Seven Q

uest

Topic One: Cells

Comm

ack H

igh Sch

ool SL Biology

0

1.1 U. 1 A ccording to the cell th e or y , li v ing organis m s are co m posed of cells.

1. When do the first cells appear in the fossil record of Earth (Slide 2)

2. the three core ideas of cell theory (Slide 5)I. All living things are made up of cellsII.III.

1. What evidence supports the idea that living organisms are composed of cells? (Slide 8)

a. Living organisms are …

b. Organelles …

c. Cells multiply …

1.1 A. 1 Q uestioning the cell th e ory using at y pical e x amples, in c lud i ng striated m uscle, gi a nt algae and aseptate fu n gal h y phae.

2. For each atypical example outline how it challenges conventional cell theory (Slides 8-13)

a. Striated muscle Challenges the idea that a cell has one nucleus Muscle cells have more than one nucleus per cell Muscle Cells called fibers can be very

long (300mm) They are surrounded by a single plasma membrane but they are multi-nucleated (many

nuclei). This does not conform to the standard view of a small single nuclei within a cell

b. Giant algae

c. Fungal hyphae

d. Blood Cells

e. Bone Cells

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1.1 U. 2 O rganis m s consis t ing of only one cell carry out a ll functi o ns o f life in that cell.

3. State the functions of life, as demonstrated by all living organisms.

1.1 A. 2 In v estigati o n of functio n s of life in P ara m ecium and one na m ed photos y nthetic uni c ellular orga n is m . 4. Below is an image of a paramecium. Label and annotate the image to indicate how it performs

each of the functions of life. (Slide 18)

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5. Below is an image of a paramecium. Label and annotate the image to indicate how it performs each of the functions of life. (Slide 20)

1.1 U. 3 S urface area to v olu m e ratio is i m portant in the li m it a tion of ce l l s i ze.

6. Explain why small cells are more efficient than big cells. (Slides 21-23)

1.1 U.5 Specialized tissues can develop by cell differentiation in multicellular organisms.7. In humans how many different types of cells are there? (Slide 24)

1.1 U. 4 M ulticellular organis m s ha v e properties that e m erge from the interaction of their cell u l a r co m ponents.

7. Unicellular organisms carry out all the functions of life, multi-cellular organisms differentiate and show emergent properties. Describe what is meant by the term emergent properties. (Slide 27)

a. Outline the advantages of cells differentiating to carry out specific functions. (Slide 28)

b. The Hierarchy of Life Video Questions (Slide 26)

I. Using termites, explain emergent properties. (0:49)

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II. How is Biology organized? (1:44)

1.1 U. 6 D ifferentiat i on in v ol v es the e x press i on of so m e genes and n ot others in a cell ’ s gen om e.

9. All cells in an organism share the same, identical, genome (i.e. they all possess the same

genetic information). Describe how newly formed cells become specialized. (Slide 28)

1.1 U. 7 The capaci t y of stem cells to di v ide and differen t iate along d i fferent pat hw a y s is necessary in e m br y onic d e v elop m ent and also m akes stem ce l ls suita b le f o r therapeutic uses.

10. Describe what is meant by the term stem cell. (Slide 29)

11. Define the following types of stem cells. Giving an example of each: (Slide 29)

a. Totipotent

b. Pluripotent

c. Multipotent

d. Unipotent

13. Stem Cell Story (video) (Slide 30)

a. What are the two types of cells stem cells can make when they divide? (4:02)

b. How many skin cells can skin one stem cell make 4:32

c. How many blood stem cells are needed to repair the entire blood system, when fighting leukemia? (6:38)

d. Where do embryonic stem cells come from? (7:16)

e. How many cell types exist in the brain? (10:53)

f. How many people in Belgium currently have diabetes? (12:20)

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1.1 A. 4 E thics of the therapeutic use of stem cells from s pecially cre a ted e m br y o s , from the u m bilical cord blood of a n ew-born baby and from a n adult’s o w n tissu e s.

