STAGE 2 BIOLOGY | Topic 2: Cells as the Basis of Life · 2018. 8. 28. · In the Cells as the Basis...

STAGE 2 BIOLOGY | Topic 2: Cells as the Basis of Life Review Questions

These review questions are to help you revise the main concepts that

are covered in this topic. Each lesson has been assigned a number

of questions that will be set for homework. The homework will not be

checked, however it is strongly encouraged that you complete the

assigned homework to assist with your understanding of the topic

and help you to identify areas that you need to work on. If you need

any help with these questions, please come and see me.

1. The cell is said to be the smallest independent unit of life. Describe three

activities that cells do that indicate they are alive

2. Define semi-permeable.

3. Define hydrophobic and hydrophilic.

4. Draw a diagram of a phospholipid and label its hydrophobic and

hydrophilic regions.

5. Draw a labeled diagram of a cell membrane.

6. Explain why the current model for the cell membrane is called the Fluid-

Mosaic Model.

7. Describe the function of two different types of proteins found in the cell

membrane.

8. Define prokaryote and eukaryote cells.

9. State the three differences between prokaryotic and eukaryotic cells.

10. Suggest a reason why prokaryotic cells are generally smaller than

eukaryotic cells.

11. Draw a table to include the following features for each of the organelles

listed and include a sketch of the organelle, a description of its main

function and whether it is present in prokaryote and/or eukaryote cells:

nucleus, nucleolus, mitochondrion, chloroplast, vacuole/vesicle, Golgi

body, endoplasmic reticulum, ribosome, lysosome, cytoskeleton.

12. Define autotroph and heterotroph.

13. Define anabolism and catabolism.

14. State the purpose of photosynthesis, including where it occurs.

15. Write a word and symbol equation for the process of photosynthesis.

16. Describe the role of ATP in photosynthesis.

17. Explain the purpose of aerobic respiration.

18. Draw a diagram of glycolysis and state where it occurs and all reactants

and products.

19. Draw a diagram of the Kreb’s cycle and state where it occurs and all

reactants and products.

20. Draw a diagram of the electron transport chain and state where it occurs

and all reactants and products.

21. Draw a summary diagram of aerobic respiration starting at photosynthesis,

showing the processes involved and the key reactants and products.

22. State the conditions in which anaerobic respiration occurs.

23. Draw a diagram of fermentation and state where it occurs and all

reactants and products. Be sure to consider both plants/yeast and

animals.

24. Draw a summary diagram of anaerobic respiration starting at

photosynthesis, showing the processes involved and the key reactants

and products.

STAGE 2 BIOLOGY | Topic 2: Cells as the Basis of Life “Cream Cheese Sandwich Model” of the Cell Membrane

In the Cells as the Basis of Life topic of Stage 2 Biology, students learn about the structure and

function of the cell membrane and learn to describe it in terms of the Fluid-Mosaic Model.

Often students have difficulty visualising the structure of the cell membrane since it is on such

a small scale. Therefore, this demonstration of the cell membrane is designed to be a fun,

light-hearted and engaging way to represent the structure of the cell membrane to students.

This demonstration will require some preparation prior to the lesson and should be stored in an

appropriate place until required. Under no circumstances should this model be eaten.

Materials required:

Two slices of bread, cream cheese, coloured sprinkles, twisties, jellybeans, clear nail polish

Basic Set-up:

Paint jelly beans with clear nail polish and allow to dry (this avoids the colour running

through the cream cheese).

Spread a thick layer (≈ 2 cm) of cream cheese on one slice of bread and top with

remaining slice.

Optional: cut model to desired size using a knife.

Put sprinkles (represent surface proteins) on the top layer of bread and press gently to

secure. Poke twisties (represent receptor-type proteins) and jellybeans (represent integral

proteins that span the membrane) into the top layer of bread.

Further Notes:

To demonstrate proteins that span the membrane, spread one slice of bread with cream

cheese (≈ 1 cm thick) and insert some jellybeans into the layer. Spread remaining slice of

bread with cream cheese (≈ 1 cm thick)and position on top of the jellybeans in such a

way that the ‘membrane’ could be carefully pulled apart, showing the internal jellybeans.

This should be practiced prior to the lesson to ensure that the technique works.

Teaching Points:

Membrane Proteins: talk about the jellybeans, twisties, sprinkles and the proteins that they

represent.

Hydrophobic and Hydrophilic Regions: if water was poured onto the model, it would run

straight off the cream cheese layer (representing the hydrophobic tails of phospholipids),

however it would soak into the bread (representing the hydrophilic heads of

phospholipids).

For more information: see “Cell Membrane - Cream Cheese Model (Rob Reid)” video at

37:40, provided with this unit plan.

