exam 3 Flashcards
belowground and function
root system-takes in water and nutrients from soil
aboveground and function
shoot system, harvests light and CO2, produce sugars
belowground and aboveground plants systems form what
the plant body
key functions of the root system -5
-anchor plant to the soil
-absorb ions and water from soil
-conduct water and ions to the shoot system
-obtain energy from the sugar in the shoot system
-store material produced in the shoot system for later use
root system diversity can be analyzed on three levels what are they
morphological diversity-among species
phenotypic plasticity- in response to environment- stress
modified roots- for unusual functions
2 types of appearances of roots in morphological diversity
tap roots; single, long, dominant, grows straight.
Fibrous roots; smaller roots in all directions
lifespan of roots in morphological diversity
perennial; live for many years
annual; die off early
roots stop ____ or die back in areas ___ resources in phenotypic plasticity
growing, lacking
in phenotypic plasticity identical plants may
have different root systems in diffferent environments
examples of modified roots
come above surface of the soil- storage of carbs
pneumatophores- function in gas exchange
Biennial plants- carrots and beets
in a plant body, the shoot system consists of one or more
stem and leaf
stem
vertical aboveground structure
-has nodes
and internodes
leaf
appendage that projects from stem laterally on stalk- petiole
apical and axillary bud may develop into
flowers
axillary (or lateral) buds
nodes just above site of leaf attachment
-may grow into a branch-a lateral extension of root system
apical buds
tip of each stem and branch
modified stems examples
cactus, stem is converted into a water storage organ
strawberry stolons produce new individuals above ground
rhizomes- below ground, store carbohydrates
thornd- for protection
leaf structure
photosynthesis occurs in leaves, large surface area. has 2 main structures- expanded blade, stem called petiole
leaves are also diverse and can be analyzed on what 3 levels
morphological, phenotypic, and modified leaves
type of leaf blades-4
simple leaf- one petiole and one leaf blade
compound leaf- one petiole and one blade divided into many leaflets
doubly compound leaf- one petiole and many blades divided into many leaflets
needle like leaf- very hot or very cold climates
arrangement of leaves
alternate- self explanatory
opposite- self explanatory
whorled- meet in the center but have leaves around the stem
rosette- weed on the ground- center point where every leaf extends from
modified leaves and examples - 6
bulbs- onion leaves store food
succulents- aloe vera store water
floral mimics- red poinsettia leaves attract pollinators
traps- venus fly trap
tendrils- pea tendrils aid in climbing
chloroplasts
site of photosynthesis
vacuoles
have cell sap, store water, waste and nutrients
primary cell wall and secondary
cellulose
lignin, cellulose, etc.
cytoplasm of adjacent plant cells are connected by
plasmodesmata
simple tissues
skin tissue- consists of a single cell type
complex tissue
contain several type of cells
three tissues system are found in plants
dermal tissue system
ground tissue system
vascular tissue system
dermal tissue systems
outermost tissue, complex tissue. consists of epidermal cells, guard cells, trichomes, and root hairs.
dermal tissue functions in shoots and roots
shoots; protection, gas exchange
roots; protection; absorption of water and nutrients
- protection: cuticle
- regulation of water loss and gas exchange:___
- other functions:___
1- waxy layer on surface of leaves and stems, minimize water loss, protection from viruses, bacteria, and fungal spores
2- stomata
3-trichomes- prevent water loss, coolness, secrete toxins, trap and digest insects
ground tissue systems
forms plants body, SIMPLE tissue
ground tissue consist of 3 distinct tissues
parenchyma, collenchyma, sclerenchyma
function of ground tissue systems
synthesis and storage of sugars(other carbs) - support and protection
parenchyma
most abundant, have thin celled walls. many are totipotent
totipotent
capacity to divide and develop into complete plant (stem cells)
parenchyma in leaves and in roots
in leaves- photosynthesis and gas exchange
in roots- storage of carbohydrates
collenchyma
have unevenly thickened cell walls, found under epidermis- outside of vascular tissues
-provide flexible structural support to actively growing up parts of the plant
sclerenchyma
primary cell wall: cellulose.
secondary cell wall; thick/rigid, made of lignin and cellulose.
