Download DIVERSITY OF LIFE Diversity: how many and what types The origin

DIVERSITY OF LIFE

Diversity: how many and what types

The origin and radiation of life: history of life on earth, Fig 26.3

Yard stick history of life:
 1000 million = 1 billion
 1 in = one hundred million years or 100,000,000 years
 39 inches = 3900 million yrs or 3.9 billion yrs
 The age of the earth:
 first life (prokaryotes)
4.5 billion 4,500,000,000
35” or 3.5 billion or 3,500,000,000

eukaryotic cells
15”

multicellular
7.0”

1st vertebrates
4.5”

plants invade land

dinos
2.5”

angiosperms
1”

dino’s extinct
0.65”
4”

A 12” ruler is long enough for all multicelluar organisms-

A 6” ruler is long enough for most of our fossil record of plants and animals

Fig 26.1
How many kingdoms are there? Fig 26.16
Protista

More diverse than plants, animals or fungi
 aquatic
 Autotrophic or heterotrophic (i.e., algae and protozoa)
 Multicellular or unicellular (brown kelp, seaweeds, plankton)
 Reproduce sexually using all known types of sexual life cycles
 Eukaryotes that are not animals, plants, or fungi
What are animals?
 Most phyla are aquatic (33) but a few important ones are terrestrial
 multicellular eukaryotes;
 heterotrophic and take in energy/food thru ingestion
 store carbohydrate as gycogen
 lack cell walls
 nervous tissue and muscle tissue
 diploid stage of life cycle dominate
What are plants?
 terrestrial (but, including secondarily aquatic plants: i.e., water lilies),
 multicellular,
 photosynthetic,
 eukaryotic
 haploid or diploid stage dominate
What are fungi?
 terrestrial
 multicellular,
 heterotrophic by absorption
 eukaryotic
 haploid stage dominates
You are responsible for knowing what Phylum and something about every creature we
talk about in lecture or see in the lab.
Animal structure and function
 examine adaptations to deal with problems faced by animals:
 acquiring energy
 exchange of gases with environment
 finding mates (and reproducing on land)
 preventing dehydration for terrestrial species
All living things require energy
 plants use solar energy
 animal energy source?
 energy held in bonds of molecules in other organisms bodies
 what happens when bonds broken?
 energy captured in ATP
 what happens to atoms of molecules?
 biosynthesis of new molecules or excreted
 summary of bioenergetics in animals in Fig 40.10
Living things exchange materials (matter) with environment
 contrast aquatic vs terrestrial organisms
 surface area to volume ratio impacts exchange (Fig 40.7)
 terrestrials must reduce surface area to volume
 as surface area/volume decreases need internal circulatory system Fig
40.8
 specialized exchange surfaces,
 for example see small intestine of mammal (fig 41.19,)
 large folds of epithelium
 surface of folds covered with smaller villi
 cells of villi covered with extentions
 surface area of human small intestine is 300 m2, the size of a tennis
court
Energy budgets show how animals use energy and materials (energy and matter)

metabolic rate is energy used per unit time
 How do you measure it?
 What is energy; give some examples
 What is matter; give some examples

Total energy expended per year depend on an animals size and metabolic rate (fig.
40.13)
 What is the advantage of being an ectotherm?
 What is the advantage of being an endotherm?

Do larger or smaller organisms have lower energy costs per kilogram?
 Fig 40.13

Homeostasis maintains nearly constant internal environment

Circulation of gases and nutrients
 gastrovascular cavity in cnidarians, planarians
 arthropods and mollusks have open circulatory system
 not blood, but hemolymph
 fig 42.2
 some invertebrates (annelids) and vertebrates have closed circulatory systems
 like open system they have a heart, but add more vessels and capillaries
 see Fig 42.8. Arteries are narrow diameter, with thicker muscular layer
than veins. Capillaries are small diameter with epithilium and basement
membrane only.
 gas and nutrient exchange occurs in capillaries; thin and blood moves
slowly
 although capillaries smaller diameter, they have greater cross sectional
area, accounting for slower blood volume (see Fig 42.10)
 valves in veins insure one way flow through low pressure areas
 blood and lymph are related but distinct in closed systems
 capillaries are leaky; water and small molecules escape into interstitial
areas (red blood cells and proteins remain inside)
 interstitial fluid is collected by lymph system, call it lymph; returned to
circulatory system
 lymph nodes filter bacteria and viruses by maintaining high populations
of white blood cells
 as metabolism of vertebrate increases, chambers in heart increase from 2 in fish
to 4 in mammals and birds (Fig 42.3)
 what selective advantage did creatures with more chambers in their
hearts have over their ancestors with fewer chambers (i.e., amphibian
type animals with 3 chambers of fish like ancestors with only 2 chambers
or birds and mammals with four chambered hearts have over their
ancestors with only 3 chambered hearts?)
Gas exchange