BIOLOGY 100 LAB PACKET

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LAB 2 – Using A Microscope to Observe Cells

In this lab you will learn about the compound light microscope and how to use it to enlarge the image of cells. You will also review the main parts of a cell underneath the microscope. You will use your textbook and the information in this lab as a reference.

Since its invention, the microscope has been a valuable tool in the development of scientific theory. Magnifying lenses have been known for as long as recorded history, but it was not until the advent of the modern compound light microscope that the device was used in biology. The microscope used most frequently in the biology lab is the compound light microscope. The compound microscope is used to magnify and resolve fine detail within a transparent specimen (one through which light can pass). The compound light microscope is so called because it has two separate lens systems; an objective lens, located near the specimen, and an ocular lens, located near the eye. Both the objective lens and ocular lens magnify the image of the object. The total magnification observed by the human eye is the product of the magnification of the two lenses (objective lens magnification multiplied by the ocular lens magnification).

The microscope is used to create an enlarged view of an object so that we can observe details not otherwise possible with the human eye. Because of the enlargement, resolution is often confused with magnification but they are not the same. Magnification refers to the size of an image. Resolution is the ability to clearly see detail. In general, the greater the magnification, the greater the resolution, but this is not always true.

As previously learned, cells are small structures and most require observation through a microscope. This lab will help you learn about the basics of microscopy and the importance of this tool when observing cellular details. You will use a microscope to observe and compare different types of cells including plant, animal, and bacterial cells.

The lab activity is divided into two main sections as outlined below. While you are working through the lab activities you should be answering the Lab 2 homework questions. All of the questions on the lab homework sheet should be answered while completing the lab activities.

Activity I: Identifying the Parts of the Microscope The microscope gives you the opportunity to see a world of things you cannot see with the naked human eye. To observe the clearest image you need understand how to use the microscope. In order to use a microscope properly you must be familiar with the optical and mechanical parts. Please be careful when using the microscope, always be sure to carry the microscope properly and observe the proper protocol when viewing a slide.

We will also use the following website as a supplemental guide to this section of the lab. Please feel free to visit the site before and/or after completing this lab. This will help you become familiar with the microscope, its parts, and how it can be used to enlarge cellular images. http://www.udel.edu/biology/ketcham/microscope/

Please review the following terms.


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A. Magnification is the process of enlarging something only in appearance, not in physical size. Magnification is important because it allows us to view very small objectives that could not be seen with the naked eye. The total magnification is calculated by multiplying the magnification of each lens.

B. Resolution is the ability to see detail. It is important because it allows differentiation between cells and cellular structures.

C. Field of View is sometimes abbreviated "FOV", it is the diameter of the circle of light that you see when looking into a microscope. As the magnifying power increases, the field of view gets smaller. You can measure this by placing a clear metric ruler on the stage and counting the millimeters from one side to the other.

D. Image Formation refers to what you see when looking through the microscope and how the image is manipulated when using the microscope.

ACTIVITY I PROCEDURE: IDENTIFYING PARTS OF THE MICROSCOPE

Obtain a microscope from your instructor. Be sure to transport the microscope correctly when you are carrying it to your lab bench. Review the microscope parts list below. Identify each of the components listed and practice using each component described. Be sure you understand the function of the parts listed in this description. Answer the corresponding lab homework questions.

When completing parts of this activity, you will need to place the letter e slide in the stage holder to answer some of the questions. Always be very careful when you are placing a slide on the microscope stage. After you have securely placed the slide on the microscope begin by using the scanning objective lens (4x) to locate the slide contents. It is important to begin with this lens because it will provide the largest field of view and it will be easier to find the object. Once your object is clearly focused using the 4x objective, move to the next highest objective (10x objective). After the image is in focus with the 10x objective, then move to the 40x objective. Do not move from one objective power to the next until your image is focused. NOTE: We will not be using the 100x objective (oil immersion lens) in this class.

Microscope Parts List:


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1. Adjustment Knobs Your microscope has two adjustment knobs which are used to focus the specimen to be studied. The

largest is the coarse adjustment knob. This is used for rapid (or coarse) focusing of the specimen when using the scanning objective lens (lowest powered objective lens, 4X). The coarse objective knob is rotated until the specimen is roughly in focus and then left alone. The fine adjustment knob controls precise focusing of the object and should be used after the object has been “found” using the course objective. Only the fine adjustment knob should be used with the higher magnification objective lenses. Moving the fine adjustment knob also helps you to determine the third dimension (depth) of the specimen you are studying.

2. Stage The stage holds the slide to be observed. Moving the coarse and fine adjustment knobs moves the

nosepiece or the stage up or down to bring the specimen into focus (this depends on the specific microscope used).

