BSC2011 Exam 2

general characteristics of animals

multicellularity

heterotrophic metabolism

internal digestion

true or false: all animals are monophyletic (have a common ancestor)

true

common ancestor development

flagellated protists similar to existing choanoflagellates and sponges

formation of colonies due to efficient pray capturing

cells in colonies began to specialize for different functions (movement, nutrition)

led to complex animals

do colonies of choanoflagellate protists count as animals

no because they do not have any specialized cells

single cells attached to stalk w flagella

structure and function of sponge choanoccytes

narrow bottom, bulbous center, narrow top

opening of upper bulb: osculum, water exits here

water and food particles in via pores that are on spicules
choanocytes and their falgella facing toward inner cavity of bulb

cleavage

early cell divisions of an embryo

patterns of cleavage characterize different animal groups

examples of cleavage patterns

radial cleavage: yolk (energy for developing embryo) distributed through egg cytoplasm, zygote and descendent cells divide evenly

spiral cleavage: new cells at angles to existing ones, creates spiral

germ layers

first layers of cells that develop in early development

diploblastic animals

2 layers

ectoderm (outer), endoderm (inner)

triploblastic animals

3 cell layers

ectoderm, endoderm, mesoderm (middle)

when do germ layers form in development?

gastrulation (invagination)

blastula (hollow, fluid filled ball w cells on outside) invaginates creating a blastopore

forms layers on inside which create germ layers

ectoderm

outer layers

outer surface (epidermal cells of skin)

cns (neurons)

neural crest (pigment cell ex melanocyte)

mesoderm

middle layer

dorsal (notochord)

paraxial (bone tissue)

intermediate (tubule cell of kidney)

lateral (red blood cells)

head (facial muscle)

endoderm

inner layer

digestive tube (stomach cell)

pharynx (thyroid cell)

respiratory tube (lung/aveolar cell)q

bilaterians

bilateral symmetry (2 mirrored sides) during embryonic development

true of false: all diplobasts are bilaterians

false, all triplobasts are bilaterians

protostomes

blastopore develops into mouth

anus forms later

ex. insects, snails

deuterostomes

blastopore develops into anus

mouth develops later

ex. vertebrates, starfish

true or false: protostomes and deuterostomes are distinct clades

true

true or false: triplobalasts are a clade

true

body plan

general structure, arrangement of organ systems, integrated functioning of body parts

5 key features of the body plan

symmetry

body cavity structure

segmentation

external appendages

complexity of nervous system

symmetry

overall shape

symmetrical

can be divided along at least one plant into similar halves

radial symmetry

body parts arranged around central axis

bilateral symmetry

can be divided into mirror image halves only on one plane

asymmetrical

no plane of symmetry

ex. placozoans and sponges

bilaterial symmetry and cephalization

concentration of sensory organs and nerve tissues at anterior end (head)

cephalizatoin

having a head

more advanced trait = more advanced animal

allows for communication, sensory reception, etc

acoelomate

no fluid filled body cavity

whole body filled with loosely connected ciliated cells (mesenchyme)

creates flexible body

psuedocoelomate

body cavity is fluid-filled space where internal organs are suspended

no mesoderm surrounding internal organs

coelomate

body cavity is coelom (housed w/in mesoderm)

lined with layer of muscular tissue (peritoneum)

enclosed on both inside and outside by mesoderm

hydrostatic skeletons

when muscles contract, fluid is pushed to another part of cavity, causes region to expand

ex. earthworm movement through hydrostatic skeleton

segmentation

facilitates specialization of body regions

allows animal to alter body shape and control precise movements

true of false: radiation of anthropods was not based on segmented body plans

false, was based

appendages

can enhance animals ability to move around among other functions

ex. antennae, claws, mouthparts, reproductive organs

nerve nets

simple collection of nerves that functions as nervous system

not brain or nervous system

in ctenophores and cnidarians

bilaterian nervous system

well coordinated CNS due to cephalization

muscle action coordinated to allow movement of appendages and body parts

sensory info gathered and processed

nerve nets on cladogram

evolved independently twice in cnidarians and cnetophores

four animal groups that are not bilaterians

sponges, cnetophores, placozoans, cnidarians

which 2 out of the 4 animal groups that are not bilaterians split first

sponges and cnetophores

sponges

monoblastic

no distinct embryonic (germ) cell layers and no true organs

spicules: skeletal elements made of silicon dioxide or calcium carbonate

spicules in glass sponges and demosponges are made of…

silicon dioxide

spicules in calcareous sponges are made of…

calcium carbonate (good in salt water)

cnetophores

“comb jellies”

radial symmetry, diploblastic

move by beating cillia arranges on 8 comblike plates called ctenes

placozoans

very simple, only 4 cell types

diplobasltic

two life stages: pelagic swimming stage (free swimming/drifting) and stage that adheres to surfaces

cnidarians

diploblastic

jellyfishes, sea anemones, corals, hydrozoans

gastrovascular cavity: functions in digestion, circulation, gas exchange, hydrostatic skeleton

life cycle: sessile polyp (like coral) and motile medusa stages

nematocysts

nematocysts

feature of cnidarians

specialized harpoon-like structures w toxins (reason why tentacles get stuck to you)

used to capture large pray

causes stinging

life cycle of cnidarian

polyp (2n) → mature polyp (2n) → young medusa (2n) → mature medusa/jellyfish (2n) → fertilization of egg and sperm (n+n) → fertilized egg (2n) → planula larva (2n)

heterotrophs

organisms that require preformed organic molecules as sources of energy and chemical building blocks

obtain energy through breaking chemical bonds of organic compounds obtained by other organisms

build their tissues (growth and cell replacement) w matter present in preexisting organic compounds

organization

most essential attribute of life

second law of thermodynamics

any organized system, left alone, tends to lose organization and become more random

animals and second law of thermodynamics connection

animals need to obtain energy so they can work to maintain their organization

how is energy needed to maintain a charge gradient across a cell membrane

energy is needed for the ion channel pumps that maintain the charge distribution of the cell

how is energy needed to maintain the retina

photoreceptors in the eyes receive light energy

neurons needs energy to maintain organization and process information received by photoreceptiors

three types of feeding

predation

suspension feeding

symbiosis

suspension feeding

animal filters tiny food particles suspended in water rather than hunting or eating large pieces of food.