Three factors impact gas exchange system
1. metabolic rate
 gas exchange and circulatory system together provide oxygen for cellular
respiration(Fig 42.18)
2. surface area-volume ratio
 as surface area-volume ration decreases as animals get bigger, they
require specialized respiratory surfaces that increase surface area for gas
exchange
3.
gas exchange in water versus air
 oxygen is more concentrated in air than water (air is 21% oxygen)
 diffusion of gases must occur across moist surface
 in air, gas exchange results in loss of water
 water contains dissolved oxygen, but much less concentrated than in air
(5 mL per liter of water…that’s only 0.5% oxygen; air would have
200mL per liter)
 cold water holds more dissolved oxygen than warm water
 flowing water captures more oxygen than still water
 AQUATIC ANIMALS: gills are outfoldings of body surface adapted for gas
exchange water (Fig 42.19)
 increase surface area
 arthropods and annelids often have thin flap of gill for each segment
 fish have gills associated with pharengeal slits
 gills of fish are very efficient at removing oxygen from water
 countercurrent exchange (Fig. 42.20 and 42.21)
 extract 80-90% of oxygen in water
 TERRESTRIAL ANIMALS: internal structures connected to outer air thru
narrow openings are adaptations for gas exchange in air
 tracheae are air tubes that ramify thru body of insects (Fig 42.22)
 muscle contraction when moving pumps air in and out of tracheae
 lungs are found in most terrestrial vertebrates
 like gills, the lungs extract oxygen and distributed in circulatory system
 like tracheae lungs are internal and open to outside with narrow openings
 increasing metabolic rate demands different adaptations of lungs in amphibians,
mammals, birds
 increase surface area for gas exchange
 amphibian have simple vascular sac-exothermic
 mammals and birds more active and require greater surface area
 mammals have alveoli-blind vascular sacs that increase surface area
for exchange. For example: humans have 100m2 for gas exchange
(300m2 in intestine)
 birds have parabronchi Fig 42.25
 Ventilation of lung
 amphibian lung sac filled by positive pressure (air pushed into lung
from mouth cavity)
 mammals contract diaphram and some muscles in rib cage to
expand thoracic cavity, creating negative pressure, and drawing in
air. Relax and thoracic cavity gets smaller and air pushed out.
Negative pressure breathing
 birds use system of air sacs to force air in one-way flow over lungs.
Countercurrent flow of air and blood supply. Why do birds need
such efficient lungs? High metabolism and fly at high altitudes
where air pressure low with concomitant decrease in partial
pressure of oxygen.
Controlling the internal environment
 temperature, osmolarity (total solute concentration)
 Exchange between the organism and outside environment is constantly
occurring
 Some small aquatic organisms may experience osmosis across outer body
wall—whether they swell up or shrivel up depends on the solute
concentration of their environment and internal fluids.
 terrestrials have waterproofed coverings, but still exchange water: loss
while breathing, sweating, urinating, gain by drinking, eating
 conformers vs regulators Fig 44.1
 Osmoconformers do not actively adjust internal osmolarity (total solute
concentration). This group cannot include terrestrials or freshwater animals,
but some marine animals have same osmolarity as surrounding water, thus they
don’t swell or shrink
 animals first evolve in sea—most invertebrates remain as marine
osmoconformers;
 hagfish, primitive vertebrates, are osmoconformers
 Osmoregulators maintain different internal osmolarity than external
environment, and to prevent swelling or shrinking, must expend energy to move
water out or in.
 marine environments
 sharks maintain lower salt concentration, but are still hypertonic to
sea water because they have urea in cells- take in water that must be
excreted through urine formed in kidneys
 bony fish are hypotonic (evolved in fresh-water) and thus lose
water, and must drink water and excrete excess salt (Fig 44.14a)
 fresh water
 take in water (hypertonic to environment) and must excrete excess
water (Fig 44,14b)
 terrestrial
 minimize water loss to dry environment (fig 44.16)
 maintain constant internal environment by conserving water
 Transport epithelia regulate water movement
 sheet of cells in contact with external environment (adaptations to
increase the surface area). These cells contain transport proteins in
membrane that control movement of solutes across epithelia--water
follows
 In insects, malphigian tubules contain transport epithelia bathed in
hemolymph (Fig 44.20). Active transport across epithelia regulates waste
excretion and water balance. What fuels active transport?
 In earthworms, with closed circulatory system, the transport epithelia are
closely associated with blood supply.
 In vertebrates, kidneys are compact but packed with tubules containing
transport epithelia
 kidney parts (fig 44.21)
 cortex
 medulla
 pelvis
 nephron: long tubule + glomerulus with Bowman’s capsule
 juxtamedullary nephron with long Loops of Henle
 Important in water retention, know based on finding that desert
animals have very long loops of henle,
 Fish, amphibians and reptiles do not have loops of henle
 birds have only short loops
 mammals have long and short loops; kangaroo rats have only long,
mountain beaver only short, human 14% long
 glomerulus is supplied with blood; pressure forces plasma and small
solute out and into bowmans capsule and into tubule
 filtration is non-selective; followed by secretion and reabsorption of
specific molecules—artificial kidneys can only filter non-selectively
 changing permeability throughout length of loop of henle sets up
countercurrent flow with increasing concentration of solutes (salt and
urea) toward medulla
 long loop of henle allows lots of water to diffuse out of the tubule
 ability to concentrate urine is key terrestrial adaptation, but the system responds
to feedback.
 Antidiuretic hormone (ADH) is discharged in response to increases in
blood osmolarity
 permeability of collecting duct to water increases and more water
is pulled out of tubule
 ADH is reduced when blood osmolarity is lowered (i.e., after drinking a
lot of water)
 permeability of collecting duct to water decreases and more water
passes out in urine
 ADH is produced in hypothalmus and released by pituitary gland
 alcohol and caffine inhibit release of ADH
 kidney is the organ for osmoregulation and nitrogenous waste excretion
 nitrogen (ammonia) is removed from proteins and nucleic acids when
they are broken down for energy or converted to carbohydrates or fats
 ammonia is toxic and soluble in water and most aquatic animals excrete
ammonia
 in fish ammonia diffuses across gills into water, with little
nitrogenous waste excretion carried on by kidney (osmoregulation
only)
 urea is less toxic than ammonia and is used by terrestrial organisms
because it can be accumulated and excreted using a minimum of water
 uric acid is insoluble is water and thought to be necessary in organisms
that produce shelled eggs: birds and reptiles—soluble wastes would
contaminate the egg
Thermoregulation
 heat is exchanged btw organism and environments
 heat is radiated from animals; heat can be absorbed from environment
 just as with osmoregulation, animal must regulate heat
 ectotherms and endotherms have different ways of maintaining temperature
 ectotherms = invertebrates, fish, amphibians, reptiles
 not cold-blooded, temp necessary for metabolism, muscle movement
 ectotherms derive most heat from environment
 have few adaptations for retaining heat
 behavioral adaptations regulate heat
 benefits
 energy not used for temp regulation; i.e., eat less
 costs
 activity limited when temp low
 endotherms, mammals and birds, and some insects and fish
 temp maintained through metabolism of animal
 generating heat requires energy, i.e., food
 adaptations for retaining heat
 feathers and hair
 countercurrent heat exchangers
 adaptations for releasing heat
 evaporative cooling


