Developmental Biology

Question 1

first 8 week of development in humans

Answer 1

embryonic development

Question 2

all development after the first 8 weeks

Answer 2

fetal development

Question 3

human gestation period is – days

Answer 3

266 (nine months)

Question 4

embryonic development is complete within the – trimester

Answer 4

first

Question 5

sperm have the ability to survive about – hours in the female system, while an egg cell only survives about – hours

Answer 5

48, 24

Question 6

sperm deposited prior to or right after – are capable of fertilizing the egg, which occurs in the fallopian tubes

Answer 6

ovulation

Question 7

200 to 500 million sperm are typically released during ejaculation but only – will make it to the egg cell

Answer 7

200

Question 8

secretions from the female system will change the membrane composition of the sperm near its –

Answer 8

acrosome

Question 9

When sperm bumps into the egg, the content of its acrosome will be released due to –

Answer 9

membrane instability

Question 10

after the acrosome is released, sperm can penetrate the – of the egg

Answer 10

corona radiata (outer layer)

Question 11

the first sperm to pass through the – will pass its nucleus into the egg

Answer 11

zona pellucida

Question 12

after one sperm passes through the zona pellucida, the egg’s membrane will – which will make it impenetrable to fertilization by other sperm

Answer 12

depolarize

Question 13

the nuclei of the egg and sperm fuse creating a

Answer 13

zygote

Question 14

one day after fertilization, the zygote performs its first meiotic division, becoming

Answer 14

an embryo

Question 15

rapid cell division characteristic of early embryonic development

Answer 15

cleavage

Question 16

within about 4 days, the embryo reaches the – stage in which it consists of a ball of cells

Answer 16

morula stage

Question 17

during early cleave, the embryo may split into two, which results in

Answer 17

identical twins

Question 18

by about six days, the center of the embryo hollows out and becomes filled with fluid and is termed

Answer 18

blastula or blastocyst

Question 19

outer cells of the blastocyst

Answer 19

trophoblast

Question 20

aid in implantation and development of extra embryonic membranes and the placenta

Answer 20

trophoblast

Question 21

the inner cell mass of the blastocyst is the source of – which have the ability to differentiate into any cell type

Answer 21

embryonic stem cells

Question 22

implantation of the embryo begins about one after fertilization and is complete by the – week

Answer 22

second

Question 23

blastocyst produces a critical hormone that is important for the maintenance of pregnancy –

Answer 23

human chorionic gonadotropin (HCG)

Question 24

HCG is the signal to the – not to degrade

Answer 24

corpus luteum

Question 25

normally, the degradation of the corpus luteum causes a decline in -- and -- and trigger menstruation

Answer 25

estrogen and progesterone

Question 26

what forms during gastrulation?

Answer 26

the three primary germ layers

Question 27

once a cell enters a germ layer, its ability to differentiate into specific cell types is --

Answer 27

limited

Question 28

cells in this layer will express genes needed to become skin cells and nervous system cells

Answer 28

ectoderm

Question 29

cells in this layer will express genes needed to become muscles, bones, and most internal organs

Answer 29

mesoderm

Question 30

cells in this layer will express genes needed to become the lining of internal body cavities, respiratory, digestive, urinary, and reproductive tracts

Answer 30

endoderm

Question 31

once gastrulation is complete, -- begins the development of the nervous system

Answer 31

neuralization

Question 32

-- form the notochord

Answer 32

mesoderm cells

Question 33

ectoderm above the notochord starts to thicken and folds inward, forming -- that continue to deepen and fuse to produce a neural tube that will eventually develop into the CNS

Answer 33

neural folds

Question 34

as differentiation continues, certain cells can influence the gene expression of other cells in the process of -- via chemical messengers

Answer 34

induction

Question 35

communication b/t cells is also used to establish -- in the embryo, which is critical to the formation of internal organs as well as the limbs

Answer 35

positional information

Question 36

-- produce proteins that are essential for guiding the development of the shape of the embryo

Answer 36

homeobox genes

Question 37

the proteins produced by the homeoboxes are - that serve to turn on specific genes within cells at specific times

Answer 37

transcription factors

Question 38

-- ensures that the right structures occur in the right places

Answer 38

induction

Question 39

the separation of fingers and toes is the result of -- of the cells at one time joined structures

Answer 39

apoptosis

Question 40

organs are developed on an -- basis with the most critical organs being produced first

Answer 40

as-needed

Question 41

by the fourth week, the -- are established and working

Answer 41

heart and limbs

Question 42

all major organs are established and most are functioning by

Answer 42

the end of the embryonic development (8th week)

Question 43

while the embryo is in the process of implanting into the endometrium, -- will be formed outside of the embryo

Answer 43

four membranes

Question 44

surrounds the embryo in a fluid-filled sac that serves a protective function and provides cushioning for the embryo and fetus

Answer 44

amnion

Question 45

is a membrane that will ultimately form the umbilical cord

Answer 45

allantois

Question 46

connection between the embryo and the placenta

Answer 46

umbilical cord

Question 47

organ that will deliver nutrients and oxygen and remove CO2 and waste

Answer 47

placenta

Question 48

where the 1st blood cells develop, in other species it serves as a source of nutrients

Answer 48

yolk sac

Question 49

will eventually become the embryo's side of the placenta

Answer 49

chorion

Question 50

the -- develops from the chorion and grows in size during development

Answer 50

placenta

Question 51

fetal hemoglobin has -- for oxygen than adult hemoglobin

Answer 51

a greater affinity

Question 52

placenta produces -- to maintain the pregnancy

Answer 52

HCG, estrogen, progesterone, and relaxin

Question 53

the hormone relaxin releases the -- that attach to the mother's pubic bones to provide more space in the birth canal

Answer 53

ligaments

Question 54

how long does it take for the placenta to fully develop

Answer 54

3 months

Question 55

fetal development is primarily refinement of the -- that are already established during embryonic development

Answer 55

organ systems

Question 56

labor is triggered by the hormone -- which is produced by the posterior pituitary gland

Answer 56

oxytocin

Question 57

oxytocin cause contractions of the uterus to -- with time

Answer 57

intensify

Question 58

-- usually ruptures during the dilation stage

Answer 58

amnion

Question 59

once the cervix is dilated, contractions continue, leading to the

Answer 59

expulsion of the baby

Question 60

after the baby is delivered, the -- is clamped and cut, which severs the connection to the placenta

Answer 60

umbilical cord

Question 61

finally, the -- is delivered at the end of labor

Answer 61

placenta