fibers; elongated
sclereids; short, variable shape
vascular tissue system consists of 2 complex tissues, what does the xylem do
xylem; conducts water and dissolved nutrients from the root system to the shoot system
xylem structure in vascular tissue system and 2 types of water conducting cells
water conducting cells, parenchyma cells, and fibers. 2 types - tracheids; long tapered, have pits (softwood) Vessel elements; short, have perforations (hard wood)
phloem structure
sieve- tube elements; lack nuclei and are directly connected to adjacent companion cells by plasmodesmata
meristems
undifferentiated-no specialized structure or function-cells that retain ability for mitosis
apical meristems
tips of each root and shoot, responsible for primary growth.
three distinct primary (plant grows in length) apical meristems
- protoderm- dermal tissue system
- ground meristem- ground tissue system
- procambium- vascular tissue system
secondary growth __ shoots and roots
widens
secondary growth
increases width of roots and shoots, provides increased structural support
secondary growth occurs due to __ (not ___)
cambium, apical meristems
cambium
vascular cambium and cork cambium
secondary xylem
WOOD
secondary phloem+primary phloem+cork cambium+ cork cells=
BARK
gas exchange in bark occurs through small opening called ___
Lenticels
dark colored inner xylem
heartwood
light colored, outer xylem
sapwood
older, innermost secondary xylem accumulates
resins and gums
in areas with seasonality, vascular cambium stops growing during the dry or cold season. this results in
annual tree rings
most adult animals have 4 tissue types
1) Nervous tissue
(2) Muscle tissue
(3) Epithelial tissue
(4) Connective tissue
tissue
group of similar cells that work together as a unit to perform the same function
nervous tissue transmit electrical signals
action potentials
changes
in permeability of plasma
membrane
nervous tissue has dendrites which
transmit
electrical signals from adjacent
cells to neurons
axons in nervous tissue
transmit electrical
signals from neurons
to other cells
pressure potential
tendency of water to move in response to pressure
turgor pressure
incoming water causes plant cell to swell, plasma membrane pushes against cell wall
wall pressure
force exerted when rigid cell wall resists expansions of cell volume
muscle tissue- long cells, voluntary movement are and function in what
skeletal muscle, attaches to bone body movement
muscle tissue- branched cells, involuntary movement are and function in what
cardiac muscle, heart walls, pump blood
muscle tissue- tapered cells, involuntary movement are and function in what
smooth muscle, digestive tract, blood vessels
epithelial tissue
Cover the outside of the body, line surfaces of organs, and form glands
organ
structure that serves a specialized function and
consists of several tissues
gland
group of cells that secrete specific molecules
Epithelial tissues have polarity, apical side and basolateral side what is the difference
apical side; faces away from other tissues
basolateral; faces the animal’s interior
simple epithelia vs stratified
simple- single layer of cells, diffusion of gases, water, nutrients
stratified- multiple layer of cells, body protection
extracellular fibers
collagen, reticular fibers, and elastin
matrix is made up of what
extracellular fibers and other materials
connective tissue
cells loosely arranged in a liquid/jelly-like/solid matrix
dense vs loose connective tissue
dense; fibrous extracellular matrix, holds tissue together tightly
loose; soft extracellular matrix
supporting vs fluid connective tissue
supporting; firm extracellular matrix, functions in structural support and protection.
fluid; liquid extracellular matrix, functions in transport
homeostasis
Stability in chemical and physical conditions within an
organism’s cells, tissues, and organs
2 different approaches to maintaining homeostasis- regulate and conform
regulate; relatively constant internal conditions even when
the environment fluctuates; Humans at 37C
conform; internal conditions fluctuate with external
environment, Antarctic rock cod with sea water.
homeostatic system based on 3 general components
- sensor
- integrator
- effector
sensor
senses external or internal environment
e.g.: Temperature receptors in the skin
integrator
evaluates incoming sensory information,
compares it to set point, determines a response
e.g.: Hypothalamus compares the set point to the current
body temperature
effector
helps restore internal condition being monitored
* e.g.: Shivering to generate warmth or fluffing of fur to
insulate and retain heat
in Mammals, a Homeostatic System Regulates
Body Temperature Through
negative feedback
thermoregulation
- conduction
- convention
- radiation
- evaporation
thermoregulatory strategies- is an animals body temp held constant?
