BSC2011 Exam 2

2 general characteristics of all animals

1. multicellular (bodies consist of more than one cell)

2. heterotrophs (obtain nutrients by consuming other organisms and cannot make their own food through photosynthesis)

ectoderm

outer tube that becomes the skin and nervous system

mesoderm

• found only in triploblastic eumetazoans

• middle layer

• becomes the muscles, bones, red blood cells, some internal organs

endoderm

inner tube that becomes the digestive tract, thyroid cells, and lungs

diploblastic animals cell layers

• 2

• endoderm & ectoderm

triploplastic animals cell layers

• 3

• ectoderm, mesoderm, endoderm

triploblastic & bilaterian

describe the same animal set using diff criteria, interchangeable. most familiar animals & show bilateral symmetry

protostomes

animals whose mouths form before their anuses (mollusks, arthropods, worms)

deuterostomes

animals whose anuses form before their mouths (echinoderms, hemichordates, chordates)

cleavage

series of rapid cell divisions after fertilization, forming smaller cells called blastomeres without increasing overall embryo size

blastula

hollow ball of cells

radial cleavage

• cells divide symmetrically and stack directly on top of each other

• echinoderms

spiral cleavage

• cells divide at oblique angles, arranging blastomeres in a spiral pattern

• mollusks, annelids, flatworms

gastrulation begins when a portion of the blastula invaginates, forming an opening called the…

blastopore (in protostomes: becomes the mouth, in deuterostomes: becomes anus)

body plan

set of morphological features common to the members of a group of animals, describing general structure & how organ systems and body parts are arranged

body plans 5 major characteristics

1. symmetry

2. body cavity structure

3. segmentation

4. external appendages

5. nervous system

radial symmetry

• exists around a central axis

• jellyfish

bilateral symmetry

• one axis divides the body into 2 equal halves

• humans, insects, and frogs are bilaterally symmetrical

cephalization

• bilaterally symmetrical organisms exhibit this

• concentration of sensory organs & nervous tissue at the anterior end

• natural selection favors this because this end encounters the environment first

acoelomates

• have no true fluid-filled body cavity separating their body walls from their digestive tracts

• mesenchyme cells fill the space, and they move by beating cilia on their ventral surface

• ex, flatworms

pseudocoelomates

• have a body cavity lined with mesoderm cells, but their internal organs are not lined with mesoderm

• organs are suspended in a pseudocoel

• ex, roundworms

coelomates

• have a body cavity and internal organs surrounded by mesoderm

• cavity: coelom

• muscular tissue: peritoneum

• ex, earthworms

hydrostatic skeleton

fluid-filled tissue that animals move by contracting muscles, shifting fluid to other regions of the cavity

anthropods

segmentation is the key to the success of … by allowing different body regions to specialize & enabling fine motor control

external appedages

clawlike appendages in insects are often modified legs, antennae, mouthparts, reproductive organs

nervous system

most important of the five body plan features

nerve nets

• ctenophore nerve net: continuous meshwork

• cnidarian nerve net: built from cells resembling the true neurons found in other animals

ganglia

• collection of neurons in different body segments

• insects & spiders have this

brain & spinal cord

• in vertebrates'

• organized central & peripheral nervous systems

• enable coordinated movement, sensory processing, complex behavior

4 major groups that are not bilaterians

1. sponges

2. ctenophores

3. placozoans

4. cnidarians

sponges

• monoblastic with no distinct cell layers/true organs

• simply a collection of cells with pores & channels that allow water to circulate through them

• have specialized cell types

sponge choanocytes move water:

through the sponge

spicules

hard skeletal elements acting as hooks to capture prey

silicon dioxide spicules

demosponges & glass sponges

calcium carbonate spicules

calcareous sponges

ctenophores

• comb jellies

• lack nematocysts & have only a simple gut for small food items

• diploblastic & radial symmetry

• bioluminscent

ctenes

• 8 comb-like plates with beating cilia used for locomotion

• defining features of ctenophores

placozoans

• primitive organs with 4 cell types

• no gut, mouth, nervous system

• asymmetric & diploblastic

• exist in 2 life stages

• pelagic: free living on open water

• surface-attached stage

cnidarians

• include 12,500 species w/ specialized stinging cells used to capture prey

• more complex than other non-bilaterians & have nervous system built from true neurons

• jellyfish, sea anemones, corals, hydras

nematocysts

harpoon like, contain toxins for capturing prey in cnidarians

polyp

sessile, tube-like attached to a surface life cycle form

medusa

• free-swimming, sexually reproductive stage

• produces gametes via meiosis

• gametes fuse to form a zygote with develops into a planula larva that settles & restarts the polyp stage

corals & sea anemones remain … throughout their lives

polyps (don’t alternate forms)

3 reasons for why animals need performed organic molecules

1. to obtain energy

2. to build tissues

3. to replace cells and grow

energy

the capacity to create or maintain organization

voltage across a membrane

• living cells maintain a charge difference across their membranes (inside more - than outside) which is crucial for nervous signaling

