Download Biology 1407 Exam 3 Plants

Biology 1407 Exam 3
The Evolution of Plants and Fungi - The Colonization of Land
Ch 17
Plants
eukaryotic, multicellular, autotrophic (photosynthesis), with a life cycle that includes both
multicellular haploid and multicellular diploid bodies, and the embryo attaches to the
parent.
Plants evolved from green algae (charophytes) 475 million years ago (mya)
An adaptive radiation into a new habitat - land
Land offered some benefits to green algae living at the edge:
- no competition or predation
- more light energy to power photosynthesis
17.1
- high gas concentration, especially carbon dioxide
But life out of water also faced some problems:
- air is dry, cell lose water quickly
- air give no buoyancy to support body
- ultraviolet light more intense and very damaging
- air has very low specific heat and changes temperature quickly
- sex cells (sperm) can not swim in air
The history of plants involves the adaptation of green algae to terrestrial life.
Adaptations include:
- roots in soil to obtain water; waterproof waxy cuticle on above ground stem
- anchoring of plants by root; strong vascular cells for transporting materials and
strengthening body
- specialization of tissues
- changes in the life cycle to allow reproduction in air:
- swimming sperm in water ----------------> pollen grain in air
- spore (1N) dispersal stage ----------------> seed (2N) dispersal stage
- gametophyte (1N) dominant ------> gametophyte and sporophyte equal
------> sporophyte (2N) dominant
Describe the “alternation of generations” in plant life cycles.
17.3
Explain the role of each of these events in life cycles: fertilization, meiosis, mitosis.
Bryophytes (nonvascular plants) - liverworts, hornworts, mosses
- from green algae about 475 mya
17.2, .4
- grow in low dense mats in moist habitats; lack true roots and leaves
- poor waterproof covering
- no vascular cells with lignin, poorly supported bodies
- spore is stage in life cycle that is dispersal stage
- male gamete (sperm) swims to egg in water
- gametophyte generation dominates, sporophyte generation dependent on
gametophyte for nutrients
Vascular plants
Lycophytes - club mosses and horsetails
17.2, .6
- from early plants about 425 mya , many extinct species
- formed dense forest during Carboniferous period (360 - 300 mya)
- have vascular cells with lignin, body well supported
- spore is stage in life cycle that is dispersal stage
- male gamete (sperm) swims to egg in water
- gametophyte generation and sporophyte generation live independently
- sporophyte grows large; has vascular cells, roots, stem and small leaves
- gametophytes remain small; do not have vascular cells
Pterophytes - ferns
17.2, .5, .6
- from early plants about 425 mya
- formed dense forest during Carboniferous period (360 - 300 mya)
- have vascular cells with lignin, body well supported
- spore is stage in life cycle that is dispersal stage
- male gamete (sperm) swims to egg in water
- gametophyte generation and sporophyte generation live independently
- sporophyte grows large; has vascular cells, roots, stem and large leaves
- gametophytes remain small; do not have vascular cells
*In early vascular plants why must the gametophyte generation remain small?
*What is the primary difference between horsetails and ferns?
*What adaptation allowed early vascular plants to grow much taller than nonvascular
plants?
Gymnosperms - conifers (cone-bearing plants), ginkgo, cycads
17.2, .7
- from ferns about 360 mya; became dominant plants during Permian period (300250 mya) and though Mesozoic Era (250 -65 mya)
- vascular cells with lignin, very well supported roots and stems
- the zygote stage of the life cycle is the dispersal stage
- seed is embryo wrapped in hard seed coat with food supply
- sporophyte generation dominates, gametophytes completely within cone
- female cones ("ovulate cone") produce spores that grow into female
gametophytes which produce eggs; all within the ovule
- male cones ("pollen cone") produce spores that grow into male gametophytes
(called pollen grains) which are released and move to female cones in the
wind. In the female cones the males release sperm and fertilize the eggs
- seeds drop from female cone and disperse by wind
- many conifers are evergreen with compact needle leaves - adaptations for dry
environments
Angiosperms - flowering plants
17.2, .8-..12
- from gymnosperm about 140 mya; most successful plants today (250,000
species of about 290,000 plants), in many environments
- zygote (seed) is the stage of the life cycle that is the dispersal stage
- sporophyte generation dominates, gametophytes completely within flower
- female part of flower (ovary) produces spores that grow into female
gametophytes which produce eggs; all within the ovules in ovary
- male part of flower (stamen) produces spores that grow into male gametophytes
(called pollen grains) which are released and move to female
flower in the wind or with animal. In the ovary the males release sperm and
fertilize the eggs
- seeds form from ovule, enclosed in ovary wall (fruit)
- vascular cells stronger than in gymnosperms
- angiosperms have much faster development than gymnosperms
- pollination and seed dispersal more efficient with flower than cone
Flowers have two main functions for plants:
- effectively bring about fertilization by attracting pollen
- flower colors, shapes, odors, etc. to attract animals
- distribute seeds to new areas
- development of fruit to move seeds by wind, animals, water, etc.
