1. Much of this is covered in the Home Component portion of this unit.
CHAPTER 31
Part II of slides
Much of this is covered in the Home Component portion of this unit.

2. 31.7 Primary growth lengthens roots and shoots
Most animals are characterized by determinate growth, stopping growth after a certain size.
Most plants have indeterminate growth, continuing to grow throughout a plant’s life.
Plant growth originates in meristems
Apical meristems at the tips of roots and in terminal buds and axillary buds of shoots initiate primary growth by producing new cells. A root or shoot lengthens as the cells elongate and differentiate.
Student Misconceptions and Concerns
Students often expect determinate growth in plants because it is characteristic of humans. However, most plant species show indeterminate growth and are capable of growing as long as they live. (31.7)
Teaching Tips
Lobsters are one of the few animals that show indeterminate growth. (31.7)
Active Lecture Tips
See the Activity “How Does a Tree Grow? Which Four Year Old Do You Agree With?” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (31.7–31.8)

3. Shoot tip (shoot apical meristem and young leaves) Vascular cambium
Lateral
meristems
Cork
cambium
Axillary bud
meristem
Figure 31.UN02 Reviewing the concepts, 31.7
Root apical
meristems

4. Vascular cylinder Cortex Root hair Epidermis Zone of differentiation
Cellulose
fibers
Zone of
elongation
Zone of
cell division
(including
apical
meristem)
Figure 31.7c Primary growth of a root
LM 200×
Root
cap
Key
Dermal
tissue system
Ground
tissue system
Vascular
tissue system

5. 31.9 The flower is the organ of sexual reproduction in angiosperms
Teaching Tips
More students will recall that stamens are the male organs if they emphasize the word’s last syllable. (31.9)
The four main parts of a flower, which are modified leaves, represent additional examples of evolutionary remodeling. (31.9)

6. 31.10 The development of pollen and ovules culminates in fertilization
Plant life cycles are characterized by an alternation of generations, in which haploid (n) and diploid (2n) generations take turns producing each other.
The diploid plant body is called the sporophyte.
Haploid spores are formed within ovules and anthers.
The spores in anthers give rise to male gametophytes, pollen grains, which produce sperm.
A spore in an ovule produces the embryo sac, the female gametophyte. Each embryo sac has an egg cell.
Pollination is the transfer of pollen from anther to stigma.
Student Misconceptions and Concerns
Students’ knowledge of sexual reproduction in animals often results in an expectation of similar processes in plants. The double fertilization typical of angiosperms requires extra time and attention to distinguish it from processes in animals. (31.10)
The development of the male and female gametophytes in flowers is often not well understood by students who are more familiar with animals. A thorough review of the alternation of generations life cycle of plants is helpful before discussing the details of plant sexual reproduction. (31.10–31.12)
Teaching Tips
Plants that produce lightweight, windborne pollen are the major sources of allergies because it remains in the air longer than heavier pollen grains. (31.10)
Coconut milk is an example of liquid endosperm. Coconut meat is solid endosperm. ( )
Active Lecture Tips
See the Activity “Concept Mapping the Alternation of Generations in Angiosperms” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (31.10)

7. 1 Pollination 3 Mitosis (of each spore) 2 3
Development of male
gametophyte
(pollen grain)
Anther
Cell within
anther
Ovary 1
Meiosis
Four haploid
spores
Figure 31.10_1 Gametophyte development and fertilization in an angiosperm (part 1)
Single spore
Pollination 3
Wall
Mitosis
(of each spore) 2
Nucleus of
tube cell
Generative cell 3
Pollen grain
released
from anther

8. Development of female gametophyte (embryo sac) Ovule Ovary Meiosis1
Meiosis
Surviving
cell (haploid
spore)
Figure 31.10_2 Gametophyte development and fertilization in an angiosperm (part 2) 2
Mitosis
Embryo
sac
Egg cell

9. Germinated
pollen grain
on stigma
Pollination 3
Wall
A pollen tube grows down into the ovule, and sperm pass through it and fertilize:
-the EGG (forming the diploid zygote)
-and a 2n central cell (forming a triploid nucleus) (becomes a food-storing tissue called ENDOSPERM.
Generative
cell
Nucleus of
tube cell 3
Pollen grain
released
from anther
Embryo
sac
Egg cell
Two sperm
in pollen
tube
DOUBLE FERTILIZATION
Figure 31.10_3 Gametophyte development and fertilization in an angiosperm (part 3) 4
Pollen
tube
enters
embryo sac
Triploid (3n)
endosperm
nucleus
Two sperm
discharged
Diploid (2n)
zygote
(egg plus
sperm) 5
Double
fertilization
occurs

