early developmental stages

Question 1

where does fertilization occur?

Answer 1

ampulla - the widest part of the fallopian tube

Question 2

why does the sperm release acrosomal enzymes when it binds to the secondary oocyte?

Answer 2

to penetrate the corona radiata and the zona pellucinda

Question 3

the first sperm to come into direct contact with the secondary oocyte’s cell membrane forms a tube like structure known as the ____________

Answer 3

acrosomal apparatus

Question 4

after penetration of the serm through the oocytes membrane, __________ is released

Answer 4

calcium ions

*this is known as the cortical reaction

Question 5

calcium ions ____________ the membrane of the ovum

Answer 5

depolarize

Question 6

what is the purpose of calcium ions depolarizing the ovums membrane?

Answer 6

1. prevents fertilization by multiple sperm cells
2. increases the metabolic rate of the newly formed diploid zygote

Question 7

the newly depolarized and impenetrable membrane of the ovum is now called the _______________

Answer 7

fertilization membrane

Question 8

two ways twins can form

Answer 8

1. dizygotic (fraternal) twins
2. monozygotic (identical) twins

Question 9

_____________ twins form from fertilization of two different eggs released during one ovulatory cycle by two different sperm

Answer 9

dizygotic (fraternal) twins

Question 10

T / F - dizygotic twins each develop their own placenta, chorion, and amnion

Answer 10

true

Question 11

___________ twins form when a single zygote splits

Answer 11

monozygotic (identical) twins

Question 12

what happens if the division of the zygote is incomplete in monozygotic twins?

Answer 12

conjoined twins

Question 13

___________ twins share the same amnion and chorion

Answer 13

monochorionic / monoamniotic

Question 14

__________ twins each have their own amnion, but share the same chorion

Answer 14

monochorionic / diamniotic

Question 15

___________ twins each have their own amnions and chorions

Answer 15

dichorionic / diamniotic

Question 16

after fertilization in the fallopian tubes, the zygote must travel to the uterus for __________

Answer 16

implantation

Question 17

as it moves to the uterus for implantation, the zygote undergoes ___________

Answer 17

cleavage

*rapid mitotic cell divisions

Question 18

the first cleavage a zygote goes through creates the ____________

Answer 18

embryo

Question 19

T / F - the first cleavage creates a unicellular embryo

Answer 19

true

*unicellularity is one of the embryo’s defining features

Question 20

T / F - as the embryo continues to go through mitosis, the total size decreases in the first few divisions

Answer 20

false

*the total size remains unchanged for the firsy few divisions

Question 21

by dividing into progressively smaller cells, what does the embryo achieve?

Answer 21

1. increases the nuclear to cytoplasmic ratio
2. increases the surface area to volume ratio

*the cell achieves increased area for gas and nutrients exchange relative to overall volume

Question 22

what are the two types of cleavage?

Answer 22

1. indeterminate
2. determinate

Question 23

___________ cleavage results in cells that can still develop into complete organisms

Answer 23

indeterminate

Question 24

____________ cleavage results in cells that are committed to differentiating into a certain type of cell

Answer 24

determinate

Question 25

embryo --> ___________ --> __________

Answer 25

embryo --> morula --> blastula

Question 26

_____________ is the fluid filled inner cavity of the blastula

Answer 26

blastocoel

Question 27

_____________ is another name for the mammalian blastula

Answer 27

blastocyst

Question 28

what two cell groups make up the blastocyst?

Answer 28

1. trophoblast 2. inner cell mass

Question 29

what does the trophoblast become?

Answer 29

chorion and placenta

Question 30

what does the inner cell mass become?

Answer 30

the organism

Question 31

the blastula moves trough the fallopian tubes to the uterus where it burrows into the _____________

Answer 31

endometrium

Question 32

______________ is produced by trophoblastic cells and eventually gives rise to the placenta

Answer 32

chorion

Question 33

what is the purpose of chorionic villi?