homeotherms; keep their body temp constant
poikilotherms; body temp changes based on environment
thermoregulation varies widely
endotherm and ectotherm
endotherm
produces adequate heat to warm its own tissue
ectotherm
relies on heat gained from the environment
honeybees use what to kill predators
heat
topor- thermoregulatory strategy
temporary drop in body temp
hibernation- thermoregulatory strategy
prolonged drop in body temp
Some animal structures conserve heat with
countercurrent heat which are
Arteries are wrapped with several small veins
Heat flows freely from warm arteries to cool veins, thus retaining heat
Countercurrent exchangers are efficient—maintain gradient between two fluids along their entire length
water potential
Potential energy of water in particular
environment, compared with potential energy of pure
water at atmospheric pressure and room temperature
in water potential net movement of water occurs as direct result of
differences in water potential from roots to shoots
water potential is the sum of which 2 factors
solute potential and pressure potential
solute potential
Tendency for water to move by osmosis in response to differences in solute concentrations.
Solutions with high concentrations of solutes have ___ solute potentials
low
hypertonic condition
h2o moves out, flaccid
vascular tissue system consists of 2 complex tissues, what does the phloem do
phloem; conducts sugars, amino acids, hormones, and other substances from roots to shoots and from shoots to roots
hypotonic solution
h2o moves in, turgid
salt adapted
species accumulate solutes in root cells,
lowering their solute potential
dry adapted
species cope by tolerating low solute
potentials.
shrubs
continue to acquire water and grow because
the solute potential of their leaves remains below the
potential of soil water
wilting
Occurs When Water Loss Leads to Loss
of Turgor Pressure
sink in bulk flow
tissue where sugar exits phloem
* developing leaves, flowers, seeds,
fruits, storage cells in roots
source in bulk flow
tissue where sugar enters phloem
* Mature leaves and stems
what is the order of bulk flow
from source to sink
Sources supply to Sinks directionally how
same side, same end
pressure flow hypothesis
-High turgor pressure near
-Low turgor pressure near
source
sink
phloem loading in pressure flow hypothesis
Water in phloem sap:
moves down this
pressure gradient (passively)
- sugars carried by active transport- passively
pressure flow hypothesis
High Turgor Pressure
Near Sources Causes Phloem Sap to Flow to Sinks
Active transport involves pumps (membrane proteins) that
change shape when they bind ATP.
cotransporters
Electrochemical gradients established by pumps are used to transport other molecules or ions by two types of membrane proteins
symporters
transport solutes against concentration
gradient- same/ drag
antiporters
actively transported solute moves in the
opposite direction. This is secondary active transport
active transport
transport of molecules across membrane
against their electrochemical gradient with use of ATP
in phloem loading proton pumps in membranes of companion cells
create
a strong electrochemical gradient that favors a
flow of protons into companion cells
A symporter in the membranes of companion cells
uses the
proton gradient to bring sucrose into
companion cells from the source cells
how does phloem unloading occur in young growing leaves
simple diffusion, sucrose is rapidly used up in cells of these leaves
how does phloem unloading occur in root cells
large vacuole that stores sucrose, surrounded by a membrane called the tonoplast
Tonoplast (membrane in root cells) contains 2 types of protein pumps that
accumulate sucrose in vacuole
Proton–sucrose antiporter
moves sucrose into
vacuole against its concentration gradient
electrolyte
a compound that dissociates into ions when dissolved in water e.g., NaC
diffusion
movement of uncharged substances down their concentration gradients
osmosis
movement of water down its concentration
gradient across a semipermeable membrane
osmolarity
concentration of solutes in solution (units: Osmoles/liter)
osmotic stress
- concentration of dissolved substances in a cell or tissue is
abnormal - water and solute concentrations are different from their set
points
osmoregulators
actively regulate their internal water and
electrolyte, independent of the surrounding environment e.g.,
humans
osmoconformers
organisms that keep their internal fluids
similar to their ambient conditions e.g., sponges and jellyfish
Marine bony fishes and cartilaginous fishes experience severe osmotic stress, what are the 2 strategies for living in the ocean
osmoregulation and osmoconformation
osmoregulation in marine animals
Tendency for water loss
+ uptake salts
* Fish drink lots of seawater
* Urinate little
* Spend a lot of energy
for salt balance
osmoconformation in marine animals
- Isosmotic with seawater,
resulting in little water loss. - High conc. of urea in blood.
