Developmental Biology

Question 1

The study of the development of a unicellular zygote into a complete, multicellular organism

Answer 1

embryology

Question 2

In mammals, an egg can be fertilized within ____ hours after ____. Fertilization occurs in the lateral, widest portion of the ____ where sperm traveling from the vagina encounter an egg.

Answer 2

12-24, fertilization, oviduct

Question 3

Early embryonic development is characterized by a series of rapid ___ ___ known as ___. These divisions lead to an increase in __ __ without a corresponding growth in ___ ____. Thus cleavage results in progressively ___ cells with an increasing ____ of nuclei to cytoplasm. Cleavage also increases the _____ ratio, thereby improving gas and ___ exchange

Answer 3

mitotic divisions, cleavage, cell number, cell protoplasm, smaller, ratio, surface-area-to-volume, nutrient

Question 4

The first complete cleavage of a zygote occurs approximately ____ hours after fertilization. The second cleavage occurs after ___ hours, and the third cleavage after approximately ___ hours, at which point the ____ reaches the ____.

Answer 4

32, 60, 72, 8-celled, uterus

Question 5

As cell division continues, a solid ball of embryonic cells known as the ___ is formed. ____ begins when this ball develops a fluid-filled cavity called the ___, which by the fourth day becomes a hollow sphere of cells called the ____. This is the stage of the embryo that ____ in the uterus.

Answer 5

morula, blastulation, blastocoel, blastula, implants

Question 6

Emergency contraception works partially by inhibiting the ____ of the ___ in the uterus, which is why it is most effective if taken within _____ hours of the time of potential fertilization

Answer 6

implantation, blastula, 72

Question 7

In an ___ pregnancy, the embryo implants outside the uterus, for example in the __ ___. An embryo typically cannot be __ for long outside of the uterus, and will __ ___ and ___ may occur. Ectopic pregnancies can be ___ if not caught in time and managed appropriately

Answer 7

ectopic, fallopian tube, maintained, abort spontaneously, hemorrhaging, fatal

Question 8

After week two, the embryo is fully implanted in the uterus and __ ___ transform the single layer cell layer of the blastula into a ____ structure called a ____. ___ primary ___ layers give rise to specific structures

Answer 8

cell migrations, 3-layered, gastrula, 3, germ

Question 9

Layer that forms the integumentary system including the epidermis, hair, eye, and nervous system

Answer 9

ectoderm

Question 10

layer that forms the epithelial linings of the digestive and respiratory tracts, and parts of the liver, pancreas, thyroid and bladder lining

Answer 10

endoderm

Question 11

layer that forms the musculoskeletal system, circulatory system, gonads, connective tissue, and potions of the digestive and respiratory organs

Answer 11

mesoderm

Question 12

By the end of gastrulation, regions of the germ layers begin to develop into a rudimentary __ ____. This process is known as ___ and start before week ___. A rod of ____ cells called the ____ develops along the _____ ___ of the embryo just under the ____ layer of the ectoderm. This rod of cells causes the overlaying ectoderm to ____ ___ and form a ___ along the dorsal surface of the embryo.

Answer 12

nervous system, neurulation, 3, mesodermal, notochord, longitudinal axis, dorsal, bend inward, groove

Question 13

The dorsal ectoderm folds on either side of the ___. These __ ___ grow upwards and finally ___, forming a closed ___ ___. This gives rise to the ___ and __ __. Once the neural tube is formed, it detaches from the __ ____.

Answer 13

groove, neural folds, fuse, neural tube, brain, spinal cord, surface ectoderm

Question 14

The cells at the tip of each neural fold are called the ___ ___ ___. These cells ___ ___ and give rise to many components of the PNS, including the __ __, __ __, __ __ and __ __.

Answer 14

neural crest cells, migrate laterally, sensory ganglia, autonomic ganglia, adrenal medulla, schwann cells

Question 15

Sometimes during development, the neural tube does not ___ __, resulting in a condition called ____ ____. The incidence of this can be decreased dramatically if the mother takes __ ___ supplements during pregnancy

Answer 15

close properly, spina bifida, folic acid

Question 16

During ____, the body organs begin to form. In this process, the cells interact, ___, change -_ __, proliferate and ___.

Answer 16

organogenesis, differentiate, physical shape, migrate

Question 17

During ___, the organs increase in size, which is a continual process from __ through ____ to ___

Answer 17

growth, infancy, childhood, adulthood

Question 18

When eggs develop in women and sperm develop in men, which permits reproduction to occur

Answer 18

gametogenesis

Question 19

The growing fetus receives ___ directly from its mother through a specialized ___ __. This system also supplies ____ and removes ___ ___ and __ ___ as well. The two components of this system are the ___ and the __ __ which both develop in the first few weeks after fertilization

Answer 19

oxygen, circulatory system, nutrients, carbon dioxide, metabolic wastes, placenta, umbilical cord

Question 20

The placenta and umbilical cord are outgrowths of the four ___ ___ formed during development: the ___, ___, ____, and __ __.

