1. KEY CONCEPT Plants have specialized cells and tissue systems.

2. Plant tissues are made of three basic cell types.
Parenchyma cells are the most common plant cell type.
store starch, oils and water
help heal wounds to the plant
have thin flexible walls

3. Collenchyma cells provide support to a growing plant.
they are strong and flexible.
celery strings are strands of collenchyma.
they have unevenly thick cell walls.

4. Sclerenchyma cells are the strongest plant cell type.
second cell wall hardened by lignin
die when they reach maturity
used by humans to make linen and rope

5. Plant organs are made of three tissue systems.
Dermal tissue covers the outside of a plant.
protects the plant
secretes cuticle of leaves
forms outer bark of trees

6. Ground tissue is found inside a plant.
provides support
stores materials in roots and stems
most commonly made of parenchyma

7. Vascular tissue transports water, minerals and organic compounds.
stem
leaf
root
two networks of hollow tubes
xylem transports water and minerals
phloem transports photosynthetic products

8. KEY CONCEPT 20-2 The vascular system allows for the transport of water, minerals, and sugars.

9. Water and dissolved minerals move through xylem.
Xylem contains specialized cells.
vessel elements are short and wide
tracheid cells are long and narrow
xylem cells die at maturity
vessel
element
tracheid

10. The cohesion-tension theory explains water movement.
Plants passively transport water through the xylem.
Cohesion is the tendency of water molecules to bond with each other.
Adhesion is the tendency of water molecules to bond with other substances.

11. Water travels from roots to the top of trees.
absorption occurs at roots
cohesion and adhesion in xylem
transpiration at leaves

12. Transpiration is the loss of water vapor through leaves.
water vapor exits leaf stomata
helps pull water to the top branches

13. Phloem carries sugars from photosynthesis throughout the plant.
Phloem contains specialized cells.
sieve tube elements have holes at ends
companion cells help sieve tube elements
unlike xylem, phloem tissue is alive

14. The Pressure-flow model explains sugar movement.
plants actively transport sugar from the source
sugar flows to the sink due to pressure differences
sugars
phloem
xylem
water
Water moves from the xylem into the phloem by osmosis, due to the higher concentration of the sugars in the phloem. The water flow helps move sugars through the phloem. 2
Sugars move from their source, such as photosynthesizing leaves, into the phloem. 1
The sugars move into the sink, such as root or fruit, where the are stored. 3

15. KEY CONCEPT 21.3 Roots and stems form the support system of vascular plants.

16. Roots anchor plants and absorb mineral nutrients from soil.
Roots provide many functions.
support the plant
absorb, transport, and store nutrients
root hairs help absorption

17. There are several parts of a root.
root cap covers the tip
root cap

18. There are several parts of a root.
root cap covers the tip
apical meristem is an area of growth
apical meristem

19. There are several parts of a root.
root cap covers the tip
apical meristem is an area of growth
vascular cylinder contains xylem and phloem
vascular cylinder

20. There are two main types of roots.
Fibrous root systems have fine branches.
Taproot systems have one main root.
Fibrous root
Taproot

21. Stems support plants, transport materials, and provide storage.
Stems have many functions.
support leaves and flowers
house most of the vascular system
store water
Baobab trees
Cactus

22. Stems support plants, transport materials, and provide storage.
Stems have many functions.
support leaves and flowers
house most of the vascular system
store water
grow underground for storage
Ginger rhizomes
Potato tubers

23. Stems support plants, transport materials, and provide storage.
Stems have many functions.
support leaves and flowers
house most of the vascular system
store water
grow underground for storage
form new plants
Strawberry stolons

24. Some stems are herbaceous and conduct photosynthesis.

25. Some stems can be woody, and form protective bark.

26. Primary growth increases a plant’s length.
Secondary growth increases a plant’s width.

27. Tree rings help determine the age of a tree.
heartwood
bands
bark
one year of growth
sapwood

28. KEY CONCEPT Leaves absorb light and carry out photosynthesis.

29. Most leaves share some similar structures.
The blade is usually broad and flat.
collects sunlight for photosynthesis
connects to the stem by a petiole
blade
petiole

30. Mesophyll is between the leaf’s dermal tissue layers.
cuticle
upper
epidermis
palisade mesophyll
spongy mesophyll
lower epidermis

31. Guard cells surround each stoma.
Stomata open and close when guard cells change shape.
When stomata are open, water evaporates and gas exchanges.
Stomata close at night and when plant loses too much water.
guard cells
stoma

32. Leaves may be simple, compound, or double compound.
Simple leaf
Compound leaf
Double compound leaf

33. Leaf veins may be parallel or pinnate.
Pinnate veins
Parallel veins

34. Leaf margins may be toothed, entire, or lobed.
Toothed margin
Entire margin
Lobed margin

35. Most leaves are specialized systems for photosynthesis.
There are two types of mesophyll cells.
both types contain chloroplasts
palisade mesophyll absorbs sunlight
spongy mesophyll connects to stomata
xylem
phloem
cuticle
upper
epidermis
palisade mesophyll
spongy mesophyll
stomata
lower epidermis

36. Leaves have many adaptations.
for extreme temperatures, ex: pine needles

37. Leaves have many adaptations.
for extreme temperatures, ex: pine needles
for water loss, ex: cactus spines

38. Leaves have many adaptations.
for extreme temperatures, ex: pine needles
for water loss, ex: cactus spines
for aquatic environments, ex: water lily

39. Leaves have many adaptations.
for extreme temperatures, ex: pine needles
for water loss, ex: cactus spines
for aquatic environments, ex: water lily
for getting food, ex: Venus’ flytrap