Quiz Friday

1
(No Transcript)
2
Quiz Friday!

• covering
• the physical environment
• biomes
• physiological ecology (today and Wednesday)

3
(No Transcript)
4
Physiological Ecology

• Two themes
• Homeostasis maintenance of constant internal
  conditions in varying environments
• Adaptation of organisms to specific environments

5
Three big problems

• Obtaining energy and nutrients
• Maintaining temperature
• Obtaining and holding onto water

6
Energy
7

• All organisms require energy to live and
  reproduce
• Heterotrophs acquire energy from organic
  material, live or dead
• most animals feed on living organisms
• decomposers (fungi, some animals) feed on dead
  organisms

8

• Autotrophs acquire energy from sunlight or
  chemicals in the environment
• Chemosynthetic autotrophs
• obtain energy from inorganic chemicals like
  methane or hydrogen sulfide
• sea-vent bacteria
• Photosynthetic autotrophs
• combine energy from sunlight and CO2 to make
  sugars
• many bacteria, some protists (algae), and nearly
  all plants

9

• Chemical equation for photosynthesis
• energy 6CO2 6H2O ? C6H12O6 6O2
• (sunlight) (from air) (from soil) (sugar)
  (to air)

10
(No Transcript)
11
Question 1. Interpret this graph
Overstory plant
Rate of photosynthesis
Understory plant
Light level
12

• All organisms store and use energy in the form of
  carbon compounds
• Respiration the process of breaking up carbon
  compounds to release CO2 and energy

C6H12O6 6O2 ? energy 6CO2 6H2O
13

• Other important nutrients (and their uses)
• Nitrogen - proteins
• Phosphorus many chemicals
• Sulfur proteins
• Potassium ion in cells
• Calcium bone, wood, cell signalling
• Magnesium chlorophyll, enzymes
• Iron hemoglobin, enzymes
• Lack of nutrients can limit plant growth

14
Water
15

• Water contains dissolved substances solutes
• Water moves from regions of low solute
  concentration to high concentration
• Movement of water across a membrane is osmosis

16
High solute concentrations attract water with a
force known as osmotic potential.
17

• Water moves freely across cell membranes
• Relative to the outside environment, a cell can
  be
• hypo-osmotic having a lower solute concentration
  than the environment
• hyperosmotic having a higher solute
  concentration than the environment
• iso-osmotic having the same solute concentration
  as the environment

18
If left unchecked, osmosis will lead to
equilibration of solute concentrations in and
outside of cells
Hypo-osmotic Iso-osmotic Hyperosmotic
19
Question 2. What happens to the slugs?
20

• For organisms, the challenge is maintaining
  proper concentrations of solutes in cells
  (homeostasis).
• semipermeable membranes some molecules cannot
  pass
• active transport moving molecules across the
  membrane, requires energy

21
Transpiration when plants lose water to the
atmosphere as they obtain CO2
Transpiration
22
Plants must take up water at their roots to make
up for transpiration Plants use osmotic
potential to draw water into their roots (root
cells are hyperosmotic) Water is pulled up
through the xylem into the leaves. Water leaves
the plant through the stomata (transpiration).
23

• Soil particles hold water at their surfaces
  against gravity.
• Smaller particles hold more water.
• Sandy soils have less water available than silts.

24

• Water loss from stomata increases with
  temperature.
• Adaptations to prevent water loss in dry
  environments
• hairs and spines
• thick, waxy covering on leaves
• stomata located deep in pits
• shedding leaves in dry season
• wilting or closing leaves

25
Today

• Finish up water relations
• Temperature
• The bigger picture

26
Question 1. Interpret this graph
Overstory plant
Rate of photosynthesis
Understory plant
Light level
27
Question 2. What happens to the slugs?
28

• Normal photosynthetic pathway
• Requires a lot of CO2, so stomata must be open,
  allowing water loss
• Water loss is a big problem in dry places

CO2 RuBP ? 2 PGA ? sugar (1
carbon) (5 carbons) (3 carbons)
29

• C4 Photosynthesis spatial separation
• Mesophyll cell, near leaf surface
• Bundle sheath cell, in leaf interior
• Occurs in many plants found in hot, dry places
  (corn)

CO2 PEP ? OAA (reaction
requires little CO2) (1 carbon) (3
carbons) (4 carbons)
OAA ? PEP CO2 ?
photosynthetic pathway (4 carbons) (3
carbons) (1 carbon)
30
(No Transcript)
31

• CAM Photosynthesis temporal separation
  (Crassulacean Acid Metabolism)
• Nighttime reaction (stomata open)
• Daytime reaction (stomata closed)
• Occurs in succulent plants, cacti

CO2 PEP ? OAA (1 carbon)
(3 carbons) (4 carbons)
OAA ? PEP CO2 (4 carbons)
(3 carbons) (1 carbon)
32

• Water Acquisition in Animals
• Wet environments
• drinking
• absorbing from the environment (amphibians)
• Dry environments
• metabolic water (C6H12O6 6O2 ? 6CO2 6H2O)
• water in food sources (insectivores)
• water reabsorbed in digestive/excretory systems

33

• Water Balance in Marine Animals
• Marine invertebrates maintain iso-osmotic
  internal solute concentrations equal to seawater
• Marine fish are hypo-osmotic compared to
  seawater.
• they gain solutes and lose water
• solutions
• constant drinking
• secreting salt into the water

34

• Sharks and rays have high concentrations of
  solutes in their blood, making them iso-osmotic
  compared to seawater.
• To maintain proper concentrations of ions, sharks
  keep urea in the bloodstream.

35
(No Transcript)
36

• Water Balance in Freshwater Fish
• Freshwater fish are hypo-osmotic compared to
  water and absorb water continuously.
• They excrete large quantities of diffuse urine
  while actively retaining salts.

37
Organisms in variable environments adjust their
solute levels based on the salinity of the water.
38
Temperature
39
Why does temperature matter?
40
(No Transcript)
41

• At hot temperatures
• biological processes speed up
• proteins and other organic compounds may break
  down
• At cold temperatures
• ice crystals may damage or destroy cells
• life processes slow or stop

42
(No Transcript)
43

• Homeothermic organisms maintain constant body
  temperature (birds and mammals)
• Poikilothermic organisms have varying body
  temperature, in response to external temperatures
  (all other animals)
• BUT poikilothermic animals may regulate their
  body temperature

44

• Endothermy body heat generated internally
• Ectothermy body heat generated externally
• Most ectotherms regulate their body temperature
  by
• basking
• moving between shade/sun
• being active at certain times of day

45

• Endothermy requires a lot of energy
• Alternative is torpor condition of lowered body
  temperature and activity

46

• Countercurrent Circulation
• Reduce rate of heat loss to the environment by
  creating a temperature gradient.
• Heat is transported from arterial blood leaving
  the body to venous blood returning to the body.

47
Optimum narrow range of environmental
conditions to which an organism is best suited
48
Each organism has an optimum environment
Local optimum
49
(No Transcript)
50

• Distributions of plant species are determined by
  precipitation and temperature
• Ecological tolerance is the range of conditions
  within which a species can survive

• Sugar maple
• summer temps below 24ºC
• winter temps above -18ºC
• annual precip. gt 50 cm

51
Different species have different ecological
tolerances.
52

• Species vary in how wide their ecological
  tolerance is
• specialists have a narrow range of tolerance
• generalists have a wide range of tolerance

53
Quiz Friday!

• covering
• the physical environment
• biomes
• physiological ecology (slides on the website
  later today)