3. Mechanical Stage Your slide is fixed into position on the stage with the mechanical stage. The slide is fastened into the

mechanical stage by using a small lever located on the mechanical stage. Two knobs located on the side of the mechanical stage are used to move the slide around to locate your specimen; one knob moves the slide from side to side (horizontally) and the other moves the slide forward and backward (vertically). The mechanical stage permits precision movements of your slide, especially nice when using the high magnifications.

4. Condenser The condenser, located below the stage, contains a system of lenses that focuses light on your specimen.

The condenser may be raised or lowered using the condenser knob. Most microscopes have a built-in light source. Use caution to avoid having the light cord hang where you might trip over it.

5. Iris Diaphragm The iris diaphragm is located on the condenser. The lever of the iris diaphragm is used to adjust the

amount of light striking the object being studied. It is important that you know the proper use of the condenser and iris diaphragm. A common problem with microscope use is having too much light which obliterates the object (more or less like trying to see something while looking directly at the sun).

6. Objective Lenses When proper illumination is provided the resolving power of a microscope depends on the quality of its

objective lenses. Our microscopes contain four objective lenses (see table below). These lens are mounted on a rotating turret or nosepiece. As you rotate the turret you will feel the lens "click" into position for proper viewing. If a lens is not in position you will observe only darkness as you look into the microscope.

Objective Lens Magnification Scanning Lens 4x Low Power Lens 10x High Power Lens 40x Oil Immersion Lens 100x

Note: The magnification of the oil immersion lens requires using the lens with special immersion oil for proper

resolution. This lens will not be used in this class, however, it is commonly used in other, higher level biology classes which require greater magnification.

7. Ocular Lens The ocular lens, or eyepiece, further magnifies the image formed by the objective lens. It does not improve

resolution. Your microscope will have either a monocular system (one ocular lens) or binocular (two ocular lens) system. The magnification of the ocular lens is 10x. Recall that the total magnification of the lens system is the product of the magnification of the ocular times the magnification of the objective lens being used (ocular X objective).


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Be sure you can correctly identify the location and function of the above structures on the actual microscope and/or virtual microscope before moving the next section.

Activity II: Viewing Different Types of Cells.

Now that you are familiar with the basic properties of microscopes and their components you will practice using the microscope to observe different types of cells. Remember, all cells are classified as either Prokaryotic or Eukaryotic. Although there are many different types of Prokaryotic cells, ALL Prokaryotic cells have specific characteristics that belong to the prokaryotic group (no nucleus, etc). The same is true of Eukaryotic cells. There are many different types of Eukaryotic cells (including animal cells, plant cells, fungal cells, etc) and they all look and function differently. However as Eukaryotic cells they all have certain characteristics in common (i.e. they all store their genetic information in the nucleus, they all have organelles, etc).

This portion of the lab will allow you to look at representative Prokaryotic and Eukaryotic cells through the microscope. Be sure to do all required activities so you can answer the corresponding lab questions on your lab 2 homework sheet. You will be viewing the following cells in the following order.

Remember, when viewing the slides underneath the microscope, you ALWAYS begin the observation with the scanning objective lens (4x) which will provide the largest field of view. After you have focused the slide using the 4x objective, move to the next highest objective (10x objective). Move to the 40x objective only after you have focused the object using the 10x objective.

Cell Review:

A. Plant Cells are Eukaryotic cells. There are many different types of plant cells. You will be viewing Elodea and Onion Cells. Although they are both plant cells, you will observe differences between the cells.

B. Animal Cells are also Eukaryotic cells. You will be looking at human cheek cells. These cells have different functional properties than elodea.

C. Euglena is also a type of Eukaryotic cell but unlike most other Eukaryotic organisms, it is a single celled organism.

D. Bacteria are abundant in our environment and in/on our body. Unlike human cells bacteria are Prokaryotic. This is particularly helpful when trying to kill the pathogenic bacteria that can make us sick.

ACTIVITY II PROCEDURE: VIEWING DIFFERENT TYPES OF CELLS

Each pair of students should obtain one of each of the above slides (elodea slide, onion cell slide, human cheek cell slide, euglena slide, and a mixed bacteria slide). Observe 1 slide at a time using correct microscope viewing protocol. View the slides in the order listed above. While viewing the slides you should be answering the corresponding Lab 2 homework questions.

STAGE 2 BIOLOGY | Cells as the Basis of Life Part 1

Photosynthesis – Leaf Disk Experiment

Performance Standards Assessed:

KA1 Demonstration of knowledge and understanding of biological

concepts.

IAE2 Obtaining, recording and representation of data, using appropriate

conventions and formats.