adjusting flow of blood to skin surface
 Negative feedback controls body temperature.
 decrease in body temp sensed by nerve cells and hypothalmus
 start shivering
 constrict blood flow to skin
 increase body temp
 start sweating
 open blood flow to skin
Nervous Systems
 Communication within body occurs exclusively by chemical signals
(hormones) in plants, but animals have both chemical signals and electrical
signals and the two systems are intertwined
 nervous system at simplest level provides: sensory input, integration, motor
output (fig 48.1)
 sensory input and motor output accomplished by neurons of peripheral
nervous system (PNS)
 integration accomplished by neurons of central nervous system (CNS)
 neurons specialized cells for transmitting signals throughout body (fig.48.2)
 cell body with nucleus an other organelles
 dendrites convey signals from tips toward cell body
 axons convey signals from cell body to tips
 Schwann cells form myelin sheath covering axons in the PNS of many
vertebrates; in CNS glial cells form myelin sheaths (fig 48.5)
 function to insulate the electrical impulses that move down the
axon;
 connect to other neurons at synaptic terminals
 sensory, motor and integration neurons
 how do nerves transmit signals?
 early work done on large neurons from squids
 knew muscle cells could be stimulated to contract with electrical signals
 at first thought they conducted electrical signals just like electric wire
 by inserting microelectrodes into axon, discovered that inside of the cell
was more negatively charged than outside (-70mV) (fig 48.6)
 if electrodes inserted along axon, and nerve stimulated, first one electrode
would record a spike of positive charge inside the axon and a fraction of a
second later, the second in line would record a spike of positive charge
 the degree of change in electrical potential in the cell did not respond to
changes in stimulation of nerve, but did impact the frequency—the nerve
impulse was an all-or-nothing response
 action potentials are electrical signals that flow down axon
 resting potential is term applied to non-stimulated neuron (most cells only occur
in this state)
 normally cells more negative inside than outside—why? (fig 48.7)
 inside: neg ions--proteins, amino acids, phosphate are rarer outside the
cell; pos ions--K
 outside: pos ions Na, some K
 membrane potential is -50 to -100 mV = resting potential
 ions can’t move thru phosolipid bilayer, thus need transport proteins or
ion channels (proteins too)
 K and Na diffuse thru ion channels passively and eventually gradient
would dissipate—Na-K active pump works in opposition to diffusion
 all cells have membrane potential, only neurons and muscle cells (excitable
cells) adapted to change membrane potential
 neurons have gated ion channels that allow nerve to change permeability to
different ions See Fig. 48.9
 nerve stimulation opens ion channel for Na+, which rushes into cell
because of:
 1. concentration gradient; [Na+] low inside cell
 2. electrical attraction; Na+ attracted into negatively charged cell
interior
 nerve stimulation also opens, but more slowly, ion channels for K+, which
rush out of cell because:
 1. [K+ ] low inside cell
 2. electrical replusion from the influx of positive charge (Na+) into
the cell
 a stimulus will open Na channels; if only a few channels open, the interior of
the cell becomes slightly more positive, but if it reaches about -50mV, then it
sets of action potential; see fig 48.8
 action potential in one part of axon stimulates the adjacent region to depolarize
too (see fig 48.10)
 Transmission speed varies
 depends on diameter of axon (larger = faster); in invertebrates large axons
important in speeding transmission rates (i.e., in thin axons 3m/s to
100m/s in giant axons)
 depends on myelin sheaths in vertebrates; saltatory conduction of impulse
 neurons are joined together by synapses (fig 48.12)
 most synapses use a chemical messenger to carry signal across a synaptic
cleft
 chemical messenger = neurotransmitter which is released from vesicles of
the presynaptic neuron
 neurotransmitter diffuses across cleft and stimulates the postsynaptic
neuron to fire
 many neurons (i.e., sensory neurons) synapse with a single postsynaptic neuron.
 firing by postsynaptic neuron depends on summation of stimuli received
by the neuron
 some neurons act in an inhibitory manner
 some neurons act in an excitatory manner
 several excitatory synapses releasing neurotransmitters at the same
time or nearly so required to stimulate postsynaptic nerve to fire
 omit details
 variety of types of neurotransmitters
 table 48.1 indicates that many are familiar names
 serotonin thought linked to mood, and sleep cycles
 endorphins
 organization of nervous systems varies with different animal groups
 simple invertebrates with nerve net, without central control, brain, or
division into CNS and PNS
 bilaterally symmetrical animals have CNS; i.e., planaria have small brain
and nerve cord (bundles of neurons)
 evolutionary trends in vertebrates
 brain size increases relative to body size in mammals and birds
 fish, amphibians and reptiles show similar ratios of brain size to
body size
 as size increases, so does compartmentalization
 forebrain with the cerebrum especially increases in some mammals,
especially humans.
cell bodies of the neurons in the cerebrum are gray matter and located in the cerebral
cortex; these neurons integrated complex behaviors and learning, thus “smarter”
mammals have more surface area in their cerebral cortex
Sensory Systems

