bio assignment 4

Based on the data, the researchers were able to conclude that the new chemotherapy drug is beneficial for increasing tumor remission time. How might have the researchers' conclusions have changed if they did not have a placebo control group?

They would have less confidence in their conclusion because they would be unsure if the drug was actually having a benefit or if it was just the placebo effect.

1. A normal gene that, if mutated, can lead to cancer is called a(n)--

proto-oncogene

1. Before a cell divides, it copies all of its chromosomes. While the two copies of a chromosome are attached they are called--

sister chromatids

As mitosis begins, __________ are linked together at the centromere.

sister chromatids

In addition to the risk of accidents, which of the following is a problem when nuclear power is used as a method of generating electrical power?

storage and disposal of spent fuel rods

3. A(n)--is a gene that encodes proteins that inhibit cell division. Such proteins normally help prevent cells from becoming cancerous.

tumor-suppressor gene

Which of the following terms describes an aspect of a scientific experiment that changes?

variable Correct A variable is the part of a scientific experiment that changes. In a controlled experiment, the independent variable is the aspect being changed, and the effect of its change is determined by measuring the dependent variable

Many of the first responders at the Chernobyl accident died within hours or days of working at the explosion site. What were they most likely to die from, and why?

acute radiation sickness due to exposure to ionizing radiation

A normal adult has 46 chromosomes per cell. During meiosis, gametes are produced with _____ chromosomes each. After fertilization, a zygote is produced with _____ chromosomes.

23 ; 46

Stages of the cell cycle Part complete Drag the labels onto the diagram to identify the stages of the cell cycle.

1) Most of the cell's life is spent in interphase, when growth occurs. Cells that are about to divide replicate their DNA. 2) In prophase microtubules form the mitotic spindle, and the nuclear envelope breaks up. 3) At metaphase the mitotic spindle is fully formed and chromosomes are lined up in the center of the cell. 4) In anaphase, sister chromatids separate and become full-fledged chromosomes that move to opposite poles. 5) In telophase chromosomes become less condensed and new nuclear envelopes form. In cytokinesis the cytoplasm divides.

We may never know how many people became ill or died as a result of the Chernobyl accident. What is the main reason why this is so difficult to determine?

Cancer might not occur for many years after exposure to ionizing radiation

2. A duplicated chromosome remains tightly paired with its partner at a region called the--which acts as the molecule of heredity.

DNA

In a blood pressure study, one group of participants receives one brand of blood pressure medication, and another group receives a different brand of blood pressure medication. Neither the researchers nor the participants know which medication is being given

Double-blind

In a diabetes study, one group of participants receives a new type of diabetes medication, and another group receives a pill that looks like medication but is not. Neither the researchers nor the participants know which group gets which treatment.

Double-blind and placebo-controlled

The cell cycle is a predictable sequence of events that makes up the lifetime of all cells. Sort the events to the phase of the cell cycle during which they occur.

Interphase -Chromosomes are duplicated in preparation for cell division. -The cytoplasm doubles, increasing the overall size and volume of the cell. Mitosis -The duplicated chromosomes separate and are distributed to two offspring nuclei. Cytokinesis -The cell divides into two offspring cells, each with a complete set of chromosomes from the parent cell

Why is ionizing radiation damaging to cells?

It knocks the electrons from the cell's molecules, forming ions and breaking bonds.

The concrete sarcophagus enclosing the damaged reactor is crumbling, allowing radiation to leak out into the environment. An animation of a new protective cover is shown in the video. Why hasn't the construction of this cover been completed?

It will be extremely expensive to build.

--is the spread of cancer cells from their site of origin to other sites in the body.

Metastasis

One of life's most important characteristics is the ability to reproduce. In humans, reproduction involves several stages and two types of cell division. Let's begin with naming the various stages in the human life cycle. Drag the labels to the diagram.

Mitosis and meiosis are types of cellular reproduction in the human life cycle. Meiosis produces gametes that have half the number of chromosomes as an adult cell. When two gametes combine during fertilization—a sperm cell from a male and an egg cell from a female—their chromosomes combine in the resulting zygote. From here into adulthood, further growth, development, and repair of cells uses mitosis to produce additional cells with the normal adult number of chromosomes.

In a weight loss study, one group of participants recieves a potential weight loss drug, and the other receives a sugar pill. The researchers know which treatment each group is receiving, but the participants do not know.

Placebo-controlled

Researchers want to learn which type of toy children prefer. To conduct their controlled experiment, they buy two different toys and place them in a room. The researchers then bring children into the room and measure how long they play with each toy. Which of the following is correct?

The independent variable is the type of toy, and the dependent variable is the length of play time.

Although the forest is growing quickly around Chernobyl, and some of the wildlife is thriving, studies show that biodiversity around Chernobyl has been reduced by over 50% since the accident. Why?

The ionizing radiation affects the DNA of the wildlife, just as it affects the DNA of humans.

A 2011 study involved 1,873 women with advanced ovarian cancer. The double-blind study sought to determine whether adding a new chemotherapy drug to the standard treatment routine was beneficial. The women were randomly divided into three groups: 1) Standard treatment plus a placebo 2) Standard treatment plus the new drug for the first of three rounds followed by a placebo 3)Standard treatment plus the new drug for all rounds Based on the data, what can you conclude about the new drug's efficacy in terms of increasing remission time (the average number of months before the tumor progressed)?

The new drug increases remission time by almost 4 months if taken with all rounds of chemotherapy.

Why is the town of Pripyat uninhabited?

The radiation levels in the town are still unsafe.

A--is a lump of abnormal cells that, although growing out of control, remains at its original site.

benign tumor

For a--participants will be assigned a shampoo to use but will not know if it is normal shampoo or the new shampoo.

blind experiment

4. An individual with a malignant tumor is said to have--

cancer

2. A duplicated chromosome remains tightly paired with its partner at a region called the

centromere

2. A duplicated chromosome remains tightly paired with its partner at a region called the--

chromatin

5. The DNA of every eukaryotic cell is stored in one or more--located in the--

chromosomes; nucleus

For a--the company's normal shampoo will be compared to the new shampoo by multiple participants, but all other conditions (i.e., water temperature, length of hair wash) will be kept the same between participants' hair washing.

controlled experiment

For a--participants will be assigned a shampoo to use but will not know if it is normal shampoo or the new shampoo. Researchers who are later analyzing hair softness will not know which type of shampoo the participants used.

double-blind experiment

The process of a sperm cell and an egg cell fusing together is called-- and produces a zygote.

fertilization

4. A(n)--is a protein that promotes cell division. In excess, such a protein may lead to cancer.

growth factor

All sodium atoms have 11 protons. The nuclei of some sodium atoms contain 12 neutrons and others contain 11. These different forms of sodium are called __________.

isotopes Correct The number of protons identifies the element that corresponds to a particular atom; isotopes of that element contain differing numbers of neutrons.

A--is an abnormally growing mass of cells that is actively spreading through the body.

malignant tumor

Adults produce gametes through a type of cellular reproduction called--

meiosis

As a baby grows into an adult, the type of cellular reproduction used is--

mitosis

As a zygote undergoes rapid cell division to develop into an embryo, fetus, and eventually baby, the type of cellular reproduction being used is--

mitosis

2. A gene that causes a cell to become cancerous is called a(n)--

oncogene