Plants are multicellular eukaryotes with cell walls made of cellulose. Plants are essential to our environment because they provide oxygen and take in carbon dioxide, create habitats for animals, and supply food for almost every living organism on Earth. Plants use photosynthesis to produce energy for themselves and other living things. Plants evolved from stoneworts, which reproduced by releasing spores, into species more capable of dispersing their seeds.
Plants: Multicellular eukaryotes with cell walls made of cellulose.
Alternation of Generations: Change back and forth from one generation to the next between haploid and diploid stages in the life cycle of plants.
Haploid: Having only one chromosome of each type.
Diploid: Having two of each type of chromosome (twice the amount of chromosomes in haploids).
Gametophyte: Haploid individual produced through asexual reproduction with spores.
Sporophyte: Diploid individual produced through fertilization of gametes (reproductive cells).
Spore: Reproductive structure adapted for dispersal and surviving extended periods of time in unfavorable conditions.
Vegetative Reproduction: Reproduction through stems, roots, or leaves.
Stonewort: An aquatic algae that is similar to the ancestor many early plants evolved from.
Rhizoid: Hair-like structure in a nonvascular plant that absorbs water and minerals and anchors the plant to a surface.
Vascular Tissue: Type of tissue in plants that transports fluids through the plant.
Lignin: Tough, hydrophobic carbohydrate molecule that stiffens and waterproofs vascular tissues of plants.
Seed: Contains an embryo and a food supply enclosed within a tough coating.
Germination: Early growth and development of a plant embryo in a seed.
Gymnosperm: Type of seed plant that produces bare seeds in cones.
Cone: Structure consisting of scales that bear naked seeds in the type of seed plants called gymnosperms.
Angiosperm: A seed plant that buds flowers.
Flower: A structure in angiosperms that consists of both male and female reproductive structures.
Weeds: Plants that grow where people do not want them, such as in fields or in gardens.
All plants undergo alternation of generations.
Plants moved on land as early as 700 million years ago. They were small and low to the ground.
4. Plants then evolved to have seeds. The tough coating of the seed protects and nourishes the embryo (a zygote that has already begun development). The growth of the plant inside the seed is called germination. This increases the chances for the embryo to survive in tough conditions.
5. Different types of seed plants emerge.