The Plant Reproduction Unit

The Plant Reproduction Unit

We have covered:– Flower structure and function– Pollination and fertilization– Seed dispersal

What’s left?– Plant life cycle, fruit formation, horticulture

techniques with plant reproduction

What we’ve covered applies to flowering plants …what about other plants?

Plant Life Cycles

Mosses, Ferns, Conifers, and

Flowering Plants

General Life Cycle of Plants

• All plants cycle between two phases during their life

• Called ‘alternation of generations’

• We’ll study this cycle in mosses, ferns, conifers, and flowering plants

Alternation of Generations

• A fertilized egg develops into the sporophyte plant, which makes spores

• Sporophytes are diploid, meaning they have a full set of chromosomes from each parent

• Sporophytes produce spores, which are haploid (one set of chromosomes)

Alternation of Generations

• Spores grow into a gametophyte plant, which is also haploid

• The gametophyte produces sperm and eggs

• The sperm and eggs eventually fuse to become the fertilized zygote

Moss Life Cycle

• Mosses were the first plants to evolve, with no vascular tissue or seeds

• Mosses rely on water for the movement of spores, sperm, and eggs

Moss Life Cycle

• Mature sporophytes release spores that grow into young gametophytes called protonema

• The protonema grow into separate gametophyte plants that we see as ‘moss’

• Antheridia on the male plant release sperm, while archegonia on the female release eggs

So Sexy!

• The egg and sperm fuse to form a zygote

• The zygote grows into a mature sporophyte, which again releases spores

Fern Life Cycle

• Ferns were next to evolve, with vascular tissue but no seeds

• In the fern life cycle, the sporophyte is what we call a ‘fern’

Fern Life Cycle

• The mature sporophyte (fern) contains structures on the bottom called sporangia, clustered into sacs called sori

• The fern releases spores from the sori, which grow into young gametophytes

• Mature gametophytes contain both antheridia and archegonia, which release sperm and eggs

Even Sexier!

• The sperm and eggs fuse to become a zygote, which grows into a mature sporophyte (fern)

Coloring Activity

• Color in the Moss and Fern Life Cycle worksheets

• Label each phase of the cycle as haploid or diploid

• Read the material on the back of them for help!

• Try to LEARN and UNDERSTAND these cycles today…we have two more next week