Archive | February, 2011

Agenda for Monday, February 28: Evolution: Mutation & Selection

28 Feb

The following students will be attending pull-outs with Dr. Allen:

Period 2:

Ariane, Lifaite, Kyle, Shalonda,

Period 3:

Priest, Tyquan,   Marcos, Kiara, Alicia, Tyra L, Chris, Shania,  Marquonda

Gizmo: Go to the following website http://www.explorelearning.com/ and login using secondp112 & cow864

Gizmo Warm-up

Gizmo Warm-upHow long could a parrot survive in Antarctica? It would probably not survive long. Parrots do not have adaptations—or helpful characteristics—to survive icy cold weather. Because of this, a parrot is not fit for Antarctica. Fitness describes how well an organism can survive and reproduce in an environment. In the Evolution: Mutation and Selection Gizmo™, you will see how a species’ fitness can change over time as it becomes better adapted to its environment.

1. On the SIMULATION pane, what is the Average fitness of the population? _____________

2. On the CONTROLS pane, experiment with the Background color sliders.

A. Which background color results in the highest fitness? ________________________

B. Which background color results in the lowest fitness? ________________________

Activity A: Variation

Get the Gizmo ready:Set the red value to 100, the green value to 255, and the blue value to 50 on the CONTROLS panel.

Introduction: An organism’s traits, or characteristics, are controlled by genes. Genes are located on rod-like structures called chromosomes. Different versions of genes that code for the same trait are called alleles. In this Gizmo, eight alleles control the color of bugs.

Question: Where does variation in a population come from?

1. Observe: Hold your cursor over one of the insects on the SIMULATION pane. The two rodlike structures under Genotype on the CONTROLS pane represent chromosomes. The three letters next to each chromosome represent alleles. Which alleles does the insect have? ____________________________________________

The alleles carried on an organism’s chromosomes make up the organism’s genotype.

2. Observe: An organism’s alleles interact to produce a certain trait. The physical expression of that trait is known as an organism’s phenotype. In the Gizmo, phenotype is expressed in RGB (red, green, blue) values. What is the phenotype of the insect?Red: _____________ Green: _____________ Blue: _____________

3. Run Gizmo: Move the Sim. speed slider all the way to the left. Click Play ( ). You will see the insects move to the left in pairs. The pairs mate and produce a set of four offspring. As soon as you see at least one offspring with an oval around it, click Pause ( ). Move your cursor over the circled offspring.

A. What is its genotype and phenotype? _____________________________________

B. How does its genotype and phenotype differ from the non-circled offspring? ___________________________________________________________________4.

Explain: The change in the circled offspring’s genotype was caused by a mutation. A mutation is a change in a gene. Mutations happen when a mistake is made during the copying of a cell’s chromosomes just before the cell divides. How might mutations cause variation into a population? ______________________________________________________________________________________________________________________________________________________________________________(Activity

5. Collect data: Move the mutation rate slider to 3.0, and click Play. Allow the Gizmo to run for another 10–15 generations. (You can see the generation number on the bottom left of the SIMULATION pane.)

Click Pause. Try to find a set of parents that has four different chromosomes. (If you can’t find any, allow the Gizmo to run a few more generations and try again.) Complete the table.



A. Look at the inheritance patterns.

What do you notice? ______________________________________________________________________________________________________________________________________________________________B. Can a single offspring inherit chromosomes from only one parent? Explain. ___________________________________________________________________C.

Did any mutations occur in this set of offspring? If so, which chromosome mutated?___________________________________________________________________7. Challenge yourself: You have already learned that mutation is one source of variation in a population. Based on what you have just seen, what is a second source of variation?

Advertisements

Natural Selection

22 Feb

Directions for Gizmo:

A. Open the following in a New Window or New Tab:

www.explorelearning.com

https://pmcsscience3.wordpress.com/2011/02/22/natural-selection/#respond

B. Use the following username: secondp112

password: cow864

C. Scroll Down to “Leave a Comment” and right-click to Open in New Tab

D. Proceed to answer questions below.

 

1. Check that LIGHT TREES is selected. Click Start and hunt moths for one year.

A. How many dark moths did you capture? _______

B. How many light moths did you capture? _______

C.  Camouflage is coloring or patterns that help an organism to blend in with the background. Which type of moth is better camouflaged on light bark? ____________

2. If a forest contained mostly light-colored trees, which type of moth would you expect to be most common? ____________________________________________________________

How many moths can you find?

Activity A:  Light trees Get the Gizmo ready:  • Click Reset. • Check that the LIGHT TREES tab is selected. Introduction: Before the 19th century in England, the air was very clean. The bark on trees was usually light in color. Abundant lichens growing on tree trunks also lightened their appearance.

Question: How does the color of a peppered moth affect survival?