Fungi
17.14-.21
- eukaryotic, multicellular, heterotrophs with absorptive feeding
- they have only multicellular haploid cells
- their cells have cell walls made of chitin; they are not mobile
- fungi produce many chemicals for digestion and protection
- spores are the dispersal stage of life cycle
- grow as chain of cells that branches (each branch is hypha) to form mycelium
- cell membrane and cell walls removed so that cytoplasm moves easily from cell to
cell (cytoplasmic streaming)
- mycelium grows into food as chain of cells;
- provides very large surface area for digestion and absorption
- rapid growth - more than 1/2 mile per day of hyphae, can become very large
- fungi reproduce asexually by breaking apart or producing asexual spores
- sexually by combining cells of different mycelium
17.15
- many form a heterokaryotic stage before fertilization
- fruiting body grows above substrate to release spores
- fungi have several important ecological and symbiotic relationships: 17.18 - .21
- evolved with plants in invasion of land
- decomposers - breakdown and recycle organic material
- mycorrhizae - symbiotic fungus and plant root association
17.0
- lichens - symbiotic fungus and algae or photosynthetic bacteria
- animals symbionts
- disease causing organisms, especially in plants
17.16 - .17
Fungi can be classified into several groups based on their fruiting bodies:
- chytrid most primitive ; have flagella
- molds (zygote fungi and glomeromycetes) produce spores in a ball-like
sproangium at the tip of a long hypha
- sac fungi (morels, cup fungi - many in lichens and plant pathogens) produce
spores in sac-like structures within the fruiting body
- club fungi (mushrooms, puffballs, shelf fungi) produce spores in club-shaped
chains of cells on gills
Biology 1407 Exam 3 Review
List the characteristics of the plant kingdom – how can plants be distinguished from other
living organisms?
Briefly describe the origin and history of plants:
List the advantages and disadvantages of the terrestrial (land) environment compared to
the aquatic environment. List the major trends in the evolution of plants.
Draw a life cycle of a typical plant. Include the following stages and events: spore,
gametophyte, gametes (sperm and egg), zygote, sporophyte, 2N cells, 1N cells,
fertilization, meiosis and mitosis.
List 5 major groups of plants as discussed in class. For each group give the following
information: presence of vascular tissue, distributive portion of life cycle,
method of movement of sperm, portion of the life cycle that dominates (can
produce its own food), structure enclosing the seed.
What allows the sporophyte body to grow much taller than the gametophyte body?
Why must the gametophyte remain small and close to the ground in non-seed plants?
Why was it necessary for the seed to become the distributive stage instead of the spore as
in primitive plants?
Seed plants evolved as they adapted to what type environment?
What were the first seed plants?
What stage of the life cycle is formed into the seed?
How are flowers more effective than cones? Describe 2 ways. Give some examples of how
these work.
List the characteristics of the Kingdom Fungi.
Draw a life cycle of a typical fungus. Include the following stages and events in your
drawing: spore, mycelium, 2N and 1N, fertilization, meiosis and mitosis.
Which is the dispersal stage of fungi?
Which is the feeding body?
What is the difference between a mycelium and a hypha?
Distinguish between mycelium and fruiting body, and give the function of each.
List and describe the important ecological relationships of fungi discussed in class.
Describe two symbiotic associations that fungi form.
Do fungi have a digestive system? Explain how fungi digest their food.
List the three groups of Fungi described in class and draw the fruiting body of each.