Asn #13 Chapter 12 - Lecture Notes

Asn #8 Planaria Regeneration Conclusion Example

Planaria are free-living aquatic flatworms of the phylum Platyhelminths. Planarians range in color from grayish-brown to deep black. They are invertebrate animals and therefore have only a simple nervous system consiting of a head region full of nerve cells and a thin string of nerve tissue that extends from the head to their tail region. Although they do not have eyes, the eyespots located on the anterior part of the worm makes them appear like they do. These flatworms are carnivorous, eating living or dead animal matter. They have a simple digestive tract and they eat from the centermost of their posterior side of the body. They live in moist, dark places such as, under rocks, leaves and other debris. These flatworms have the ability to be male or female and are therefore referred to as hermaphrodites.

This lab activity was performed in an attempt to investigate the regeneration abilities of these flatworms. Regeneration is an asexual reproduction method that produces fragments of the adult which eventually becomes a brand new worm. In lab groups of 2-3 people, this investigation allowed students to compare and describe the regenerative properties of Planarians involving various types of cuts. Each group was given an opportunity to choose a particular type of cut (see data section) and deliver that excision to their worm. After about three observations, the students could accept or reject their hypothesis and answer the problem or title they had chosen. Both qualitative and quantitative research techniques were utilized in this experiment.

(answer to a title in italics)...Regeneration is a form of asexual reproduction. The flatworms can fragment on almost any portion of their anatomy and then develop into a whole worm that is a clone of the parent fragment. This type of reproduction can benefit a species such as the Planarians when their environmental conditions are favorable and stable. However, if the environment should undergo drastic changes that require the animal to adapt in order to survive, asexual reproduction is not the best form of reproduction.

The hypothesis of this experiment was rejected because ...... . As shown in the data section, ..... (here you can discuss what happened to the worm over the course of the data collection process and refer the reader to the qualitative and/or quantitative data sections.


**comparisons/trends seen in our experiment...

1. Planarians cut lengthwise grew wider (cut 2)
2. Those cut crosswise grew slightly longer (cut 1/3)
3. The region that is cut appeared wider as new tissue is added.
4. All cut sections remained dark for the first 24 or so hours. Afterwhile, the new growth area is a somewhat grey.
5. Cuts 1 and 3 regenerated the fastest. The slowest of regeneration cuts were those that were lengthwise.

Chapter 10 Assessment

Reviewing Content:
1.D
2.C
3.B
4.C
5.C
6.A
7.B
8.B
9.A
10.A

Understanding Concepts:
11. During cell division, a cell divides into two new daughter cells.

12.When a cell is small, the information stored in its DNA is able to meet all of the cell's needs. But if a cell were to grow without limit, an "information crisis" would occur.

13. Cell volume is the amount of material inside the cell. Surface area is the total area of the cell's membrane. Ration of surface area to volume is the surface area divided by the volume.

14. A cell's ration of surface area to volume decreases as it grows larger. This means that the area available for diffusion also decreases. Thus is a cell grows too large, it is unable to take in all needed materials and expel all its wastes. These problems impose limits on the growth of a cell.

15. Well before cell division, each chromosome is replicated. At the beginning of cell division, each chromosome consists of two identical sister chromatids.

16. Together, interphase and cell division make up the cell cycle.

Mitosis Notes Answers

NOTE: I WILL BE SCANNING THE ACTUAL PAGE LATER ONCE I GET MY SCANNER TO WORK.

Cell division occurs in a series of stages or phases.

1st: INTERPHASE
-Chromosomes are copied (# doubles)
-Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at end of this phase

[drawing]<- Centromere

2nd: PROPHASE
-Mitosis begins (cell begins to divide)
-Centrioles (or poles) appear and begin to move to opposite ends of the cell
-Spindle Fibers form between the poles

3rd: METAPHASE
-Chromatids (for pairs of chromosomes) attach to the spindle fibers

4th: ANAPHASE
-Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell

5th: TELOPHASE
-Two new nuclei form
-Chromosomes appear as chromatin (threads rather than rods)
-Mitosis ends

6th: CYTOKINESIS
-Cell membrane moves inward to create two daughter cells - each with its own nucleus with identical chromosomes

Layout Of Asn #4

Sorry guys they entered in reverse page 1 is at the bottom.

Background Information Sites

Please tell me if any of these sites don't work so I can find the actual link for it.
● http://www.course-notes.org/Biology/Outlines/Chapter_36_Transport_in_Vascular_Plants

● http://www.answers.com/topic/homeostasis

● http://www.ekcsk12.org/faculty/jbuckley/regbio/lifeprocqz.html


● http://staff.jccc.net/PDECELL/cells/diffusion.html

● http://atomic-molecular-optical-physics.suite101.com/article.cfm/what_is_osmosis

● http://biology.arizona.edu/sciconn/lessons/mccandless/reading.html

● http://www.ehow.com/how-does_4566607_cell-maintain-homeostasis.html

mthml:file://F:\Marira's Paper\BIOLOGY\Membrane Transport.mht

● http://www.associatedcontent.com/pop_print.shtml?content_type=article&content_type_id...

● http://associated content.com/article/1388434/homeostasis_an_overview_of_the_nutr...

Example Titles

1. How do the processes of osmosis and diffusion maintain homeostasis in a living system?

2. Why do living cells carry out osmoregulation?

3. Why are Living Things referred to as "osmotic systems"?