CHAPTER 5 HOMEWORK

Cells are found in all organisms and are the basic units of life. Cell Theory CR #1

All life is made of cells OR Cells are the units of structure and function in all organisms

All cells come from preexisting cells Hypothesis: a testable statement that explains an observation Theory: an organizing model based on data from many tested

hypotheses – almost no data opposing theory has been found CR #4 –

Prokaryotes: no membrane enclosing DNA (no nucleus)Eukaryotes: have a nucleus and other membrane-bound organelles

Organelles….(notes mirror our class notes)

NOTES PG. 99-107

2. How did the use of stains advance the study of cells? Dyes have allowed scientists to see the smaller structures and organelles

within the cells5. Describe the structure and function of the plasma membrane. Outer membrane that controls the passage of materials into and out of

the cell, made of two thin layers of lipids and embedded proteins.6. Discuss the functions of three cell organelles. 7. How has the meaning of the word cell changed since the time of Robert

Hooke? Cell now encompasses all the organelles within the cell and their

specialized functions whereas Robert Hooke observed and named an empty cell.

CR PG. 107 #1,2,4-7

1. What activities are involved in metabolism? Biologically important molecules are processed Energy is transferred to ATP Waste materials are released (including CO2)

2. Why do cells constantly take in and get rid of substances In order to grow, repair, maintain organization and reproduce, cells

must take in energy & raw materials. Waste products are always going to be generated from these metabolic processes.

3. What is a concentration gradient? How does if affect diffusion? The concentration of molecules between areas of high and low

concentration form a gradient, areas of successively lower concentration

CR #1-6 PG. 111

4. How does osmosis affect an animal cell? How does it affect a plant cell? The diffusion of water through the membranes of plant and animal cells is

much the same except that plant cell walls don’t usually rupture or shrink as the plasma membrane does.

5. Why are membranes said to be differentially permeable? Membranes allow the movement of some materials and not others. This

movement is usually based on size or charge (+ or -)6. Distinguish between passive and active transport? Passive Transport does not rely on the use of ATP – transport proteins move

substances from high to low concentration so no ATP is needed Active Transport energy is used and materials can be moved from high to

low OR from low to high concentrations. This requires the use of ATP (energy)

1. In what way might diffusion limit the size of cells? Diffusion can give cells what they need but as cells get large, diffusion

takes a long time and is inefficient. Therefore, once cells reach a certain size, they are programmed to stop growing and/or divide into smaller cells.

2. Describe the activities in each phase of the cell cycle. Interphase: Growth, Synthesis, Growth Prophase: Metaphase: Anaphase Telophase Cytokinesis

CR #1-6 PG. 111

3. What does the term replication mean? Exact copying so that the resulting cell is identical to the original, parent

cell.4. What is the role of the spindle apparatus in mitosis? Spindle fibers attach to the centromere and pull the sister chromatids

apart from each other. It determines the direction of cell division5. In your own words, describe the process of mitosis.

6. What is the biological importance of cell division? It is how organisms grow and repair themselves. It is also how asexual

reproduction of organisms takes place.

2. Which cell parts can you see using the highest magnification of your microscope? What does this indicated about the sizes of these parts compared with all the other cell parts you cannon see? We could see the cell wall, nucleus, nucleolus, chloroplasts and large

vacuoles. All other cell organelles are too small or too thin to be seen.

AQ #2-5, 7, 8 PG. 123

3. While working in a police laboratory, you are given a tiny sample of material and asked to identify it as either plant or animal matter. How could you decide which it is? Under the microscope, you could look for the presence of a cell wall, or

chloroplasts (plant cell) or their absence (animals cell). You could further test the cell with iodine. A positive test for

polysaccharide would be a likely indication that it was a plant cell.

4. Trace the path of a molecule as it enters and moves through a plant cell and eventually enters a vacuole. Through which structures must it pass? Cell wall, plasma membrane, cytosol (cytoplasm), vacuole.

5. On the basis of your understanding of osmosis, describe what would happen to a marine jellyfish placed in a freshwater stream, a frog placed in ocean water. Some fish (for example, shad and striped bass) annually swim from the ocean into freshwater rivers and back. How are they able to do this? The jellyfish would swell up if placed in fresh water (hypotonic) and the

frog cells would dehydrate if placed in ocean water (hypertonic). Fish that live in both fresh and salt water maintain water balance in

their tissues through several mechanisms. In salt water, they continuously drink, void little urine and excrete salts actively through their gills. In fresh water, they take in only a little water by drinking, absorb salt through their gills and excrete water as urine.

7. THC is a chemical that stops chromosomes from separating during anaphase of mitosis. What do you think the nuclei of two resulting cells might look like if a cell were sprayed with THC during mitosis? THC is the active ingredient in marijuana If the THC inhibits chromosome movement and if the chromosomes

have already replicated then one resulting cell might be expected to have double the normal number of chromosomes and might live (would most likely die if human). The other cell, containing no chromosomes, will die.

8. Almost every living thing, including you, starts off as a single cell. When you grow, however, you have cells that are extremely different from each other. Consider the difference between your brain cells, skin cells, and stomach cells – all of which were formed by the genetic information in your chromosomes. What does this suggest about the genetic information in your chromosomes. What does this suggest about the genetic information found in that first cell. All the genetic information for an entire individual is found in the

chromosomes of the zygote. Every cell contains all of that genetic information. In some cells, part of that genetic information is turned on and some of it is turned off.