1.
The three stages of true labor, or order of occurence, are _______, ______, and _______.
Correct Answer
A. Dilation, expulsion, placental
Explanation
The correct answer is dilation, expulsion, placental. This is the correct order of occurrence during true labor. Dilation refers to the opening of the cervix, allowing the baby to move through the birth canal. After dilation, expulsion occurs when the baby is pushed out of the mother's body through contractions. Finally, the placental stage occurs when the placenta is delivered.
2.
Hormones produced by the ___________ are responsible for maitaining the pregnancy during the first 3-4 months. The hormone responsible for preventing degeneration of the corpus luteum is _____________ produced by the trophoblast.
Correct Answer
B. Corpus luteum, human chorionic gonadotropin (hCG)
Explanation
During the first 3-4 months of pregnancy, the hormones produced by the corpus luteum are responsible for maintaining the pregnancy. The hormone produced by the trophoblast that prevents degeneration of the corpus luteum is human chorionic gonadotropin (hCG).
3.
Indicate the germ layers responsible for development of the following structures: (a) muscle, bone, and peritoneum: _________; (b) nervous system and epidermis _________; (c) epithelial linings of respiratory and gastrointestinal tracts: ___________.
Correct Answer
C. Mesoderm, ectoderm, endoderm
Explanation
Muscle, bone, and peritoneum are derived from the mesoderm layer. The nervous system and epidermis are derived from the ectoderm layer. The epithelial linings of the respiratory and gastrointestinal tracts are derived from the endoderm layer.
4.
Labor is an example of a negative feedback cycle that ends with the birth of an infant.
Correct Answer
B. False
Explanation
Labor is an example of a positive feedback cycle, not a negative feedback cycle. In a positive feedback cycle, the initial stimulus is amplified, leading to a greater response. In the case of labor, contractions cause the release of oxytocin, which in turn stimulates more contractions, leading to the birth of the infant. Therefore, the statement that labor is an example of a negative feedback cycle is incorrect.
5.
Which of the following statements is correct? Enter choice A-E without parenthesis or spaces. (a) Normal traits always dominate over abnormal traits; (b) Occassionally an error in meiosis called nondisjunction results in an abnormal number of chromosomes; (c) The mother always determines the sex of the child because she has either an X or Y gene in her oocytes; (d) Most patterns of inheritance are simple dominant-recessive inheritances; (e) Genes are expressed normally regardless of any outside influence such as chemicals or radiation.
Correct Answer
B
b
Explanation
The correct statement is (b) "Occasionally an error in meiosis called nondisjunction results in an abnormal number of chromosomes." This statement is correct because nondisjunction is a type of error that can occur during meiosis, leading to an abnormal distribution of chromosomes in the resulting gametes. This can result in conditions such as Down syndrome, where there is an extra copy of chromosome 21. The other statements are incorrect: (a) normal traits do not always dominate over abnormal traits, (c) the sex of the child is determined by the father's contribution of either an X or Y chromosome, (d) most patterns of inheritance are not simple dominant-recessive, and (e) genes can be influenced by outside factors such as chemicals or radiation.
6.
Amniotic fluid (1) is derived entirely from a filtrate of maternal blood; (2) acts as a fetal shock absorber; (3) provides nutrients to the fetus; (4) helps regulate fetal body temperature; (5) prevents adhesions between skin of the fetus and surrounding tissues.
Correct Answer
B. 2, 4, 5
Explanation
Amniotic fluid acts as a fetal shock absorber, helps regulate fetal body temperature, and prevents adhesions between the skin of the fetus and surrounding tissues. It is not derived entirely from a filtrate of maternal blood and does not provide nutrients to the fetus. Therefore, the correct answer is 2, 4, 5.
7.
Which of the following structures develop during the fourth week after fertilization? (1) embryonic folding; (2) the neural tube; (3) otic placode (beginning of the ear); (4) beginning of the eye; (5) upper and lower limb buds.
