Biology Homework II PDF

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Question and answer homework assignment on the film Life's Greatest Miracle....

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Dr. Kim Sadler Biology 1031 26 February 2019 Life’s Greatest Miracle

Passing on your DNA 1. Why is sexual reproduction more advantageous than cloning? I.

Cloning would be an extremely dangerous method of reproduction, as it would result in all individuals having identical immune systems, making every clone susceptible to one parasite. Sexual reproduction allows for variety in immune systems.

The Egg's Journey 2. Describe the path the egg takes after being released from the ovary. I.

Each month, an immature egg cell is selected from two ovaries. This egg cell will receive attention from hundreds of other support cells who help feed and tend to the egg until it grows. When this process of growth is finished, the egg, along with it’s support, ooze out of the ovary where it proceeds to the Fallopian tube, leading it to the uterus.

The Sperm's Journey 3. How many sperm are produced each day? What kind of obstacles will a sperm encounter once it enters the female?

I.

The average man produces roughly a thousand new sperm every second, which is around a hundred million new sperm every day.

II.

Sperm face many immediate challenges. Because the vagina is acidic, not many sperm survive long enough to start swimming. A. The sperm's first major obstacle is in the cervix, the passageway to the uterus. This is usually locked shut, plugged with mucus, which keeps bacteria and sperm out; however, the few days a month during ovulation, the mucus become watery enough for the sperm to channel through. B. Some sperm caught up in the cilia lining the tube may have a better chance at fertilization. In the cilia lining is where the chemicals in the woman's body may alter the sperm's outer coating. Only these altered coating sperm are able to fertilize the egg. C. One of the final obstacles that the sperm face is the support cells which protect the egg; only few sperm make it through. D. Further underneath is another obstacle for the sperm; a cumulation of cells that covers the egg in a thick shell of protein, which is called the "zona." This step is where the sperm must hook up to the proteins from the egg with its own proteins that protrude from the sperm cap. If the sperm can precisely match up, the sperm will release powerful enzymes that will make a hole

in the zona, allowing it to finally make its way through.

The First Two Weeks 4. What is a blastocyst? How long does it take to reach the uterus? I.

A blastocyst is hundreds of smaller cells, which are trapped within the hard shell of the zona.

II.

They arrive in the uterus about five days after fertilization.

The Embryo Takes Shape 5. Describe the three cell layers that develop and include what parts of the body those cell layers will become. I.

There are three cell layers which will develop into very different systems in the future. A. The first lower layer will form structures like the lungs, liver, and lining of the digestive tract. B. The second middle layer will become structures such as, the heart, muscles, bones and blood. C. Finally The third top layer become the nervous system, incorporating the spinal cord, brain, out skin, and hair.

6. How are genes turned on? I.

A gene is turned on when the cell creates a specific protein. These proteins are the building blocks of the human body which are responsible for structures such as skin, tendons, bones, and so on.

II.

In order for a gene to turn on, something must be loosened up in a specific section in order for the cell to latch on and read the DNA.

Messages in the Gene 7. Before the 7th week of development, how can you tell the sex of the fetus? I.

Before significant development of an embryo, the way to identify the sex is to look at the chromosomes in a cell. There will be a single pair among the 23 that will enable the doctor to tell. If the embryo has two X chromosomes, then it will be a girl; if there are both an X and a Y chromosome, then it will be a boy.

Feeding the Growing Fetus 8. How does the fetus obtain nourishment? Does the blood of the mother and fetus mix? I.

The fetus obtains nourishment from the mother through the placenta. The blood of the mother and fetus do not mix, as there is a barrier preventing this mixing.

The Third Trimester 9. All the major organs are fully developed, what is the fetus’s main job? I.

To grow and develop their organs into a more functional and specified structures.

10. Why is human childbirth so much more dangerous than the births of other animals? I.

Because of human anatomy and structure, human births are far more dangerous than animal births because humans have a brain that is much larger than most animals and well as a narrow pelvis, which results in the baby having to contort a considerable amount to make it through such a narrow space....