Answer 33

microscopic finger like projections that penetrate the endometrium that support maternal - fetal gas exchange

Question 34

the umbilical cord consists of _____ veins and _________ arteries

Answer 34

2 arteries 1 vein

Question 34

the embryo is connected to the placenta by the ___________

Answer 34

umbilical cord

Question 35

explain the differences in the blood carried by the umbilical cord vein and arteries

Answer 35

vein = carries freshly oxygenated blood from the placenta to the embryo arteries = carry deoxygenated blood and waste away from the embryo to the placenta to be exchnaged

Question 36

until the placenta is fully functional, the embryo is supported by the ________

Answer 36

yolk sac

Question 37

the yolk sac is also a site of early ___________ development

Answer 37

blood cell

Question 38

_____________ is an embryonic membrane that i involved in early fluid exchnage between the embryo and yolk sac

Answer 38

allantonis

Question 39

_________ is a thin, tough embryonic membrane that surrounds the allantonis and is filled with amniotic fluid

Answer 39

amnion

Question 40

what is the purpose of the amnion membrane?

Answer 40

to act as a shock absorber during maternal motion

Question 41

___________ is the generation of three distinct cell layers

Answer 41

gastrulation

Question 42

gastrulation begins with a small invagination in the blastula, that creates a tube through the middle, this new structure is called a __________

Answer 42

gastrula

Question 43

the membrane invagination into the blastocoel is called the ___________

Answer 43

archenteron

Question 44

the archenteron later develops into the ___________

Answer 44

gut

Question 45

the opening of the archenteron is called the ______________

Answer 45

blastopore

Question 46

in deuterostomes (humans), the blastopore develops into the ________

Answer 46

anus

Question 47

in protostomes (humans), the blastopore develops into the ________

Answer 47

mouth

Question 48

what are the primary germ layers and where are they located?

Answer 48

1. ectoderm (outermost) 2. mesoderm (middle) 3. endoderm (innermost)

Question 49

what does the ectoderm give rise to?

Answer 49

"attractoderm" - things that attract use to others (cosmetic features, smarts) epidermis hair nails epithelia of nose, mouth, lower anal canal lens of eye nervous system inner ear

Question 50

what does the mesoderm give rise to?

Answer 50

"meansoderm" - means of getting around (bones, muscle, circulatory system, gonads) musculoskeletal system circulatory system excretory system gonads muscular tissue connective tissue adrenal cortex notochord

Question 51

what does the endoderm give rise to?

Answer 51

"endernal organs" - linings of internal organs (digestive, respiratory)

Question 52

_____________ is when only the genes needs for that particular cell type are transcribed

Answer 52

selective transcription

Question 53

____________ is the ability of one group of cells to influence the fate of nearby cells

Answer 53

induction

Question 54

how is induction mediated?

Answer 54

inducers *diffuse from the organizing cells to the responsive cells

Question 55

____________ is the development of the nervous system

Answer 55

neurulation

Question 56

a rod of mesodermal cells known as the _______ forms along the long axis of the organism like a primitive spine

Answer 56

notochord

Question 57

the notochord induces a group of overlying ectodermal cells to slide inward to form the ___________

Answer 57

neural folds

Question 58

the neural folds surround a ___________

Answer 58

neural groove

Question 59

the neural folds grow toward one another until they fuse into a ________

Answer 59

neural tube

Question 60

at the tip of each neural fold are _____________ that migrate outward to form the PNS

Answer 60

neural crest cells

Question 61

what tissues do neural crest cells develop into?

Answer 61

sensory ganglia autonomic ganglia adrenal medulla schwann cells

Question 62

___________ are substances thet interfere with development, casuing defects or even death of the developing embryo

Answer 62

teratogens

Question 63

examples of teratogens?

Answer 63

alcohol prescription drugs viruses bacteria environmental chemicals

Question 64

how does hyperglycemia in a mother effect the embryo's development?

Answer 64

overexposure to sugar can result in a fetus too large to be delivered

Question 65

how does maternal folic deficiency affect the embryonic development?

Answer 65

may prevent complete closer of the neural tube, resulting in spina bifida