nutrition

study of how animals meet their needs for chemical substances and energy

interconversion of molecules in animals

lipid molecules → carbohydrates

not complete, some molecules must be fully formed and obtained from food

essential nutrients

required but cannot be synthesized by animal

standard amino acids

20 amino acids animals need to build proteins

animals can synthesize some of these

essential amino acids

amino acids that cannot be synthesized and must come from food

essential fatty acids

omgea-3 and omega-6

3 and 6 refer to # of carbon position of the last double bond

PVT. TIM HALL

8 essential amino acids for adult humans

phenylalanine

valine

tryptophan

threonine

isoleucine

methionine

histidine (only required in infants)

arginine*

lysine

leucine

essential vitamins

A (vision)

K (blood clotting)

essential minerals

chemical elements that animals require in addition to C, O, H, N

ex. Ca, P (bone strength), I (thyroid horomes), Fe (hemoglobin)

energy content of food

measured by amount of heat food produces when burned in presence of O₂ forcing CO₂ and H₂O

calorie

amount of heat needed to raise 1g of H₂O 1 degree Celcius

food labels

kilocalories (1000 calories)

1 Joule

0.239 calories

metabolic rate

amount of chemical bond energy consumed and converted to heat per day

three types of food molecules

lipids (fats and oils)

carbohydrates

proteins

what happens when an animal consumes more chemical-bond energy than it needs

some can be stored as energy dense lipids

true or false: animals with lower metabolic rates have lower food needs

true, the opposite is also true

animals with high metabolic rates need to find and eat a lot of food per unit of time to replace energy being consumed

true or false: physical activity increases metabolic rate

true

humans: linear increase

fish: exponential increase due to resistance in water

birds: high and low speeds metabolic rate is high

basal metabolic rate (BMR)

measured when an animal is in a comfortable thermal environment and has not eaten recently

scaling relationships

animals characteristics as functions of body size

BMR per gram body weight decreases as animal size increases

small mammals need more food per gram of body weight than large mammals do

intersitial fluids

cells in an animals body that are bathed with body fluids

regulation

occurs when internal environment stays constant even when external environment changes

provides stability but energetically expensive

regulators

animals that can maintain constant internal conditions like temperature

conformers

animals with internal environments that vary to match the external environment

energetically cheap but animals cells must be able to cope with changes in their environment

intracellular vs extracellular fluid

intra = fluid inside cells

extra = rest of the body fluid in the body including plasma and interssital fluid

epithelia

sheet of epithelial cells that covers a body surface, organ, or lines a body cavity

functions: pumps ions between fluids on either side, secretes hormones, mucous, digestive enzymes, milk, sweat, absorbs nutrients from gut, serves sensory functions like smell and taste, separates fluid compartments

simple epithelium

single layer of cells on nonliving basement membrane

lines blood vessels, intestines, other tubules

roles of cell membranes

pumps ions between intra and extracellular fluid

receiving and producing physiological signals (cells receptors)

control diffusion of ions/molecules

tissue

assemblage of cells of similar type

organ

2+ types of tissue w defined structural relationship to each other

multi-organ system

multiple organs working together

levels of organization in midgut (small intenstine)

small intestine organ in digestive organ system

small intestine composed of connective tissue, smooth muscle tissue, and nervous tissue

intestine lined w simple epithelium, digestive enzymes, absorption of nutrients, secretion of hormones and mucous

homeostasis

refers to the stability of the internal environment and the mechanisms that maintain it

con of regulation of homeostasis

energetically expensive

homeotherms

animals that maintain a constant internal body temperature (thermoregualtion)

thermoneutral zone (TNZ)

range of external temperatures in which metabolic rate is minimal and does not change with external temperature

not much energy has to be expended to keep body temp w/in homeostatic range

true or false: outside of the TNZ, metabolic rate lowers

false, metabolic rate rises

pokilotherms or ectotheerms

body temperatures are variable and are determined by the external temperature

no internal body temp regulation

vary widely in body temperature limits

how do poikilotherms and ectotherms regulate their body temperatuer

behavioral thermoregulation ex. physical positioning of body in shade or sun

true or false: in general poikilotherm metabolic rate is higher than homeotherm body temperature when external temperatures are low

false, when external temperatures are low, metabolic rates of homeotherms are higher than poikilotherms

homeothermy relationship between external temperature and metabolic rate

metabolic rate rises as the temperature falls below the TNZ (body requires energy to keep the body warm)

TNZ

metabolic rate rises as the temperature increases above the TNZ (body requires energy to keep it cool)

food needs additional to this

poikiliothermy relationship between external temperature and metabolic rate

metabolic rate rises because as the external temperature rises, the animal’s internal temperature also rises

homeotherm mechanisms that can increase metabolic rate in cold environemnts

shivering: skeletal muscles contract and energy is converted from ATP to heat

nonshivering thermogenesis