1. Plant Reproduction and Biotechnology
Chapter 38
Plant Reproduction and Biotechnology

2. I. Sexual Reproduction

3. A. Alternation of Generation
Diploid sporophyte makes haploid spores through meiosis
Spores divide by mitosis giving rise to male and female gametophytes
Gametophytes develop and produce gametes
These fuse and form a diploid zygote
This becomes the seed → sporophyte

5. B. Flowers

6. 1. 4 Whorls Sepals – non-reproductive, cover flower
Petals – non-reproductive, attract pollinators
Stamen – male / anther (pollen), filament
Carpals – female / style, stigma, ovary, ovule
Stem attaches to receptacle
Pollen grains – male gametophyte
Embryo sac – female gametophyte / form in ovules

9. 2. Flower Types
Complete flowers have all 4 organs / incomplete flowers lack one part
Bisexual flowers have stamen and carpals / unisexual flowers lack stamen or carpals
Monoecius are unisexual with staminate and carpellate flowers on the same plant / dioecious have flowers on different plants

10. What type of Flower are they?

12. C. Gametophytes

13. 1. Male Gametophyte
Microsporocyte (2N) undergoes meiosis forming 4 microspores which may become male gametophytes
Microspores divide by mitosis producing 2 cells / generative (sperm) and tube (pollen tube)
This is a pollen grain and is considered the male gametophyte when the generative cell divides to form 2 sperm

15. 2. Female Gametophyte
In ovules a megasporocyte goes through meiosis forming 4 megaspores, only one survives
The megaspore divides 3 times by mitosis forming 8 nuclei in one large cell
This is portioned into an egg cell, 2 synergids (guide pollen tubes), 3 antipodal cells, and 2 polar nuclei

17. D. Preventing Self-Pollination
Plants mature at different times
Plants are structurally different
Self Incompatibility
- works like an opposite immune system
- identifies “self” genes and stops fertilization

18. E. Double Fertilization
2 sperm are placed inside the embryo sac
One fertilizes the egg and the other combines with the polar nuclei to form the triblastomic endosperm
Double fertilization ensures that the endosperm only develops in fertilized eggs

20. F. Endosperm, Embryo, and Seed Development

21. 1. Endosperm Development
Precedes embryo development
It is initially made of a milky super cell and becomes partitioned and solid later
Endosperm stores the nutrients or ships them to the cotyledons

22. 2. Embryo Development Uneven transverse division occurs first
Separates the cell into the terminal (embryo) and basal (suspensor) sides
Develops into the protoderm (dermal), ground meristem (ground), and the procambium (vascular)
Root-shoot axis and radial patterns are formed

24. 3. Seed Development
Seed Coat – protects the seed / formed from the integuments
Hypocotyl – point where cotyledons attach
Radical – embryonic root
Epicotyl – above the hypoctyl, plumule attaches here
Monocots have a coleoptile which protects the shoot tip and a coleorhiza which protects the root tip

26. G. Fruit Ovary of the flower which protects and attracts
Pericap – thick wall of the fruit
Becomes softer, sweeter, and changes color when the seeds are ready to go

27. H. Dormancy Dehydrates the seed
Increases chances of proper seed germination
May need light, cold, chemical attacks, or fire for germination to occur
Gibberellins are hormones that kick germination off
Gibberellins are produced after imbibition occurs

30. II. Asexual Reproduction
Fragmentation – separating a parent plant into parts
Apomixis – forming seeds with out fertilization / dandelions
Cuttings – callus forms (undifferentiated) at the end of a cut and adventitious roots develop
Graft – attach a scion to the stock / grapes
Test-tube and Protoplast fusion

31. III. Biotechnology (Genetic Engineering)
Transgenic – genetically engineered to express foreign genes from another species
Ex. Rice with daffodil genes / cotton, maize, and potatoes with Bt genes
What’s your opinion?