21 Plant Structure and Function tissue.ppt

21 Plant Structure and Function tissue.ppt

1. 21.1 Plant Cells and Tissues
KEY CONCEPT
Plants have specialized cells and tissue systems.

2. 21.1 Plant Cells and Tissues
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. 21.1 Plant Cells and Tissues
–they are strong and flexible.
–celery strings are strands of collenchyma.
–they have unevenly thick cell walls.
•Collenchyma cells provide support to a growing plant.

4. 21.1 Plant Cells and Tissues
–second cell wall hardened by lignin
–die when they reach maturity
–used by humans to make linen and rope
•Sclerenchyma cells are the strongest plant cell type.

5. 21.1 Plant Cells and Tissues
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. 21.1 Plant Cells and Tissues
–provides support
–stores materials in roots and stems
–most commonly made of parenchyma
•Ground tissue is found inside a plant.

7. 21.1 Plant Cells and Tissues
stem
leaf
root
–two networks of hollow
tubes
–xylem transports water
and minerals
–phloem transports
photosynthetic products
•Vascular tissue transports water, minerals and organic
compounds.

8. 21.2 The Vascular System
KEY CONCEPT
The vascular system allows for the transport of
water, minerals, and sugars.

9. 21.2 The Vascular System
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. 21.2 The Vascular System
–Plants passively transport water through the xylem.
–Cohesion is the tendency of water molecules to bond
with each other.
•The cohesion-tension theory explains water movement.
–Adhesion is the
tendency of water
molecules to bond
with other
substances.

11. 21.2 The Vascular System
–absorption occurs at roots
•Water travels from roots to the top of trees.
–cohesion and adhesion in xylem
–transpiration at leaves

12. 21.2 The Vascular System
–water vapor exits leaf stomata
–helps pull water to the top
branches
•Transpiration is the loss of water
vapor through leaves.

13. 21.2 The Vascular System
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. 21.2 The Vascular System
–plants actively transport sugar from the source
–sugar flows to the sink due to pressure differences
sugars
phloem xylem
water
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
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
•The Pressure-flow model explains sugar movement.

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

16. 21.3 Roots and Stems
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. 21.3 Roots and Stems
root cap
–root cap covers the tip
•There are several parts of a root.

18. 21.3 Roots and Stems
apical meristem
–root cap covers the tip
•There are several parts of a root.
–apical meristem is an area
of growth

19. 21.3 Roots and Stems
–vascular cylinder contains
xylem and phloem
vascular cylinder
–root cap covers the tip
•There are several parts of a root.
–apical meristem is an area
of growth

20. 21.3 Roots and Stems
–Fibrous root systems have fine branches.
Fibrous root Taproot
•There are two main types of roots.
–Taproot systems have one main root.

21. 21.3 Roots and Stems
Pictures to Study for Test!

22. 21.3 Roots and Stems
Roots
–monocots versus dicots.
Monocot Dicot

23. 21.3 Roots and Stems
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

24. 21.3 Roots and Stems
–grow underground for storage
Ginger rhizomes Potato tubers
Stems support plants, transport materials, and provide
storage.
•Stems have many functions.
–support leaves and flowers
–house most of the vascular system
–store water

25. 21.3 Roots and Stems
–grow underground for storage
Stems support plants, transport materials, and provide
storage.
•Stems have many functions.
–support leaves and flowers
–house most of the vascular system
–store water
–form new plants
Strawberry
stolons

26. 21.3 Roots and Stems
•Some stems are herbaceous and conduct photosynthesis.

27. 21.3 Roots and Stems
•Some stems can be woody,
and form protective bark.

28. 21.3 Roots and Stems
•Secondary growth increases a plant’s width.
•Primary growth increases a plant’s length.

29. 21.3 Roots and Stems
•Tree rings help determine the age of a tree.
heartwood
bands bark
one year
of growth
sapwood

30. 21.3 Roots and Stems
Monocot Stem

31. 21.3 Roots and Stems
Dicot Stem

32. 21.4 Leaves
KEY CONCEPT
Leaves absorb light and carry out photosynthesis.

33. 21.4 Leaves
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

34. 21.4 Leaves
•Mesophyll is between the leaf’s dermal tissue layers.
cuticle
upper
epidermis
palisade
mesophyll
spongy
mesophyll
lower
epidermis

35. 21.4 Leaves
–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
•Guard cells surround each stoma.

36. 21.4 Leaves
•Leaves may be simple, compound, or double compound.
Simple leaf Compound leaf
Double compound leaf

37. 21.4 Leaves
•Leaf veins may be parallel or pinnate.
Pinnate veinsParallel veins

38. 21.4 Leaves
•Leaf margins may be toothed, entire, or lobed.
Toothed margin Entire margin Lobed margin

39. 21.4 Leaves
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

40. 21.4 Leaves
–for extreme temperatures,
ex: pine needles
•Leaves have many adaptations.

41. 21.4 Leaves
•Leaves have many adaptations.
–for extreme temperatures,
ex: pine needles
–for water loss,
ex: cactus spines

42. 21.4 Leaves
–for aquatic environments,
ex: water lily
•Leaves have many adaptations.
–for extreme temperatures,
ex: pine needles
–for water loss,
ex: cactus spines

43. 21.4 Leaves
–for aquatic environments,
ex: water lily
–for getting food,
ex: Venus’ flytrap
•Leaves have many adaptations.
–for extreme temperatures,
ex: pine needles
–for water loss,
ex: cactus spines

44. 21.4 Leaves
Monocot leaf

45. 21.4 Leaves
Dicot leaf