14. Complete the table to compare the different sources of stem cells available: (Slide 34)

Comparison of stem cell sources

Embryo Cord blood Adult

Differentiation Can differentiate

into any cell type

Limited capacity to

differentiate (without

inducement only

naturally divide into

blood cells)

Genetic damage

Due to accumulation of

mutations through the life of

the adult genetic damage

can occur

Compatibility

5

15. Complete the table to compare the different sources of stem cells available: (Slide 32)

Comparison of stem cell sources

Embryo Cord blood Adult

Ease of extraction Can be

obtained from

excess

embryo’s by

IVF programs

Limited capacity to

differentiate (without

inducement only

naturally divide into

blood cells)

Difficult to obtain as there are very few and are buried deep in

tissues

Ethics of the extraction

Can only be obtained by destruction of an embryo

Growth potential Almost unlimited Reduced potential Reduced potential

Tumor risk Low risk of Development Low risk of Development

Cord blood saving lives Video (Slide 34)

16. What makes up cord blood? (22secs)17. How long can cord blood last? (30 secs)18. What are some diseases that can be treated with cord blood? 19. What is Hurler syndrome? (1:26)

1.1 A. 3 U se of stem cells to tre a t S targardt’s disease a n d one other na m ed condition.

20. Complete the table to detail the use of stem cells in the treatment of specific conditions. (Slides 35-41)

Condition Stargardt's macular dystrophy Leukemia

Outline the condition andthe problems it causes

• Affects around one in 10,000 children

• Recessive genetic (inherited) condition

• The mutation causes an active transport protein on photoreceptor

cells to malfunction

• The photoreceptor cells degenerate• the production of a dysfunctional

protein that cannot perform energy

transport

• that causes progressive, and

eventually total, loss of central

visionDescribe treatment ofthe conditionusing stem cells

The benefit of using stemCells

Stem cells are currently the only

viable treatment for this condition.

Name:

21. Therapeutic cloning remains a controversial area of medicine.a. Outline the main arguments for therapeutic cloning (Slide 42)

•Stem cell research may pave the way for future discoveries and beneficial technologies that would not have occurred if their use had been banned

•May be used to cure serious diseases or disabilities with cell therapy (replacing bad cells with good ones)

•

•

• Cells are taken at a stage when the embryo has no nervous system and can arguably feel

no pain

Stem cells can be created without the need for fertilization and destruction of ‘natural’ human embryos – induced pluripotent stem cells

22. Outline the main arguments against therapeutic cloning (Slide 43)

•Involves the creation and destruction of human embryos (at what point do we afford the right to life?)

•Embryonic stem cells are capable of continued division and may develop into cancerous cells and cause tumors

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•

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• The embryo which is created could potentially be used in IVF and develop into a human fetus, so are we creating human life to destroy it?

• Although cloning humans reproductively is illegal, this has not been ratified by all nations. Potential for a race to clone the first human.

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Name:

I.2 U. 3 E lectron m icroscopes h av e a m uch h igher resolu t ion than lig h t m icrosco p es.

1. State the definition of resolution: (Slide 47)

2. Complete the table below comparing the resolution of the eye with light and electron microscopes: (Slide 47)

resolution

Millimetres (mm)

Micrometres(μm)

Nanometres (nm)

Human eye 100,000

Light microscopes 0.0002

Electron microscopes

0.001 1

3. Explain why electron microscopes have a better resolution that light microscopes. (Slide 47)

4. State what is meant by the term Ultrastructure and how it relates to an electron microscope. (Slide 48)

5. State Outline the scale of objected studied in Biology (Slide 49)

Name:

1.1 S. 1 U se of a lig h t m icrosco p e to in v esti g ate the stru c ture of cel l s and tissu e s, w ith dra w ing of cel l s. C alculation of the m agnification of d r a w ings and the actual si ze of struct u res and ultr a structures s ho w n in dra w ings or m icrographs. ( P ractical 1 )

6. The diagram below shows the characteristic rod-shaped structure of E. coli bacteria.

b. Calculate the magnification of the image.

c. State the method (shown here) by which bacteria reproduce

7. Calculate the actual size of the structures delineated in yellow.

Diatom x 1,000

http://www.mos.org /sln/SEM/diatom.htm l1-'

http://www.mos.org/s ln/SEM/mbead.btm l()

Diatom x 5,000

http://www.mos.org /sln/SEM/diatomb.btml0

Hy odermic needle x100

http://www.mos.org/sln/SEM/needle.h tml0

8. Calculate the magnification of these scale bars using a rule and formula I/AM:

1.2 U. 1 P rokar y otes ha v e a si m ple cell stru c ture w ithout co m part m e n talizatio n . AND 1.2 S. 1 D ra w ing of the ultrastructu r e of prokar y otic ce l ls b a sed on elec t ron m icrographs.