10. 31.11 The ovule develops into a seed
After fertilization, the ovule becomes a seed, and the fertilized egg within it divides and becomes an embryo.
The other fertilized cell develops into the endosperm, which stores food for the embryo.
Near the end of its maturation, the seed loses most of its water and forms a hard, resistant seed coat.
Student Misconceptions and Concerns
The development of the male and female gametophytes in flowers is often not well understood by students who are more familiar with animals. A thorough review of the alternation of generations life cycle of plants is helpful before discussing the details of plant sexual reproduction. (31.10–31.12)
Teaching Tips
Coconut milk is an example of liquid endosperm. Coconut meat is solid endosperm. ( )

11. Embryonic leaves Embryonic shoot Embryonic root Cotyledons Seed coat
Common bean (eudicot)
Fruit tissue
Cotyledon
Seed coat
Figure 31.11b Seed structure in eudicots and monocots
Endosperm
Embryonic
leaf
Embryonic
shoot
Sheath
Embryonic
root
Corn (monocot)

12. 31.12 The ovary develops into a fruit
While the seeds are developing from ovules, hormonal changes triggered by fertilization cause the flower’s ovary to grow, thicken, and mature into a fruit.
A fruit is a mature ovary that acts as a vessel, housing and protecting seeds and helping disperse them from the parent plant.
Student Misconceptions and Concerns
The development of the male and female gametophytes in flowers is often not well understood by students who are more familiar with animals. A thorough review of the alternation of generations life cycle of plants is helpful before discussing the details of plant sexual reproduction. (31.10–31.12)
The distinction between fruits and vegetables is a frequent, if trivial, point of contention. Module specifically notes the structures and functions of fruits. To promote further understanding, consider discussing the meaning of the term “vegetable.” (31.12)
Teaching Tips
Seed dispersal mechanisms are diverse and reflect specific adaptive strategies. The inventor of Velcro was inspired by the seed dispersal mechanisms of the common burdock plant. (31.12)

13. 31.13 Seed germination continues the life cycle
A seed is a sort of “escape pod” in which an embryo lies dormant, surrounded by a supply of food and protected from the elements.
A seed starts to germinate when it takes up water and expands.
The embryo resumes growth and absorbs nutrients from the endosperm.
An embryonic root emerges, and a shoot pushes upward and expands its leaves.
Eudicot
Teaching Tips
Seed production in plants clearly illustrates the ability of organisms to produce more offspring than can survive, a premise of natural selection. While discussing seed production, consider reminding students of this important principle, well illustrated in plants. (31.13)

14. 31.13 Seed germination continues the life cycle
Corn and other monocots-
A protective sheath surrounding the shoot pushes upward and breaks through the soil.
The shoot tip then grows up through the tunnel provided by the sheath.
The corn cotyledon remains in the soil and decomposes.
Monocot
Teaching Tips
Seed production in plants clearly illustrates the ability of organisms to produce more offspring than can survive, a premise of natural selection. While discussing seed production, consider reminding students of this important principle, well illustrated in plants. (31.13)

15. 31.14 Asexual reproduction produces plant clones
A clone is an asexually produced, genetically identical organism or group of organisms.
Asexual reproduction can occur…
Fragmentation
Specialized reproductive structure
Teaching Tips
Depending on your prior discussions of animal reproduction and diversity, you might challenge your students to identify natural examples of animal cloning. Cnidarians and flatworms are groups that are often mentioned as examples. (31.14–31.15)

16. You should now be able to
Explain how the cultivation of plants has produced the plants we use for food.
Compare the structure of monocots and eudicots.
Compare the structures and functions of roots, stems, and leaves.
Define a tissue system. Describe the three main types of tissue systems found in young eudicot roots, stems, and leaves.
Describe the three unique structures found in most plant cells.
Describe the structures and functions of the five major types of plant cells.

17. And…..You should be able to
Describe and compare primary and secondary growth.
Describe the parts of a flower and their functions.
Describe the processes and events that lead to double fertilization.
Explain how a seed forms.
Compare the structures of eudicot and monocot seeds and explain the significance of seed dormancy.
Describe the structure and functions of fruit.
Describe and compare germination in bean and corn plants.
Describe examples of cloning in plants.
Compare the advantages and disadvantages of asexual versus sexual plant reproduction.