Answer 20

extra-embryonic membranes, amnion, chorion, allantois, yolk sac

Question 21

The amnion is a thin, tough membrane containing the watery fluid called __ ____. This acts as a __ __ of __ __ during gestation and __ ___ from uterine contractions during labor

Answer 21

amniotic fluid, shock absorber, external pressure, localized pressure

Question 22

Placenta formation begins with the ___, a membrane that completely surrounds the ____. This structure assists with the transfer of ___ from the mother to the fetus

Answer 22

chorion, amnion, nutrients

Question 23

A third membrane called the ___, develops as an outpocketing of the ____. Blood vessels of the ___ ___ enlarge and become the __ __ which will connect the fetus to the developing placenta. The __ ___, site of early development of blood vessels, becomes associated with the __ __.

Answer 23

allantois, gut, allantoic wall, umbilical vessels, yolk sac, umbilical walls

Question 24

Human gestation is approximately ___ ___ long and can be subdivided into ____ ___.

Answer 24

nine months, three trimesters

Question 25

During the first weeks, the major ___ begin to develop. The heart begins to beat at approximately ___ days, and soon afterward, the __, ___, __ and ___ start to form. By five weeks, the embryo is __ mm in length, and by six it has grown to ___ mm. The ____ skeleton begins to turn into ____ by the seventh week. By the end of 8 weeks, most of the organs have formed, the ___ is fairly developed, and the embryo is referred to as a ___. At the end of the third month the fetus is about ___ cm long.

Answer 25

organs, 22, eyes, gonads, limbs, liver, 10, 15, cartilaginous, bone, brain, fetus, 9

Question 26

During the second trimester, the fetus does a lot of ___. It begins to __ __ in the amniotic fluid, its face appears ___, and its __ and __ elongate. By the end of the sixth month, the fetus is ___ cm long

Answer 26

growing, move around, human, fingers, toes, 30-60

Question 27

The seventh and eighth months are characterized by continued __ ___ and further ___ __. During the ninth month, ____ are transported by highly selective active transport from the mother to the fetus. The __ ___ slows and the fetus becomes less active as it has ___ ___ to move about

Answer 27

rapid growth, brain development, antibodies, growth rate, less room

Question 27

Childbirth in the first stage, the cervix thins and ____, and the amniotic sac ____, releasing its fluids. In the second stage, __ ____ result in the birth of the baby. The __ ___ is cut after. During the final stage, the uterus contracts, expelling the ___ and the __ __.

Answer 27

dilates, ruptures, rapid contractions, umbilical cord, placenta, umbilical cord

Question 28

The embryo develops into an adult through the process of maturation, which involves __ __, ___ and ___. The last is complete when all organs reach __ __

Answer 28

cell division, growth, differentiation, adult from

Question 29

Errors during fetal development

Answer 29

congenital disorders

Question 30

chemical and biological agents that cause congenital disorders

Answer 30

teratogens

Question 31

When a mother passes on an infection directly to the offspring during development or during birth

Answer 31

vertical transmission

Question 32

Other environmental factors that can lead to birth defects include poor ____, ___ and __ __ or restraint

Answer 32

nutrition, radiation, physical trauma

Question 33

In plant embryology, the zygote divides mitotically to form the embryo which consists of ___ parts

Answer 33

5

Question 34

the precursor of the upper stem and leaves

Answer 34

epicotyl

Question 35

seed leaves, dicots have two seed leaves, while monocots only have one

Answer 35

cotyledons

Question 36

the lower stem and root

Answer 36

hypocotyl

Question 37

feeds the embryo; in dicots, the cotyledon absorbs it

Answer 37

endosperm

Question 38

develops from the outer covering of the ovule; the embryo and its seed coat together comprise the seed

Answer 38

seed coat

Question 39

The ___, which is most seeds develop, is formed from the _____ walls, the base of the ___ and other consolidated flower ____ components. The fruit serves as a means of effective ___ ___ by ___ water, or animals. The seed is released from the ___ and will ___ under proper conditions of temperature, moisture and oxygen

Answer 39

fruit, ovary, flower, pistil, seed dispersal, air, ovary, germinate

Question 40

Growth in higher plants is restricted to the ____ cells called ___ cells. These tissues undergo active cell reproduction, and gradually ___ and differentiate into cell types characteristic of the species

Answer 40

embryonic, meristem, elongate

Question 41

Meristem found in the tips of roots and stems; growth in length occurs only at these points

Answer 41

apical meristem

Question 42

Meristem located between the xylem and phloem which permits the growth in diameter and can differentiate into new xylem and phloem cells.

Answer 42

lateral meritstem / cambium