Correct Answer
C. 1, 2, 3, 4, 5
Explanation
During the fourth week after fertilization, all of the structures mentioned in the answer options develop. Embryonic folding occurs as the embryo starts to fold in on itself. The neural tube forms, which is the precursor to the brain and spinal cord. The otic placode, which is the beginning of the ear, also develops. Additionally, the beginning of the eye and the upper and lower limb buds form during this time. Therefore, the correct answer is 1, 2, 3, 4, 5.
8.
A fluid-filled sphere of cells that enters the uterine cavity.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
6
Explanation
A blastocyst is a fluid-filled sphere of cells that enters the uterine cavity. This stage occurs during early embryonic development, after the morula stage. The blastocyst consists of an outer layer of cells called the trophoblast, which will eventually form the placenta, and an inner cell mass, which will develop into the embryo. The blastocyst is important for implantation into the uterine wall and the further development of the embryo.
9.
Cells produced by cleavage.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus.
Correct Answer
2
Explanation
Cleavage is the process of cell division that occurs in the early stages of embryonic development. It results in the formation of blastomeres, which are the cells produced by cleavage. Therefore, choice 2, blastomeres, is the correct answer.
10.
The developing individual from week nine of pregnancy until birth.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
11
Explanation
The correct answer is 11 because the developing individual from week nine of pregnancy until birth is referred to as a fetus.
11.
The outer covering of cells of the blastocyst.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
5
Explanation
The correct answer is "trophoblast". The trophoblast is the outer layer of cells in the blastocyst, which is the early stage of development after the zygote undergoes cleavage and forms a morula. The trophoblast plays a crucial role in implantation and the formation of the placenta.
12.
Membrane derived from trophobast.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
10
Explanation
The correct answer is 10. The chorion is a membrane derived from the trophoblast, which is the outer layer of cells in the blastocyst. The chorion plays a crucial role in the development of the placenta and is responsible for the exchange of nutrients and waste between the mother and the fetus.
13.
Early division of the zygote.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
1
Explanation
The correct answer is 1. Cleavage refers to the early division of the zygote. During cleavage, the zygote undergoes rapid cell divisions, resulting in the formation of smaller cells called blastomeres. This process eventually leads to the formation of a solid ball of cells called a morula, which further develops into a blastocyst. Therefore, cleavage is the most appropriate choice to describe the early division of the zygote.
14.
A solid sphere of cells still surrounded by the zona pellucida.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
3
Explanation
The correct answer is (3) morula. The morula is a stage in embryonic development where the zygote undergoes multiple rounds of cell division, resulting in a solid ball of cells. At this stage, the cells are still surrounded by the zona pellucida, a protective layer that helps the embryo implant into the uterus. The morula will eventually develop into a blastocyst, where a fluid-filled cavity forms in the center of the cell mass.
15.
Event in which differentiation into the three primary germ layers occur.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
8
Explanation
During gastrulation, the process of differentiation into the three primary germ layers occurs. This is when the zygote undergoes a series of cell movements and rearrangements, resulting in the formation of the ectoderm, mesoderm, and endoderm. These germ layers give rise to different tissues and organs in the developing embryo.
16.
Embryonic development of structures that will become the nervous system.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
9
Explanation
Neurulation is the process in embryonic development where the neural plate forms and eventually develops into the nervous system. This includes the formation of the neural tube, which will give rise to the brain and spinal cord. Therefore, choice 9, neurulation, is the correct answer as it directly relates to the embryonic development of structures that will become the nervous system.
17.
The formation of blood vessels to support the developing embryo.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
4
Explanation
Angiogenesis is the process of forming new blood vessels from pre-existing ones. In the context of the developing embryo, angiogenesis is crucial for the formation of blood vessels to support the growing embryo. It allows for the delivery of oxygen and nutrients to the developing tissues and the removal of waste products. Therefore, choice 4, angiogenesis, is the correct answer as it directly relates to the formation of blood vessels to support the developing embryo.
18.
