Biology 1407 - Notes for Exam 1
Review:
Biology – the scientific study of life . What is science?
Ch1
A way of knowing based on observation and measurement
1.7-.8
How does this compare with other ways of knowing? (theology and philosophy)
- only physical measurement evidence is accepted :“factual”, natural causes, can
be experimentally tested
- intuition (“common sense”) can be misleading; some examples:
- supernatural explanation (beyond natural laws and therefore not measurable) not
accepted; cannot be experimentally tested
- Hypothesis - proposed answer
- Theory - very well supported hypothesis
- Experiment must be repeatable
- Testable hypothesis = Falsifiable
- No absolute truths - latest conclusions - allows self-correction and more
accurate conclusion
- No value judgments (morals, ethics)
Biology - the scientific study of life . - What is life?
- living organisms made of common elements – no unique elements
2.1
- working definition of life based on observations of what living organisms do
1.4
1. Order - chemical structural complexity (levels of organization)
1.1
2. Metabolism - energy utilization to produce and control chemical processes
3. Regulation of internal environment
4. Grow and develop through stages
5. Respond to environmental stimuli
6. Reproduce - production of offspring with similar genetic information (DNA)
7. Ability to change - evolve and adapt
1.6
Levels of organization in living organisms
Biosphere
Ecosystem
Community
Population
Organism (individual)
Organ system
Organ
Tissue
Cell
Organelle
Molecule
Atom
1.1
What is reductionism and how is it
important in studying life?
1.3
What are emergent properties and why are
they important to the study of life? 1.1-.33
What property emerges at the cell level?
Living organisms have common structure (cells and cell structures)
1.3
Genetic information (DNA) determines structure
1.4, Ch 10
DNA → RNA → proteins ↓→ cell structure
→ enzymes control cell chemistry ( metabolism )
Mutations in DNA produce variation in living organisms of many traits - random
events, chance
Variation allows →↓ → adaptation by natural selection
1.6, Ch 13
↓ [variations that increase reproductive success accumulate,
↓ other variations decrease - not chance ]
↓
→ speciation - populations that are isolated accumulate different
mutations; genetic differences increase through
time - prevent inter-reproduction
- therefore life has a history of change
Ch 14
* Unifying concept in biology - explains unity and diversity
History of Earth and early life:
15.4 (16.1)
- Earth formed about 4.6 bya
- oldest fossils about 3.5 bya ( of Archaea)
- dominance of prokaryotes (Archaea and Bacteria) and accumulation of oxygen
atmosphere
- oldest eukaryote fossils about 2.1bya
- oldest multicellular eukaryotes fossils about 1.2 bya
(algae)
- oldest animal fossils about 600 mya
Prokaryotic cells (bacteria and archaea)
1.3, Ch 16
primitive - 3.5 billion years ago
smaller - 1-5 m (micron, = .001 millimeter)
simple - no nucleus, no internal membranes, less DNA
extremely numerous, all environments on Earth, genetically and metabolically
diverse
Eukaryotic cells (more closely related to archaea than to bacteria)
- earliest fossils from about 2 b.y.a.
- larger - 10 -100 m (about 1000 X volume)
- complex - have a nucleus, internal membranes, more DNA
- endosymbiotic hypothesis - origin of mitochondria and chloroplasts 4.16, 16.12
(16.17)
"protists"
- complex eukaryotic cells, mostly single cell
16.11-.20
-very diverse group , most eukaryotes are "protists"
- different groups ancestors of multicellular plants, animals and fungi
“Protozoa” (animal-like), “algae” (plant-like), and fungi-like single
celled (slime molds)
History of life - later years
The Evolution of Plants and Fungi - The Colonization of Land
Ch 17
Plants are 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
(17.2)
- 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
(17.3)
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)------> gametophyte and ------> sporophyte (2N)
dominant
sporophyte equal
dominant
Describe the “alternation of generations” in plant life cycles. Explain the role of each of
these events in life cycles: fertilization, meiosis, mitosis.
17.3
(17.4)
*List the advantages and disadvantages of the terrestrial (land) environment to the aquatic
environment. List the major trends in plant evolution.
*Draw a life cycle of a typical plant, including the following stages and events: spore,
gametophyte, gametes (sperm and eggs), zygote, sporophyte, 2N cells, 1N cells,
fertilization, meiosis, mitosis.
*Describe the differences between plant and animal life cycles.
Bryophytes (nonvascular plants) - liverworts, hornworts, mosses
(17.3, 17.5)
- 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
(17.3, 17.7)
- from early plants about 425 mya , many extinct species
17.2, .6
- 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
(17.3, .6, .7)
- from early plants about 425 mya
17.2, .5, .6
- 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 (17.3, .8)
- from ferns about 360 mya; became dominant plants during Permian period
(300- 250 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 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
("ovulate cone") 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 (17.3, .9- .13)
- 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.
* What were the first seed plants, when did they evolve and to what environment?
*What stage of the life cycle is formed into the seed?
*Why was it necessary for the seed to become the distributive (scattering) stage instead of
the spore as in primitive plants?
*How are flowers more effective than cones? Describe two ways.
*Describe the adaptations of flowers that increase the chances of pollination.
*Describe the adaptations of flowers that increase the dispersal of seeds.
*How has the evolution of flowering plants been profoundly influenced by their
interaction with animals?
*List 5 major groups of plants as discussed in class. For each group give the following
information: presence of vacular tissue, distributive stage of life cycle, method of
movement of sperm, portion of life cycle that dominates (can produce its own
food), structure enclosing the seed.
Fungi
17.14-.21 (17.15)
- 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
*List the characteristics of the Kingdom Fungi.
*Do fungi have a digestive system? Explain how fungi digest their food.
- 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
(17.16, .18)
- fruiting body grows above substrate to release spores
*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?
- fungi have several important ecological and symbiotic relationships: 17.18 - .21
- evolved with plants in invasion of land
- decomposers - breakdown and recycle organic material
(17.19-.22)
- mycorrhizae - symbiotic fungus and plant root ass ociation 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: (17.17)
- 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 clubshaped chains of cells on gills
*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.
*List the major groups of Fungi and draw the fruiting body of each.