- Spend a lot of energy
to prevent toxic effects of
high urea concentrations
salt excretion in osmoregulators and osmoconformers
regulators- 400mmol/L- through gills, chloride cells
conformers- 600mmol/L - through rectal glands- shark
How do freshwater fishes maintain water and electrolyte balance
- Tendency to lose salt
across their gill epithelium by diffusion. - Tendency to absorb water.
- Lots of dilute urine.
- Drink little water.
- Active transport needed
to reabsorb salts at gills
anadromous fish
live in salt water and
migrate to freshwater water
to breed. e.g., bass, salmon
catadromous fish
live in freshwater water and
migrate to salt water to breed.
e.g., American eel
in salt water, ____ is on basolateral side of the chloride cell
cotransporter
in freshwater, contransporter is on __ side of the chloride cell
apical
outer region of the kidney
cortex
renal artery brings ___ with nitrogenous wastes
blood
renal vein carries ____ ____ away
cleaned blood
inner region of the kidney
medulla
nephron is the what for the kidney
ultimate filtration unit
5 parts of the nephron
renal corpuscle, proximal tubule, loop of henle, distal tubule, collecting duct
renal corpuscle
filters blood, forming a filtrate (ions, water, nutrients, and wastes)
proximal tubule
epithelial cells reabsorb nutrients, ions,
and water from filtrate into blood
loop of henle
absorbs water
distal tubule
reabsorbs ions, water, toxins, drugs
collecting duct
urea moves into blood, water reabsorption
Urine formation begins in renal corpuscle which is made up of
glomerulus and bowmans capsule
glomerulus
cluster of capillaries that bring
blood to the nephron from the renal artery
bowmans capsule
the region of the nephron that surrounds the glomerulus
glomerular capillaries have what for filtration
large pores
tubular reabsorption and its 2 modes
Proximal Convoluted Tubule
)Transcellular
2)Paracellular
microvilli in active transport
greatly increase epithelial surface area
Proximal tubule functions in ____ ______of
selected molecules out of the filtrate.
active transport
Na+-K+ ATPase
pump primary active
requires energy
antiport
Ion and Water Movement Is Driven by a
Concentration Gradient in the
interstitial fluid
descending limb in the loop of henle
highly permeable
to water but almost completely
impermeable to solutes
ascending limb in the loop of henle
highly permeable
salts (Na+ and Cl-) to moderately
permeable to urea, and almost
completely impermeable to water
loop of henle remains what
osmotic gradient
As fluid flows down
descending limb, fluid inside
loop ___ water to the tissue
surrounding nephron.
This movement of water is
passive, …
loses, down its osmotic
gradient.
thin ascending limb
fluid inside nephron loses Na and Cl
how do the ions move in the thin ascending limb
passively along electrochemical gradients
thick ascending limb
Near the cortex,
osmolarity of
surrounding interstitial
fluid is low
how are ions transported in thick ascending limb
Na+ and Cl-
are actively transported
out of nephron in the
thick ascending limb
vasa recta
removes water and solutes that leave
the Loop of Henle
what is the structure of the vasa recta
vessels
that runs along the loop
Vasa recta joins up with small veins at
the top of the medulla and ultimately
form the
renal vein
distal tubule fluid and what does it contain
Fluid is hypoosmotic
* contains urea and other waste products
collecting duct- 3 characteristics
Fluid is called urine
* dilute when individual is
well hydrated
* concentrated when the
individual is dehydrated
Changes in the distal tubule and collecting duct are
controlled by
hormones
what is produced by adrenal glands (salt changes-Na levels are low)
aldosterone
what does aldosterone lead to
activation of sodium potassium pumps
If an individual is dehydrated, the brain releases
antidiuretic hormone (ADH)
ADH has 2 important effects on epithelial cells in the
collecting duct
insertion of aquaporins and increases permeability to urea
insertion of aquaporins
into the apical membrane and
large amounts of water are reabsorbed
increases permeability to urea
favoring water reabsorption
Many aquaporins, water is
conserved, and urine is
____ relative to blood
hyperosmotic
Few aquaporins, water is impermeable, and urine is___ relative to blood
hypoosmotic
nerve net
diffuse arrangement of cells e.g., cnidarians (jellyfishes,
hydra, and anemones) and ctenophores (comb jellies
central nervous system
large numbers of neurons
aggregated into clusters called ganglia e.g., brain and spinal cord in
humans
peripheral nervous system
all neurons and other
components of nervous system outside the CNS e.g., cranial nerves
(involved in sense perception) and spinal nerves in humans.
