Ch. 10 Questions

p.243 1-5

Q: Give two reasons why cells divide.
A: There are two main reasons as to why cells divide. The first is that when cells become too large, they can't make enough DNA (genetic material) to supply the cell. The second is because the greater surface area of the cell makes transporting nutrients and waste difficult.

Q: How is a cell's DNA like the books in a library?
A: A cell's DNA is like a library because if thea cell were a small town, as more and more people came into the town and checked out books, there would be a greater demand for books.

Q: What is the solution to the problems caused by cell growth?
A: The solution to problems caused by cell growth is for the cell to split into two smaller cells, which is called cell division.

Q: As a cell increases in size, which increases more rapidly, its surface area or its volume?
A: As a cell increases in size, its volume increases more rapidly.

Q: Calculate the surface area, volume, and ratio of the surface area of an imaginary cubic cell with a lenghe of 4 cm.
A: To calculate the ratio of surface area to volume of an imaginary cubic cell with a length of 4cm, first find the surface area by multiplying length X width X 6 (4 X 4 X 6=96). Next, find the volume by multiplying length X width X height (4 X 4 X 4=64). To get the ratio, divide the surface area by the volume (96/64=3:2)



p.249 1-6

Q: Name the main events of the cell cyle.
A: The main events of the cell cycle consist of the cell growing, making a copy of its DNA, and dividing into two new "daughter" cells.

Q: Describe what happens during each of the four phases of mitosis.
A: prophase - chromosomes become visible, and the two tiny structures in the cytoplasm near the nuclear envelope go to opposite poles of the nucleus

spindle fibers form, and the nuclear envelope disappears

metaphase: homologus chromosomes line up in the middle of the

cell and spindle fibers attach

anaphase: chromatids move to opposite ends of the cell

telophase: two new cells form, cytokinesis occurs, and the nucleus reforms

Q: Describe what happens during interphase.
A: During interphase, chromosomes are threadlike chromatin and copy to make "sister" chromatids, which are held together by a centromere.

Q: What are chromosomes made of?
A: Chromosomes are made of DNA and proteins.

Q: How do prokaryotic cells divide?
A: Prokaryotic cells divide by copying its genetic information and then simply separating the contents of the cell into two new parts.

Q: How is cytokinesis in plant cells similar to cytokinesis in animal cells?
A: Cytokinesis in plant cells is similar in animal cells because both use a cell membrane to separate the cytoplasm.



p.252 1-5

Q: What chemicals regulate the cell cycle? How do they work?
A: Cyclins, as well as internal and external regulators, regulate the cell cycle by triggering cell division and controlling the timing of the process.

Q: What happens when cells do not respond to the signals that respond that normally regulate growth?
A: When cells do not respond to the signals that normally regulate growth, cancer developes and creates tumors that can harm the rest of the body.

Q: How do cells respond to contact with other cells?
A: Cells respond to contact with other cells by not increasing in size.

Q: Why can cancer be considered a disease of the cell cycle?
A: Cancer can be considered a disease of the cell cycle because it causes control to be lost over the cell cycle.

Q: Write a hypothesis about what you think would happen if cylcin were injected into a cell that was in mitosis.
A: If cyclin were injected into a cell that was in mitosis, then the four phases of mitosis would occur faster and cells would be divided quicker.



p.257 1-10

Q: The rate at which materials enter and leave through the cell membrane depends on the cell's...
A: volume

Q: The process of cell division results in...
A: two daughter cells

Q: Pairs of identical chromatids are attached to eachother at an area called the...
A: centromere

Q: If a cell has 12 chromosomes, how many chromosomes will each of its daughter cells have after mitosis?
A: six

Q: At the beginning of cell division, a chromosome consists of two...
A: chromatids

Q: The phase of mitosis during which chromosomes become visible and the centrioles seperate from one antother is...
A: Prophase

Q: Metaphase is best illustrated in which figure?
A: B

Q: The timing fo the cell cycle in eukaryotic cells is controlled by a group of clsely related proteins known as...
A: cyclins

Q: In the cell cycle, external regulators direct cells to...
A: speed up or slow down cell cycle

Q: Uncontrolled cell division occurs in...
A: cancer

Cell Growth & Divison Glossary

cell division- when cells divide into two, new cells

cytokinesis- division of the cytoplasm during cell division

chromatid- one of two identical parts of a duplicated chromosome

centromere- area where the chromatids of a chromosome are attached

interphase- period of the cell cycle between cell divisions

cell cycle- series of events that cells go through as they grow and divide

mitosis- a part of eukaryotic cell division during which the cell nuclues divides

spindle- fanlike microtubule structure that helps separate the chromosomes during mitosis

prophase- first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the oppostie sides of the nucleus

metaphase- second phase of mitosis, during which the chromosomes line up across the center of the cell

anaphase- third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

telophase- fourth/final stage of mitosis, during which the chromosomes begin to disperse into a tangle of dense material

centriole- one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope

cyclin- one of a family of closely related proteins that regulate the cell cycle in eukaryotic cells

cancer- disorder in which some of the body's own cells lose the ability to control growth