Result of the fusion of male and female pronuclei.Enter choice 1-11 without parenthesis or spaces. (1) cleavage; (2) blastomeres; (3) morula; (4) angiogenesis; (5) trophoblast; (6) blastocyst; (7) zygote; (8) gastrulation; (9) neurulation; (10) chorion; (11) fetus
Correct Answer
7
Explanation
The fusion of male and female pronuclei results in the formation of a zygote.
19.
Stimulates the corpus luteum to continue production of progesterone and estrogen.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
3
Explanation
Human chorionic gonadotropin (HCG) stimulates the corpus luteum to continue production of progesterone and estrogen.
20.
Increases the flexibility of the pubic symphysis and helps dilate the uterine cervix during labor.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
6
Explanation
Relaxin is the correct answer because it is a hormone that is responsible for increasing the flexibility of the pubic symphysis and helping to dilate the uterine cervix during labor. This hormone is released by the ovaries and the placenta during pregnancy, and its main function is to relax the ligaments and connective tissues in the pelvic area, allowing for easier passage of the baby through the birth canal.
21.
Secreted by the placenta; helps establish the timing of birth and increases the secretion of cortisol for fetal lung maturation.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
5
Explanation
Corticotropin-releasing hormone is secreted by the placenta and helps establish the timing of birth. It also increases the secretion of cortisol, which is important for fetal lung maturation.
22.
Helps prepare mammary glands for lactation; regulates certain aspects of maternal and fetal metabolism.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
2
Explanation
Human somatomammotrophin, also known as human placental lactogen, is a hormone that helps prepare mammary glands for lactation. It also regulates certain aspects of maternal and fetal metabolism.
23.
Stimulates uterine contractions; responsible for the milk ejection reflex.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
1
Explanation
Oxytocin is the correct answer because it stimulates uterine contractions and is responsible for the milk ejection reflex.
24.
Promotes milk synthesis and secretion; inhibited by progesterone during pregnancy.Enter choice 1-6 without parenthesis or spaces. (1) oxytocin; (2) human somatomammotrophin; (3) human chorionic gonadotropin; (4) prolactin; (5) corticotropin-releasing hormone; (6) relaxin
Correct Answer
4
Explanation
Prolactin is the correct answer because it promotes milk synthesis and secretion. During pregnancy, progesterone inhibits the action of prolactin to prevent milk production. However, after childbirth, progesterone levels decrease, allowing prolactin to stimulate milk production and secretion.
25.
The control of inherited traits by the combined efforts of many genes.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
7
Explanation
Polygenic inheritance refers to the control of inherited traits by the combined efforts of many genes. This means that multiple genes contribute to the expression of a particular trait, resulting in a wide range of phenotypic variations. Polygenic inheritance is responsible for traits such as height, skin color, and intelligence, where the phenotype is influenced by the interaction of multiple genes.
26.
The two alternative forms of a gene that code for the same trait and are at the same location on homologus chromosomes.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
3
Explanation
The correct answer is "alleles". Alleles are the two alternative forms of a gene that code for the same trait and are at the same location on homologous chromosomes. They can be either the same (homozygous) or different (heterozygous).
27.
Abnormal number of chromosomes due to failure of homologus chromosomes or chromatids to separate.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
14
Explanation
14) nondisjunction
Nondisjunction is the failure of homologous chromosomes or chromatids to separate during cell division, resulting in an abnormal number of chromosomes. This can lead to aneuploidy, which is an abnormal number of chromosomes in a cell. Therefore, choice 14, nondisjunction, is the correct answer that explains the given statement.
28.
Inheritance based on genes that have more than two alternative forms; an example is the inheritance of blood type.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
6
Explanation
The correct answer is 6 - multiple-allele. Inheritance based on genes that have more than two alternative forms is known as multiple-allele inheritance. An example of multiple-allele inheritance is the inheritance of blood type, where there are three possible alleles (A, B, and O) that determine the blood type of an individual.
29.