3 types of neurons
- sensory neurons
- interneurons
- motor neurons
sensory neurons
carry information to CNS and from sensory cells.
* skin, eyes, ears, and nose to respond to light, sound, touch.
* inside the body, monitor conditions for homeostasis, such as blood pH and oxygen levels
interneurons
pass signals from one neuron to another
motor neurons
send signals from CNS to effector cells in
glands or muscles.
Motor neurons and sensory neurons are bundled together into
long strands called
nerves
cell body (soma) of a neuron
includes the nucleus
an involuntary response to an
environmental stimulus
reflex action
dendrites in a neuron
highly branched
short projects
axons in a neuron
one or more
relatively long projections
____receive signals from axons of other neurons, and a neuron’s
___ sends signals to the dendrites and cell bodies of other neurons
dendrites, axon
rules for ion movement- membrane potential- 3
- From HIGHER to LOWER
concentration. - Away from LIKE charge, towards
OPPOSITE charge. - Depends on permeability of
membrane, requires special proteins
like pumps, carriers, channels, etc.
membrane potential
refer to a separation of charge
immediately adjacent to the plasma membrane
Ions move across membranes in response to concentration + charge
gradients
electrochemical gradient
what is the charge on membrane potentials
negative
resting potential
difference in
charge across membrane when
neuron is not communicating
with other cells
extracellular fluid
more Na + and Cl-
interior of membrane
Na+ & Cl- down, K+ & amino acids & organic solutes up
Ions such as these can cross plasma membranes efficiently in only one of three ways
primary active transport,
secondary active transport, and diffusion
At rest, __ __ of a neuron is relatively impermeable to
most cations
plasma membrane
primary active transport
uses ATP (e.g., Na+/K+ pump)
secondary active transport,what kind of energy does it use
uses electrochemical energy
(e.g., co-transporters: symport, antiport
diffusion
no energy, ion channel
resting potential of neuron maintained, 1- Na+-K+ ATPase pump
Na+= out of cell, K+= inside the cell
Na+= higher conc. out membrane, K+= higher conc. inside membrane
resting potential of neuron maintained, 2 -Neurons have high number of K+ ___ ___
allows leak of K+ across membrane due to diffusion
leak channels
resting potential of neuron maintained, 3- as K+ moves out of cell
inside becomes more negative
resting potential of neuron maintained- 4- buildup of negative charge begins to attract K+ and __ concentration gradient
counteract
equilibrium potential
membrane reaches voltage at which
equilibrium exists between
concentration gradient vs electrical gradient
Concertation gradient (that favors movement of K out)
Electrical gradient (that favors movement of K in)
action potential
rapid, temporary change in a membrane potential;
has three phases:
phase in which the membrane becomes
less negative and moves toward a positive charge
depolarization
rapid depolarization
changes membrane back to a negative
charge
hyperpolarization
membrane becomes more negative
than it was during the resting potential
action potential depends on
voltage gated channel
neurotoxins
block Na+ voltage gated channels
initial depolarization leads to the opening of Na channels which ___ the membrane further which
leads to the opening of more
depolarizes, positive feedback
how is action potential propagated - 3 steps
- at the start, the influx of Na+
- charge of spreading away from the Na+ channels
- they depolarize adjacent “downstream” portions of the membrane
action potentials propagate in one
direction
Once Na+ channels have opened
and closed, they are less likely to open again for a short period of
time
refractory state
hyperpolarization phase in action potential propagation
Membrane is more negative than resting period
* Keeps positive charges that spread upstream from triggering an action potential
* During this phase, a much stronger stimulus would be necessary to raise the membrane potential to threshold
potential
how does the diameter of axons affect the speed
cations meet less resistance in
axons with large diameters than
those in narrow axons
how does a large diameter of axons determine speed of action potential
axons transmit
action potentials much more quickly than small axons
how does myelination of axons affect speed of action potential
- Membranes of accessory cells wrap around neurons
Schwann cells: accessory cells in PNS
Oligodendrocytes: accessory cells in CNS
in myleination of axons Where these cells wrap around an axon, they form a