what are perceptions? things like: colors, sight, sound, smells

perceptions based on matter and energy that can stimulate nerve cells

Sensory receptors transduce stimulus energy
 energy stimulates a change in membrane permeability

Sensory receptors classified by type of energy they transduce
 mechanoreceptors
 stretching of membrane results in depolarization
 pain receptors
 thermoreceptors
 chemoreceptors

 electromagnetic receptors (light, electricity, magnetism)

Reproduction
 Asexual produces offspring without meiosis
 fission-protista, invertebrates (anenome, planaria)
 budding-hydra
 fragmentation and regeneration-cnidarians, some annelids, planaria
 limited to simple body plans; common in plants
 Sexual reproduction involves meiosis and usually the fusion of gametes
 most species have males and females with fusion of gametes occuring
EITHER
 externally-aquatic; lots of eggs produced
 internally
 some species are parthenogenetic-egg develops without fertilization
 aphids, water fleas, adults from unfertilized eggs are haploid—why
would a species reproduce this way?


in wasps, bees, mites males develop from unferilized eggs—whats
the effect of this? female/male ratio is high
in vertebrates unfertilized eggs double their chromosome number to
produce diploid copies of mother
 tradeoff between asexual vs sexual reproduction
 hermaphrodites produce eggs and sperm
 i.e., earthworms
 sequential hermaphrodites
 sex can be determined by environmental cues