Cell in which one or more chromosomes of a set is added or deleted.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
4
Explanation
In genetics, aneuploidy refers to the condition where there is an abnormal number of chromosomes in a cell. This can occur when one or more chromosomes of a set are either added or deleted. Therefore, choice 4, "aneuploid," is the correct answer for this question.
30.
Refers to an individual with different alleles on homologus chromosomes.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
10
Explanation
An individual with different alleles on homologous chromosomes is referred to as heterozygous.
31.
Traits linked to the X chromosome.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
8
Explanation
Traits linked to the X chromosome are known as sex-linked inheritance. This means that the genes responsible for these traits are located on the X chromosome. In humans, males have one X and one Y chromosome, while females have two X chromosomes. Therefore, males are more likely to express X-linked traits because they only have one copy of the X chromosome. Females can be carriers of X-linked traits if they have one copy of the mutated gene on one of their X chromosomes. The presence of a Barr body, which is an inactivated X chromosome, is also related to sex-linked inheritance.
32.
Permanent inheritable change in an allele that produces a different variant of the same trait.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
13
Explanation
A permanent inheritable change in an allele that produces a different variant of the same trait is known as a mutation. Mutations can occur in various ways, such as changes in the DNA sequence or alterations in the structure of a gene. These changes can lead to the production of a different protein or the absence of a protein, resulting in a different phenotype or trait.
33.
Neither member of the allelic pair is dominant over the other, and the heterozygote has a phenotype intermediate between the homozygous dominant and the homozygous recessive.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
5
Explanation
The given statement describes a situation where neither allele in an allelic pair is dominant over the other, and the heterozygote has a phenotype that is intermediate between the two homozygotes. This is a characteristic of incomplete dominance, where the heterozygous genotype results in a blending or mixing of the phenotypes of the two homozygous genotypes.
34.
Refers to how the gentic makeup is expressed in the body; the physical or outward expression of a gene.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
2
Explanation
Phenotype refers to how the genetic makeup is expressed in the body, specifically the physical or outward expression of a gene.
35.
A homozygous dominant, homozygous recessive, or heterozygous genetic makeup; the actual gene arrangement.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
1
Explanation
The given correct answer is "genotype." Genotype refers to the genetic makeup of an organism, which can be homozygous dominant (having two dominant alleles), homozygous recessive (having two recessive alleles), or heterozygous (having one dominant and one recessive allele). This term describes the actual gene arrangement in an individual.
36.
Refers to a person with the same alleles on homologous chromosomes.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
9
Explanation
Homozygous refers to a person with the same alleles on homologous chromosomes.
37.
Inactivated X chromosome in females.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
16
Explanation
The correct answer, 16, is referring to the Barr body. The Barr body is the inactivated X chromosome in females. In females, one of the two X chromosomes is randomly inactivated during embryonic development, forming a dense, inactive structure called the Barr body. This process ensures that females have the same dosage of X-linked genes as males, who only have one X chromosome. The Barr body can be visualized in the nucleus of cells and is used as a diagnostic tool in certain genetic disorders.
38.
Heterozygous individuals who possess a recessive gene (but do not express it) and can pass the gene on to their offspring.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
11
Explanation
Heterozygous individuals who possess a recessive gene (but do not express it) and can pass the gene on to their offspring are called carriers. Carriers are individuals who carry a copy of a recessive gene but do not show any symptoms or traits associated with that gene. They can pass the gene on to their offspring, increasing the likelihood of the trait being expressed in future generations.
39.
Interchange of portions of nonhomologous chromosomes.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
15
Explanation
Translocation is the correct answer because it refers to the interchange of portions of nonhomologous chromosomes. This process can result in genetic disorders or abnormalities.
40.