9. Prokaryotes have a simple cell structure.a. Define the term prokaryote. (Slide 55)

b. Draw and label (including function of each part) prokaryote. Include cell wall, plasma membrane, pili, flagella, nucleoid (naked DNA), ribosomes and a scale bar using the hyperlink. (Slide 58)

10.This image is a transmission electron micrograph of a bacterium.

Identify the labelled structures:

I

II

III

IV

1.2 A. 2 P rokar y otes di v ide by binary fission.

11. Outline the process of binary fission (Slide 59)

1.2 U. 2 E ukar y otes ha v e a compart m entalized cell s tru c ture.

12. Plant and animal cells are eukaryotic.a. Define the term eukaryote. (Slide 60)

b. Outline the benefits compartmentalization provides to eukaryote cells compared when with prokaryotes. (Slide 63)

1.2 A. 1 S tructure and function of organelles w ithin e x ocrine gland ce l ls of the pa n creas and w ithin pal i sa d e m esoph y ll cells of the l e af.

13. Complete the table to summary the organelles commonly found in eukaryotes.(Slides 62-74)

Organelle Function Diagram (labelled wherenecessary)

How to identify it on anelectron micrograph

Nucleus

Mitochondrion Site of ATP production by aerobic respiration (if fat is used as a source of energy it is digested here)

Has a double membrane. A smooth outer membrane (2) and a folded inner membrane (1). The folds are referred to as cristae (3). The space inthe middle is called the matrix(4). The shape varies.

Freeribosomes (80S)

• Synthesizes proteins to function in the cytoplasm, for use within the cell, e.g. enzymes

RoughEndoplasmic Reticulum (rER)

• rER synthesizes proteins which are transported, by vesicles, to the golgi apparatus for modification before secretion outside the cell

Image: http://ww w .sciencegeek.net/Biolog y / r eview/g r aphics/Unit2/mitochond r ion.jpg

Organelle Function Diagram (labelled wherenecessary)

How to identify it on anelectron micrograph

GolgiApparatus

Vesicles • Used to transport materials inside of a cell

Lysosomes

Vacuoles • In Plant cells, large and permanent, often occupying the majority of the cell volume

• In animals, smaller and temporary and used for various reasons, e.g. to absorb food and digest it

Flagellum • Used to move the cell

Cilia

Microtubulesand centrioles

Chloroplast • contain chloroplasts• Stacks of thylakoids• The site of photosynthesis

14. Cell walls are not true organelles. (Slide 74)a. What is the function of the cell wall and where can it be found?

b. In plant cells what is the cell wall mainly composed of?

1.2 S.2 Drawing of the ultrastructure of eukaryotic cells based on electron micrographs.

15. The ultrastructure of plant and animal cells is very different.c. Distinguish between the structure of plant and animal cells (Slide 75)

d. Draw and label the ultrastructure of a generalized eukaryote animal cell. Include all the relevant organelles from the two questions above (Slides 76-77)

e. Draw and label the ultrastructure of a generalized eukaryote Plant cell. Include all the relevant organelles from the two questions above.(Slide 78)

1.2 S. 3 Interpretati o n of electron m icrographs to identify organelles a nd deduce t he function of speci a liz e d cells.

16. Deduce the function of each of the following images. For each deduction refer to the identified organelles and argue the evidence. (Slides 79-85)

f. These image show most of a cell membrane and single cell.

http:/ / ww w .vcbio . science. r u.n l /im a ges/tem - plant - ce l l.jpg

1.2 U. 1 P hospholip i ds form bila y ers in w ater due to the a m phipathic properties o f phospholi p id m olecule s .

1. Draw a diagram of a single phospholipid molecule. Label the hydrophobic and hydrophilic sections. (Slide 94)

2. Explain how hydrophobic and hydrophilic properties of the phospholipid bilayer allow a membrane to maintain its structure. (Slide 94)

1.3 S. 1 D ra w ing of the fluid m o s aic m odel.

3. Draw and label a simplified (2D) diagram of the plasma membrane. (Slide 95)Include: phospholipid bilayer, integral and peripheral proteins, glycoproteins and cholesterol.

1.3 A. 1 C holesterol i n m am m alian m e m bra n es reduces m e m brane f l uidity and per m eability to so m e sol u tes.

The hydrophobic hydrocarbon tails usually behave as a liquid. Hydrophilic phosphate heads act more like a solid. Though it is difficult to determine whether the membrane is truly either a solid or liquid it can definitely be said to be fluid. It is important to regulate the degree of fluidity in order that:

• It needs to be fluid enough that the cell can move• It needs to be fluid enough that the required substances can move across the membrane• If too fluid however the membrane could not effectively restrict the movement of substances across

itself.