IAE3 Analysis and interpretation of data and other evidence to formulate

and justify conclusions.

IAE4 Evaluation of procedures and their effect on data.

Performance Standards for Stage 2 Biology

- Investigation, Analysis, and Evaluation Knowledge and Application

A Designs a logical, coherent, and detailed biological investigation.

Obtains, records, and represents data, using appropriate conventions and formats accurately and highly effectively.

Systematically analyses and interprets data and evidence to formulate logical conclusions with detailed justification.

Critically and logically evaluates procedures and their effect on data.

Demonstrates deep and broad knowledge and understanding of a range of biological concepts.

Develops and applies biological concepts highly effectively in new and familiar contexts.

Critically explores and understands in depth the interaction between science and society.

Communicates knowledge and understanding of biology coherently, with highly effective use of appropriate terms, conventions, and representations.

B Designs a well-considered and clear biological investigation.

Obtains, records, and represents data, using appropriate conventions and formats mostly accurately and effectively.

Logically analyses and interprets data and evidence to formulate suitable conclusions with reasonable justification.

Logically evaluates procedures and their effect on data.

Demonstrates some depth and breadth of knowledge and understanding of a range of biological concepts.

Develops and applies biological concepts mostly effectively in new and familiar contexts.

Logically explores and understands in some depth the interaction between science and society.

Communicates knowledge and understanding of biology mostly coherently, with effective use of appropriate terms, conventions, and representations.

C Designs a considered and generally clear biological investigation.

Obtains, records, and represents data, using generally appropriate conventions and formats with some errors but generally accurately and effectively.

Undertakes some analysis and interpretation of data and evidence to formulate generally appropriate conclusions with some justification.

Evaluates procedures and some of their effect on data.

Demonstrates knowledge and understanding of a general range of biological concepts.

Develops and applies biological concepts generally effectively in new or familiar contexts.

Explores and understands aspects of the interaction between science and society.

Communicates knowledge and understanding of biology generally effectively, using some appropriate terms, conventions, and representations.

D Prepares the outline of a biological investigation.

Obtains, records, and represents data, using conventions and formats inconsistently, with occasional accuracy and effectiveness.

Describes data and undertakes some basic interpretation to formulate a basic conclusion.

Attempts to evaluate procedures or suggest an effect on data.

Demonstrates some basic knowledge and partial understanding of biological concepts.

Develops and applies some biological concepts in familiar contexts.

Partially explores and recognises aspects of the interaction between science and society.

Communicates basic biological information, using some appropriate terms, conventions, and/or representations.

E Identifies a simple procedure for a biological investigation.

Attempts to record and represent some data, with limited accuracy or effectiveness.

Attempts to describe results and/or interpret data to formulate a basic conclusion.

Acknowledges that procedures affect data.

Demonstrates limited recognition and awareness of biological concepts.

Attempts to develop and apply biological concepts in familiar contexts.

Attempts to explore and identify an aspect of the interaction between science and society.

Attempts to communicate information about biology.

The Floating Leaf Disk Assay for Investigating Photosynthesis

Introduction:

Trying to find a good, quantitative procedure that students can use for exploring photosynthesis is a

challenge. The standard procedures such as counting oxygen bubbles generated by an elodea stem

tend to not be “student” proof or reliable. This is a particular problem if your laboratory instruction

emphasizes student-generated questions. Over the years, I have found the floating leaf disk assay

technique to be reliable and understandable to students. Once the students are familiar with the

technique they can readily design experiments to answer their own questions about photosynthesis.

The biology behind the prodedure:

Leaf disks float, normally. When the air spaces are infiltrated with solution the overall density of the

leaf disk increases and the disk sinks. The infiltration solution includes a small amount of Sodium

bicarbonate. Bicarbonate ion serves as the carbon source for photosynthesis. As photosynthesis

proceeds oxygen is released into the interior of the leaf which changes the buoyancy--causing the

disks to rise. Since cellular respiration is taking place at the same time, consuming oxygen, the rate

that the disks rise is an indirect measurement of the net rate of photosynthesis.

Materials:

Sodium bicarbonate (Baking soda)

Liquid SoapPlastic syringe (10 cc or larger)—remove any needle!

Leaf material

Hole punch

Plastic cups

Timer

Light source

Optional:

Buffer Solutions

Colored Cellophane or filters

Leaf material of different ages

Variegated leaf material

Clear Nail polish

Procedure:

Prepare 300 ml of bicarbonate solution for each trial.

The bicarbonate serves as an alternate dissolved source of carbon dioxide for photosynthesis.

Prepare a 0.2% solution. (This is not very much it is only about 1/8 of a teaspoon of baking

soda in 300 ml of water.)