myelin sheath
gap in myelin sheath
node of Ranvier
The autoimmune disease multiple sclerosis (MS) develops
when the immune system targets oligodendrocytes, destroying myelin
in the CNS
synaptic cleft
tiny space between 2target cells
synaptic vesicles
store neurotransmitters
presynaptic neuron
contains synaptic vesicles
postsynaptic cell
cell/axon on the other side
neurons meet and transfer information at
synapses
In response to the influx of Ca2+, synaptic vesicles fuse with
presynaptic membrane, then release neurotransmitter into synaptic cleft by
exocytosis
Neurotransmitters bind to receptors on postsynaptic membrane, acting like
a ligand
ligands
Molecules that bind to specific site on a receptor molecule
what is the role of neurotransmiters in synaptic transmission
Many neurotransmitters bind to receptors called ligand-gated ion
channels, which then open and admits flow of ions
Neurotransmitter’s ___ ____ is transduced to an electrical
signal (change in membrane potential of postsynaptic cell)
chemical signal
Some neurotransmitters bind to receptors that activate ____ ___(chemical changes inside postsynaptic cell)
second messengers, gene expression
what are post synaptic potentials
When neurotransmitters bind, ligand-
gated channels on postsynaptic cells
open and allow Na+ to enter the cell,
causing depolarization
- Excitatory postsynaptic potentials
(EPSPs): cause membrane to
depolarize, increasing likelihood of an
action potential
post synaptic potentials-if several EPSPs occur close together, they sum and make the
neuron likely to fire an action potential
summation
post synaptic potentials- When neurotransmitters binding leads
to an outflow of potassium ions or
anions, postsynaptic membrane
hyperpolarizes
postsynaptic potentials- Inhibitory postsynaptic potentials
(IPSPs): cause membrane to be
hyperpolarized, decreasing likelihood
of
action potential
post synaptic potential- If EPSP and IPSP occur at the
same time in the same
postsynaptic cell, they may
cancel each other out
post synaptic potential- Synapses can also be
modulatory―meaning
they
modify a neuron’s response to
other EPSPs or IPSPs
central nervous system consists of
brain and spinal cord,
integrates information
peripheral nervous system
neurons outside of CNS
what is afferent division in PNS
transmits sensory information to CNS
what does efferent division do in PNS
carries
signals that allow body to respond to changed
conditions in an
appropriate way
somatic nervous system
voluntary responses, conscious
control: e.g., skeletal muscles
autonomic nervous system
involuntary responses, not under
conscious control: e.g., cardiac
muscles
spinal cord
made
up of many nerves, serves as
an information conduit
Virtually, all the information
that enters the spinal cord is
sent to the ____ for
processing
brain
Brains of all vertebrates
functionally divided into three main parts based on sensory
function
forebrain(smell)
midbrain(vision)
hindbrain(hearing and balance)
cerebrum
bulk of brain, most of
the forebrain, divided into left and
right hemispheres
diencephalon
relays sensory information to cerebellum
brain stem
connects brain to spinal cord
cerebellum
coordinates complex motor patterns
the two hemispheres are connected by a thick band of axons called
corpus callosum
In mammals, the ____ is very large and focuses on reasoning
and ___, and processing of multiple sensory and
motor functions
cerebrum, memory
cohesion- tension theory -Water in xylem should experience a strong pulling
force during
transpiration
After water is absorbed through root hair, it travels
through the root cortex toward the vascular tissues via
one of three routes
symplastic route( plasmodesmata)
transmembrane(aquaporins)
apoplastic(via spaces between cells)
what is the casparian strip made of
waxy compund- suberin
in root pressure hypothesis Influx of ions lowers water
potential of xylem, drawing in
water from nearby cells and
creating ___ pressure that
forces ___ up xylem
positive, water
in cohesion tension theory Transmission of pulling force from leaf surface to root
is possible because
xylem forms continous network from roots to leaves
all water molecules held together by cohesion
xerophytes- plant feature that reduces water loss through transpiration- does what
has adaptations for dry enviornments
Evaporation from leaves pulls water through roots and
shoots under
negative pressure
capillary action moves water through
xylem
A ___ in the membranes of companion cells
uses the proton gradient to bring sucrose into
___ cells from the source cells
symporter, companion