1. Predict: Over time, what will to happen to the populations of light and dark moths on light trees? ____________________________________________________________________ 2.

Experiment: Click Start and hunt peppered moths on light tree trunks for five years. In each year, try to capture as many moths as you can. (Hint: Use the spacebar on your keyboard to advance to the next tree.) After 5 years, select the TABLE tab and record the percentages of each moth type. (Note: The table shows current populations of each moth, not the number of captured moths.)

Year Dark moths Light moths 0   1   2   3   4   5

3. Analyze: What do your results show? ___________________________________________  _________________________________________________________________________4. Apply: Which type of moth do you think was more common before the 19th century, when most trees were light in color? _________________________________________________

5. Extend your thinking: What strategies did you use to hunt for moths?

Cells & Mitosis Reinforcement

17 Feb

In the Comments area below, answer the following questions. If you work with a partner, be sure to include both names in the Name area of teh comments menu.

 

Mitosis Reading & Analysis

16 Feb

After reading the following passage, answer the following questions.

Why is cell division important?
What do you, an octopus, and an oak tree have in common? You share many characteristics, but an important one is that you are all made of cells—trillions of cells. Where did all of those cells come from? As amazing as it might seem, many organisms start as just one cell. That cell divides and becomes two, two become four, four become eight, and so on. Many-celled organisms, including you, grow because cell division increases the total number of cells in an organism. Even after growth stops, cell division is still important. Every day, billions of red blood cells in your body wear out and are replaced. During the few seconds it takes you to read this sentence, your bone marrow produced about six million red blood cells. Cell division is important to one-celled organisms, too—it’s how they reproduce themselves, as shown in Figure 1. Cell division isn’t as simple as just cutting the cell in half, so how do cells divide? 

Like this dividing amoeba, a one-celled organism reaches a certain size and then reproduces.
An octopus and amoeba
Figure 1 All organisms use cell division. Many-celled organisms, such as this octopus, grow by increasing the numbers of their cells increase.

Length of Cycle  The cell cycle, as shown in Figure 2, is a series of events that takes place from one cell division to the next. The time it takes to complete a cell cycle is not the same in all cells. For example, the cycle for cells in some bean plants takes about 19 hours to complete. Cells in animal embryos divide rapidly and can complete their cycles in less than 20 minutes. In some human cells, the cell cycle takes about 16 hours. Cells in humans that are needed for repair, growth, or replacement, like skin and bone cells, constantly repeat the cycle.

Circle graph - cell cycle
Figure 2 Interphase is the longest part of the cell cycle.
IdentifyWhen does cell growth occur?
1. Define mitosis. How does it differ in plants and animals?
2. Identify two examples of asexual reproduction in many-celled organisms.SC.F.2.3.1
3. Describe what happens to chromosomes before mitosis.
4. Compare and Contrast the two new cells formed after mitosis and cell division.
5.6. Think Critically Why is it important for the nuclear membrane to disintegrate during mitosis?What Happens after DNA is copied & chromosomes duplicate?

7.     Which phase involves the chromosomes separating?

8.     In what order to the phases of mitosis occur?

9.     What Happens after DNA is copied & chromosomes duplicate?

10. Solve One-Step Equations If a cell undergoes cell division every 5 min, how many cells will there be after 1 h? MA.B.2.3.2

Gizmo Cell Division

14 Feb

In the comments area below, copy/paste and answer the following questions:

Prior Knowledge
1. Cells reproduce by splitting in half, a process called cell division. What do cells need to do between divisions to make sure that they don’t just get smaller and smaller?

2. The genetic information of a cell is carried in its DNA (short for deoxyribonucleic acid). What do cells need to do between divisions to make sure that a full set of DNA gets passed on to each daughter cell?

Gizmo Warmup

On the SIMULATION pane of the Cell Division Gizmo™, check that the Cycle Length is set to 12 hours. Click Play ( ), observe until the maximum number of cells is shown, and then click Pause ( )

1. Look at the cells. Do they all look the same?

2. Cells that are in the process of dividing are said to be in mitosisor cytokinesis. Cells that are not dividing are in interphase.

Check the Magnify box and move the cursor over the cells.
A. Of the 100 cells shown, how many are in the process of dividing?
B. Select the BAR CHART tab, and turn on Show numerical values. How many cells are in the interphase stage of their life cycle?
C. Based on these two observations, would you say that a cell spends most of its life cycle in interphase or in mitosis/cytokinesis?

