Transcript
How many sperm cells can enter the egg at fertilization?
One
Two
Three
Four
How many sperm cells can enter the egg at fertilization?
One
Only one sperm enters the egg; otherwise the zygote would end up with an abnormal number of chromosomes.
© 2017 Education, Inc.
True or False? All of the oocytes produced in a woman complete meiosis.
True
False
© 2017 Education, Inc.
True or False? All of the oocytes produced in a woman complete meiosis.
False
Only the oocytes that are fertilized finish meiosis. The second telophase creates a nucleus around chromosomes from both the sperm and egg.
© 2017 Education, Inc.
Tissues and organs are initially established in the _____ stage of development.
blastocyst
trophoblast
embryo
fetal
© 2017 Education, Inc.
Tissues and organs are initially established in the _____ stage of development.
embryo
Earlier stages are mainly concerned with increasing the numbers of cells and laying down the framework for tissue development of the embryo.
© 2017 Education, Inc.
True or False? The placenta is developed from a combination of mother’s and baby’s tissues.
True
False
© 2017 Education, Inc.
True or False? The placenta is developed from a combination of mother’s and baby’s tissues.
True
The placenta is formed from embryonic tissue (chorion and chorionic villi) and maternal tissue (endometrium).
© 2017 Education, Inc.
A male fetus develops when _____.
an X chromosome is present
the Y chromosome is absent
two X chromosomes are present
an X and Y chromosome are present
© 2017 Education, Inc.
A male fetus develops when _____.
an X and Y chromosome are present
If the Y chromosome is present, the sex-determining (SRY) region of the chromosome is activated and testes-determining factor is made, stimulating the testes to make testosterone, with the resulting development of a male. If the Y chromosome is absent, a female develops.
© 2017 Education, Inc.
Labor begins when _____.
the fetal lungs are fully developed
the placenta produces high levels of progesterone
nine months have passed
the fetal pituitary is mature
© 2017 Education, Inc.
Labor begins when _____.
the fetal pituitary is mature
The fetal pituitary times the pregnancy and, when ready, releases ACTH to stimulate the fetal adrenal gland to secrete steroids that result in increased estrogen and decreased progesterone secretion from the placenta, initiating labor.
© 2017 Education, Inc.
Which of the following structures enable fetal blood to bypass the lungs prior to birth?
Ductus venosus and ductus arteriosus
Ductus arteriosus and foramen ovale
Foramen ovale and ductus venosus
Foramen ovale and umbilical arteries
© 2017 Education, Inc.
Which of the following structures enable fetal blood to bypass the lungs prior to birth?
Ductus arteriosus and foramen ovale
The foramen ovale enables blood to pass directly from the right atrium to the left atrium, bypassing the lungs. The ductus arteriosus shunts blood from the pulmonary artery directly to the aorta, preventing blood from entering the fetal lungs. After birth, the foramen ovale and the ductus arteriosus close within a few days to a week.
© 2017 Education, Inc.
Which organ(s) is/are the last to reach full maturity?
Heart
Ovaries and testes
Liver
Brain
© 2017 Education, Inc.
Which organ(s) is/are the last to reach full maturity?
Brain
The brain is one of the last organs to reach full maturity. Parts of the cerebral cortex don’t reach full maturity until about 18 years of age.
© 2017 Education, Inc.
True or False? The chromosomes in most cells get shorter with each round of cell division.
True
False
© 2017 Education, Inc.
True or False? The chromosomes in most cells get shorter with each round of cell division.
True
The enzymes involved in DNA replication are unable to replicate all the way to the end. This means that chromosomes become shorter with each round of replication. There are numerous repetitive nucleotides at the ends, called telomeres, which protect the chromosome genes from eroding.
© 2017 Education, Inc.
