Biology Chapter 3: Embryogenesis and Development

Question 1

What is fertilization?

Answer 1

The joining of a sperm and an ovum

Question 2

Where does fertilization occur?

Answer 2

ampulla of the fallopian tube

Question 3

What does sperm use to penetrate the corona radiata and zona pellucida?

Answer 3

Uses acrosomal enzymes

Question 4

What happens when the sperm contacts the oocytes plasma membrane?

Answer 4

Establishes the acrosomal apparatus and injects its nucleus

Question 5

What is the cortical reaction?

Answer 5

A sperm penetrates, causing a release of calcium ions, preventing additional sperm from fertilizing the egg and increases the metabolic rate of the resulting diploid zygote.

Question 6

How do fraternal twins result?

Answer 6

Fertilization of two eggs by two different sperm

Question 7

How do identical twins result?

Answer 7

Splitting of a zygote in two

Question 8

What is cleavage?

Answer 8

Early divisions of cells in the embryo - result in a larger number of smaller cells, as the overall volume does not change.

Question 9

When does the zygote turn into an embryo?

Answer 9

After 1 division

Question 10

What is indeterminate cleavage?

Answer 10

results in cells that are capable of becoming any cell in the organism.

Question 11

What is determinate cleavage?

Answer 11

results in cells that are committed to differentiating into a specific cell type

Question 12

What is a morula?

Answer 12

solid mass of cells seen in early development

Question 13

What is the blastula?

Answer 13

has a fluid-filled center called a blastocoel and two different cell types, including trophoblasts and inner cell mass

Question 14

Where does the blastula implant?

Answer 14

in the endometrial lining and forms the placenta

Question 15

What is the chorion?

Answer 15

contains the chorionic villi, which penetrates the endometrium and create the interface between maternal and fetal blood.

Question 16

What supports the embryo?

Answer 16

It is supported by the yolk sac.

Question 17

What is the allantois?

Answer 17

It is involved in early fluid exchange between the embryo and the yolk sac

Question 18

What is the amnion?

Answer 18

Lies just inside the chorion and produces amniotic fluid

Question 19

How is the organism connected to the placenta?

Answer 19

The umbilical cord

Question 20

What happens during gastrulation?

Answer 20

The archenteron is formed with a blastopore at the end. As it grows through the blastocoel, it contacts the opposite side, establishing the three primary germ layers.

Question 21

What does the ectoderm become?

Answer 21

The epidermis, hair, nails, epithelia of the nose, mouth and anal canal, nervous system and lens of the eye

Question 22

What does the mesoderm become?

Answer 22

Much of the musculoskeletal, circulatory and excretory systems, gonads, connective tissue layers of the digestive and respiratory systems, adrenal cortex

Question 23

What does the endoderm become?

Answer 23

Becomes much of the epithelial lining of the respiratory and digestive tract, parts of the pancreas, thyroid, bladder and distal urinary tracts.

Question 24

What is neurulation?

Answer 24

development of the nervous system and begins after the formation of the three germ layers.

Question 25

What are the steps to neurulation?

Answer 25

1. Notochord induces a group of ectodermal cells to form new folds 2. The neural folds fuse to form the neural tube, which becomes the central nervous system 3. The tip of each fold becomes the peripheral nervous system.

Question 26

What are teratogens?

Answer 26

substances that interfere with development, causing defects or even death of the developing embryo

Question 27

What is determination?

Answer 27

commitment to a specific cell lineage, which may be accomplished by uneven segregation of cellular material during mitosis or morphogens.

Question 28

What is differentiation?

Answer 28

Refers to the changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line.

Question 29

What are stem cells?

Answer 29

Cells that are capable of developing into various cell types. They can be classified by potency.

Question 30

Totipotent cells

Answer 30

able to differentiate into all cell types including the three germ layers and placental structures.

Question 31

Pluripotent cells

Answer 31

Able to differentiate into all three of the germ layers and their derivatives.

Question 32

Multipotent cells

Answer 32

Able to differentiate only into a specific subset of cell types

Question 33

Autocrine signals

Answer 33

act on the same cell that released the signal

Question 34

Paracrine signals

Answer 34

act on cells in the local area

Question 35

Juxtacrine signals

Answer 35

act through direct stimulation of the adjacent cell

Question 36

Endocrine signals

Answer 36

act on distant tissues after traveling through the blood stream.

Question 37

Growth factors

Answer 37

peptides that promote differentiation and mitosis in certain tissues

Question 38

Reciprocal induction

Answer 38

When two tissues induce further differentiation in each other

Question 39

Apoptosis

Answer 39

programmed cell death via the formation of apoptotic blebs that can be absorbed and digested by other cells

Question 40

What are uses of apoptosis?

Answer 40

To form certain anatomical structures or removing damaged cells

Question 41

What is regenerative capacity?

Answer 41

The ability of an organism to regrow certain parts of the body. The liver has high regenerative capacity, while the heart has low regenerative capacity.

Question 42

What is senescence?

Answer 42

The result of multiple molecular and metabolic processes, e.g. the shortening of telomeres during cell division.

Question 43

What is exchanged at the placenta?

Answer 43

Nutrients, gas and waste

Question 44

What is the difference in the fetal hemoglobin?

Answer 44

It has higher affinity for oxygen, which assists in the transfer and retention

Question 45

What does the placenta secrete?

Answer 45

estrogen, progesterone, and hCG

Question 46

What are the three shunts of the fetal circulatory system?

Answer 46

1. Foramen ovale - r.a. to the left. atrium, bypassing the lungs 2. Ductus arteriosus - connects the pulmonary artery to the aorta, bypassing the lungs 3. Ductus venosus - connects the umbilical vein to the inferior vena cava, bypassing the liver

Question 47

What happens in the first trimester?

Answer 47

organogenesis occurs (development of heart, eyes, gonads, limbs, liver, brain)

Question 48

What happens in the second trimester?

Answer 48

tremendous growth, movement begins and it becomes distinctly human, digets elongate

Question 49

What happens in the third trimester?

Answer 49

Rapid growth and brain development continue and antibodies are transferred to the fetus

Question 50

What are contractions coordinated by?

Answer 50

prostaglandins and oxytocin