Uncategorized 14 - BIOLOGY JUNCTION

Leeuwenhoek Article

Anton van Leeuwenhoek (1632-1723)

. . . my work, which I’ve done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof.

Anton van Leeuwenhoek. Letter of June 12, 1716

Anton van Leeuwenhoek was an unlikely scientist. A tradesman of Delft, Holland, he came from a family of tradesmen, had no fortune, received no higher education or university degrees, and knew no languages other than his native Dutch. This would have been enough to exclude him from the scientific community of his time completely. Yet with skill, diligence, an endless curiosity, and an open mind free of the scientific dogma of his day, Leeuwenhoek succeeded in making some of the most important discoveries in the history of biology. It was he who discovered bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells, microscopic nematodes and rotifers, and much more. His researches, which were widely circulated, opened up an entire world of microscopic life to the awareness of scientists.

Leeuwenhoek was born in Delft on October 24, 1632. (His last name, incidentally, often is quite troublesome to non-Dutch speakers: “layu-wen-hook” is a passable English approximation.) His father was a basket-maker, while his mother’s family were brewers. Anton was educated as a child in a school in the town of Warmond, then lived with his uncle at Benthuizen; in 1648 he was apprenticed in a linen-draper’s shop. Around 1654 he returned to Delft, where he spent the rest of his life. He set himself up in business as a draper (a fabric merchant); he is also known to have worked as a surveyor, a wine assayer, and as a minor city official. In 1676 he served as the trustee of the estate of the deceased and bankrupt Jan Vermeer, the famous painter, who had had been born in the same year as Leeuwenhoek and is thought to have been a friend of his. And at some time before 1668, Anton van Leeuwenhoek learned to grind lenses, made simple microscopes, and began observing with them. He seems to have been inspired to take up microscopy by having seen a copy of Robert Hooke’s illustrated book Micrographia, which depicted Hooke’s own observations with the microscope and was very popular.

Leeuwenhoek is known to have made over 500 “microscopes,” of which fewer than ten have survived to the present day. In basic design, probably all of Leeuwenhoek’s instruments — certainly all the ones that are known — were simply powerful magnifying glasses, not compound microscopes of the type used today. A drawing of one of Leeuwenhoek’s “microscopes” is shown at the left. Compared to modern microscopes, it is an extremely simple device, using only one lens, mounted in a tiny hole in the brass plate that makes up the body of the instrument. The specimen was mounted on the sharp point that sticks up in front of the lens, and its position and focus could be adjusted by turning the two screws. The entire instrument was only 3-4 inches long, and had to be held up close to the eye; it required good lighting and great patience to use.

Compound microscopes (that is, microscopes using more than one lens) had been invented around 1595, nearly forty years before Leeuwenhoek was born. Several of Leeuwenhoek’s predecessors and contemporaries, notably Robert Hooke in England and Jan Swammerdam in the Netherlands, had built compound microscopes and were making important discoveries with them. These were much more similar to the microscopes in use today. Thus, although Leeuwenhoek is sometimes called “the inventor of the microscope,” he was no such thing.

However, because of various technical difficulties in building them, early compound microscopes were not practical for magnifying objects more than about twenty or thirty times natural size. Leeuwenhoek’s skill at grinding lenses, together with his naturally acute eyesight and great care in adjusting the lighting where he worked, enabled him to build microscopes that magnified over 200 times, with clearer and brighter images than any of his colleagues could achieve. What further distinguished him was his curiosity to observe almost anything that could be placed under his lenses, and his care in describing what he saw. Although he himself could not draw well, he hired an illustrator to prepare drawings of the things he saw, to accompany his written descriptions. Most of his descriptions of microorganisms are instantly recognizable.

In 1673, Leeuwenhoek began writing letters to the newly-formed Royal Society of London, describing what he had seen with his microscopes — his first letter contained some observations on the stings of bees. For the next fifty years he corresponded with the Royal Society; his letters, written in Dutch, were translated into English or Latin and printed in the Philosophical Transactions of the Royal Society, and often reprinted separately. To give some of the flavor of his discoveries, we present extracts from his observations, together with modern pictures of the organisms that Leeuwenhoek saw.

In a letter of September 7, 1674, Leeuwenhoek described observations on lake water, including an excellent description of the green charophyte alga Spirogyra: “Passing just lately over this lake, . . . and examining this water next day, I found floating therein divers earthy particles, and some green streaks, spirally wound serpent-wise, and orderly arranged, after the manner of the copper or tin worms, which distillers use to cool their liquors as they distil over. The whole circumference of each of these streaks was about the thickness of a hair of one’s head. . . all consisted of very small green globules joined together: and there were very many small green globules as well.”

A letter dated December 25, 1702, gives descriptions of many protists, including this ciliate, Vorticella: “In structure these little animals were fashioned like a bell, and at the round opening they made such a stir, that the particles in the water thereabout were set in motion thereby. . . And though I must have seen quite 20 of these little animals on their long tails alongside one another very gently moving, with outstretched bodies and straightened-out tails; yet in an instant, as it were, they pulled their bodies and their tails together, and no sooner had they contracted their bodies and tails, than they began to stick their tails out again very leisurely, and stayed thus some time continuing their gentle motion: which sight I found mightily diverting.”

On September 17, 1683, Leeuwenhoek wrote to the Royal Society about his observations on the plaque between his own teeth, “a little white matter, which is as thick as if ‘it were batter.” He repeated these observations on two ladies (probably his own wife and daughter), and on two old men who had never cleaned their teeth in their lives. Looking at these samples with his microscope, Leeuwenhoek reported how in his own mouth: “I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, very prettily a-moving. The biggest sort. . . had a very strong and swift motion, and shot through the water (or spittle) like a pike does through the water. The second sort. . . oft-times spun round like a top. . . and these were far more in number.” In the mouth of one of the old men, Leeuwenhoek found “an unbelievably great company of living animalcules, a-swimming more nimbly than any I had ever seen up to this time. The biggest sort. . . bent their body into curves in going forwards. . . Moreover, the other animalcules were in such enormous numbers, that all the water. . . seemed to be alive.” These were among the first observations on living bacteria ever recorded.

Leeuwenhoek looked at animal and plant tissues, at mineral crystals and at fossils. He was the first to see microscopic foraminifera, which he described as “little cockles. . . no bigger than a coarse sand-grain.” He discovered blood cells, and was the first to see living sperm cells of animals. He discovered microscopic animals such as nematodes and rotifers. The list of his discoveries goes on and on. Leeuwenhoek soon became famous as his letters were published and translated. In 1680 he was elected a full member of the Royal Society, joining Robert Hooke, Henry Oldenburg, Robert Boyle, Christopher Wren, and other scientific luminaries of his day — although he never attended a meeting. In 1698 he demonstrated circulation in the capillaries of an eel to Tsar Peter the Great of Russia, and he continued to receive visitors curious to see the strange things he was describing. He continued his observations until the last days of his life. After his death on August 30, 1723, the pastor of the New Church at Delft wrote to the Royal Society: . . . Anton van Leeuwenhoek considered that what is true in natural philosophy can be most fruitfully investigated by the experimental method, supported by the evidence of the senses; for which reason, by diligence and tireless labor he made with his own hand certain most excellent lenses, with the aid of which he discovered many secrets of Nature, now famous throughout the whole philosophical World.

