Development-CMP

=Development= Chapters 16.1, 17.1, and 17.2

16.1** (1) How many chromosomes does a mother contribute to a new individual? A father? In the egg, there are 23 chromosomes, and in the sperm, there are also 23. When fertilization occurs, the chromosomes combine for a total of 46.
 * Human Life Cycle 16

(2) Where does meiosis occur in males? in females? In women, meiosis occurs when eggs are being made in the ovaries. In men, meiosis occurs when the sperm is being made in the testes. (3) Compare and egg cell to a sperm cell. Sperm are only produced by men and eggs are only produced by women. Though each contain 23 chromosomes, when fertilization occurs, the chromosomes from the sperm transfer into the egg so the zygote can be formed.

(4) What is the difference between meiosis and mitosis. Meiosis: a process in which the 23 chromosomes of either the sperm or the egg are formed. Mitosis: a process of transferring the 23 chromosomes in the sperm to the egg to form the zygote.

17.1** (5) Describe in detail how fertilization occurs When a man and a woman have sexual intercourse, the man releases sperm into the woman's uterus. Then, the sperm travel to the ovaries where the egg is, though only one will actually fertilize it. The chromosomes from the sperm will be copied into the egg so that there will be altogether 46 chromosomes to from the zygote.
 * Development Chapter 17

(6) What is polyspermy and how is prevented during fertilization? Because only one sperm can fertilize an egg, there is a plasma membrane around the egg that shuts off other sperm once fertilization actually occurs. It is impossible for more than one sperm to fertilize an egg, because it can only have 46 chromosomes.

(7) Describe the processes involved in development. 1. Clevage: 2. Growth: 3. Morphogenesis: 4. Differentiation:
 * 17.2**

(8) What are the extraembryonic membranes and what is their role? The extraembryonic membranes are what regulate the feeding of the newly formed zygote. If the cells of the future baby do not get enough nourishment, they will die. The membranes are around the embryo, which is the name for the growing cell cluster that was formed through fertilization.

(9) What happens during pre-emrbyonic development? This is the stage in which the zygote grows into more cells, forming a small cluster that will eventually grow enough into a baby, provided that there are no problems with pregnancy and that the cells receive adequate nourishment. It starts the second that conception occurs, and lasts until the end of the first week of pregnancy.

(10) What happens during embryonic development? Pre-embryonic development is when the embryo attaches itself to the wall of the uterus in order to get nutrition. It starts in the first week of pregnancy and lasts until the end of the second month.

(11) What are the primary germ layers and what body structures come from each layer? The Endoderm (inside): The Mesoderm (middle): The Ectoderm (outside):