4. The presence of cholesterol in the membrane restricts the movement of phosolipids and other molecules. How does this affect the physical properties of the membrane? (Slide 96)

5. The presence of cholesterol disrupts the regular packing of the of the hydrocarbon tails of phospholipid molecules. What impact does this have on the physical properties of the membrane? (Slide 99)

1.3. U. 3 C holesterol i s a co m ponent of ani m al cell m e m branes.

6. Cholesterol is a type of lipid, but it is not a fat or oil. What group does it belong to?

7. Cholesterol makes up around about 20% of the mass of cell membranes. This percentage varies greatly and some membranes, e.g. bacteria, do not contain it at all.

a. Where in the plasma membrane can cholesterol be found? (Slide 97)

b. What properties cause it to be located in this position? (Slide 97)

1.3 S. 2 A nal y sis of e v idence from electron m icroscopy that led to t h e proposal o f the D a v son- D anielli m odel.

8. Outline the structure of the Davson-Danielli model of the cell membrane. (Slide 102)

9. Why was the model proposed, what did it help explain? (Slide 102)

10. Outline the Singer-Nicholson fluid mosaic model of the cell membrane. (Slides 104-107)

1.3. U. 2 M e m brane proteins are di v erse in t e r m s of struc t ure, position in the m embrane and function.

http://www.ib.bioninja.com.au/_Media/tracie_med.jpeg

11. List the six main functions of the membrane proteins. (Slide 116)

T :

R :

A :

C :

I :

E :

12. State the functions of glycoproteins found in the plasma membrane (Slide 101)

1.4 U. 1 P articles m o v e across m e m branes by si m ple diffusion, fa c ili t ated diffusi o n, os m osis and acti v e transport.

1. Define selectively permeable in the context of the plasma membrane. (Slide 120)

2. Define diffusion. (Slide 122)

3. Define osmosis.(Slide 125)

4. Distinguish between solute, solvent and solution.

5. Osmosis occurs not just by simple diffusion, but also by facilitated diffusion.

a. Give examples of cells that use facilitated diffusion as well as simple diffusion.

6. Explain what is happening in this diagram:

7. In the space below, draw a diagram of a plant cell before and after plasmolysis. Explain how osmosis causes plasmolysis. (Slides 126-128)

1.4 A. 2 Tissues or o rgans to be used in m edical proced u res m ust be bathed in a solution w ith the sa m e os m olarity as the c y top l asm to prevent os m osi s .

8. Compare cells to the solution there are in as isotonic, hyper or hypotonic: (Slide 129)

a. Isotonic :

b. Hypertonic :

c. Hypotonic :

9. Explain what would happen to the cells of tissues and organs immersed in these solutions: (Slide 129)

a. Isotonic :b. Hypertonic :c. Hypotonic :

10. List the common medical procedures in which an isotonic saline solution is useful. (Slide 131)

11. How do integral proteins move material across a membrane without the use of energy? (Video on Slide 135)

1.4. S. 1 E sti m ation of os m olarity in tissu e s by bathing s am ples in h y potonic and h y pertonic s olutions. ( P ractical 2)

[The below question is in addition to the lab and is used to test your understanding of the procedure. It is not a replacement for it.]

12. An experiment was carried out to estimate the osmolarity of three different varieties of potato. 10mm diameter cores were taken from each variety and their masses recorded. After immersion in different concentrations of sodium chloride solution for six hours the cores were dried and re-weighed. The results are shown below:

Concentration of the sodium

chloride solution (+/-0.1M)

Percentage mass change of potato cores

(+/- 0.01%)

Variety A Variety B Variety C

0.0 12.34 14.38 13.03

0.1 5.86 10.14 7.73

0.2 -3.7 6.56 4.88

0.3 -13.34 -0.5 0.81

0.4 -20.43 -5.73 -6.73

0.5 -24.53 -10.77 -13.68

a. Draw and label a graph to show the results. Your graph should include descriptive axis titles and linear best fit trend lines. (If graph plotting software is used then paste in the printed graph below)

b. Suggest a reason why % change in mass is plotted rather than the absolute change in mass or the final mass of the potato cores.

c. State whether water moved into or out of the different varieties of potato at 0.0M sodium chloride solution. Give evidence to support your answer.

d. State whether water moved into or out of the different varieties of potato at 0.5M sodium chloride solution. Give evidence to support your answer.

e. Deduce which variety of potato had the highest concentration of solutes in its cells.

f. Using the best-fit line estimate the osmolality (in M of sodium chloride solution) of each variety of potato.