• sodium-potassium pumps require energy to maintain voltage

specialized cells in the retina

retina has 3 layers: light sensing, visual processing, and signal conveying which requires energy & materials

herbivory

eating plants/plant material

suspension feeding

• capturing food particles (tiny animals, algal cells, dead organic matter) suspended in water

• sponges use this

animal nutrition

study of how animals obtain chemical substances & energy needed to survive and grow

9 essential amino acids

• PVT TIM HiLL

• phenylalanine

• valine

• tryptophan

• threonine

• isoleucine

• methionine

• histidine

• leucine

• lysine

essential fatty acids

cannot be synthesized by the body & must come from food (ex: omega 3, omega 6)

essential vitamins

diverse organix compounds required in small quantities

vitamin A

vision (photoreceptor function)

vitamin K

blood clotting

vitamin C & E

antioxidants

essential minerals

chemical element, other than C,H,O,N, required in small amounts

calcium & phosphorus

bones

iodine

thyroid hormone

iron

hemoglobin & eletcron transport system

calorie

amount of heat required to raise 1 gram of water by 1 degree Celsius

cellular respiration

Food + O2 —→ CO2 + H2O + Energy (ATP & Heat)

3 food molecule types typicall respired

1. lipids

2. carbohydrates

3. proteins

metabolic rate

how quickly it burns energy in chemical bonds, which leaves the body as heat

scientists commonly estimate metabolic rate indirectly by measuring

oxygen consumption (since oxygen is consumed during cellular respiration)

basal metabolic rate (BMR)

the energy needed for basic physiological process, measured at rest, in a comfortable environment, when the animal has not eaten recently

total metabolic rate

BMR + energy for non-resting activities such as physical activity, thermoregulation, and digestion

2 factors affecting total metabolic rate

1. physical activity

2. size

physical activity total metabolic rate

• increase in physical activity increase metabolic rate

• humans: linear (running speed & O2 consumption)

• fish: exponential growth (moving faster requires more energy)

• birds: u-shaped (high takeoff energy costs)

size total metabolic rate

• larger animals require more energy overall, but less energy per unit of body weight than smaller animals

• 
  

mass-specific metabolic rate decreases as…

organism size increases

conformers

allow their internal environment to match the external environment, changing when external conditions change

regulators

maintain a constant internal environment despite external changes

thermoregulation

organisms control their inner body temperature to keep it within the optimal range, regardless of environmental temperature

temperature regulators

• maintain constant internal temperature

• mammals & birds

temperature conformers

• allow their internal temperature to track external changes

• fish & frogs

regulation provides more … but requires more … & …. metabolic rates

stability, energy, higher

epithelial tissue

either covers the body’s surface or lines a body cavity

simple epithelium

single cell layer rests on a basement membrane, a nonliving extracellular layer between epithelial cells & underlying connective tissue

simple epithelium lines the intestines, blood vessels, performing functions like:

1. moving ions across the sheet from one fluid to the other

2. releasing secretions such as mucus, digestive enzymes, hormones, sweat, and milk

3. taking up nutrients from the gut

4. sensing the environment

cell membranes

• separate extracellular from intracellular fluid

• carries receptors, pumps ions in & out, limits diffusion through selective channels

digestion

enzymatic hydrolysis of food into smaller chemical components

absoption

uptake of digestion products into the blood

villi

in the small intestine, fingerlike projections formed by epithelial tissue that increase surface area for nutrient absorption

homeostasis

process by which the body maintains a stable internal environment optimal for normal functioning

poikilotherms (ectotherms)

• get most of their heat from the environment and do not use internal mechanisms to regulate body temperature

• fish, reptiles, insects

• metabolic rate increases with external temperature

• regulate internal temperature via behavioral thermoregulation (basking, seeking shade, burrowing)

homeotherms (endotherms)

• use internal mechanisms to derive heat from cellular metabolism

• mammals & birds

• allows survival in colder habitats but is energetically costly

both poikilotherms & homeotherms engage in…

behavioral thermoregulation

shivering thermogensis

shivering produces heat through skeletal muscle contraction

non-shivering thermogenesis

relies mainly on brown adipose tissue, whose mitochondria skip ATP synthesis during oxidative phosphorylation & release energy directly as heat

fur & feathers

insulate against heat loss

specialized blood flow patterns

animals direct warm blood toward body’s core to minimize heat loss at extremities

sweating & panting

when its hot, homeotherms use evaporative cooling to increase heat loss

homeotherms have higher metabolic rates than equal-sized poikilotherms at all temperatures because…

they expend energy to maintain constant internal temperature

thermoneutral zone (TNZ)

• range of external temperatures over which a homeotherm’s metabolic rate is at its minimum

• horizontal portion of homeotherm’s graph

• TNZ sits below body temperature because the body always produces some heat

• outside TNZ, homeotherms must shiver/ burn brown fat when cold or sweat/ptant when hot

the thermoneutral zone is found only in

homeotherms (mammals & birds)

regulatory control systems

gather information, compare it to a set point, send commands to maintain a variable in homeostatic range

controlled variable

property being held in range, such as body temperature

sensors

detect the variable’s current level

control mechanism (integration center)

compares the sensor reading to the set point & decides which effectors to activate