AP Biology Unit 10 Animal Evolution

characteristics of animals

heterotrophs

multicellular complex bodies

no cell walls

hox genes

specialized tissue

sexual reproduction

amniotic egg

has a shell that allows the animal to live on land exclusively

morula

when a growing embryo becomes a solid ball of 64 cells

blastula

a hollow ball of cells

asymmetrical

no symmetry

radial symmetry

cutting the animal in half anywhere from top to bottom will result in two identical sections

bilateral symmetry

only one line can divide the organism into a mirror image

cephalization

formation of a head

sequence of gasulation

1)fertilization

2) cleavage

3) gastrulation

4) cell differentiation

ecological causes

the emergence predator prey relationships caused diversity

geological causes

the increase in oxygen would allow multicellular animals

genetic causes

changes in hox gene at this time lead to a variety of body plans

characterizing animals with…

1) type of symmetry

2) type of coelom

3) type of gastrulation

coelom

fluid air filled

pseudocoelom

have a body cavity but mesoderm does not line digestive tract

acoelom

without air or fluid filled cavity

protosome

animals whose blastopore forms the mouth first

deuterostome

animals whose blastospore forms the anus first

fertilization

joining of sperm and egg

• sperm head (nucleus) enters egg

• occurs in fallopian tube

cleavage

repeated mitotic divisions of zygote

• skip G1 and G2

• unequal divisions establishes body plan

  • different cells receive different portions of egg cytoplasm and therefore different regulatory signals

• 1st step to becoming multicellular

embryo

baby from conception - 8 weeks

fetus

8 weeks - birth

gastrulation

formation of 3 layered gastrula

begins to show the first signs of differentiation

ectoderm, mesoderm, endoderm

ectoderm

becomes outer body tissues

• skin, nails, teeth

• nerves, eyes, lining for mouth

mesoderm

becomes middle tissues

• blood and lymph, bone and notochord, muscle

• excretory and reproductive systems

endoderm

become the inner lining

• digestive system

• lining of respiratory, excretory and reproductive systems

cell differentiation

after gastrulation

involves giving specific jobs to cells

• neurulation

• organogenesis

• morphogenesis

ectotherm

animals that CANNOT regulate their own body temperature

endotherm

animals that CAN regulate their own body temperature

neurulation

development of nervous system

occurs soon after gastrulation is complete

formation of notochord and neural tube

• develop into nervous system → the brain and the spinal cord

organogenesis

formation of the organs

totipotent stem cells

can form all cell types including placental cells

pluripotent stem cells

can form all cell types not including placental cells

multipotent stem cells

can still differentiate but are limited

morphogenesis

limbs start to assume shape

hox genes

responsible for determining where different body structures go

extraembryonic membranes

membranes form to protect and nourish the developing embryo

amnion and chorion

amnion membrane

protects embryo and prevents dehydration

chorion membrane

exchange gases for the embryo

allantois

disposal of waste

placenta

begins developing at implantation of the blastocyst

exchanges nutrients, gases, waste products between mom and baby

eumetazoa

describes actual animals but does not include sponges

protozoa

single celled

blastopore

the in-folding of cells during gastrulation

yolk sac

contains nutrients in yolk

birth

40 weeks of gestation

1) cervix dilation

2) expulsion

3) after birth

all chordates have

1) notochord

2) dorsal hollow nerve chord

3) pharyngeal slits

4) muscular, post-anal tail

notochord

a rigid but flexible rod between the digestive tube and the dorsal nerve cord

dorsal hollow nerve cord

hollow bundle of nerve fibers

pharyngeal slits

allow for exchange of nutrients

fish: body structure

bony and cartilaginous skeleton

jaws and paired appendages

scales

fish: thermy

ectotherms

fish: respiration

gills for gas exchange

fish: heart chambers

2

fish: kind of reproduction

external fertilization

fish: development

external development in aquatic egg

amphibians: body structure

legs(tetrapod)

moist skin

amphibians: thermy

ectotherms

amphibians: respiration

lungs (positive pressure)

diffusion through the skin

amphibians: heart chambers

3

amphibians: kind of reproduction

external fertilization

amphibians: development

external development in aquatic egg

metamorphosis (tadpole to adult)

reptiles: body structure

dry skin, scales, armor

reptiles: thermy

ectotherms

reptiles: respiration

thoracic breathing; negative pressure, lungs

reptiles: heart chambers

3

reptiles: kind of reproduction

internal fertilization

reptiles: development

external development in amniotic egg

birds: body structure

feathers and wings

thin, hollow bone; flight skeleton

birds: thermy

endotherms

birds: respiration

very efficient lungs and air sacs

birds: heart chambers

4

birds: reproduction

internal fertilization

birds: development

external development in amniotic egg

mammals: body structure

hair

specialized teeth

mammals: thermy

endotherms

mammals: respiration

lungs; diagrapgm

mammals: heart chambers

4

mammals: kind of reproduction

internal fertilization and development in uterus

mammals: development

in uterus

nourishment → placenta

monotremes

egg-laying mammals

marsupials

pouched mammals

short-lived placenta

placental

true placenta