Chapter 38

A fruit is (A) a mature ovary. (B) a mature ovule. (C) a seed plus its integuments. (D) an enlarged embryo sac.

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.

Which statement concerning grafting is correct? (A) Stocks and scions refer to twigs of different species. (B) Stocks and scions must come from unrelated species. (C) Stocks provide root systems for grafting. (D) Grafting creates new species.

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 \(S_{2} S_{3}\) flower? (A) \(S_{1}\) pollen from an \(S_{1} S_{3}\) flower (B) \(S_{2}\) or \(S_{3}\) pollen from an \(S_{2} S_{3}\) flower (C) \(S_{3}\) pollen from an \(S_{1} S_{1}\) flower (D) \(S_{1}\) pollen from an \(S_{1} S_{1}\) flower

The black dots that cover strawberries are actually fruits formed from the separate carpels of a single flower. The fleshy and tasty portion of a strawberry derives from the receptacle of a flower with many separate carpels. Therefore, a strawberry is (A) a simple fruit with many seeds. (B) both a multiple fruit and an accessory fruit. (C) both a simple fruit and an aggregate fruit. (D) both an aggregate fruit and an accessory fruit.

Critics of GM foods have argued that transgenes may disturb cellular functioning, causing unexpected and potentially harmful substances to appear inside cells. Toxic intermediary substances that normally occur in very small amounts may arise in larger amounts, or new substances may appear. The disruption may also lead to loss of substances that help maintain normal metabolism. If you were your nation's chief scientific advisor, how would you respond to these criticisms?

Humans have engaged in genetic manipulation for millennia, producing plant and animal varieties through selective breeding and hybridization that significantly modify genomes of organisms. Why do you think modern genetic engineering, which often entails introducing or modifying only one or a few genes, has met with so much opposition? Should some forms of genetic engineering be of greater concern than others? Explain.

In a short essay (100-150 words), discuss how a flower's ability to reproduce with other flowers of the same species is an emergent property arising from floral parts and their organization.