Add 1 drop of dilute liquid soap to this solution. The soap wets the hydrophobic surface of the

leaf allowing the solution to be drawn into the leaf. It’s difficult to quantify this since liquid

soaps vary in concentration. Avoid suds.If your solution generates suds then dilute it with more

bicarbonate solution.

Cut 10 or more uniform leaf disks for each trial.

Single hole punches work well for this but stout plastic straws will work as well.

Choice of the leaf material is perhaps the most critical aspect of this procedure.The leaf

surface should be smooth and not too thick. Avoid plants with hairy leaves. Ivy, fresh spinach,

Wisconsin Fast Plant cotyledons--all work well. Ivy seems to provide very consistent

results.Many different plant leaves work for this lab.My classes have found that in the spring,

Pokeweed may be the best choice.

Avoid major veins.

Infiltrate the leaf disks with sodium bicarbonate solution.

Remove the piston or plunger and place the leaf disks into the syringe barrel. Replace the

plunger being careful not to crush the leaf disks. Push on the plunger until only a small volume

of air and leaf disk remain in the barrel (< 10%).

Pull a small volume of sodium bicarbonate solution into the syringe. Tap the syringe to

suspend the leaf disks in the solution.

Holding a finger over the syringe-opening, draw back on the plunger to create a vacuum. Hold

this vacuum for about 10 seconds. While holding the vacuum, swirl the leaf disks to suspend

them in the solution. Let off the vacuum. The bicarbonate solution will infiltrate the air spaces

in the leaf causing the disks to sink. You will probably have to repeat this procedure 2-3 times

in order to get the disks to sink. If you have difficulty getting your disks to sink after about

3 evacuations, it is usually because there is not enough soap in the solution. Add a few

more drops of soap.

Pour the disks and solution into a clear plastic cup. Add bicarbonate solution to a depth of about 3

centimeters. Use the same depth for each trial. Shallower depths work just as well.

For a control infiltrate leaf disks with a solution of only water with a drop of soap--no bicarbonate.

Place under the light source and start the timer. At the end of each minute, record the number of

floating disks. Then swirl the disks to dislodge any that are stuck against the sides of the cups.

Continue until all of the disks are floating.

Data Collection and Analysis

These data are from an demonstration investigation using grape ivy leaf disks.

Minutes Disks

1 0

2 0

3 0

4 0

5 0

6 0

7 1

8 1

9 1

10 1

11 4

12 7

13 8

14 10

The point at which 50% of the leaf disks are floating (the median) is the point of reference for this

procedure. By extrapolating from the graph, the 50% floating point is about 11.5 minutes. Using the

50% point provides a greater degree of reliability and repeatability for this procedure. As Steucek, et.

al. (1985) described this term is referred to as the ET50.

The problem with ET50 is that it goes down as the rate of photosynthesis goes up--it is an inverse

relationship and creates the following type of graph (data from Steucek, et al. 1985.):

To correct for this representation of the data and present a graph that shows increasing rates of

photosynthesis with a positive slope the ET50 term can be modified by taking the inverse or 1/ET50.

This creates a graph like this(data from Steucek, et al. 1985.):

Extension:

In this graph, the light was turned off at 14 minutes and the cups with their floating disks (grape ivy)

were placed in the dark.

Every minute, I removed the dark cover and counted how many were still floating. Then I stirred the

disks. Note that after a while the disks begin to sink. Why? Cellular respiration removes the oxygen

from the cell spaces. The rate that the disks sink is an indirect measure of the rate of cellular

respiration. Can you think of a way to how you might measure the gross rate of photosynthesis with

this technique?

STAGE 2 BIOLOGY | Topic 2: Cells as the Basis of Life Anaerobic Respiration Demonstration

Ask students to put their hand up in the air and pump it in and out

continually (form a fist and then open again). Initially, this is a very

simple task. However, as time goes on, it begins to burn. This burning

sensation is due to lactic acid build up, indicating that the muscles

have switched from aerobic to anaerobic respiration. Since the arm

is up in the air, fresh oxygenated blood cannot get to the hand

quick enough and gradually the oxygen levels in the blood

decrease, which prevents aerobic respiration from occurring. Since

anaerobic respiration is much less efficient in producing ATP, the arm

will very quickly fatigue and the student will have to stop.

Brianna Lush (a1667331)

Biology Curriculum and Methodology B

Term 2, 2017

STAGE 2 BIOLOGY

Skills and Applications Task: Topic Test

Cells as the Basis of Life Part 1 – Cell Structure and Respiration

Time Duration: 5 minutes reading time + 60 minutes writing time

Total marks: 58 marks

Name: _________________________ Student Number: ____________________

Performance Standards Assessed:

KA1 Demonstration of knowledge and understanding of biological concepts.

