and Fertilization“ HowStuffWorks Videos "Plant Biology: Pollination and Fertilization“ HowStuffWorks Videos "Plant Biology: Pollination and Fertilization“ HowStuffWorks Videos "Plant Biology: Germination and Growth" HowStuffWorks Videos "Plant Biology: Germination and Growth" HowStuffWorks Videos "Plant Biology: Germination and Growth" HowStuffWorks Videos "Plant Biology: Germination and Growth" ml#LILY ml#LILY ml#LILY ml#LILY Excellent picturesExcellent pictures

Gymnosperms - seeds form inside cones. - Cones open to let out the tiny seeds - The seed coat protects the seed from drying out. - Some plants reproduce sexually without bearing seeds. Examples include ferns and mosses.

Seed Dispersal in Angiosperms  Fruit aids in dispersal of seeds.  All About Seeds All About Seeds All About Seeds  Name and briefly describe 4 methods of seed dispersal from page 67.  Why is seed dispersal important?

Flower Dissection Objectives  To identify the major parts of a plant and flower and describe the function of each part.  To thoughtfully, safely and respectfully complete an anatomical dissection.

Materials  Lily bloom  Paper plates/plastic tray  Scissors or razor blade (to open the ovary)  Hand lens  Tweezers  Dissecting scope (One for the class)

Procedure 

Tomato Plant Investigation Tomato Seedling Growth Chart

Graphing Procedure 1. Title – put a descriptive title at the top of the page Tomato Plant Growth Tomato Plant Growth 2. Variables 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. Range (subtract smallest # from largest #) X-axis – 35 days X-axis – 35 days Y-axix – 15 cm or 30 cm Y-axix – 15 cm or 30 cm

Graphing Procedure 4. Labelling Label the independent variable on the X-axis Label the independent variable on the X-axis Label the dependent variable on the Y-axis Label the dependent variable on the Y-axis 5. Increments Mark the increments Mark 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. Plotting Data Represent each entry with a dot Represent each entry with a dot Join the dots with a line Join the dots with a line