1.
What is it called when the blastocyst attaches to the lining of the uterus?
Correct Answer
C. Implantation
Explanation
Implantation is the correct answer because it refers to the process in which the blastocyst, which is the early stage of embryo development, attaches to the lining of the uterus. This is a crucial step for pregnancy to occur, as it allows the embryo to receive nutrients and oxygen from the mother's blood supply. Ovulation is the release of an egg from the ovary, mitosis is a type of cell division, and fertilization is the fusion of sperm and egg.
2.
Which tissue in the mother's blood is responsible for the development of the embryo?
Correct Answer
A. Placenta
Explanation
The placenta is responsible for the development of the embryo in the mother's blood. It is an organ that forms during pregnancy and connects the developing fetus to the uterine wall. The placenta provides oxygen and nutrients to the embryo, removes waste products, and produces hormones that are necessary for pregnancy. It acts as a barrier between the mother and the fetus, allowing for the exchange of substances while protecting the embryo from harmful substances.
3.
Which of the following shows the correct order?
Correct Answer
A. Zygote, embryo, fetus
Explanation
The correct order is zygote, embryo, fetus. This is the correct chronological sequence of development in human reproduction. After fertilization, the zygote is formed. It then develops into an embryo, which is the early stage of development. Finally, the embryo develops into a fetus, which is the later stage of development before birth.
4.
What is it called when an ovum is first fertilized?
Correct Answer
C. A zygote
Explanation
When an ovum is first fertilized, it is called a zygote. This is the initial stage of development after the fusion of the sperm and egg. The zygote contains the complete set of genetic information from both parents and will undergo cell division to form an embryo. The zygote is the earliest form of a developing organism and marks the beginning of pregnancy.
5.
Where does the implantation occur, and does the zygote start developing?
Correct Answer
D. In the uterus
Explanation
The correct answer is in the uterus. Implantation occurs when the fertilized egg, or zygote, attaches itself to the lining of the uterus. This is where the zygote starts developing into an embryo and eventually a fetus. The uterus provides the necessary environment for the embryo to receive nutrients and oxygen from the mother's blood supply. Implantation in the fallopian tube, ovary, or vagina would not be viable for the development of a healthy pregnancy.
6.
Which vein/artery carries blood rich in carbon dioxide and nitrogenous waste products from the fetus to the placenta?
Correct Answer
D. Umbilical artery
Explanation
The umbilical artery carries blood rich in carbon dioxide and nitrogenous waste products from the fetus to the placenta.
7.
Which of the following consist of a hollow ball of cells?
Correct Answer
C. Blastocyst
Explanation
A blastocyst consists of a hollow ball of cells. It is an early stage of embryonic development, occurring about 5-6 days after fertilization. The blastocyst is formed when the morula, a solid ball of cells, undergoes further division and differentiation. The outer layer of the blastocyst, called the trophoblast, will eventually develop into the placenta, while the inner cell mass will give rise to the embryo itself. The hollow structure of the blastocyst is important for implantation into the uterine wall and the subsequent development of the embryo.
8.
What is the number of chromosomes in a human zygote?
Correct Answer
C. 46
Explanation
A human zygote is formed when a sperm cell fertilizes an egg cell. Both the sperm cell and the egg cell contribute 23 chromosomes each, resulting in a total of 46 chromosomes in the zygote. These 46 chromosomes contain the genetic information that determines various traits and characteristics of the individual.
9.
By what the developing embryo is connected to the placenta?
Correct Answer
B. The umbilical cord
Explanation
The developing embryo is connected to the placenta through the umbilical cord. The umbilical cord serves as a lifeline between the embryo and the placenta, providing nutrients and oxygen to the developing fetus and removing waste products. It contains blood vessels that transport these essential substances back and forth, ensuring the nourishment and growth of the embryo.
10.
Which of the following is suitable for this description?
The embryos of the twins develop into two fetuses, each with its own placenta and umbilical cord.
Correct Answer
B. Fraternal twins
Explanation
Fraternal twins are suitable for this description because they are formed when two separate eggs are fertilized by two different sperm cells. Each embryo develops into its own fetus with its own placenta and umbilical cord. This is in contrast to identical twins, where a single fertilized egg splits into two embryos, resulting in twins that share the same placenta and umbilical cord. Siamese twins is not a suitable answer as it refers to conjoined twins who are physically connected to each other. "All kinds of twins!" is a general statement and does not specifically address the description given.