Citation:

Ford, B. J. 1991. The Leeuwenhoek Legacy. Biopress, Bristol, and Farrand Press, London. <http://www.ucmp.berkeley.edu/history/leeuwenhoek.html>

Line Graph on Paper

How To Construct a Line Graph On Paper
Step	What To Do	How To Do It
1	Identify the variables	Independent Variable – (controlled by the experimenter) Goes on the X axis (horizontal) Should be on the left side of a data table Dependent Variable – (changes with the independent variable) Goes on the Y axis (vertical) Should be on the right side of a data table
2	Determine the variable range.	Subtract the lowest data value from the highest data value. Do each variable separately.
3	Determine the scale of the graph.	Determine a scale. (the numerical value for each square), that best fits the range of each variable. Spread the graph to use MOST of the available space.
4	Number and label each axis.	This tells what data the lines on your graph represent.
5	Plot the data points.	Plot each data value on the graph with a dot. You can put the data number by the dot, if it does not clutter your graph.
6	Draw the graph.	Draw a curve or a line that best fits the data points. Most graphs of experimental data are not drawn as “connect-the-dots”.
7	Title the graph.	Your title should clearly tell what the graph is about. If your graph has more than one set of data, provide a “key” to identify the different lines.

Little Rock School District

Little Rock School District

Sophomore Biology

Month/SLEs

Content/Skills

Essential Questions

Assessments

Lab Activities

Strategies/Resources

August

Student Learning Expectations:

Nature of Science

Standard 10: Students shall demonstrate an understanding that science is a way of knowing.

Explain why science is limited to natural explanations of how the world works

NS.10. B.1

Explain why science is limited to natural explanations of how the world works

NS.10. B.2

Compare and contrast hypotheses, theories, and laws

NS.10. B.3

Distinguish between a scientific theory and the term “theory” used in general conversation

NS.10. B.4

Summarize the guidelines of science:

A. Explanations are based on observations, evidence, and testing

B. Hypotheses must be testable

C. Understandings and/or conclusions may change with additional empirical data

D. Scientific knowledge must have peer review and verification before acceptance

Standard 11: Students shall design and safely conduct scientific inquiry

NS.11. B.1

Develop and explain the appropriate procedure, controls, and variables (dependent and independent) in scientific experimentation

NS.11. B.2

Research and apply appropriate safety precautions (refer to ADE Guidelines) when designing and/or conducting scientific investigations

NS.11. B.3

Identify sources of bias that could affect experimental outcome

NS.11. B.4

Gather and analyze data using appropriate summary statistics

NS.11. B.5

Formulate valid conclusions without bias

NS.11. B.6

Communicate experimental results using appropriate reports, figures, and tables

Standard 12: Students shall demonstrate an understanding of current life science theories.

NS.12.B.1

Recognize that theories are scientific explanations that require empirical data, verification, and peer review

NS.12.B.2

Understand that scientific theories may be modified or expanded based on additional empirical data, verification, and peer review

Standard 13: Students shall use mathematics, science equipment, and technology as tools to communicate and solve life science problems

NS.13.B.1.

Collect and analyze scientific data using appropriate mathematical calculations, figures, and tables

NS.13.B.2

Use appropriate equipment and technology as tools for solving problems (e.g., microscopes, centrifuges, flexible arm cameras, computer software and hardware)

NS.13.B.3

Utilize technology to communicate research findings

Standard 14: Students shall describe the connections between pure and applied science.

NS.14.B.1

Compare and contrast biological concepts in pure science and applied science

NS.14.B.2

Discuss why scientists should work within ethical parameters

Standard 15: Students shall describe various life science careers and the training required for the selected career

NS.15.B.1

Research and evaluate science careers using the following criteria:

educational requirements
salary
availability of jobs
working conditions

The major content themes of biology

Ø Matter and Energy

Ø Cells

Ø Interdependence

Ø Reproduction and Inheritance

Ø Evolution

Ø Homeostasis and Stability

What science is and is not

Ø Deals only with natural world

Ø Explanations can be tested

Ø Explanations are used to make predictions

Ø Is revised to account for new evidence

Ø Also refers to a body of knowledge that has accumulated after repeated attempts to verify/refute

Process of science

Ø Starts with observation

Ø Form inferences

Ø Develop hypotheses

Ø Test hypotheses

Ø Form Theories

Hypotheses vs. theories vs. laws

Ø What if statements

Ø Researched, hypothesized and tested

Ø Statements of occurrences in natural world

Ø Peer collaboration

Ø Peer verification

Designing an Experiment

Ø  Stating the problem

Ø  Forming hypotheses

Ø  Setting up controlled experiment

Ø  Recording and analyzing results

Ø  Drawing conclusions

Ø *Science Fair Proposals

Graphing

Ø How raw data must be organized to reveal patterns

Ø How to take data and create charts

Ø Using charts to create graphs

Ø Interpret results by what is seen and not what it is thought to be

Analyzing data includes

Ø Understanding slope and rates of change

Ø Extrapolating information from graphs

Ø Recognizing patterns in data plots

Ø The role of dependent and independent variables

A theory is more than a guess

Ø It involves research

Ø Tested hypothesis

Ø Peer review

Ø Must be repeatable

Ø May combine several ideas

Ø Ex. Plate Tectonic Theory and how it developed

The tools of science are

Ø Mathematics

Ø The metric system

Ø Various lab equipment

Ø Data collecting equipment

Ø Rulers

Ø Calculators

Ø Computers

The role of science in society

Ø Science leads to changes in technology

Ø the goal of science is to improve human condition

Ø Life has value and should be respected even during research

Ø Pure science is research that leads to the research being applied or used for the good of humankind

Careers in science

Ø What are some of the various life science careers?

Ø What kind of training does it take to be a life scientist?

Ø What are the working conditions and compensation for being a life scientist?

How can you use the same skills and strategies as a scientist to learn about your world?

Guiding Questions

1. What is the importance of the major themes of biology?

2. What is the role of experimental design in biology?

3. What systematic procedures are necessary to investigate biological problems?

4. What are important tools used in the study of biology?

5. What are useful data types and how are they analyzed?

6. What important mathematical manipulations should be performed on qualitative data?

7. Why is the scientific method a logical process for observing the natural world

8. What is the difference between a hypothesis and a theory?

9. Why it is important to acknowledge that science is a human endeavor, not separate from society but a part of society?

10. In what ways do scientists make accommodations for differences in racial, social, and ethnic backgrounds among scientists?

Essential Question

What are some of the various roles that science plays in society, especially in the workforce?

Anchor Assessments:

Scientific Method Lab (Vitruvian Man) Lab Report

Anchor Assessment

Careers in Life Science Term Paper and Presentation

Equipment Survey

Problem Solving

Liquid Volume Lab OR Volume Lab

Mystery Canisters OR Length Lab

Scientific Method: Vitruvian Man

August Vocabulary

Resources

Outline for Lab Reports

Rubric for Lab Reports

Rules for Diagramming

Lab Safety Contract

Lab Safety Test

Solutions and Dilutions

Literacy Items ( found in LRSD Biology Literacy Notebook)

“Owls use dung to “Fish” for Beetles”

“Distinguishing Science and Pseudoscience”

“Scientific Laws, Hypotheses, and Theories”

“Wrong! Wrong! Wrong!”

“Designing an Experiment”

“The effects of steroids on athletes”

“Experimental Design/Presentation Rubric”

“ Experimental Design Reference”

“Natural plant defenses-fight or flight?”

“Suicide grasshoppers”

“Brainwashed by Parasite Worms”

“Toads that Go Pop in the night”

“Weapons of Mouse Destruction?”

“A Weed, a Fly, a Mouse and a Chain of Unintended

Consequences”

“Future Tech, Spare Parts”

“Device Uses Sewage Bacteria to Produce Electricity”

“Locus Inspire Technology That May Prevent Car Crashes”

“Scientists sticking it to nature by replicating tiny gecko feet”

September

Ecological and Biological Relationships

Standard 8: Students shall demonstrate an understanding of ecological and behavioral relationships among organisms.

EBR.8. B.1

Cite examples of abiotic and biotic factors of ecosystems.
EBR.8. B.2

Compare and contrast the characteristics of biomes.
EBR.8. B.3

Diagram the carbon, nitrogen, phosphate, and water cycles in an ecosystem.
EBR.8. B.4

Analyze an ecosystem’s energy flow through food chains, food webs, and energy pyramids.
EBR. 8. B.5

Identify and predict the factors that control population, including predation, competition, crowding, water, nutrients, and shelter.
EBR.8 B.6

Summarize the symbiotic ways in which individuals within a community interact with each other: commensalisms, parasitism and mutualism

EBR.8. B.7

Compare and contrast primary succession with secondary succession.
EBR.8. B.8

Identify the properties of each of the five levels of ecology: organism, population ,community ,ecosystem and biosphere

MC 2.B.6

Compare and contrast the functions of autotrophs and heterotrophs

Standard 9: Students shall demonstrate an understanding of ecological impact of global issues.

EBR.9. B.1

Analyze the effects of human population growth and technology on the

Environment/biosphere.

EBR.9. B.2

Evaluate long range plans concerning resource use and by-product disposal in terms of their environmental, economic, and political impact.

EBR.9. B.3

Assess current world issues applying scientific themes (e.g., global changes in climate, epidemics, pandemics, ozone depletion, UV radiation, natural resources, use of technology, and public policy).

Molecules and Cells

Standard 1: Students shall demonstrate an understanding of the role of chemistry in life processes.

MC.1.B.1

Describe the structure and function of the major organic molecules found in living systems:

Carbohydrates

Proteins

Lipids

Nucleic Acids

MC.1.B.2

Investigate the properties and importance of water and its significance for life:

· surface tension

· adhesion

· cohesion

· polarity

· pH

MC. 1.B.3

Describe the relationship between an enzyme and its substrate molecule(s)

MC. 1.B.4

Explain the role of energy in chemical reactions of living systems:

activation energy
exergonic reactions
endergonic reactions

Ecology

Levels of Organization

Ø biosphere àBiomeà ecosystem à community à population à species à organism

Energy flow

Ø Autotroph vs. Heterotroph

Ø Producers: photosynthesis and chemosynthesis

Ø Consumers: herbivore, carnivore, detritivore, omnivore, decomposer

Ø Feeding relationships: food chain vs. food web

Ø Energy conversion and transfer by trophic levels

Biosphere recycling

Ø Water cycle

Ø Nutrient cycles: Carbon, Nitrogen, Phosphorous

Ecosystem productivity and biomass

Factors shaping ecosystems:

Ø Climate zones and Greenhouse phenomenon

Ø Biotic and Abiotic factors

Ø Niche concept

Ø Community interactions: competition, predation, symbiotic interactions (commensalisms, mutualism, parasitism)

Succession

Ø Primary succession and pioneer species

Ø Secondary succession

Biomes

Ø Identify defining characteristics of each

Ø Terrestrial biomes: tropical rain and dry forests, savanna, desert, grassland, temperate woodland and shrubland, temperate forests, coniferous forests, boreal (taiga) forests, tundra

Ø Aquatic ecosystems:

Ø Freshwater – flowing, standing,

Ø Wetland

Ø Estuary

Ø Marine – photic vs. aphotic

Ø Zones, intertidal, coastal, coral

Ø Reef, open ocean, benthic zone

Population growth

Ø Factors affecting and limiting growth

Ø Density-dependent and density independent factors

Ø Carrying capacity vs. exponential growth

Ø Describe human population growth, analyze age structures, describe how humans growth has affected other species

Human impact on the environment:

Ø Biodiversity threat

Ø 6th mass extinction

Ø pollution, acid rain, ozone depletion, and greenhouse affect

Ø global warming

Ø exotic (introduced) species

Ø conservation efforts and how individuals can affect change

Review basic chemistry concepts:

Ø atomic structure

Ø bonding

Ø covalent, ionic, hydrogen

Ø elements and isotopes

Carbon

Ø chemistry of carbon

Ø macromolecules of life – identify and describe structure (monomers) and examples of polymers

Ø lipids, carbohydrates, proteins,

Ø nucleic acids

Chemistry of water:

Ø polarity

Ø hydrogen bonding

Ø water properties

Ø solutions and suspensions

Ø pH – acids and bases and buffers

Enzymes

Ø reactions and activation energy

Ø enzymes as catalysts

Ø 3-D structure of enzymes

Ø examples of enzymes

Ø how enzymes work

Ø regulation of enzymes

How are all living things connected to one another and to the universe?

1. How are the biotic factors of an ecosystem different from the abiotic factors?

2. What are the biotic and abiotic factors present in a temperate deciduous forest?

3. What is the general climate in each of the 7 major biomes?

4. What role does the climate play in determining the types of organisms that can live in specific biomes?

5. How does carbon enter the living part of the carbon cycle?

6. How does carbon re-enter the environment from living things?

7. How does nitrogen cycle from the environment into living things?

8. How does water enter and exit the biotic part of the water cycle?

9. How does energy cycle through an ecosystem?

10. What are some specific factors that limit growth of animal populations?

11. What are three types of symbiotic relationships between organisms? Give an example of each type or relationship.

12. How does primary succession differ from secondary succession?

13. How do humans impact the carbon cycle and what are the global consequences?

14. What factors should be taken into consideration when deciding the location for a new landfill?

15. What human activities have impacted the ozone layer?

16. Why is sustainable use of natural resources important?

Biochemistry

How do molecules sustain living things?

1. What are the major groups of organic compounds and how do they function in living things?

2. What is an enzyme and how does it function in cells?

3. Why is water essential to life?

4. What are the distinguishing chemical and physical properties of water?

Anchor Assessment:

Biomes Brochure

And

Models from Carbohydrate Modeling Lab

Models from Amino Acid Modeling Lab

Ecology Labs

Population Ecology (Goldfish) OR Random Sampling

Food Web construction and manipulation

Biomes Brochures

Graphing Growth Rate

Loss of Vegetation (trophic interaction)

Biochemistry Labs

Measuring pH

Chemistry of Carbohydrates (models)

Testing for Organic Compounds

Properties of Water Lab

Chemistry of Amino Acids and Proteins (models)

Pineapple Enzyme Lab OR Lactase Enzyme Lab

September Vocabulary

HOLT INTERACTIVE “Ecosystem Dynamics”

Literacy Materials (Ecology)

“Soil Fertility in Agricultural Systems”

“Power or Plants?”

“What’s the big Deal About dirt?”

“ A Diverse Ecosystem Offers Little or No Protection Against Invading Species”

“Earth’s Uncanned Crusaders: Will Sardines Save Our Skin?”

“A melting Glacier in Tibet serves as an Example and a Warning”

“Overfishing is Emptying World’s Rivers, Lakes, Experts Warn”

“Global Warming is Spurring Evolution, Study Says”

“Is Global Warming Harmful to Health?”

Literacy Materials-Biochemistry

“Enzymes may help brain clean the slates”

“Enzyme may aid people with Celiac Disease”

“Tiny Invader”

“Lactic acid is not muscles’ foe, it’s fuel”

October( thru end of 1st 9 weeks)

Nature of Sci.

Standard 12

Students shall demonstrate an understanding of current life science theories.

NS.12.B.4.

Relate the development of the cell theory to current trends in cellular biology.

Molecules and Cells

Standard 2: Students shall demonstrate an understanding of the structure and function of cells.

MC 2.B.1
Construct a hierarchy of life from cells to ecosystems.
MC 2.B.2

Compare and contrast prokaryotes and eukaryotes.
MC 2. B.3

Describe the role of sub-cellular structures (organelles, ribosomes, & cytoskeleton) in the life of a cell.

MC.2.B.5

Compare and contrast the structures of an animal cell to a plant cell.

October (thru remainder of month during 2nd 9 weeks)

MC 2.B.4

Relate the function of the plasma (cell) membrane to its structure.

MC. 2.B.11

Discuss homeostasis using thermoregulation as an example.
MC.2. B. 7

Compare and contrast active transport and passive transport mechanisms:

Diffusion
Osmosis
Endocytosis
Exocytosis
Phagocytosis
Pinocytosis

Cell structure and function

Ø History: Hooke, van Leeuwenhoek

Ø History: cell theory (Schleiden, Schwann, Virchow)

Ø Symbiotic theory: Margulis

Ø Levels of Organization

Atoms -> Molecules->Cells-> Tissue->Organ->Organ System->Organism->Species->Population-> Community->Ecosystem->Biome->Biosphere

Ø Eukaryotes vs. Prokaryotes

o Be able to compare and contrast

Eukaryotic cell structure

o Organelles

o Cytoplasm

o Nucleus

o Compare plant vs animal cell

Ø Levels of organization

Microscope use:

Ø Identify parts of a microscope

Ø Make specimen slides

Ø Identify parts of cell

Ø Cell membrane structure and function

Ø Lipid bilayer

Ø Cell wall

Ø Diffusion through

Ø Osmosis

Ø Active transport

Ø Homeostasis

Cells Essential question

What are the activities cells carry out that are necessary to sustain life?

Guiding Questions

1. The invention of what important tools led to the formation of the cell theory?

2. What is the cell theory? What evidence supports the cell theory?

3. What are prokaryotic cells?

4. What are eukaryotic cells?

5. How do prokaryotic and eukaryotic cells compare?

6. What organelles are found in eukaryotic cells?

7. What is the function of each organelle?

8. What is the difference between animal and plant cells?

Plasma Membrane Essential Question:

How does the Plasma membrane function as the gateway of a cell?

1. How do the responsibilities of cells in multi cellular organisms compare to the cells that comprise single-celled organisms?

2. What is the composition of the cell (plasma) membrane?

3. What are the processes that allow materials to enter and exit the cell?

4. What is homeostasis?

5. How do cells maintain homeostasis?

Anchor Assessment:

Cell Analogy

Anchor Assessment:

Plasma Membrane Drawings

Use of Microscope & Techniques For Better Use

Cells-Basic Unit of Life

osmosis/diffusion from AP lab book

Plasmolysis with Elodea

October Vocabulary

HOLT INTERACTIVE “Cell Transport and Homeostasis”

Literacy Materials (Cell)

“How Human Cells Get Their Marching Orders”

“ Stressed to Death”

“Stem Cell Surprise”

“ Cells that Read Minds”

November

Cellular Respiration and Photosynthesis

Standard 3: Students shall demonstrate an understanding of how cells obtain and use energy. (Energetics)
MC.3.B.1

Compare and contrast the structure and function of mitochondria and chloroplasts.
MC.3 B.4

Describe and model the conversion of light energy to chemical energy by photosynthetic organisms (light dependent & independent reactions).
MC.3.B.5

Compare and contrast cellular respiration and photosynthesis as energy conversion pathways.

MC.3.B.2

Describe and model the conversion of stored energy (glycolysis, citric acid cycle, electron transport chain) in organic molecules into usable cellular energy (ATP).

Standard 2: Students shall demonstrate an understanding of the structure and function of cells.

MC.3.B.3

Compare and contrast aerobic and anaerobic respiration (lactic acid and alcoholic fermentation).

MC.3.B.4 Describe and model the conversion of light energy to chemical energy by photosynthetic organisms:

light dependent reactions
light independent reactions

The Cell Cycle
MC.2.B.8

Describe the main events in the cell cycle (mitosis, interphase, & cytokinesis), including the differences in plant and animal cell division.
MC.2.B.9

List in order and describe the stages of mitosis (prophase, metaphase, anaphase, & telophase).
MC.2.B.10

Analyze the meiotic maintenance of a constant chromosome number from one generation to the next.

Photosynthesis

Ø Explain where plants get energy to produce food

Ø Describe the role of ATP in cellular activities

Photosynthesis overview:

Ø Experiments of van Helmont, Priestley, Ingenhousz

Ø Photosynthesis equation

Ø Describe role of light and chlorophyll

Photosynthesis reactions

Ø Describe structure and function of chloroplast

Ø Light-dependent reactions – describe what happens

Ø Light-independent reactions – describe Calvin cycle

Ø Identify factors that affect the rate of photosynthesis

Cellular respiration

Ø Chemical pathways

o Explain what cellular respiration is

o Describe what happens during glycolysis and products produced

o Name and describe two main types of fermentation

Ø Krebs cycle and Electron transport

o Describe what happens during Krebs cycle and products produced

o Explain how high-energy electrons are used in transport chain

o Identify pathways the body uses to release energy during exercise

Compare photosynthesis and cellular respiration

Cell cycle and Growth/Division

Ø Describe and identify typical stages in cell’s life cycle

Ø Somatic cell reproduction

o Mitotic stages, identify and describe

Ø Gamete production

o Meiosis, identify and describe stages

o Spermatogenesis vs. Oogenesis

Ø Compare mitosis and meiosis

Ø Regulation of cell cycle

Ø How do cancer cells differ from other cells

Cellular Energetics”

Why do living things make or eat food?

Guiding Questions

1. How is the sun the ultimate source of energy for all living things?

2. How do organisms produce and use energy?

3. What is cellular fuel?

4. What are the reactants and products of respiration?

5. What is the difference between aerobic and anaerobic respiration?

6. What is the role of ATP in photosynthesis and respiration?

Mitosis & Meiosis:

How do cells grow, divide, and make new cells?

Guiding Questions

1. What are mitosis and meiosis and which cells perform each process?

2. How does the chromosome number in parent cell and daughter cells differ with regards to mitosis and meiosis?

3. What is the difference in the way plant and animals undergo cell division?

4. How does crossing over act as the genetic mechanism for diversity?

Anchor Assessments:

Cellular Energetics Open Response item

“How do certain living things use sunlight to make food and why are they eaten?”

Compare and Contrast Respiration vs. Photosynthesis. Be sure to include the cell structures involved in each and how energy flows from the sun through living things.

Compare/Contrast Essay on Mitosis vs. Meiosis

Flip Book

Respiration & Photos Labs

Chromatography/ Photosynthesis lab from AP book

Respiration of Germinating Seeds Lab

Mitosis & Meiosis Labs

Cell Reproduction/ Mitosis Flip-Book

November Vocabulary

HOLT INTERACTIVE” Cellular Respiration”

HOLT INTERACTIVE “Photosynthesis”

HOLT INTERACTIVE “Cell Reproduction”

Literacy Materials

“Lactic Acid Is Not Muscles’ Foe, It’s Fuel”

“Breakthroughs/Immunology”

“Modified Mice Stay Super-fit”

“In the Genes”

“Grow in The Dark”

“Source of Half Earth’s Oxygen Gets Little Credit”

December

Heredity and Evolution

Standard 4: Students shall demonstrate an understanding of heredity.

HE.4.B.1

Summarize the outcomes of Gregor Mendel’s experimental procedures.
HE.4.B.2

Differentiate among the laws and principles of inheritance (dominance, segregation, independent assortment).
HE.4.B.3

Use the laws of probability and Punnett squares to predict genotypic and phenotypic ratios.
HE.4.B.4Examine different modes of inheritance

· sex linkage

codominance
crossing over
incomplete dominance
multiple alleles

HE.4.B.5

Analyze the historically significant work of prominent geneticists.
HE.4.B.6

Evaluate karyotypes for abnormalities such as monosomy & trisomy.

Genetics

The work of Gregor Mendel

Ø Describe Mendel’s work and summarize his conclusions

Ø Explain principle of dominance

Ø Law of segregation and independent assortment

Probability

Ø Describe what probability is

Ø Explain how probability is used in genetics

Ø Construct and read Punnett Squares

Patterns of inheritance

Ø Simple dominance

Ø Co-dominance

Ø Incomplete dominance

Ø X-linked

Ø Pedigree and karyotypes

o Mutations/diseases

Genetics:

Why do living things not look the same?

Guiding Questions

1. What are Mendel’s laws of heredity?

2. What are genotype and phenotype?

3. How do the terms heterozygous, homozygous, dominant and recessive relate to Mendelian genetics

4. What are the potential effects of genetic recombination and mutation on organisms?

Anchor Assessment:

Performance Assessment: Correctly Created and Diagnosed

HOLT INTERACTIVE “Heredity”

Literacy Materials

“ Gene that led to man found”

“ Gene Study Identifies 5 Main Human Populations, Linking Them to Geography”

“Still Evolving , Human Genes Tell New Story”

“Without Gene, timid Mice Turn into Daredevils”

“Study Offers New Insight Into Why Learning Disorders Are Genetic”

“Early Risers have Mutated Gene, Study Says”

“A Gene for Romance? So It seems( Ask the Vole)

January

Standard 5: Students shall investigate the molecular basis of genetics.

HE.5.B.1

Model the components of a DNA nucleotide and an RNA nucleotide.
HE.5.B.2

Describe the Watson-Crick double helix model of DNA, using the base-pairing rule (adenine-thymine, cytosine-guanine).
HE.5.B.3

Compare and contrast the structure and function of DNA and RNA.
HE.5.B.4

Describe and model the processes of replication, transcription, and translation.
HE.5.B.5

Compare and contrast the different types of mutation events, including point mutation, frameshift mutation, deletion, and inversion.
HE.5.B.6

Identify effects of changes brought about by mutations (beneficial, harmful, & neutral).

Molecules and Cells

Standard 1

MC.1.B.1

Describe the structure and function of nucleic acids found in living systems.
Nature of Science

Standard 12

NS.12.B.6

Relate the chromosome theory of heredity to recent findings in genetic research (e.g., Human Genome Project-HGP, chromosome therapy).

NS.12.B.7

Research current events and topics in Biology

Standard 6: Students shall examine the development of the theory of biological evolution.
HE.6.B.1

Compare & contrast Lamarck’s explanation of evolution with HE.6.B.2

Darwin’s theory of evolution by natural selection.
HE.6.B.3

Recognize that evolution involves a change in allele frequencies in a population across successive generations.
HE.6.B.4

Analyze the effects of mutations and the resulting variations within a population in terms of natural selection.
HE.6.B.5

Illustrate mass extinction events using a time line.
HE.6.B.6

Evaluate evolution in terms of evidence as found in the following:

fossil record
DNA analysis
artificial selection
morphology
embryology
viral evolution
geographic distribution of related species
antibiotic and pesticide resistance in various organisms

Nature of Science

Standard 12

NS.12.B.2

Compare the processes of relative and radioactive dating to determine the age of fossils.

NS.12.B.3

Understand that scientific theories may be modified or expanded based on empirical data, verification, & peer review.

Heredity and Evolution

Standard 6

HE.6.B.7

Interpret a Cladogram

Molecular biology

Ø History of DNA – Griffith, Avery, Pauling, Franklin, Watson/Crick

Ø Summarize relationship between genes and DNA

Ø Describe structure of DNA

Ø Summarize events of DNA replication

Ø RNA and protein synthesis

o Compare DNA and RNA

o Describe types of RNA

o Stages in protein synthesis

§ Transcription

§ Translation

o Contrast gene and chromosomal mutations

Ø Gene regulation

Ø Genetic engineering

Evolution

What is evolution?

Ø Fact and theory

Ø Review what a theory is

History of evolutionary thought

Ø Lamarck

Ø Darwin and Wallace

Ø Voyage of the Beagle

Darwin’s theory

Ø Four postulates

Ø Influences on his theory: Hutton, Lyell, Malthus, Wallace

Ø Support for natural selection

Other mechanisms of evolutionary change

Ø Genetic drift

Speciation and Extinction

Evidence for evolution

Ø Fossil record

Ø Geographic distribution

Ø Comparative morphology

Ø Comparative embryology

Ø Artificial selection

Ø Observational examples (resistant bacteria)

Genetic equilibrium

Ø Hardy-Weinberg conditions

How does DNA function as the basic set of instructions for all living things?

Guiding Questions

1. How can the structure and function of DNA and RNA be characterized?

2. How are the structures of DNA and RNA similar and different? How do DNA and RNA molecules replicate themselves? What was the nature of the quest for discovering the source of heredity in living things?

3. What types of methodology were used to conclude that DNA is the genetic material?

4. How can the structure of DNA be described? Who are notable contributors to our knowledge of DNA? What are the roles of DNA and RNA in the construction of proteins?

5. What is involved in the processes of transcription and translation?

6. What are some of the new DNA techniques molecular biologists have created to allow them to identify, study, and modify genetic information?

7. What is the Human Genome Project?

8. What are some issues that have arisen as a result of new DNA technologies?

9. How does DNA function as the basic set of instructions for all living things?

Evolution

How do species change over time?

Guiding Questions

1. What were some early models for how life formed on Earth?

2. What types of evidence support the theory of evolution?

3. How do environmental pressures cause variations in populations?

4. How does natural selection explain the idea of change over time?

Anchor Assessment

Performance Assessment: Correctly Constructed DNA models

Anchor Assessment

Graphing Data from Gene frequency (Beans) Lab OR Evolution (Peppered moth) Lab

DNA Labs

1. Isolating DNA (strawberries)

Strawberry DNA Extraction

And

2. DNA models

DNA models with protein Synthesis Lab

Model Templates

And

3. Who ate the Cheese-Electrophoresis Lab

Electrophoresis Template

Base Pairs of Crime Scene DNA for Who ate the Cheese

Evolution Labs

Evolution (Peppered moth)

Gene frequency (Beans)

Hemoglobin and Fitness

January Vocabulary

HOLT INTERACTIVE “Gene Expression”

Literacy Materials

“Molecular Structure of nucleic Acids”

“Chemical Achievers: Watson, Crick, Wilkins, and Franklin”

“Human, Chimp Ancestors may Have Mated, DNA suggests

Literacy Materials-Evolution

Global warming is spurring evolution, study says

Still evolving, human genes tell new story

New study supports idea that primates, dinosaurs coexisted

Twenty species we may lose in the next twenty years

Hobbit-like human ancestor found in Asia

Fear of snakes, spiders rooted in evolution

Sex speeds up evolution

Rodent has long lineage

Fins to limbs: New fossil gives evolution insight

Spike seen in drug-resistant germ

Fins to limbs: New fossil gives evolution insight

Hard-wired for prejudice

Classification and the Diversity of life

Standard 7: Students shall demonstrate an understanding that organisms are diverse.
CDL.7.B.1

Differentiate among the different domains (Bacteria, Archaea, & Eukarya).
CDL.7.B.2

Differentiate the characteristics of the six kingdoms:

Eubacteria
Archaea
Protista
Fungi
Plantae
Animalia

CDL.7.B.3

Identify the seven major taxonomic categories:

kingdom
phylum
class
order
family
genus
species

CDL.7.B.4

Classify and name organisms based on their similarities and differences applying taxonomic nomenclature using dichotomous keys.

Bacteria, Protists and Fungi

CDL.7.B.6

Compare and contrast the structures and characteristics of viruses (lytic and lysogenic cycles) with non-living and living things.
CDL.7.B.7

Evaluate the medical and economic importance of viruses.
CDL.7.B.8 Compare and contrast life cycles of familiar organisms

sexual reproduction
asexual reproduction
metamorphosis
alternation of generations

CDL.7.B.9

Classify bacteria according to their characteristics and adaptations.
CDL.7.B.10

Evaluate the medical and economic importance of bacteria.
CDL.7.B.11

Describe the characteristics used to classify protists:

plant-like
animal-like
fungal-like

CDL.7.B.12

Evaluate the medical and economic importance of protists .
CDL.7.B.13

Compare and contrast fungi with other eukaryotic organisms.
CDL.7.B.14

Evaluate the medical and economic importance of fungi.

Classification

Ø What is taxonomy?

Ø Explain how living things are organized

Ø Describe binomial nomenclature

Ø Explain Linnaeus’s hierarchical system

Ø Modern evolutionary classification

o Cladistics and acquired characteristics

o Explain evolutionary relationships

Ø Kingdoms and Domains

o Name the six kingdoms and explain characteristics of each

o Describe domain system of classification

Microbiology

Ø Viruses and Bacteria

Ø Protists

Multicellular organisms – structure and function

Ø Fungi

How do scientists organize all the known living things on Earth?

Guiding Questions

1. What do taxonomists use to determine similarity between organisms?

2. How does taxonomy lend insight into the process of evolution

3. What are the major divisions in the modern classification system?

Why are bacteria, protists and fungi so abundant, diverse and successful?

Guiding Questions

1. How do microscopic organisms affect our lives?

2. How do viruses compare to organisms? What are the components of a typical virus?

3. How do viruses replicate?

4. How are viruses specific to particular host cells?

5. How does the virus that causes AIDS reproduce?

6. How can the spread of AIDS be prevented

7. What are the distinguishing characteristics of monerans, protists, and fungi in terms of anatomic features, food getting and reproductive methods; metabolic activities, and environmental responses?

Anchor Assessment:

Cladistics Lab

Cladogram

Anchor Assessment

Project Based Assessment:

Wanted Poster

Students construct a wanted poster on any disease causing bacteria or virus. At minimum it must include a picture, a description of the microorganism and the symptoms it causes

Classification Labs

Cladistics Lab

Dichotomous Key Lab (Mythological Creatures &/or Sharks)

PamishanTaxonomy

Virology Lab

Patient Zero

Communicable Disease Lab (LRSD Lab Handbook)

And

Bread Mold Lab(LRSD Lab Handbook)

February Vocabulary

Literacy Materials (classification)

Creating order out of chaos

It’s alive

Stinging fire ants have good points

Group revamps world of taxonomy

Linnean naming system faces challenges

Team races to catalog every species on earth

Literacy Items (Microorganisms)

The mighty worm

Device uses sewage bacteria to produce electricity

Plants
CDL.7.B.15

Differentiate between vascular and nonvascular plants.
CDL.7.B.16

Differentiate among cycads, gymnosperms, and angiosperms.
CDL.7.B.17

Describe the structure and function of the major parts of a plant:

roots
stems
leaves
flowers

CDL.7.B.18

Relate the structure of plant tissues (epidermal, ground, and vascular) to their functions.
CDL.7.B.19

Evaluate the medical and economic importance of plants.

CDL.7.B.5

Investigate Arkansas’ biodiversity using appropriate tools and technology.

Ø Plants

o Vascular vs. non-vascular plants

o Tissue types

What is the importance of plants in our lives?

Guiding Questions

1. What are distinguishing differences between nonvascular and vascular plants?

2. What specific roles do dermal, vascular, and ground tissues play in plants?

Anchor Assessment:

Lab Report on Seed germination inquiry lab

Seed germination inquiry lab

Flower Dissection

Seed Identification and Dissection

Fruit Dissection

March Vocabulary

Literacy Materials(Botany)

Natural plant defenses- fight or flight?

Soil fertility in agricultural systems

Power or plants

April

CDL.7.B.2

Differentiate the characteristics of the kingdom Animalia

CDL.7.B.20

Identify the symmetry of organisms:

radial
bilateral
asymmetrical

Ø Animals

o Animal characteristics: symmetry, anatomy, physiology

What are the similarities and differences among animals?

Guiding Questions

1. What are the basic body plans of all animals?

2. Why are body plans useful in classifying animals?

Anchor Assessment:

Animal Phyla Lab-Correct Phyla Descriptions

Animal Phyla Lab

May

Differentiate the characteristics of the kingdom Animalia .

Compare and contrast the major invertebrate classes according to their nervous, respiratory, excretory, circulatory, and digestive systems

Differentiate the characteristics of the kingdom Animalia.

Compare and contrast the major vertebrate classes according to their nervous, respiratory, excretory, circulatory, digestive, reproductive and integumentary systems.

Compare and contrast life cycles of familiar organisms

sexual reproduction
asexual reproduction
metamorphosis

Invertebrates

Dissection and comparative anatomy

Vertebrates

Dissection and comparative anatomy

Why are invertebrates so diverse, successful and abundant?

Guiding Questions

1. How are the body plans of invertebrates different from those of vertebrates?

2. What are the eight major invertebrate phyla and the major characteristics of each in terms of anatomical features; food getting and reproductive methods; metabolic activities; and environmental responses?

How does the spinal cord allow diversity in the form and function of vertebrates?

Guiding Questions

1. What distinguishes chordates from other animals?

2. What are the major structural and functional adaptations found in fish, amphibians, reptiles, birds, and mammals? What are the major vertebrate systems that can be studied and compared?

3. How did the evolution of the spinal cord allow for diversity in the form and function of vertebrates?

Labeled/colored diagram from Earthworm Dry Lab

Grasshopper Dissection

Frog dissection on FrogGuts

Pig Dissection

(FroGuts Software-link to brochure)

Literacy Materials

Suicide grasshoppers brainwashed by parasite worms

Toads that go pop in the night

Weapons of Mouse destruction?

Earth’s uncanned crusaders: Will sardines save our skin?

Owls use dung to “fish” for beetles

Lab 11a Behavior Ap

Lab 11 Animal Behavior

Introduction:

Ethology is the study of animal behavior. An animal’s behavior is its response to sensory input. There are three types of behaviors: orientation, agonistic, and mating.

Orientation behaviors take the animal to its most favorable environment. Taxis is when an animal moves toward or away from a stimulus. Taxis is often characterized by light, heat, moisture, sound, or chemicals. Kinesis is another type of movement that involves orientation. Kinesis is a movement that is random and doesn’t involve a stimulus. So an animal would respond to light by moving everywhere in random directions.

Agonistic behavior is when animals respond to each other in aggressive or submissive movements. Like the hair on dogs backs when they get ready to fight. Another excellent example is the Betta fish, which is sometimes studied in labs.

Mating behaviors are activities that involve finding, courting, and mating with a member of the same species. An example would be a peacock fluffing up its feathers to attract females.

Hypothesis:

Pill bugs will prefer the wet side to the dry side of the petri dishes because they are used to living in dark moist conditions, such as under rocks or in rotting trees.

Materials:

Materials used in this experiment involved: a double petri dish combination, 10 pillbugs, bedding material, scissors, pencils, 2 pieces of filter paper, a piece of black construction paper, and a watch.

Methods:

Place 10 pillbugs in the petri dishes along with a little bedding material in each container. Observe them for about 10 minutes noting any observations that are characteristic to the bugs. Once that is done, take a piece of filter paper and soak it in water, then put the wet piece in the bottom of one of the containers. Put the other dry paper in the bottom of the other container. Put 5 pillbugs on each side and count how many bugs there are on each side every 30 seconds for 10 minutes.

Our designed experiment involved the same methods except substituting filter paper with a piece of black construction paper. Cut out the circular paper from a sheet of black paper and put it in one of the containers along with some bedding material. Place 5 pillbugs on each side and count how many there are on each side every 30 seconds for 10 minutes.

Results:

Table 11.1

Time (mins)	Number in wet Chamber	Number in dry Chamber
0	5	5
.5	9	1
1.0	8	2
1.5	8	2
2.0	9	1
2.5	10	0
3.0	9	1
3.5	7	3
4.0	9	1
4.5	9	1
5.0	8	2
5.5	7	3
6.0	9	1
6.5	7	3
7.0	7	3
7.5	7	3
8.0	8	2
8.5	9	1
9.0	7	3
9.5	8	2
10.0	9	1

Table 11.2

Time (Mins)	Number in wet Chamber	Number in dry Chamber
0	5	5
.5	9	1
1.0	6	4
1.5	7	3
2.0	5	5
2.5	6	4
3.0	5	5
3.5	7	3
4.0	6	4
4.5	8	2
5.0	3	7
5.5	2	8
6.0	6	4
6.5	0	10
7.0	2	8
7.5	5	5
8.0	0	10
8.5	2	8
9.0	1	9
9.5	5	5
10.0	7	3

1. What conclusion do you draw from your data? Explain physiological reasons for the behavior observed in this activity.

– The bugs preferred it in the wet conditions. They probably like it there because they live in place like that, under rocks or in trees or just in the soil. That is probably the only way they can keep cool and obtain moisture.

2. Obtain results from all lab groups in your class. With respect to humidity, light temperature, and other environmental conditions, which types of environment do isopods prefer? How do the data support these conclusions? Give specific examples.

– Our class didn’t exchange data with each other.

3. How do isopods locate appropriate environments?

– They use their antennae for a lot of their locating. One thing that I observed was they did use their antennae when they were walking around. They probably don’t have very good eyesight.

4. If you suddenly turned a rock over and found isopods under it, what would you expect them to be doing? If you watched the isopods for a few minutes, how would you expect to see their behavior change?

– I would expect them to scurry around, probably find and tunnel and go down it to keep out of the sunlight. If you found one that wasn’t already underground, I would probably see it walking out in the grass, looking for another object to go under.

5. Is the isopod’s response to moisture best classified as kinesis, or taxis? Explain your response.

– I think it’s best classified as kinesis because they moved around in random directions. Some of them just sat there while the others were moving around.

1. Select one of the variable factors above, and develop a hypothesis concerning the pillbug’s response to the factor.

– Background Color- I hypothesize that the pillbugs will prefer the dark background color over the light background color because they are used to living in dark places for most of their lives.

2. Use the material available in your classroom to design an experiment. Remember that heat is generated by lamps.

A) State the objective of your experiment.

– To see if background color has anything to do with behavioral responses in pillbugs to their environment.

B) List the materials you will use.

– Scissors, black construction paper, pillbugs, petri dish containers, and bedding material, as well as a watch.

C) Outline your procedure in detail.

– Our designed experiment involved the same methods as the real experiment except substituting filter paper with a piece of black construction paper. Cut out the circular paper from a sheet of black paper and put it in one of the containers along with some bedding material. Place 5 pillbugs on each side and count how many there are on each side every 30 seconds for 10 minutes.

Error Analysis:

Not many things could have drastically changed our results. All we had to do was to watch them and watch the time. If the bugs were forced into one of the chambers then that could have changed our results. Also if we hadn’t had kept a good time method then we could have been lost.

Conclusions:

The bugs like it in the wet environment because that is what it’s used to. It’s an easy way to get water and stay cool in their environment. They also liked the dark background because, again, that is what they are used to in their environment, under rocks or other things.

Lab 3 Sample Ap Mitosis & Meiosis

Mitosis and Meiosis

Introduction
There are two types of nuclear division, mitosis and meiosis. Mitosis is usually used for the growth and replacement of somatic cells, while meiosis produces the gametes or spores used in an organism’s reproduction.

Mitosis is the first of these studied in this lab. It is easily observed in cells that are growing at a rapid pace such as whitefish blastula or onion root tips, which are used in this lab. The root tips contain an area called the apical meristem that has the highest percentage of cells undergoing mitosis. The whitefish blastula is formed directly after the egg is fertilized. This is a period of rapid growth and numerous cellular divisions where mitosis can be observed.

Just before mitosis the cell is in interphase. In this part of the cell cycle the cell will have a distinct nucleus and nucleoli where the thin threads of chromatin are duplicated. After duplication the cell is ready to begin mitosis and its starts with a step called prophase. In prophase, the chromatin thicken into distinct chromosomes and the nuclear envelope breaks open releasing them into the cytoplasm. The first signs of the spindle begin to appear. Next the cell begins metaphase, where the spindle attaches to the centromere of each chromosome and moves them to the same level in the middle of the cell. This level position is called the metaphase plate. Anaphase begins when the chromatids are separated and pulled to opposite poles. Then, the final stage is telophase. The nuclear envelope is reformed and the chromosomes gradually uncoil. Cytokinesis may occur, in which case, a cleavage furrow will form and the two daughter cells will separate.

Meiosis is more complex and involves two nuclear divisions. The two divisions are called Meiosis I and Meiosis II and they result in the production of four haploid gametes. This process allows increased genetic variation due to crossing over where genes can be exchanged. The process, like mitosis, depends on interphase to replicate the DNA. Meiosis begins with Prophase I. In this stage, homologous chromosomes move together to form a tetrad and synapsis begins. This is where crossing over occurs resulting in the recombination of genes. Metaphase I moves the tetrads to the metaphase plate in the middle of the cell, and Anaphase I reduces the tetrads to their original two stranded form and moves them to opposite poles. Telophase I then prepares the cell for its second division. Meiosis II generally resembles mitosis except that the daughter cells are haploid instead of diploid. DNA replication does not occur in Interphase II, and prophase, metaphase, anaphase, and telophase occur as usual. The only change is the number of chromosomes.

The process of crossing over can be easily studied in Sordaria fimicola, an ascomycete fungus. Sordaria form a set of eight ascospores called an ascus. They are contained in a perithecium until they are mature and ready for release. Crossing over can be observed in the arrangement and color of these asci. If an ascus has four tan ascospores in a row and four black ascospores in a row (4:4 arrangement), then no crossing over had taken place. However, if the asci has black and tan ascospores in sets of two (2:2:2:2 arrangement) or two pairs of black ascospores and four tan ascospores in the middle (2:4:2 arrangement), then crossing over had taken place.

Hypothesis
Mitosis occurs in whitefish blastula and onion root tip, and it is easily observable. Meiosis and crossing over occurs in the production of gametes and spores.

Materials
This lab requires prepared slides of whitefish blastula, onion root tips, and Sordaria, pencil, paper, a light microscope, and a chromosome simulation kit.

Methods
Exercise 3A.1: Observing Mitosis

Prepared slides of whitefish blastula and onion root tips were observed under the 10X and 40X objectives. A cell in each stage of mitosis were identified, and then sketched.

Exercise 3A.2: Time for Cell Replication

Using a high power objective, every cell in a field of view was observed. Each cell was counted as being in one of the stages of mitosis and recorded. At least 200 cells and 3 fields of vision were counted and recorded. Next, the percentage of cells in each stage was recorded and the amount of time spent in each phase was calculated.

Exercise 3B.1: Simulation of Meiosis

In this part of the lab, a chromosome simulation kit was used to demonstrate meiosis. Two strands of the same color were connected to simulate DNA replication in both of the homologous pairs. Next, the chromosomes were entwined to represent synapsis. Sections of beads were switched between the pairs as in crossing over and were aligned at the equator. Next, anaphase was simulated as the homologous pairs were separated and then telophase was simulated by pushing the chromosomes into two separate cells (circles).

Meiosis II was simulated as well. The DNA is not replicated in Interphase II. The chromosomes again move to the equator and in Anaphase II the two chromatids were separated and moved to opposite poles. Telophase II separates them into four different cells.

Exercise 3B.2: Crossing Over during Meiosis in Sordaria

Prepared slides of Sordaria fimicola were observed under a light microscope. Over 100 asci were identified as either 4:4 or asci showing crossover and recorded. The percentage of each and the map units were calculated.

Results

Whitefish Blastula

Onion Root Tip

Table 3.1: Time for Cell Replication

Number of Cells
Field 1	Field 2	Field 3	Total
Interphase	42	36	47	125	61.27%	14 hours 42 minutes
Prophase	10	13	18	41	20.10%	4 hours 49 minutes
Metaphase	6	5	4	15	7.35%	1 hour 46 minutes
Anaphase	2	3	2	7	3.43%	49 minutes
Telophase	7	5	4	16	7.84%	1 hour 59 minutes
				204

Table 3.2: Compare Mitosis and Meiosis

	Mitosis	Meiosis
Chromosome number of parent cells	Diploid (2n)	Diploid (2n)
Number of DNA replications	Once	Once
Number of divisions	One	Two
Number of daughter cells produced	Two	Four
Chromosome number of daughter cells	Diploid (2n)	Haploid (n)
Purpose	Growth and repair	Production of gametes or spores

Simulation of the Meiosis I

Table 3.3: Sordaria

Number of 4:4

Number of Asci Showing Crossover

Total Asci

% Asci Showing Crossover Divided by 2

Gene to Centromere Distance (Map Units)

117

27.35%

27.35

Meiosis with Crossing Over – 2:4:2 Arrangement

Questions:

Why is it more accurate to call mitosis “nuclear replication” rather than “cellular division”?

It is more accurate to say “nuclear replication” to describe mitosis because the actual cell splitting occurs in cytokinesis. The whole process of mitosis is a series of steps that split the nucleus into two separate nuclei at opposite poles.

Explain why the whitefish blastula and onion root tips are selected for a study of mitosis.

The blastula is a hollow ball of cells that forms from the fertilization of an egg. Rapid growth occurs and numerous cellular divisions making mitosis in various stages easy to observe. Onion root tips are also a region of high percentage of cells going through mitosis because this is where most of the root growth takes place.

If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results differ?

There would be virtually no cells undergoing division, so many more of the cells observed would have been in interphase where they elongate an differentiate.

Based on the data in Table 3.1, what can you infer about the relative length of time an onion root-tip cell spends in each stage of cell division?

Prophase is the longest stage of mitosis and then going in sequential order each decreases in the length of time it takes to complete.

List three major differences between the events of mitosis and meiosis.

In mitosis, the nucleus is only divided once, while in meiosis the nucleus is divided twice. Another difference is that mitosis produces two identical daughter cells, but meiosis produces up to four different daughter cells. Also, synapsis and crossing over do not take place in mitosis, but do take place in meiosis.

How are Meiosis I and Meiosis II different?

Meiosis I begins with a tetrad and separates the homologous pairs. Meiosis II separates the two sister chromatids.

How do oogenesis and spermatogenesis differ?

Oogenesis produces an egg cell, while spermatogenesis produces sperm cells.

Why is meiosis important for sexual reproduction?

In meiosis the chromosome number is reduced to n so that it can be fertilized. Also, meiosis allows for crossing over, which results in variations in organisms.

Error Analysis
There was little chance for error in this lab. It was mostly observation and sketching. However in Exercise 3A.2, the numbers for telophase were off. The calculations obtained for its time were too high; it should have been the shortest stage of meiosis. This may be caused by misidentifying the stages or counting the daughter cells as two different cells. Misidentification could have caused errors in the other parts of this lab as well.

Discussion and Conclusion
Mitosis was observed and timed in Lab 3A. The stages of mitosis are prophase, metaphase, anaphase, and telophase, prophase being the longest and telophase the shortest. Meiosis was simulated in Lab 3B and then crossing over was observed in Sordaria and the map units were determined. The gene to centromere distance in the Sordaria was 27.35 map units.

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