Chapter 21: What is a Plant?

1
Chapter 21 What is a Plant?

• 21.1 Adapting to Life on Land

2
Section 21.1 Vocabulary

• Adaptation
• Cuticle
• Leaf
• Root
• Stem
• Vascular tissue
• Nonvascular tissue
• Vascular plant
• Nonvascular plant

• Seed
• Alternation of Generations
• Sporophyte
• Gametophyte
• Spore
• Diploid
• Haploid

3
What is a Plant?

• Multicellular
• Eukaryotic
• Photosynthetic
• Cell walls with cellulose

4
Adaptations in Plants

• For most land plants water must be absorbed from
  the soil to survive.
• Land plants evolved structural and physiological
  adaptations that help protect the gametes from
  drying out.
• Land plants must also withstand the forces of
  wind and weather and be able to grow against the
  force of gravity.

5
Preventing Water Loss

• Most fruits, stems, and leaves are covered with a
  protective waxy layer call the cuticle which
  creates a barrier that prevents the water in the
  plants tissues from evaporating.

6
Carrying Out Photosynthesis

• The leaf is a plant organ that grows from a stem
  and usually is where photosynthesis occurs
• Leaves differ greatly in size and shape.

7
Putting Down Roots

• Because soil is a plants primary source of water
  plants can take in water and nutrients from the
  soil with their roots.
• A root is a plant organ that absorbs water and
  minerals usually from soil.

8
Putting Down Roots

• Roots contain tissues that transport the
  nutrients to the stem.
• Some roots are used for storage.

9
Transport Material

• Water moves from the roots of a tree to its
  leaves, and the sugars produced in the leaves
  move to the roots through a stem.
• A stem is a plant organ that provides support for
  growth.

10
Transport Material

• Stems contain tissues for transporting nutrients
  to different parts of the plant.
• In green plants stems can contain chlorophyll and
  photosynthesize.
• Most stems contain vascular tissue which are made
  up of tube like, elongated cells through which
  water, food, and other materials are transported.
  
• Plants that possess vascular tissue are known as
  vascular plants.
• Examples pine and maple trees, ferns, English
  ivy, and sunflowers.

11
Transport Material

• Mosses and several other small, less familiar
  plants called hornworts and liverworts are
  classified as nonvascular plants because they do
  not have vascular tissue.

12
Reproductive Strategies

• A seed is a plant organ that contains an embryo,
  along with a food supply, and is covered by a
  protective coat.
• A seed protects the embryo from drying out and
  also can aid in its dispersal.

13
Reproductive Strategies

• Land plants can reproduce by seed or spores.
• In non-seed plants, which include mosses and
  ferns, the sperm require film of water on the
  gametophyte plant to reach the egg.

14
Reproductive Strategies

• In seed-plants, which include all conifers and
  flowering plants, sperm reach the egg without
  using a film of water.
• This explains why non-seed plants live in wetter
  habitats than most seed plants.

15
Alternation of Generations

• The lives of plants include two stages, or
  alternating generations.

16
Alternation of Generations

• The gametophytes generation of a plant results in
  the developments of gametes.
• All cells of the gametophyte generation,
  including the gametes are haploid (n).
• The sporophyte generation begins with
  fertilization.
• All cells of the sporophyte are diploid (2n) and
  are produced by mitosis and cell division.
• Spores are produced in the sporophyte body by
  meiosis and are therefore haploid (n).

17
Alternation of Generations

• In non-seed plants such as ferns, spores have
  hard outer coverings
• Spores are released into the environment where
  they can germinate into haploid gametophyte
  plants.
• These plants produce male and female gametes.
• After fertilization, a new sporophyte develops
  within a seed.
• The seed eventually is released and the new
  sporophyte plant grows.

18
Alternation of Generations

• Journal Drawing
• Draw the life cycle of plants
• Use different colors to represent the gametophyte
  (haploid) generations and the sporophyte
  (diploid) generation.
• Read the Problem-Solving Lab on pg. 563 and be
  prepared to discuss in class.

