Chapter 27 Biology Essay

Submitted By vmicheals1
Words: 1522
Pages: 7

Chapter 27
Homework Assignment
1. What are the three methods of asexual reproduction? Describe each method and include an example of an animal that undergoes this type of reproduction.

Asexual reproduction is a form of reproduction where only one parent is involved in the process. There are four different ways that asexual reproduction occurs; fission, budding, spore formation and fragmentation. The first method, fission, is when lower level organisms divide into two separate cells, and the divided piece becomes a new organism. The nucleus of the cell has to divide each time, and then the cytoplasm surrounds it. Organisms that undergo fission are usually bacteria like the amoeba and protozoa.

The next method is budding, which is more often seen in multicellular organisms and fungi. This method requires the parent organism to grow a bud. Once a bud is grown, the nucleus of the organism divides and it passes the divided piece into the new cell or “bud”. The bud still stays on the parent cell, growing until a wall is formed and it becomes an individual cell. An example of an organism that reproduces through budding is yeast or a hydra.

The third is spore formation – when a parent cell grows large and forms a spore sac, dividing its nucleus into many pieces, until the spore sac is developed and releases the spores which grow and become their own cells. An example of an organism born from spore formation is clostridium and bacillus and several other types of fungus.

Fourth is the process of fragmentation, where a parent organism breaks itself up into fragment pieces, and then the fragments develop into organisms on their own. Examples of organisms that use fragmentations are alga and spirogyra.

2. What is the difference between spermatogenesis and oogenesis? Describe the differences between the two, and include how many sperm and eggs are produced from each diploid cell.

The main difference between spermatogenesis and oogenesis are their functions; the first makes sperm and forms the testes, and the last is responsible for making eggs in the ovaries. During spermatogenesis involves 2 meiotic divisions of genetic material, which form one spermatogonium and four spermatids. All of this comes together to form four sperm cells.

There are also two meiotic divisions in the process of oogenesis, which then creates one oogonium, one ovum and three polar bodies. All of these come together to form a single ovum which is much bigger than sperm cells.

From this, one can see that size, volume and function are the main differences between the two.

3. What is an ectopic pregnancy?

When you look at the actual definition of ectopic, or “out of place,” you can begin to understand what an ectopic pregnancy is. Typically, a pregnancy follows a process where an egg implants and grows in the uterus, until it is a full formed fetus. When it is an ectopic pregnancy, the egg settles and grows in the fallopian tubes, which do not allow for growth and development of a fetus.

These pregnancies cannot be kept until term, and are dangerous for the mother.

4. Compare the bacterial sexually transmitted diseases (STDs) chlamydia, gonorrhea, and syphilis with the viral STDs HIV, HPV, and genital herpes. What are their symptoms, mortality rate, and method of treatment?

While all STD’s can be uncomfortable and life altering, there are differences between bacterially transmitted STD’s and viral STD’s.

Chlamydia, which is a bacterially transmitted STD is common and treatable, but can be the cause of later infertility. Symptoms include burning and itching penis, discharge and painful urination for men, and itching vaginally, discharge, odor and pain during sex for women. Chlamydia can be treated with a course of antibiotics, and more than 1 million cases typically occur in the U.S. each year.

Gonorrhea is another bacterially transmitted STD, which is a harmful bacterium that grows typically in the genital area. Symptoms for men include