Seeds and pollen contain sporopollenin to make them resistant to drying. Gymnosperms (conifers) and angiosperms (flowering plants) are heterosporous and have separate megasporangia (which produce the female gametophyte with eggs) and microsporangia (which produce microspores that develop into pollen grains containing sperm). When pollen enters the ovulate cone in gymnosperms, a pollen tube grows to reach the female gametophyte. Meiosis then occurs to produce haploid megaspores. Once fertilized, these form seeds. Angiosperms have petals to attract pollinators. Stamen produce pollen while pistils or carpals have a sticky stigma to capture pollen. A pollen tube grows down to the ovule, which develops into a seed when fertilized. The wall of the ovary thickens into a fruit. This lecture also covers monocots vs. dicots, seed structure, asexual reproduction, and self-pollination prevention
Seeds and pollen are
adaptations that allow seed plants to thrive on land. These
structures contain sporopollenin in their walls and are therefore
resistant to desiccation.
Seed plants are heterosporous,
producing two different types of spores, megaspores and microspores.
Each microspore develops into a grain of pollen. Female
gametophytes develop from megaspores.
Gymnosperms have seeds that are
not enclosed within fruits. Most gymnosperms are conifers; ginkgoes
and cycads are also gymnosperms.
The reproductive organ in
angiosperms is the flower. The pistil is the female reproductive
organ and consists of the stigma, style and ovary. The male
reproductive organ is the stamen, which consists of the filament and
Double fertilization occurs in
angiosperms. One sperm fertilizes the egg to form a diploid zygote
and the other fuses with the two polar nuclei to form a triploid
After fertilization, the ovule
develops into a seed. The ovary develops into fruit that encloses
and protects the seeds.
Plants can reproduce asexually
through vegetative propagation. The result is an offspring that is
genetically identical to the parent plant.
Gymnosperms and Angiosperms
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
The book and CD package include two full length practice exams that are presented with all questions answered and explained. The author also presents detailed reviews of all test topics and includes multiple-choice and free-response questions with answers at the end of each topic's chapter.
This book includes a review of the AP Biology exam format and scoring, proven strategies for answering multiple-choice questions, and hints for tackling the essay questions. The practice tests include answers and explanations and there is also proven test-taking strategies for both the multiple choice and essay parts.