Diversity of life and common challenges to lifeThree Domains of Life on Earth:

Archaea

Eubacteria

Eukaryota

What are the kingdoms of Eukaryota?Protistan

– Diverse, differ enormously

– Have a nucleus, mitochondria and possibly chloroplasts

– Sexual or asexual reproduction

– Single cells to multicellular

– Autotrophs or heterotrophs

– May move by cilia and flagella

What are the kingdoms of Eukaryota?Fungi

– Bread molds, sac fungi, club fungi– Heterotrophs

• Most are saprobes; obtain nutrients from nonliving organic matter• Only a few are parasites• Serve impt role in ecosystems – are vital decomposers and plant symbionts

– Multicellular– Mycelia (branching tubular threads of hyphae)– Cell walls contain chitin– Reproductive structure = fruiting body = mushroom

• Spores can resist dehydration• Remain dormant until environmental conditions favor germination

Lichen: a composite organism

A symbiosis: fungus + photosynthetic algae; what is the advantage?

Fungus composes bulk of the structure

Mycorrhiza – another symbiosis

• Mutualism between fungi and a plants

– 90% of Vascular Plant Families

– Necessary for colonization of land plants?

• What does fungus gets from plant?

• What does plant get from fungus?

with

without

What are the kingdoms of Eukaryota?• Protistans

• Fungi

• What are the other two kingdoms?

Commonality of Life on EarthAll organisms made of cells

- single cells- integrated multi-cellular organisms with

Division of labor: tissues, organs, organ systemsLiving organisms can compartmentalize

Plant response to a wound or pathogenWalls thicken; Toxins and resins produced

All living things must obtain energy from: sun and inorganic molecules = ? eating other organisms

All organisms reproduce asexual – mitosis for growth, repair and for cloning selfsexual – generates diversity

All organisms involved in relationships with other species All organisms evolve

- Land plants and land animals arose from aquatic ancestors- Both face new challenges in the drier environment- Form and internal functions are answers to these challenges

All organisms eventually die and go extinct

Move gases, water, nutrients– Internal transport- Vascular, respiratory and circulatory

systems– Maintain water balance; screen toxins– kidneys, stomata, liver– Dispose of waste – complete digestive system?

Defend against external threats– Predators, disease, parasites– Competition

Challenges differ among habitats Physical resources vary:

– Water– Nutrients– Temperature

• Interpret environmental signals and adjust internal response• Maintain a stable internal environment = homeostasis

– Maintaining a stable fluid environments for all living cells

All organisms must accomplish certain tasks to maintain order, structure

RECEPTOR(e.g., free

nerve endingin the skin)

INTEGRATOR(such asthe brain)

EFFECTOR(a muscleor a gland)

STIMULUS (input into the system)

RESPONSE(system’soutput)

RESPONSE to the stimulus leads to change. The change is “fed back” to the receptor. In negative feedback, the response cancels or counteracts the original stimulus.

Three components interact to provide homeostasisEnvironmental cue or an activity alters a condition internallyAlteration triggers a response and mediates the internal condition

Example of negative Feedback - Body temperature regulation:1) Body temp rises b/c of sunshine internal conditions in body change breath harder, blood vessels dilate, sweat glands secrete more less metabolic heat is retained body temp drops2) Body temp falls muscles shiver, blood shunted to interior of body, more metabolic heat produced body temp rises

Positive Feedback• External or internal cue alters internal environment• The alteration triggers a response• The response intensifies the change in the internal

condition

– Example: childbirth: pressure on uterine wall production of oxytocin uterine muscles contract more pressure on uterine wall more oxytocin produced etc. until fetus is ‘born’