An allele that masks the presence of another allele and is fully expressed.Enter choice 1-16 without parenthesis or spaces. (1) genotype; (2) phenotype; (3) alleles (4) aneuploid; (5) incomplete dominance; (6) multiple-allele; (7) polygenic inheritance; (8) sex-linked inheritance; (9) homozygous; (10) heterozygous; (11) carriers; (12) dominant trait; (13) mutation; (14) nondisjunction; (15) translocation; (16) Barr body
Correct Answer
12
Explanation
The correct answer is "dominant trait". A dominant trait is an allele that masks the presence of another allele and is fully expressed. When an individual has one dominant allele and one recessive allele for a particular trait, the dominant allele will be expressed in the phenotype, while the recessive allele will be masked. This is why the presence of the dominant allele is fully expressed and can be observed in the individual's physical characteristics.
41.
The embryonic membrane that entirely surrounds the embryo.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
3
Explanation
The correct answer is (3) amnion. The amnion is a membranous sac that surrounds and protects the developing embryo. It is filled with amniotic fluid, which provides cushioning and support for the growing fetus. The amnion plays a crucial role in maintaining a stable environment for the embryo, regulating temperature, and preventing desiccation. It also allows for movement and growth of the developing fetus.
42.
Functions as an early site of blood formation; contains cells that migrate into the gonads and differentiate into the primitive germ cells.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
6
Explanation
The correct answer is 6. The yolk sac functions as an early site of blood formation and contains cells that migrate into the gonads and differentiate into the primitive germ cells.
43.
Becomes the principal part of the embryonic placenta; produces human chorionic gonadotropin.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
4
Explanation
The correct answer is (4) chorion. The chorion is the outermost membrane of the embryo and becomes the principal part of the embryonic placenta. It is responsible for producing human chorionic gonadotropin (hCG), a hormone that is important for maintaining pregnancy.
44.
Modified endometrium after implantation has occurred; separates from the endometrium after the fetus is delivered.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
1
Explanation
After implantation has occurred, the endometrium undergoes modifications and is referred to as decidua. The decidua is responsible for providing nourishment and support to the developing fetus. It separates from the endometrium after the fetus is delivered.
45.
Contains the vascular connections between mother and fetus.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
9
Explanation
The correct answer is 9, umbilical cord. The umbilical cord is a flexible cord-like structure that connects the developing fetus to the placenta. It contains blood vessels that allow for the exchange of nutrients, oxygen, and waste products between the mother and the fetus.
46.
The fetal portion is formed by the chorionic villi and the maternal portion is formed by the decidua basalis of the endometrium; allows oxygen and nutrients to diffuse from maternal blood into fetal blood.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
2
Explanation
The correct answer is 2 (placenta). The placenta is formed by the chorionic villi (fetal portion) and the decidua basalis of the endometrium (maternal portion). It serves as the site of exchange between the maternal and fetal blood, allowing oxygen and nutrients to diffuse from the maternal blood into the fetal blood.
47.
Serves as an early site of blood vessel formation.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
5
Explanation
The correct answer is 5 - allantois. The allantois is a membrane that forms during embryonic development and serves as an early site of blood vessel formation. It plays a role in the exchange of gases and waste products between the embryo and the placenta.
48.
Finger-like projections of the chorion that bring maternal and fetal blood vessels into close proximity.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
8
Explanation
Chorionic villi are finger-like projections of the chorion that bring maternal and fetal blood vessels into close proximity. These villi play a crucial role in facilitating the exchange of nutrients and waste products between the mother and fetus during pregnancy. They increase the surface area available for this exchange, allowing for efficient transfer of oxygen, nutrients, and hormones from the mother to the fetus, and removal of waste products from the fetus.
49.
Plays an important role in induction whereby an inducing tissue stimulates the development of an unspecialized responding tissue into a specialized tissue.Enter choice 1-9 without parenthesis or spaces. (1) decidua; (2) placenta; (3) amnion (4) chorion; (5) allantois; (6) yolk sac; (7) notochord; (8) chorionic villi; (9) umbilical cord
Correct Answer
7
Explanation
The notochord plays an important role in induction whereby an inducing tissue stimulates the development of an unspecialized responding tissue into a specialized tissue.