Chapter 38 - Chapter 38 Angiosperm Reproduction and...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 38 - Angiosperm Reproduction and Biotechnology Chapter 38 Angiosperm Reproduction and Biotechnology Lecture Outline Overview: To Seed or Not to Seed Sexual reproduction is not the sole means by which flowering plants reproduce. Many species can also reproduce asexually, creating offspring that are genetically identical to them. The propagation of flowering plants by sexual and asexual reproduction forms the basis of agriculture. For 10,000 years, plant breeders have altered the traits of a few hundred angiosperm species by artificial selection, transforming them into today’s crops. Concept 38.1 Pollination enables gametes to come together within a flower Sporophyte and gametophyte generations alternate in the life cycles of plants. The life cycles of angiosperms and other plants are characterized by an alternation of generations, in which haploid (n) and diploid (2n) generations take turns producing each other. o The diploid plant, the sporophyte, produces haploid spores by meiosis. o These spores divide by mitosis, giving rise to multicellular male and female haploid plants—the gametophytes. o The gametophytes produce gametes—sperm and eggs. o Fertilization results in diploid zygotes, which divide by mitosis to form new sporophytes. In angiosperms, the sporophyte is the dominant generation, the conspicuous plant we see. o Over the course of seed plant evolution, gametophytes became reduced in size and dependent on their sporophyte parents. Angiosperm gametophytes are the most reduced of all plants, consisting of only a few cells. In angiosperms, the sporophyte produces a unique reproductive structure, the flower. o Male and female gametophytes develop within the anthers and ovules, respectively, of a sporophyte flower. o Pollination by wind, water, or animals brings a male gametophyte (pollen grain) to a female gametophyte contained in an ovule embedded in the ovary of a flower. Union of gametes (fertilization) takes place within the ovary. Ovules develop into seeds, while the ovary itself develops into the fruit around the seed.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Flowers are specialized shoots bearing the reproductive organs of the angiosperm sporophyte. Flowers, the reproductive shoots of the angiosperm sporophyte, are typically composed of four whorls of highly modified leaves called floral organs, which are separated by very short internodes. o Unlike the indeterminate growth of vegetative shoots, flowers are determinate shoots in that they cease growing once the flower and fruit are formed. The four kinds of floral organs are the sepals, petals, stamens, and carpels. o Their site of attachment to the stem is the receptacle. Sepals and petals are sterile. o Sepals, which enclose and protect the floral bud before it opens, are usually green and more leaflike in appearance than the other floral organs.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern