Unit 1 Biology 2007

Unit 1Biology

2007Unity and Diversity

Area of study 1Cells in action

Name: _____________

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Unit 1 Biology 2007

ContentsTimeline 3Outline and key knowledge 4Word of the day 5Activity 1: who Lives Where? 6Worksheet: Viruses 9Information sheet: Plant and Animal cells 10Assessment Task 1: Investigating Cell Organelles 11Information Sheet: Building and transporting proteins 13Activity 2: Cell Diversity 14Information Sheet: Cellular Processes 19Activity 3: Cellular Respiration and Photosynthesis 20Information Sheet: Aerobic respiration 25Information Sheet: Photosynthesis 26Activity 4: Modelling a cell 27Activity 5: Transport of material into and out of a cell 33Worksheet: Biochemistry of cells 41Activity 6: Modelling mitosis and meiosis 43Assessment Task 2: Journey into a cell 45Revision 46

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Unit 1 Biology 2007

TimelineWeek

Theory/Reading Activities

1.1 OverviewClassification of cellsCell structure and function

Activity 1: Who Lives Where?AT 1: Investigating Cell Organelles

1.2 Cell structure and function Activity 2: Cell DiversityAT 1: Investigating cell organelles

1.3 Cellular processesRespirationPhotosynthesis

Activity 2: Cell DiversityActivity 3: Cellular respiration and photosynthesis

1.4 Cell structure and function AT 1: Investigating cell organelles presentationsActivity 4: Modelling a cell

1.5 Cellular processesTransport

Quiz: cellular structure and functionActivity 5: Transport of materials in cells

1.6 Biochemistry of cellsCell Division

Worksheet: Biochemistry of cellsActivity 6: Modelling Mitosis

1.7 Functioning Organisms Revision

1.8 Test: CellsVac* This is a guide only as other factors may impact on actual available classtime.

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Unit 1 Biology 2007

Cells in actionThis area of study focuses on the activities of cells. Students investigate the relationship between specialised structures of cells and the processes that maintain life. All organisms, whether unicellular or multicellular, require a relatively stable internal environment for optimal functioning. Students examine how membranes contribute to survival of cells by controlling the movement of substances within cells, and between cells and their external environment. Students undertake practical investigations into cell structure and functioning in autotrophs and heterotrophs. They consider the development of ideas and technological advances that have contributed to our knowledge and understanding of cell biology. Students investigate the implications of current and emerging techniques and technologies that make use of, and further our knowledge of, cells as functional units.

Outcome 1

On completion of this unit the student should be able to design, conduct and report on a practical investigation related to cellular structure, organisation and processes.

To achieve this outcome the student will draw on the key knowledge outlined in area of study 1, and key skills listed on page 12.

Key knowledge

This knowledge includes

cell structure: prokaryotic and eukaryotic cells at light and electron microscope levels; cellular organisation;

cell functioning: specialised parts of cells and their functions; biochemical processes including photosynthesis and cellular respiration in terms of inputs and outputs; general role of enzymes in biochemical activities of cells;

composition of cells: major groups of organic and inorganic substances including carbohydrates, proteins, lipids, nucleic acids, water, minerals, vitamins; their general role in cell structure and function;

internal and external environments of cells; plasma membranes; membrane transport including diffusion, osmosis, active transport; surface area to volume ratio;

cell replication: purposes of cell replication (mitosis and cytokinesis); cell

growth, cell size and cell division.

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Unit 1 Biology 2007

Word of the dayEach lesson you will be given biological word to research in readiness for the next lesson. This is designed to improve your biological vocabulary as well as encouraging some responsibility for learning!

A basic definition will earn you 5 points, but if you go ahead and be creative such as writing a poem about the term, using it in a sentence which clearly illustrates its meaning, create a comic, or even design some artwork of your own (that means not downloaded from the net!) you can earn up to 10 points. At the beginning of each lesson I will review each persons definitions score and record them; this will ultimately be reported on the slms. The good ones will be displayed around the room.

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Stem cells

AUTOTROPHIC

DNA

Unit 1 Biology 2007

Activity 1: Concept Introduction-Who Lives Where? Most scientists agree that the Earth is approximately 4.5 billion years old. By the time the Earth was approximately 1 billion years old microscopic organisms had found a way to live on the volatile young Earth. However, it would take another 3 billion years before plants and animals would appear. We see that humans, plants and animals have been around for only a very short time in comparison to the time that microscopic organisms have existed. During the last three billion years these tiny life forms have gone through a tremendous evolution so as to adapt to the changing conditions on Earth. They can be found living in almost any environment imaginable. Of great interest to scientists is the unique way that these tiny organisms live in conditions in which all other forms of life fail. By better understanding how these life forms interact with their surroundings we hope to better understand how life could exist in the extreme environments found on other planets and moons in our solar system and beyond.

In this activity you will investigate three hypothetical environments and three bacterial life forms that could exist on Earth. For each we have provided a table with a partial list of characteristics that describe:

1) how the different environments support life and 2) the different needs of each bacteria in order to live within a particular

environment. It will be your task to examine the characteristics that are provided for each environment and bacteria and then, based on this information, you will need to complete each table by deciding which bacteria could live in which environment.

In the table below we have listed the characteristics for each environment and bacteria. In the column next to each characteristic is the possible range of values that you will need to consider when matching each bacterial type with its environment.

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Unit 1 Biology 20071. Complete (fill in) each of the tables for these hypothetical environments and

bacteria by determining which of the bacteria could live in which of the environments.

* The process of making glucose (sugar) from its own breakdown products or from the breakdown products of lipids (fats) or proteins. Gluconeogenesis occurs mainly in cells of the liver or kidney.

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Unit 1 Biology 20072. State which bacteria (A, B, or C) you decided could live in which environment (X,

Y, or Z.)3. How did you choose which environment bacteria A could live in? How did you rule

out the other environments? What characteristics of the other environments made them too extreme for bacteria A? What were the determining/limiting characteristics for the other bacteria and their corresponding environments? Explain your reasoning.

4. Which of the bacteria use a carbon source that is organic and which of them use a source of inorganic carbon?

To describe how bacteria interact with their environment it is useful to consider the different ways the bacteria use energy and produce or consume food. To describe these different processes we use the following labels.

chemoUses Chemical

Energy

photoUses light or

photon energy

and autotrophUses an inorganic

carbon source

HeterotrophUses an organic carbon

source

By combining the label for how the bacteria uses energy (chemo or photo) with the label that describes the type of carbon source needed by the bacteria (autotroph and heterotroph) we can generate a label that describes the interaction between the bacteria and its environment.

5. Label bacteria A, B, and C using the labels above.

6. Which of these bacteria live anaerobically and which live aerobically? Explain how you know.

7. Life forms that can live in extreme environments are often given special names. For instance a "thermophile" can live at extremely high temperatures near the boiling temperature of water. A "psychrophile" can live at extremely cold temperatures near the freezing temperature of water, and a "halophile" is able to live in conditions that have an extremely high concentration of salts.

Which of these hypothetical bacteria (A, B, or C) is a thermophile, a psychrophile or a halophile?

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Unit 1 Biology 2007

Viruses: the Living Dead?

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Unit 1 Biology 2007

Information Sheet: Plant and animal cells

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Unit 1 Biology 2007

Assessment Task 1: Investigating Cell OrganellesIn this section we are looking at cells, considered the basic units of life. Even though cells are the basic units, they also are made up of smaller structures which are highly organised. Just as the body is made up of organs, each having different shapes and functions, so cells contain organelles which also have their own structure and function.

The cell can be compared to a factory, it makes products that need to be packaged and transported to places inside and outside the cell. It needs energy to make its products, and more materials around, and blueprints to work from. The aim of this investigation is to understand how these organelles function individually and together to allow the cell to do its work.

You will be working in groups of 2 to 3 people NO MORE! Each group will be responsible for a different organelle: nucleus, mitochondria, endoplasmic reticulum, chloroplast, ribosome, golgi apparatus and lysosome and vacuole.

Each group is required to produce the following as part of the investigation:1. Oral report: your group will prepare a five to seven minute oral report on the

organelle. You should include the following points: What is the structure of the organelle? Where is it located in the cell? What does it do for the cell (what are its functions)? As well as the model you will need to use other visual aids such as overhead

transparencies, powerpoint presentation, web sites with animations or diagrams and text on the whiteboard.

2. A physical 3D model: your group will build a model that you will use during your presentation to show the rest of the class what the organelle looks like. The model should be constructed of material that may be compared to both the structure and function of your organelle. (For example the membrane might be thin and flat to represent structure. The mitochondria might contain sugar to represent function.) Points to consider: The model will be displayed in the room after you make your presentations. Be creative! Include an index card that has the name of the organelle and a word or very

brief statement about its function

3. A written component: your group needs to complete a portfolio of planning: for example notes from resources, list of resources used, plans for the model with information related to components used, notes for the oral report (if you used transparencies or powerpoint presentation the slides should be included), allocation of roles etc.

Suggested resourcesText: it is recommended you use this as a starting point and should be read before the library lesson.Books: the library has several very good biology texts which will contain useful information.Journals: scientific journals may contain articles related to discoveries about organelles especially with the improvement in technology and nanotechnology.Web: There are some terrific diagrams, electron micrographs, descriptions and animations but be selective some are definitely better than others!

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Unit 1 Biology 2007Hints

Once you have done some reading, brainstorm as a group about how you might present the information and what visual aids you will use as part of the presentation.

Before your research day make some decisions about how to build your model and what materials you will need. Also decide who work on this aspect.

During the next few days you will have the opportunity to examine real cells under the microscope and electron micrographs to assist your understanding.

AssessmentYour grade for this task will be based on:

How well your presentation (including the model and written component) clearly presents the structure and function of your organelle.

An open book quiz (to be taken after the presentations), which will cover all the organelles.

VH

H M L VL

NS

Information(25)

Inclusion of relevant informationEvidence of researchAppropriateness of language

Presentation(20)

Involvement of group membersClarity of presentationQuality of visual aids

Model(10)

CreativityConstruction

Written Component(10)

PlanningResources

Ability to work effectively as a team: effective communication, time management, negotiation, division of labour etc(10)Quiz(25)Total(100)Grade

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Unit 1 Biology 2007Information Sheet: Building and Transporting Proteins

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Unit 1 Biology 2007

Activity 2: Cell DiversityCells are very diverse in their structure and function, but most contain the same basic structure. In this investigation you will look at a number of different eukaryotic cells to determine the nature of the structures within them. You are required to make diagrams, interpret your observations and do some basic research and analysis, Questions have been included which you are expected to answer in full to develop your understanding of the nature of cells. These questions, or similar, will form the basis of one of the SAC’s related to this outcome.

Key KnowledgeStudents should be able to demonstrate knowledge of• Cellular environments• Cell structure, functioning and specialization• Experimental methods used to investigate cells

Key skillsStudents should demonstrate the ability to• Distinguish between prokaryotic and eukaryotic cells• Identify cellular organelles and state their function• Compare plants and animal cells• Relate cell functions to the survival of unicellular and multicellular organisms• Use microscopy techniques to section, stain, examine and draw cells• Analyse and draw valid conclusions from data

Before you start!A microscope allows us to see things that are too small to be seen with the naked eye, and whilst this is useful, being able to estimate the actual size of such an object is also important, especially when comparing prokaryotic and eukaryotic cells.We will be using one similar to that pictured below.

Before you use one of these microscopes you must watch the demonstration by your teacher on their use.

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Unit 1 Biology 2007Part A: Biological Drawing and Staining1. View the prepared slides of stained cheek cells under the microscope. Make a

labelled drawing of the cheek cell stained with methylene blue as seen under high power (H.P.). Remember you need to focus and centre the slide on L.P. first!

2. You should observe and include in your diagram the plamsa membrane, nucleus, nucleolus, granula cytoplasm and nuclear membrane.

3. Now observe the unstained cheek cells and record any differences with respect to the stained material. Classify the differences by indicating whether they were advantageous or disadvantageous.

4. Collect a piece of onion tissue from your teacher and place on the microscope slide. Ensure no overlapping occurs, Place one drop of water onto the tissue. Place one edge of a cover slip next to the tissue and then gently lower the cover slip over the tissue. View the unstained tissue under H.P. (remember you need to focus and centre the slide on L.P. first!)

5. Repeat step 3 but use a drop of methylene blue instead of water this time.

6. Draw a H.P. labelled diagram of three to four stained onion cells. Include cell wall, nucleus, granular cytoplasm, 2 nucleoli and nuclear membrane.

Onions have layers!

7. Compare the stained and unstained onion tissue and note any differences. Classify the differences by indicating whether they were advantageous or disadvantageous.

8. How many layers of cells are there in this sample? Justify your answer.

9. Make a sketch of what you believe the three dimensional shape of an onion cell to be. Explain why you think so.

10. What are the similarities and differences between the plant and animal cells?

11. Explain why other structures, although possibly present in the cells, were not observed.

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Unit 1 Biology 2007Part B: Cell DiversityA number of microscope slides of both preserved and fresh material are provided. You are required to view all of the slides.

Paramecium (video and prepared slides)Paramecium are single celled organisms found in pond water.

1. Draw a H.P. diagram of a paramecium sp. including; cell membrane, cilia, pellicle, food vacuole, contractile vacuole.

2. Summarise the function of the organelles observed.3. Explain how a paramecium sp. might utilise the processes of pinocytosis,

phagocytosis and exocytosis.4. Explain why the paramecium sp. needs the contractile vacuoles (some

research will be necessary!).5. Identify one other organelle that would be expected to assist with the action

of the cilia and contractile vacuoles. Explain how it would assist these organelles.

Nitella (Prepared specimen)

Nitella is an aquatic plant with very large cells.

6. Make a L.P. drawing of a portion of an unstained cell. Include the cell wall, chloroplasts, cytoplasmic strands, nucleus and nuclear membrane.

7. Notice the cytoplasmic streaming (movement of material around the cell), Why does Nitella possess cytoplasmic streaming whereas many other cells you have observed did not?

8. Observe a cell that has been stained with iodine. Note differences relative to the unstained material and classify them as advantageous or disadvantageous.

9. Indicate the function of the cell wall, chloroplasts and cytoplasmic strands.

Blood Smear (Human Stained – prepared)10. Based on your observations of the cells, draw a likely three dimensional shape

for the red blood cells. Estimate its size based on your knowledge of the field of view diameter. What advantage is this shape to the red blood cells?

11. Red blood cells have very few organelles. How might this assist its function? Mature red blood cells do not possess a nucleus. Is it correct to say that it never possessed a nucleus? Explain.

12. Suggest a likely explanation for the significant differences in shape and structure between red and white blood cells.

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Unit 1 Biology 2007Giant Multipolar Neurone (prepared stained specimen)

13. Draw a H.P. labelled diagram of a single neurone (nerve cell). Include plasma membrane, nucleus, nucleus, soma (cell body) dendrites and axons.

14. Research on what basis a nerve impulse passes along a nerve from one neurone to the next.

15. How is a nerve cell specialised to carry out its function.

Part C: Electron MicroscopyThis section refers to a series of electron micrographs of mitochondrion, golgi apparatus, a synapse and a euglenoid. Copies are in this instruction sheet, but larger copies will be on display in the laboratory. There are also samples in your text which you may refer to.

Mitochondrion (Longitudinal section)1. What is the function of a mitochondrion?2. Label the diagram provided: outer membrane, cristae, inner membrane and

matrix.

3. What can be inferred about a cell that has a relatively high proportion of

mitochondrion with respect to its volume?

Golgi Apparatus and Ribosomes4. What is the function of golgi apparatus?5. Identify and label the golgi apparatus and at least one ribosome on the

diagram.

6. What is the function of a ribosome?7. What can be inferred about a cell with a high proportion of golgi bodies as well

as a high proportion of ribosomes relative to other cells?8. Briefly outline the process of protein production stating the role of at least

four organelles found in a eukaryotic cell.9. Explain why golgi bodies, ribosomes, mitochondria and endoplasmic reticulum

were not observed using a light microscope.

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Unit 1 Biology 2007EuglenoidIdentify the following organelles on the diagram:

1. Nucleus2. Nucleolus3. Mitochondria4. Golgi bodies5. Chloroplasts

Just in case you thought you had finished a few questions to conclude!1. Explain why the plasma membrane was not observed in many of the plant and

protist cells?2. Use a table to summarise the similarities and differences between plant and

animal cells.3. In this investigation we concentrated on eukaryotic cells. How do prokaryotic

cells differ from eukaryotic cells?4. Suggest possible explanations for the following observations:

a) flight muscles fibres of bats contain very large numbers of mitochondria.

b) one kind of cell has a prominent golgi complex, while another kind of cell appears to lack this organelle.

5. Which organelles in a cell are responsible for:a) control centre of the cellb) site of entry or exit of substances to or from a cellc) energy sourced) internal transport systeme) site of packaging for export from the cellf) “self-destruct button” for the cell

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Unit 1 Biology 2007

Information Sheet: Cellular Processes

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Unit 1 Biology 2007

Activity 3: Cellular Respiration and PhotosynthesisPart A: Respiration1. Write the word and balanced chemical equation for cellular respiration.

2. Complete the following sentences using the words in the list. Some words may be used more than once.

aerobic anaerobic ATP carbon dioxidecells cellular respiration cytoplasm diffusionenergy enzymes glucose glycolysismitochondria osmosis oxygen pHphotosynthetic temperature two water

Respiration is the process by which the _____________ of an organism obtain the energy they require from the food that they have consumed or in the case of ________________ organisms the carbohydrate they produce. The most common type of cellular respiration is aerobic respiration, which involves the use of ______________ in the breakdown of organic molecules such as ________________. During this process, energy contained in the organic molecules is converted into a form that can be used by the cell and the organism for growth, maintenance, reproduction or other essential processes. This process occurs in ______________ stages. The first stage, _______________ ,does not require ________________________ and occurs in the __________________ of the cell. It is called _________________. For each molecule of glucose, glycolysis produces small amounts of _______________ very rapidly. This is in the form of ________ which can be easily used by the cell. The second stage of energy release is called ________________________________. It is ___________________ and requires the presence of oxygen to occur. This stage occurs in the _______________________ of the cell and produces almost 20 times the number of _______________ molecules than is produced by glycolysis. The process is under the control of _________________ and is therefore influenced by such things as __________________ and _____. During the process of breaking down the glucose, other products are formed. These are ______________ and ___________________ which are then removed by the cell by the processes of _________________ and _________________.

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Unit 1 Biology 20073. Draw a flow chart demonstrating the various stages of cellular respiration and

where they occur.

4. State at least five uses a cell might have for the energy produced by aerobic respiration.

5. What is fermentation?

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Unit 1 Biology 20076. Our muscles are able to carry out both aerobic and anaerobic respiration.

Describe circumstances under which you would expect them to carry out each process.

7. Mammals and birds maintain relatively stable body temperatures that are usually slightly higher than their surroundings. What would be the advantages and disadvantages of this?

Part B: Photosynthesis8. Write the word and balanced chemical equation for photosynthesis

9. In what type of cells does photosynthesis usually occur and where are they found in the plant?

10. What organelle is the site of photosynthesis? Draw a labelled diagram of this structure.

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Unit 1 Biology 2007

11. Complete the following table.Compound required Compound(s)

producedPart of chloroplast where process occurs

Stag

e

Light

de

pend

ent

Light

In

depe

nden

t

12. Summarise the importance of photosynthesis to humans and other animals.

13. What are the ideal conditions for photosynthesis? Explain why.

Part C In the table state the main characteristics of photosynthesis and respiration.Respiration Photosynthesis

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Unit 1 Biology 2007

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Unit 1 Biology 2007

Information Sheet: Aerobic respiration

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Unit 1 Biology 2007

Information Sheet: Photosynthesis

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Unit 1 Biology 2007

Activity 4: Modelling CellsIn this activity you will be making a three dimensional model of an animal cell.The work should be carried out in pairs, although you will need to share one packet of jelly with another group. Collect the tray of ingredients per pair including a mat to work on.

Before you start, just a few points!Wash your hands thoroughly with soap and warm water! Only work on the mats provided. The mats are used only for working with lollies to minimise any possible contamination but they need to be cleaned thoroughly at the end.You are required to handle boiling water so take extreme care to avoid any burns. Heat proof gloves are available if you wish.

Procedure1. Make up the jelly according to the manufacturers instructions, however to make

the jelly very firm add an extra tablespoon of gelatine to the jelly crystals before you add the boiling water. Make sure you mix the crystals in thoroughly to get a firm jelly. The gelatine will not affect the flavour of the jelly. Each pair should get half the jelly solution.The jelly represents the cytoplasm. What is the role of the cytoplasm in a cell?

2. Line a polystyrene cup with cling wrap. This will make the jelly easier to remove once it has set. Now pour in the jelly solution making sure you leave at least 2 cms from the top of the cup. Label your cup clearly.

a) The cling wrap represents the cell membrane. Outline the functions of the cell (plasma) membrane.

b) There are obvious differences between the cling wrap and a cell membrane. Outline at least two differences.

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Unit 1 Biology 2007c) Are there any similarities? If so what are they?

d) What are the similarities and differences between the set jelly and actual cytoplasm?

You are now going to add the organelles to your model cell.3. First add the gum ball or jaffa. a) This represents the nucleus. If the cell is like a factory, what is the function of the

nucleus?

b) What other structures are found in the nucleus? What is their role?

4. The cell obviously needs energy to function. Add a number of small jelly beans to the jelly solution.

a) What organelle is responsible for providing the energy requirements of the cell in a form that it can utilise?

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Unit 1 Biology 2007b) Name and write a simple chemical equation for the processes that this organelle

undertakes.

c) Draw a diagram of the structure of this organelle. Label the parts and clearly state where each part of the process occurs.

5. The cell also needs to be able to produce a number of different types of substances to assist in its functioning. The role of the ribosomes is to manufacture __________________________. Name 5 different kinds of these.

The ribosomes are represented by 100’s and 1000’s so add a spoonful to the solution and stir.

6. The organelle responsible for transporting materials such as those produces by the ribosomes around the cell is the ________________________________________. This actually fills up quite a bit of the cell. Why?

The thin tubular strips of liquorice should be added to the jelly solution to represent this organelle. How is the structure of the liquorice similar to the organelle? How is it different?

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Unit 1 Biology 20077. The products of synthesis need to be packaged and transported. This is carried

out by the _______________________. Draw a labelled diagram of this organelle and provide a brief explanation of how it carries out its function.

Add the large jelly beans to the jelly solution to represent this organelle.

8. Animal cells also have structures called lysosomes (mini M & M’s). Explain the role of lysosomes in a cell.

9. An animal may also divide. To do this specialised structures called spindles are produced by organelles called centrioles (pieces of musk sticks).

Now place the “cell” in the fridge to set completely. It will be ready for the next lesson.

10. Plant cells differ in a number of ways they contain cell walls as well as cell membranes and vacuoles. Explain the roles of these organelles in a plant cell.

Cells Crossword

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Unit 1 Biology 2007

Across1. Gives plant cells firm regular shape.2. Carbon dioxide and water combine in a special way to form this.3. Bodies which pinch off vesicles at end.4. Site of protein manufacture.5. Keeps cell contents separate from external environment.6. Strong substance that makes up cell walls.7. Spaces between cells are called ____________ cellular spaces.8. Network of membranes attached to the nucleus.9. That which is outside the cell.10. Complex mix of proteins, water and other substances which houses the cell organelles.11. Substance produced by ribosomes.12. Power-house of the cell.

Down13. Vesicles containing enzymes.14. Large fluid filled space found in plant cells.15. Structure in cell with particular function.16. Composed of DNA and protein (found in nucleus).17. Structures responsible for cell transport.18. ER without ribosomes looks _________ under the microscope.19. ER with ribosomes looks __________ under the microscope.20. Nucleic acid found in ribosomes.21. Abbreviation for rough endoplasmic reticulum.21. Organelle found in animal cell which plays a role in division.23. Nucleic acid found in chromosomes.24. Organelle which contains instructions for cell function.

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Unit 1 Biology 2007

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Unit 1 Biology 2007

Activity 5: Transporting materials into and out of a cellOrganisms of any size need to get substances like oxygen, water and glucose into their cells and remove waste products such as carbon dioxide and water. They require these substances for processes such as respiration, synthesis and the break down of materials.

Diffusion is one way a cell can move small solutes into or out of a cell. Diffusion operates bas molecules move constantly in straight lines in random motion. As the molecules bump into one another and other molecules they change direction. In an area of high concentration they will bump into each other and the container more frequently, and eventually they will move into an area that is less congested with other molecules. Eventually over time the molecules are evenly distributed throughout the container they are in.

Place a teabag into a beaker of hot water and observe the movement of the soluble material for at least 10 minutes. Write a description of this movement. Then check again at the end of the lesson and again describe any changes.

Explain how temperature, size of molecules and the concentration of molecules might affect the rate of diffusion.

What compounds might a cell need to move around the cell?

How do plants utilise diffusion?

How do animals utilise diffusion?

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Unit 1 Biology 2007Osmosis relies on the same principle of molecule movement, but refers specifically to the movement of water molecules. In this instance water molecules tend to move from a region of low solute concentration to a region of high solute concentration.

View the video segment of red blood cells. Watch carefully what happens as distilled water is added to the red blood cells.

Describe what happens.

Explain, in terms of osmosis, what has occurred.

Would you expect the same thing to happen with plant cells? Why?

Now view the video segment of the pondweed spirogyra. The initial phase is in pond water.

Draw a few of the cells, making sure you clearly draw and label any observable structure.

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Unit 1 Biology 2007

The video clip will show the spirogyra being irrigated with salt solution. Observe carefully what happens to the spirogyra.

Again draw a few of the cells to show the difference between the two situations. Clearly indicate that the cells are in salt solution.

Explain in terms of osmosis what has occurred.

The video clip should then show the spirogyra being irrigated with distilled water. Again observe carefully what happens.

Draw these cells to illustrate differences in the three situations. Title the diagrams clearly.

Explain, in terms of osmosis what has occurred.

Why did these cells not burst like the red blood cells?

Give an explanation for the fate of each of the following cells:A marine alga washed into a freshwater environment.

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Unit 1 Biology 2007

A marine protozoan cell in freshwater.

A freshwater algal cell in the marine environment,

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Unit 1 Biology 2007The size and shape of cells can also influence the rate of diffusion of materials.In this section you will be modelling the effect of size and shape on the rate of diffusion using agar (gelatine).

Warning: The chemicals used in this activity are dangerous. Do not touch the cubes with your bare hands, use the gloves provided. If you are allergic to latex alternatives are available. Use safety glasses to ensure eye safety and wear a lab coat to protect your clothing.

You have been provided with three cubes of agar of different sizes made with phenolphthalein which gives the cubes their pink colour. Place the cubes in a beaker of sulphuric acid (use only enough sulphuric acid to just cover the cubes). As the sulphuric acid diffuses into the cubes the phenolphthalein will change to clear.

Time how long it takes for each cube to go completely clear in the table below. Then complete the other calculations.

Cube side Time taken to become

clear

Surface areaSA

Volume SA:V

1cm

2cm

3cm

Volume = length x width x heightSurface area = length x width x 6

What causes the blocks to become clear?

What can you assume regarding the movement of the acid as part of the block becomes clear?

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Unit 1 Biology 2007What is the relationship between the SA:V and the time taken for the cube to become clear? Explain in terms of osmosis and diffusion.

As a cell increases in size, what happens to its ability to supply its volume with nutrients?

During the evolution of life on earth, organisms have found survival value in becoming larger. Instead of single cells becoming larger, organism cells have tended to stay microscopic in size and the whole organism has become multicellular. What role does SA:V play in this evolutionary trend?

Given that cells need to obtain their requirements from the surrounding environment and get rid of wastes often by diffusion, it would take a long time for the cells of large multicellular organisms to obtain the requirements or indeed remove the wastes. What feature and structures do these organisms have that allows them to overcome this problem?

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Unit 1 Biology 2007 You have also been provided with some other agar shapes also containing

phenolphthalein. Place these in the beaker of acid ensuring they are covered. Turn them over every two minutes with a plastic spoon. Do not touch the shapes or the acid with you bare hand.

Time how long each shape takes to become clear and record this in the table below. Then complete the other calculations.

Shape Dimensions(cm)

VolumeFormula

Volume SAformula

SA SA:V Time taken to become clear

Sphere r = 1.86 4/3r2 4r2

Sheet L = 9W = 3H = 1

L x W x H

Cube L = 3W = 3H = 3

L x W x H

Cylinder r = 1.7h = 3

r2h 2rh+2r2

Based on the results what would the ideal shape for a cell be? Explain.

In general motile animal cells are smaller (10 – 20 u) than a typical plant cell (30 – 50 u) Use the information gained in this activity to suggest a possible reason for the difference.

Other mechanisms cells use to obtain requirements involve __________________ ________________. The cell can remove wastes by __________________ which involves larger molecules in vesicles. These vesicles ___________ with the plasma membrane and then open to release the contents. _____________________ and ___________________ are the processes by which cells may incorporate molecules into the cell.

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Unit 1 Biology 2007Paramecium is a unicellular organism that lives in freshwater. It has a relatively high internal solute concentration compared with its environment.

Explain in terms of osmosis what you would expect to happen to the levels of water molecules if the organism is in its normal freshwater environment?

What structures does paramecium have to overcome this problem?

How do the structures operate?

How does paramecium obtain the nutrients it requires?

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Unit 1 Biology 2007

Worksheet: Biochemistry of Cells

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Unit 1 Biology 2007

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Unit 1 Biology 2007

Activity 6: Modelling Mitosis 1. In your books construct a table with three columns and 6 rows. Collect a sheet

from your teacher and cut out the diagrams and texts. Place the diagrams in the correct order of the stages of mitotic division in an animal cell and paste them into your books. Then match and paste the correct text label to each diagram. Next to this write a brief statement describing what is occurring.

2. The following diagram illustrates the growing root tip of an onion. Colour in and label the various stages of mitosis.

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Unit 1 Biology 20073. Look at the microscope slide under the microscope of the growing root tip of an

onion. Identify the various stages of mitosis.

4. Collect the “chromosomes, there should be three pairs plus the same number of each again. Using the “chromosomes” supplied, model the various stages of mitosis. Ensure you identify each stage as well to ensure you remember.

5. What are the three main ways organisms utilise mitosis?

6. Instead of growing into one big cell, cell division usually occurs once a cell reaches a certain size. Why is this so?

7. What is cytokinesis? During which stage does this process occur?

8. True or falseTrue Fals

eWhen a cell plate begins to form, the animal cell is at the stage of cytokinesis.When mitosis occurs without cytokinesis, the result is a cell with more than one nucleus.Mitosis is responsible for producing gametes.

Replication of DNA occurs in metaphase.

Interphase is the stage in which the cell remains during most of its life.

A cell usually divides once it reaches a certain size to ensure it can supply its volume with sufficient nutrients and remove wastes.The number of chromosomes in each daughter cell is half that of the parent cell.Cancer is the result of uncontrolled mitosis

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Unit 1 Biology 2007

Assessment Task 2: Journey into a Cell!In this activity you will be writing a creative essay based on factual information about a journey into a cell. This will require you to assemble and edit scientific information on cells, then write and illustrate a creative story. This task aims to further develop your actual understanding of the material.

Step 1: decide what type of cell, plant or animal, you will be writing aboutStep 2: plan and outline your story

Introduction: the setting of your story. How are you getting into the cell? What type of cell are you in? What do you see around you?

Part 2: what is happening to you? Begin to develop the plot. What is it like to be inside a cell? What is the focus of the story? Will you trying to get out of this cell or will something happen to you?

Part 3: continue the adventure. How are you travelling around inside the cell? How are you reacting to what is happening inside the cell. How are the different organelles reacting with you? What are the various organelles doing? How would this look?

Conclusion: resolve the adventure. How will your story end? How will you leave the cell, if you do? Tie up all the loose ends of your story.

Step 3: Now you are ready to begin researching and writing your story. Drafting is always a good idea. Have your teacher check your work.

Step 4: Write and illustrate your story.

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