KA2 Development and application of biological concepts in new and familiar contexts.

KA4 Communication of knowledge and understanding of biological concepts and

information, using appropriate terms, conventions and representations.

IAE1 Design of a biological investigation.

IAE4 Evaluation of procedures and their effect on data.

STAGE 2 BIOLOGY – Cells as the Basis of Life Topic Test

Part 1: CELL STRUCTURE AND RESPIRATION

SECTION A - Multiple Choice Questions

(18 marks)

Answer all questions in this section.

Each of the multiple choice questions in Section A involves choosing from four alternative answers.

Read each question carefully. Then indicate the one alternative that you consider best answers the

question by drawing a circle around the corresponding letter on this answer booklet. It is in your

interest to give an answer to every question in this section of the paper, as no marks are deducted

for incorrect answers. Each question is worth 2 marks. You should spend about 15 minutes on this

section.

Question 1

In what organelle does photosynthesis occur?

a. Cytoplasm

b. Mitochondria

c. Endoplasmic reticulum (ER)

d. Chloroplast

(2 marks) [KA1]

Question 2

Animal cells are easily distinguishable from plant cells given:

a. Their thick cellulose wall.

b. The presence of mitochondria within the cell.

c. The lack of chloroplast within the cell.

d. They are much larger than plant cells and contain membrane-bound organelles.

(2 marks) [KA1]



Question 3

Which of the following statements is true about the organisation of DNA in prokaryotes and

eukaryotes?

a. Eukaryotes contain linear DNA, whereas prokaryotes do not contain any DNA.

b. Prokaryotes contain circular DNA, where as eukaryotes contain linear DNA.

c. Prokaryotes contain linear DNA, where as eukaryotes contain circular DNA.

d. Both prokaryotes and eukaryotes contain linear DNA.

(2 marks) [KA1]

Question 4

Cyanide, a toxic chemical, is known to block the electron transport chain in the

mitochondria of plant cells. Which one of the following statements best describes what

could happen to plant growth if a plant was sprayed with cyanide?

a. Cyanide would have no effect on plant growth, because the electron transport chain

is not a process that is required for growth.

b. Cyanide would cause plant growth to increase, because blocking the electron

transport chain causes a greater amount of ATP to be produced which provides

more energy for growth.

c. Cyanide would cause plant growth to increase, because blocking the electron chain

causes a smaller amount of ATP to be produced which provides less energy for

growth.

d. Cyanide would cause plant growth to decrease, because blocking the electron

chain causes a smaller amount of ATP to be produced which provides less energy

for growth.

(2 marks) [KA2]



Question 5

The process of breaking down glucose into two molecules of pyruvate is called:

a. Glycolysis

b. Aerobic respiration

c. Fermentation

d. Photosynthesis

(2 marks) [KA1]

Question 6

The stomata, located on the underside of a leaf, have the ability to open and close. In hot

and humid conditions, the stomata should close as the guard cells become flaccid. If the

stomata remained open in hot and humid conditions, what would happen to the amount of

water in the leaf and hence the rate of photosynthesis?

a. Water would be lost from the leaf by evaporation, but this would have no effect on

the rate of photosynthesis.

b. Water would be lost from the leaf by evaporation, causing the rate of

photosynthesis to decrease.

c. No water would be lost by evaporation, but open stomata would allow more carbon

dioxide to diffuse into the leaf, causing the rate of photosynthesis to increase.

d. No water would be lost by evaporation, but the open stomata would allow more

sunlight into the leaf, causing the rate of photosynthesis to increase.

(2 marks) [KA2]



Question 7

Which one of the following statements is evidence that prokaryotic cells existed before

eukaryotic cells?

a. Prokaryotic organisms are single-celled and less complex than eukaryotic

organisms.

b. The oldest-known prokaryotic fossils are at least 3.5 billion years old whereas the

oldest-known eukaryotic fossils are at least 1.5 billion years old.

c. Prokaryotic organisms are able to live and thrive in hostile environments such as

hydrothermal vents, swamps and wetlands.

d. The cells of prokaryotic organisms do not contain membrane-bound organelles

where as the cells of eukaryotic organisms do contain membrane-bound organelles.

(2 marks) [KA1]

Question 8

In a championship competition, a marathon runner decided to pull out of the race because

of extreme weakness and burning sensation in his legs. Which one of the following

statements best describes the reason why these symptoms may be occurring?

a. Continuous use of a muscle causes it to become deprived of oxygen and anaerobic

respiration begins. This leads to the build up of lactic acid which causes the burning

sensation. Since energy production from respiration is reduced, there is less ATP

available which causes muscle weakness.

b. Continuous use of a muscle causes it to become deprived of oxygen and aerobic

respiration begins. This leads to the build up of ethanol which causes the burning

sensation. Since energy production from respiration is increased, there is less ATP


c. Continuous use of a muscle causes it to become enriched with oxygen and aerobic




d. Continuous use of a muscle causes it to become enriched with oxygen and

anaerobic respiration begins. This leads to the build up of ethanol which causes the

burning sensation. Since energy production from respiration is increased, there is

more ATP available which causes muscle weakness.

