36. Plant Reproduction

Evaluate these statements about double fertilization. Select True or False for each sentence. T/F Two zygotes are formed, but only one survives. T/F One sperm fuses with an egg while the other sperm fuses with polar nuclei. T/F It results in the formation of a diploid embryo and triploid endosperm. T/F Both sperm involved in double fertilization form within the same pollen tube.

Double fertilization means that a. flowers must be pollinated twice to yield fruits and seeds. b. every egg must receive two sperm to produce an embryo. c. one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei. d. every sperm has two nuclei.

In angiosperms, are sperm and eggs produced by mitosis or meiosis? Which cells are spores? Which structures are gametophytes?

Some plant species produce male and female individuals in which the males have an XY genotype and the females have an XX genotype. After double fertilization, what would be the genotypes of the embryos and endosperm nuclei? (A) embryo XY/endosperm XXX or embryo XX/endosperm XXY (B) embryo XX/endosperm XX or embryo XY/endosperm XY (C) embryo XX/endosperm XXX or embryo XY/endosperm XYY (D) embryo XX/endosperm XXX or embryo XY/endosperm XXY

In a species showing sporophytic incompatibility, which type(s) of pollen could successfully fertilize an S2S3 flower? (A) S1 pollen from an S1S3 flower (B) S2 or S3 pollen from an S2S3 flower (C) S3 pollen from an S1S1 flower (D) S1 pollen from an S1S1 flower

What are the advantages and disadvantages of self-fertilization versus those of outcrossing?

DRAW IT Draw and label the parts of a flower.

Make a sketch of a simplified flower with all four organs, and indicate how the pattern of expression for just two genes (e.g., 'D' and 'E') could, hypothetically, regulate the development of each organ. Consider that what's important is whether a gene is on or off and that a structure can be specified when neither gene is expressed.

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? Considering the gooseberry flower shown here, what types of cues might attract bees to the plant? What type of rewards do bees seek?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? Researchers conducted controlled experiments to test for effects of different types of pollination on cape gooseberry fruit size and seed production. The types of pollination included self-pollination, cross-pollination by bees, and manual cross-pollination (transferring pollen from one plant to another by hand). Results are shown in the graphs here. Compared to self-pollination, do bees have a significant impact on fruit mass? How about on seed formation?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? Why might it be advantageous for plants to promote cross-pollination? What are the advantages of self-pollination?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? In general, larger fruits tend to earn higher profits for farmers who grow cape gooseberries as a crop. Compared to self-pollinated flowers, what is the approximate percentage of difference in fruit size of bee-pollinated flowers?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? Based on the data in the graphs provided, approximately how many ovules are found in each gooseberry carpel?

Most flowering plants can achieve pollination in several different ways. Those that produce pollen and carpels on the same plant may be self-pollinated, but they may also be cross-pollinated by insects or other pollinators. The cape gooseberry (Physalis peruviana) shown here is able to produce seed whether it is self- or cross-pollinated. Is one type of pollination better for reproductive success than the other? Global bee populations have been declining over the past decade. What impact might this have on the world's human population?