Activity A
1. Observe: Click Play and hold the cursor over the cell. Observe the cell as it divides several times. (This happens quickly!) What do you notice happening during this process?
2. Summarize: On the DESCRIPTION pane, read about each phase in the cell cycle. In the spaces below, sketch the cell in each phase and summarize what occurs in your own words
3. Analyze: Use your summaries and the Gizmo to answer the following questions: A. What are the four phases of mitosis?
A. What are the four phases of mitosis?
B. During which phase is the DNA duplicated?
C. What is the relationship between chromatin and chromosomes?
D. In which phase are chromatids pulled apart?
E. What is the role of the centrioles?
F. In which phase does a new nuclear membrane develop?
G. A cell has a single line of chromosomes. What is the phase
4. During which three phases are individual chromosomes no longer visible?4. Think and discuss: Why is it important that the cell’s DNA is duplicated before cell division?

Research: Prominent African-American Scientists & Inventors

10 Feb

Rotations for Research

Period 2

Thursday: Bailey > Kanu

Friday: Lagrandeur > Williams

Period 3

Thursday: Byrd > Jenkins

Friday: Olesco > Wright

February, as you all may know, is Black History Month. It is also a good opportunity to learn about the many African-American scientists, both from our past and present, that have contributed much to our society. After finding the information below about ONE scientist, summarize your findings in three full paragraphs [5 sentences minimum per paragraph].

1. Go to the following website for a list of prominent scientists:
http://en.wikipedia.org/wiki/List_of_African_American_inventors_and_scientists

2. After choosing one scientist, look for the following information through searching the internet:

3. What period [years] was the scientist alive?

4. What study of research did the scientist focus on?

5. What was his greatest achievement?

6. What type of education did he receive? What school[s] did he/she attend?

7. Did he/she receive any special awards or recognition?

8. How did he/she change their profession?

Your three paragraph summary should be written in the “Comments” section below this post!

Gizmo: Cell Structure

7 Feb

1. Go to the following website:

http://www.explorelearning.com/index.cfm

2. If you do not remember your username, password, use the following:
username: secondp112
password: cow864

Gizmo

Student Exploration: Cell Structure
Vocabulary: cell wall, centriole, chloroplast, cytoplasm, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondria, nuclear envelope, nucleolus, nucleus, organelle, plasma membrane, plastid, ribosome, vacuole, vesicle

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. What are some of the structures inside a cell that help it to live and perform its role in an
organism? _________________________________________________________________________________________________________________________________________
2. How do you think plant cells differ from animal cells? (Hint: What can plants do that animals
cannot?) ___________________________________________________________________________________________________________________________________________

Gizmo Warm-up
The Cell Structure Gizmo™ allows you to look at typical animal and plant cells under a microscope. To start, click Sample to take a sample of an animal cell. Use the Zoom slider to see the cell at a magnification of 1000x (1000 times larger than normal).
1. Use the up/down and left/right sliders to manipulate the cell. Find the red arrow pointing to the centrioles. Make a sketch of the centrioles in the space below.
2. Read the description of the centrioles. What is their function? __________________________________________________________________________________________________________________________________________________________________________
Activity A:
Animal cells
Get the Gizmo ready:
• Check that an Animal cell is mounted on the microscope.
• Set the Zoom to 500x.

Question: Organelles are specialized structures that perform various functions in the cell. What are the functions of the organelles in an animal cell?
1. Label: Locate each organelle in the animal cell. Label the organelles in the diagram below.
2. Match: Read about each organelle. Then match each organelle to its function/description.
____ Cytoplasm
____ Lysosome
____ Mitochondria
____ Centriole
____ Endoplasmic reticulum
____ Vacuole
____ Plasma membrane
____ Nucleus
____ Ribosome
____ Nuclear envelope
____ Golgi apparatus
____ Vesicle
____ Nucleolus
A. Structure that organizes motion of chromosomes.
B. Stack of membranes that packages chemicals.
C. Membrane that protects the nucleus.
D. Membrane that surrounds and protects the cell.
E. Sac filled with digestive chemicals.
F. Structures that converts nutrients to energy.
G. Passageways where chemicals are made.
H. Jelly-like substance within the plasma membrane.
I. Structure that manufactures ribosomes.
J. Structure that contains DNA and directs the cell.
K. Package created by the Golgi apparatus.
L. Small structure that synthesizes proteins.
M. Sac that stores water, nutrients, or waste products.Activity B:
Plant cells
Get the Gizmo ready:
• Select View plant cell, and click Sample.
• Set the Zoom to 500x.
Question: What functions do the organelles in a plant cell perform?
1. Label: Locate each organelle in the plant cell. Label the organelles in the diagram below.
2. Compare: What structures are present in an animal cell, but not in a plant cell? ___________________________________________________________________________________

What structures are present in a plant cell, but not in an animal cell? ___________________________________________________________________________________________
3. Fill in: Name the organelle or organelles that perform each of the following functions.
A. _____________________ convert sunlight to chemical energy.
B. The _____________________ and the _____________________ help to support
the plant cell and help it to maintain its shape.
C. _____________________ store food or pigments.
D. The _____________________ converts food into energy. It is found in both plant
cells and animal cells.