2014 Pearson Education Inc 1 Results Shaded side

© 2014 Pearson Education, Inc. 1

Results Shaded side Control Light Boysen-Jensen Illuminated side Light Darwin and Darwin Gelatin (permeable) Light Tip removed © 2014 Pearson Education, Inc. Opaque cap Transparent cap Mica (impermeable) Opaque shield over curvature 2

Results Excised tip on agar cube Growth-promoting chemical diffuses into agar cube Control (agar cube lacking Control chemical) © 2014 Pearson Education, Inc. Offset cubes 3

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CELL WALL 3 Low p. H activates expansins. H 2 O H 2 Acidity increases. © 2014 Pearson Education, Inc. Plasma membrane H H H 1 Proton pump activity increases. 4 Cell wall-loosening enzymes cleave cross-linking polysaccharides. ATP H H Plasma membrane H Cell wall CYTOPLASM Nucleus Cytoplasm Vacuole 5 Sliding cellulose microfibrils allow cell to elongate. 5

(b) Grapes from control vine (left) and gibberellintreated vine (right) (a) Rosette form (left) and gibberellin-induced bolting (right) © 2014 Pearson Education, Inc. 6

Aleurone Endosperm -amylase GA Water Scutellum (cotyledon) © 2014 Pearson Education, Inc. Sugar GA Radicle 7

Red mangrove (Rhizophora mangle) seeds Coleoptile Maize mutant © 2014 Pearson Education, Inc. 8

ein mutant (a) ein mutant © 2014 Pearson Education, Inc. ctr mutant (b) ctr mutant 9

0. 5 mm Protective layer Abscission layer Stem © 2014 Pearson Education, Inc. Petiole 10

(a) Before exposure to light © 2014 Pearson Education, Inc. (b) After a week’s exposure to natural daylight 11

Phototropic effectiveness 1. 0 436 nm Refracting prism 0. 8 0. 6 0. 4 White light 0. 2 0 400 450 500 550 600 650 700 Wavelength (nm) (a) Light wavelengths below 500 nm induce curvature. © 2014 Pearson Education, Inc. (b) Blue light induces the most curvature of coleoptiles. 12

Results Red Dark Red Far-red Dark (control) Red © 2014 Pearson Education, Inc. Far-red Red Dark Red Far-red 13

Red light Synthesis Pr Pfr Far-red light Slow conversion in darkness (some species) © 2014 Pearson Education, Inc. Responses to Pfr: • Seed germination • Inhibition of vertical growth and stimulation of branching • Setting internal clocks • Control of flowering Enzymatic destruction 14

Noon © 2014 Pearson Education, Inc. 10: 00 PM 15

24 hours (a) Short-day (long-night) plant Light Critical dark period Flash Darkness of light (b) Long-day (short-night) plant Flash of light © 2014 Pearson Education, Inc. 16

24 hours R R FR Critical dark period © 2014 Pearson Education, Inc. Short-day Long-day (long-night) (short-night) plant 17

Statoliths (a) Primary root of maize bending gravitropically (LMs) © 2014 Pearson Education, Inc. 20 m (b) Statoliths settling to the lowest sides of root cap cells (LMs) 18

© 2014 Pearson Education, Inc. 19

(a) Unstimulated state (leaflets spread apart) © 2014 Pearson Education, Inc. (b) Stimulated state (leaflets folded) 20

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Vascular cylinder Air tubes Epidermis 100 m (a) Control root (aerated) © 2014 Pearson Education, Inc. 100 m (b) Experimental root (nonaerated) 22

4 Recruitment of parasitoid wasps that lay their eggs within caterpillars 1 Wounding 1 Chemical in saliva 3 Synthesis and release of volatile attractants 2 Signal transduction pathway © 2014 Pearson Education, Inc. 23

Infected tobacco leaf with lesions 4 2 Signal 5 Hypersensitive 3 response Signal transduction pathway 6 Signal transduction pathway 7 Acquired resistance 1 Avirulent pathogen R protein Avr effector protein R-Avr recognition and hypersensitive response © 2014 Pearson Education, Inc. Systemic acquired resistance 24