1. Chapter 38 ~Plant Reproduction and Development

2. I. Sexual Reproduction n A. Alternation of generations: haploid (n) and diploid (2n) generations take turns producing each other u 1. Sporophyte (2n): F a. produces haploid spores by meiosis; these spores divide by mitosis giving rise to male and female haploid plants called…. F b. Gametophytes (n): develop and produce gametes

3. Have you labeled a flower lately?

4. B. Floral variations n 1. Floral organs: sepals, petals, stamens (male ), carpels (female) u a. complete: all 4 floral organs u b. incomplete: lacking 1 or more floral organs u c. perfect: both stamens and carpels on 1 flower

5. u d.imperfect: lacking either a stamen or carpel u e. monoecious: staminate and carpellate flowers on 1 plant) u f. dioecious: staminate and carpellate flowers on separate plants

6. C. Gametophyte development u 1. Male gametophyte: microsporocyte (in pollen sacs of anther) divides by meiosis into 4 haploid microspores; F a. mitosis produces a generative cell (sperm) and a tube cell (pollen tube)= a pollen grain u 2. Female gametophyte : megasporocyte (in ovule) divides by meiosis to 4 cells, only 1 survives to a haploid megaspore; F a. 3 mitotic divisions forms the embryo sac; F b. includes: 1 egg cell (female gamete) and 2 polar nuclei (synergids)

8. D. Pollination – pollen grain lands on stigma n 1. pollen lands on stigma – pollen has 2 sperm cells & a vegetative nucleus n 2. veg. nucleus grows a tube down the style to the ovary n 3. ovule contains 1 egg & 7 accessory cells inside the embryo sac n 4. pollen tube enters embryo sac via micropyle (small opening)

9. Pollen tube with haploid male gametophyte nuclei.

10. Allergenic Pollen (poplar, alder, timothy grass, ragweed, sagebrush, scotchbroom)

12. E. Plant fertilization - sperm combo’s with egg n 1. one sperm fertilizes the egg n 2. nucleus of 2nd sperm fuses w/2 of the accessory cell nuclei forming a triploid nucleus – this grows to form into the endosperm which is the food for the embryo n 3. using 2 sperm for fert. = Double Fertilization n 4. The seed grows from the fertilized ovule…..

14. n a. mature seed: u 1) seed coat (protection) u 2) cotyledons (seed leaves) u 3) hypocotyl (lower embryonic axis) u 4) radicle (embryonic root) u 5) epicotyl (upper embryonic axis) u 6) plummule (shoot tip) u 7) coleoptile (sheath for embryonic shoot)

15. The seed

16. Seeds in a Pod

17. F. The fruit n 1. Fruit protects seeds and aids in their dispersal n 2. Pericarp (thickened wall of fruit forms from the ovary wall) n 3. Fruit types: u a. simple (1 ovary/1 flower)~ cherry, soybean u b. aggregate (1 flower with many ovaries) blackberry u c. multiple (inflorescence; groups of flowers w/ gps of ovary) ~ pineapple

18. G. Seed germination – breaking out of seed dormancy – triggers vary in dif species n 1. Seed dormancy (low metabolic rate and growth suspension) – some can stay dormant for thousands of years! n 2. Imbibition (uptake of water) – water instigates the growth process n 3. Radicle grows 1st, then shoot tip (hypocotyl); stimulated by light