Although nondisjunction is a random event, there are many more individuals with an extra

Which of the following is not a function of mitosis in humans? a. repair of wounds b. growth c. production of gametes from diploid cells d. replacement of lost or damaged cells

In what sense are the two daughter cells produced by mitosis identical?

Why is it difficult to observe individual chromosomes during interphase?

A biochemist measures the amount of DNA in cells growing in the laboratory. The quantity of DNA in a cell would be found to double a. between prophase and anaphase of mitosis. b. between the G1 and G2 phases of the cell cycle. c. during the M phase of the cell cycle. d. between prophase I and prophase II of meiosis

Which two phases of mitosis are essentially opposites in terms of changes in the nucleus?

Complete the following table to compare mitosis and meiosis: Mitosis Meiosis a. Number of chromosomal duplications b. Number of cell divisions c. Number of daughter cells produced d. Number of chromosomes in daughter cells e. How chromosomes line up during metaphase f. Genetic relationship of daughter cells to parent cells g. Functions performed in the human body

If an intestinal cell in a dog contains 78 chromosomes, a dog sperm cell would contain __________ chromosomes.

A micrograph of a dividing cell from a mouse shows 19 chromosomes, each consisting of two sister chromatids. During which stage of meiosis could this micrograph have been taken? (Explain your answer.)

Tumors that remain at their site of origin are called __________, and tumors that have cells that can migrate to other body tissues are called __________.

A diploid body (somatic) cell from a fruit fly contains eight chromosomes. This means that __________ different combinations of chromosomes are possible in its gametes

Although nondisjunction is a random event, there are many more individuals with an extra chromosome 21, which causes Down syndrome, than individuals with an extra chromosome 3 or chromosome 16. Propose an explanation for this.

A mule is the offspring of a horse and a donkey. A donkey sperm contains 31 chromosomes and a horse egg has 32 chromosomes, so the zygote contains a total of 63 chromosomes. The zygote develops normally. The combined set of chromosomes is not a problem in mitosis, and the mule combines some of the best characteristics of horses and donkeys. However, a mule is sterile; meiosis cannot occur normally in its testes or ovaries. Explain why mitosis is normal in cells containing both horse and donkey chromosomes but the mixed set of chromosomes interferes with meiosis

You prepare a slide with a thin slice of an onion root tip. You see the following view in a light microscope. Identify the stage of mitosis for each of the outlined cells, ad.

Interpreting Data The graph in the right hand column shows the incidence of Down syndrome in the offspring of normal parents as the age of the mother increases. For women under the age of 30, how many infants with Down syndrome are born per 1,000 births? How many for women at age 40? At age 50? How many times more likely is a 50-year-old woman to give birth to a baby with Down syndrome than a 30-year-old woman?

As described in the Biology and Society section, some species (including some endangered species) have been shown to be capable of reproduction via parthenogenesis, without participation of a mate. What implications might this have on efforts to repopulate endangered species? What drawbacks might a parthenogenesis program have on the well-being of the species it targets?

Every year, about a million Americans are diagnosed with cancer. This means that about 75 million Americans now living will eventually have cancer, and one in five will die of the disease. There are many kinds of cancers and many causes of the disease. For example, smoking causes most lung cancers. Overexposure to ultraviolet rays in sunlight causes most skin cancers. There is evidence that a high-fat, low-fiber diet is a factor in breast, colon, and prostate cancers. And agents in the workplace, such as asbestos and vinyl chloride, are also implicated as causes of cancer. Hundreds of millions of dollars are spent each year in the search for effective treatments for cancer, yet far less money is spent on preventing cancer. Why might this be true? What kinds of lifestyle changes can you make to help reduce your risk of cancer? What kinds of prevention programs could be initiated or strengthened to encourage these changes? What factors might impede such changes and programs? Should we devote more of our resources to treating cancer or to preventing it? Defend your position.

The practice of buying and selling gametes, particularly eggs from fertile women, is becoming increasingly common in the United States and some other industrialized countries. Do you have any objections to this type of transaction? Would you be willing to sell your gametes? At any price? Whether you are willing to do so or not, do you think that other people should be restricted from doing so?