Varity A :

Variety B :

Variety C :

13. Annotate the diagram below to show how protein channels are used in the facilitated diffusion of potassium in axons. (Sliden135)

1.4. U. 1 P articles m o v e across m e m branes by si m ple diffusion, fa c ili t ated diffusi o n, os m osis and acti v e transport. C ont’d

14. ATP is the source of energy for active transport. Explain how ATP releases energy, using a simple diagram.(Slide 136)

1.4. A 1 S tructure and function of sodium–potassium pu m ps for acti v e transport a nd potassi u m channels for facilitat e d di f fusion in a x ons.

15. Annotate the diagram below to show how a protein pump is used in the active transport of sodium and potassium ions across the plasma membrane of axons. (Slide 137)

1.4. U. 3 V esicles mov e m aterials w ithin cel l s.

16. What is a macromolecule? Give one example of a macromolecule produced in the cell. (Slide 139)

17. What is a vesicle? (Slide 139)

18. Outline the uses of vesicles within cells. (Slide 139)

19. Complete and annotate the diagram below to show the process of vesicle transport of a protein molecule through a eukaryote cell. Begin with protein synthesis in the Rough ER and finish with exocytosis though the plasma membrane. Label all organelles shown. (Slide 140)

1.4 U. 2 The fluidity of m e m bra n es allo w s m aterials to b e taken into cells by en d oc y tosis or r eleased by e x oc y tosis.

20. Differentiate between exocytosis and endocytosis. (Slide 141)

21. Exocytosis is often characteristised as being either pinocytosis or phagocytosis. Distinguish between two terms. (Slide 142)

1.5. A. 1 Ev idence from P asteur’s e x peri m ents that spont a neous gene r ation of ce l ls and organi sm s does not now occur o n E arth.

Louis Pasteur designed an experiment to test whether sterile nutrient broth could spontaneously generate microbial life. To do this, he set up two experiments.

• In both, Pasteur added nutrient broth to flasks and bent the necks ofthe flasks into S shapes

• Each flask was then heated to boil the broth in order than all existingmicrobes were killed.

• After the broth had been sterilized, Pasteur broke off the swan necksfrom the flasks in Experiment 1, exposing the nutrient broth within them to air from above.

• The flasks in Experiment 2 were left alone. http://bcs. w hfree m an.co m /thelife w ire/content/c h p03/0302003.

html

1. In which flask(s) would you expect microbes grow? (Slide 149)

2. Explain the reasons for your answer to the above question.(Slides 147-151)

3. How does the evidence derived from this experiment refute the idea of spontaneous generation?

1.5 U. 1 C ells can o n ly be for m ed by di v ision of pre-e x isting cells.

1. State the three core ideas of cell

theory: (Slide 149)

a.

b.

c.

2. Aside from Pasteur’s experiments what evidence do Biologists have that cells can only be formed by division of pre-existing cells? Outline the evidence below: (Slides 153-158)

1.5 U. 2 The first c e l l s m ust ha v e arisen from non-li v ing m aterial.

There are two theories of where the first cells come from on Earth. Panspermia and Organic Evolution. Although both of these theories do not completely answer where the first cells come from they provide some of the first steps that may lead to an answer in the future. Below is some ideas how some of the key problems might have been solved. Outline the following points:

a. Explain Panspermia (Slide 159)

b. List the four things needed of Organic Evolution to have occurred below (Slides 161-170)

c. The non-living synthesis of simple organic molecules is a key step in understanding how complex molecules like sugars and amino acids appear on Earth. List below some of the molecules contained in the early atmosphere and ocean of Earth (Slide 161)

d. Where is it thought that Organic Evolution might have occurred on Earth? (Slides 165-166)

e. Outline the formation of the nucleus and other membrane bound organelles. (Slides 165-166)

1.5. U 3 The origin of eukar y otic cells can be e x plained by the endos ym biotic theor y .

3. State the definition of endosymbiotic theory: (Slides 172-175)

4. As shown by the diagram below there are several key stages in the theory.

5. Describe the evidence supporting the theory for mitochondria and chloroplasts: (Slide 175)

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