(2 marks) [KA2]



Question 9

Below is a photomicrograph of a plant cell. What is the name of the organelle labelled ‘X’?

a. Ribosome

b. Vacuole

c. Vesicle

d. Cytoplasm

(2 marks) [KA1]

[Section A total – 18 marks]



SECTION B – Short Answer Questions

(24 marks)

Answer all questions in the spaces provided. You should spend about 25 minutes on this section.

Answers may be in note form. The allocation of marks and performance standards are shown in

brackets at the end of each part of each question.

QUESTION 10

a. State where the largest production of ATP occurs during aerobic respiration.

(2 marks) [KA1]

b. Explain how energy is obtained from ATP.

(4 marks) [KA4]

c. State two examples of cellular processes that require energy from ATP.

(2 marks) [KA1]

[Question 10 total – 8 marks]



QUESTION 11

Refer to the following diagram, which shows the structure of part of the cell membrane.

a. Name the molecules represented by W and X.

Molecule W:

Molecule X:

(2 marks) [KA1]

b. Explain why the current model for the cell membrane is called the Fluid-Mosaic

Model.

(2 marks) [KA1]

c. Describe the characteristics of phospholipids that make them suitable to form

membranes.

(4 marks) [KA4]




QUESTION 12

Scientists studied a group of saltbush plants of the genus Atriplex. They measured the

amount of CO2 used by the saltbush leaves (UCO2) and compared this with the amount of

CO2 produced by the leaves (PCO2). A large range of different-aged plants were used for

the experiment. Twenty leaves of each plant age were tested in this experiment.

a. Write the chemical equation for the process that takes place in plants and uses CO2.

(2 marks) [KA1]

b. State two factors that should be held constant in the experiment above.

(2 marks) [IAE1]

c. Explain why the scientists tested twenty leaves of each age.

(2 marks) [IAE4]

d. State where the PCO2 comes from.

(2 marks) [KA2]




SECTION C – Extended Response Question

(16 marks)

You should spend about 15 minutes on this section – 2-3 minutes planning and 10-12 minutes

writing. Credit will be given for clear, well-expressed answers that are well organised and relevant

to the question.

Question 13 – 16 marks [KA1, KA4]

Some evolution theories suggest that prokaryotic cells were the first life on the planet.

However, most of the living things we see each day are multicellular organisms that are

made up of eukaryotic cells. The evolution theories suggest that over millions of years,

prokaryotic cells have slowly evolved to become more highly organised and specialized,

which has allowed the formation of large, multicellular organisms to occur. It is thought that

this evolutionary development of the eukaryotic cell has occurred through the process of

endosymbiosis.

Explain the process of endosymbiosis and describe one advantage of a symbiotic

relationship in bacteria.

Describe the evidence which suggests that eukaryotic cells evolved from

prokaryotic cells through an endosymbiotic event.



END OF TEST



Marks Grid

Question Marks IAE1 IAE2 IAE3 IAE4 KA1 KA2 KA3 KA4 Difficulty

1 2 X Easy

2 2 X Easy

3 2 X Easy

4 2 X Medium/Hard

5 2 X Easy

6 2 X Medium

7 2 X Easy/Medium

8 2 X Medium/Hard

9 2 X Easy

10 (a) 2 X Easy

10 (b) 4 X Medium

10 (c) 2 X Easy/Medium

11 (a) 2 X Easy

11 (b) 2 X Easy/Medium

11 (c) 4 X Medium/Hard

12 (a) 2 X Easy/Medium

12 (b) 2 X Medium

12 (c) 2 X Medium

12 (d) 2 X Easy/Medium

13 16 X X Medium

TOTAL 58 1 1 12 4 3



SOLUTIONS

SECTION A - Multiple Choice Questions

(18 marks)

Question 1

In what organelle does photosynthesis occur?

a. Cytoplasm

b. Mitochondria

c. Endoplasmic reticulum (ER)

d. Chloroplast

(2 marks) [KA1]

Question 2

Animal cells are easily distinguishable from plant cells given:

a. Their thick cellulose wall.

b. The presence of mitochondria within the cell.

c. The lack of chloroplast within the cell.

d. They are much larger than plant cells and contain membrane-bound organelles.