19
Section 21.2 Survey of the Plant Kingdom
20
21.2 Vocabulary

• Evolution
• Frond
• Cone
• Hepaticophyta
• Anthocerophyta
• Bryophyta
• Psilophyta
• Lycophyta

• Arthrophyta
• Pterophyta
• Cycadophyta
• Gnetophyta
• Ginkophyta
• Coniferophyta
• Anthophyta
• Know examples for each phyla

21
Phylogeny of Plants

• Some botanists use plant characteristics to
  classify plants into divisions.
• A plant division is similar to phylum in other
  kingdoms
• The production of seeds can be used as a basis to
  separate the divisions into two groups
• Non-seed plants
• Seed Plants

22
Non-Seed Plants

• These plants produce hard-walled reproductive
  cells called spores.
• Non-seed plants include vascular and nonvascular
  organisms

23
Hepaticophyta

• small plants commonly called liverworts
• flattened bodies
• nonvascular
• grow in moist environments
• water moves throughout the organism by osmosis
  and diffusions

24
Hepaticophyta

• There are two kinds of liverworts
• Thallose broad body that looks like a lobed leaf
• Leafy creeping plants with three rows of thin
  leaves

25
Anthocerophyta

• small thallos plants
• sporophytes resemble the horns of animals, which
  gives them their common name- hornworts
• grow in damp, shady habitats and rely on osmosis
  and diffusion to transport nutrients

26
Bryophyta

• mosses
• also rely on osmosis and diffusion to transport
  material
• some have elongated cells that conduct water and
  sugars
• usually less than 5 cm tall and have leaflike
  structures that are only one or two cells thick.
• spores formed in capsules

27
Psliophyta

• known as whisk ferns
• have thin, green stems
• vascular plants, but do not have roods or leaves
• small scales that are flat, rigid, overlapping
  structures cover each stem
• only one genus is found in the southern US

28
Lycophyta

• club mosses
• vascular plants found in moist environments
• have stem, roots, and leaves
• leaves are very small and contain vascular tissue
• usually less than 25 cm, but the ancestors grew
  as tall as 30m
• used as part of the coal that is now used by
  people for fuel

29
Arhrophyta

• horsetails
• vascular
• have hollow jointed stems surrounded by whorls of
  scale like leaves
• primarily a fossil group, but there are about 15
  species that exist today

30
Pterophyta

• ferns
• most diverse non-seed vascular plants
• have leaves called fronds that vary in length
  from 1cm to 500cm
• found almost everywhere, but primarily in the
  tropics

31
Seed Plants

• Produce seeds, which in dry environments are a
  more effective means of reproduction that spores.
• Seeds consist of an embryo, food supply, and a
  hard protective seed coat.
• All have vascular tissue

32
Cycadophyta

• About 100 species of cycads
• Palm like trees with scaly trunks and can be
  short or more than 20 m
• Produce male and female cones on separate trees

33
Cycadophyta

• Cones scaly structures that support male or
  female reproductive structures.
• Cycad cones can be as long as 1m
• Seeds are produce in female cones.
• Male cones produce clouds of pollen

34
Gnetophyta

• Three genera of gnetophytes
• Gnetum 30 species of tropical trees and climbing
  vines
• Ephedra 35 species that grow as shrubby plants
  in deserts and arid regions.

35
Gnetopyta

• 3. Welwitschia one spescies which is found in
  the deserts of southwest Africa. Its leaves grow
  from the base of a short stem that resmbles a
  large, shallow cap.

36
Ginkgophyta

• One living species, Ginkgo biloba
• Small fan-shaped leaves
• Have male and female reproductive structures on
  different trees

37
Ginkgophyta

• The seeds produced on female trees have an
  unpleasant smell, so Ginkgos planted in parks are
  usually the male tree.
• Resistant to insects and air pollution

38
Coniferophyta

• Conifers, cone-bearing trees such as pin, fir,
  cypress, and redwood
• Vascular seed plants that produce seeds in cones
• Identified by the characteristic of cones or
  leaves that are needle-like or scaly

39
Coniferophyta

• Bristlecone pines are the oldest known living
  trees in the world

40
Coniferophyta

• Pacific yew is a source of cancer-fighting drugs.
  

41
Anthophyta

• Flowering plants
• Largest and most diverse group of seed plants
  living on Earth
• Approximately 250,000 species
• Produce flowers form which fruits develop which
  usually contains one or more seeds
• This division has two classes
• monocotyledons
• dicotyledons

42
Anthophyta