Mastering 39

Plant hormones act by directly affecting the activities of _____. genes and enzymes enzymes membranes signal transduction pathways genes

Evergreen trees lose their leaves _____. every winter every fall in the spring in the summer steadily all year

The abscission layer is indicated by the letter ______. D C E B A

The breakdown of chlorophyll reveals the _____ pigments of a leaf. anthocyanin phycoerythrin xanthophylls carotenoid melanin

The formation of the abscission layer cuts off transport of substances to and from the leaf. As the concentration of sugar trapped within a leaf increases, _____ pigments are produced. melanin phycoerythrin carotenoid anthocyanin xanthophyll

The protective layer that forms between the abscission layer and the stem consists of _____. weak, colorless, thin-walled cells a layer of green palisade cells mycorrhizae irregularly shaped cells with very thick, lignified secondary walls densely colored cells filled with a waxy layer

After leaf abscission, growth will resume from the _____. protective layer palisade layer abscission layer axillary bud petiole

_____ trees lose their leaves in preparation for winter. Conifer Pine Deciduous Fir Spruce

What is the physical basis of the phototropic response? Cell transport Photosynthesis Cell shortening Cell elongation

True or false? Auxin is asymmetrically distributed in shoots because the auxin on the side of the plant facing the source of light is destroyed.

Where does the majority of stem growth in a plant occur? Lateral branches. Apical meristem. Axillary buds. Both the apical meristem and lateral branches.

Which of the following statements about hormones is true? Hormones are small inorganic molecules. Hormones are produced only in plants. Hormones can function at very low concentrations. Hormones are produced at the sites where they are needed

Which term describes the direction of auxin transport in a plant? Circular. Multidirectional. Polar. Bidirectional.

How does auxin produce gravitropism in a plant that is placed on its side? Auxin accumulates on the lower surface of the root and inhibits elongation of cells in that region. Auxin accumulates on the lower surface of the root and stimulates elongation of cells in that region. Auxin accumulates on the side of the leaf opposite the sunlight and inhibits elongation of cells in that region. Auxin accumulates on the side of the leaf opposite the sunlight and stimulates elongation of cells in that region.

How does auxin produce phototropism? Auxin accumulates in cells on the side of the plant facing the source of light and stimulates their elongation. Auxin accumulates in cells on the side of the plant facing the source of light and causes them to shorten. Auxin accumulates in cells on the side of the plant opposite the source of light and causes them to shorten. Auxin accumulates in cells on the side of the plant opposite the source of light and stimulates their elongation

Which organism does not cause disease in plants? Bacteria. Virus. Fungus. Herbivore.

Which structure does not protect stems and leaves from damage by herbivores? Trichomes. Stomata. Thorns. Spines

True or false? Plants do not produce many defenses against pathogens unless they are threatened because defensive structures and compounds require much energy and materials to produce and maintain.

What is the initial localized response of a resistant plant to pathogen invasion? Systemic acquired resistance. Plant death. Systemin production. Hypersensitive response

Which compound is not used in the localized response to pathogen invasion? Nitric oxide. Proteinase inhibitors. Phytoalexins. Salicylic acid

Which of the following statements about systemic acquired resistance (SAR) in plants is false? Hormones produced by an attacked leaf carry a signal to the rest of the plant. A suite of genes called the pathogenesis-related loci is expressed in response to a signal from an attacked leaf. Salicylic acid is the only compound involved in SAR signaling. SAR results in the production of protective compounds distant from the site of initial infection.

How does a plant defend against herbivores? Plant cells produce salicylic acid to warn the rest of the plant about the attack. The hormone systemin is produced at the site of injury and signals the plant to produce proteinase inhibitors. Plant cells at the site of attack are killed to starve the herbivore of nutrients. The plant produces molecules that stimulate the herbivore's digestive enzymes.