(2 marks) [KA1]

Question 3

Which of the following statements is true about the organisation of DNA in prokaryotes and

eukaryotes?

a. Eukaryotes contain linear DNA, whereas prokaryotes do not contain any DNA.

b. Prokaryotes contain circular DNA, where as eukaryotes contain linear DNA.

c. Prokaryotes contain linear DNA, where as eukaryotes contain circular DNA.

d. Both prokaryotes and eukaryotes contain linear DNA.

(2 marks) [KA1]



Question 4

Cyanide, a toxic chemical, is known to block the electron transport chain in the

mitochondria of plant cells. Which one of the following statements best describes what

could happen to plant growth if a plant was sprayed with cyanide?

a. Cyanide would have no effect on plant growth, because the electron transport chain

is not a process that is required for growth.

b. Cyanide would cause plant growth to increase, because blocking the electron

transport chain causes a greater amount of ATP to be produced which provides

more energy for growth.

c. Cyanide would cause plant growth to increase, because blocking the electron chain

causes a smaller amount of ATP to be produced which provides less energy for

growth.

d. Cyanide would cause plant growth to decrease, because blocking the

electron chain causes a smaller amount of ATP to be produced which

provides less energy for growth.

(2 marks) [KA2]

Question 5

The process of breaking down glucose into two molecules of pyruvate is called:

a. Glycolysis

b. Aerobic respiration

c. Fermentation

d. Photosynthesis

(2 marks) [KA1]



Question 6

The stomata, located on the underside of a leaf, have the ability to open and close. In hot

and humid conditions, the stomata should close as the guard cells become flaccid. If the

stomata remained open in hot and humid conditions, what would happen to the amount of

water in the leaf and hence the rate of photosynthesis?

a. Water would be lost from the leaf by evaporation, but this would have no effect on

the rate of photosynthesis.

b. Water would be lost from the leaf by evaporation, causing the rate of

photosynthesis to decrease.

c. No water would be lost by evaporation, but open stomata would allow more carbon

dioxide to diffuse into the leaf, causing the rate of photosynthesis to increase.

d. No water would be lost by evaporation, but the open stomata would allow more

sunlight into the leaf, causing the rate of photosynthesis to increase.

(2 marks) [KA2]

Question 7

Which one of the following statements is evidence that prokaryotic cells existed before

eukaryotic cells?

a. Prokaryotic organisms are single-celled and less complex than eukaryotic

organisms.

b. The oldest-known prokaryotic fossils are at least 3.5 billion years old whereas the

oldest-known eukaryotic fossils are at least 1.5 billion years old.

c. Prokaryotic organisms are able to live and thrive in hostile environments

such as hydrothermal vents, swamps and wetlands.

d. The cells of prokaryotic organisms do not contain membrane-bound organelles

where as the cells of eukaryotic organisms do contain membrane-bound organelles.

(2 marks) [KA1]



Question 8

In a championship competition, a marathon runner decided to pull out of the race because

of extreme weakness and burning sensation in his legs. Which one of the following

statements best describes the reason why these symptoms may be occurring?

a. Continuous use of a muscle causes it to become deprived of oxygen and

anaerobic respiration begins. This leads to the build up of lactic acid which

causes the burning sensation. Since energy production from respiration is

reduced, there is less ATP available which causes muscle weakness.

b. Continuous use of a muscle causes it to become deprived of oxygen and aerobic

respiration begins. This leads to the build up of ethanol which causes the burning

sensation. Since energy production from respiration is increased, there is less ATP


c. Continuous use of a muscle causes it to become enriched with oxygen and aerobic




d. Continuous use of a muscle causes it to become enriched with oxygen and

anaerobic respiration begins. This leads to the build up of ethanol which causes the

burning sensation. Since energy production from respiration is increased, there is

more ATP available which causes muscle weakness.

(2 marks) [KA2]



Question 9

Below is a photomicrograph of a plant cell. What is the name of the organelle labelled ‘X’?

a. Ribosome

b. Vacuole

c. Vesicle

d. Cytoplasm

(2 marks) [KA1]

[Section A total – 18 marks]

SECTION B – Short Answer Questions

(24 marks)

QUESTION 10

a. State where the largest production of ATP occurs during aerobic respiration.

Electron transport chain

(2 marks) [KA1]

b. Explain how energy is obtained from ATP.

One ATP molecule contains 3 phosphate groups. The bond between the last

two phosphate groups is a weak bond and can be easily broken. When this

bond breaks, ATP becomes converted to ADP and phosphate, causing free

energy to become available for use. (4 marks) [KA4]



c. State two examples of cellular processes that require energy from ATP.

Two of the following examples: synthesis of macromolecules, cell division

(miosis and meiosis), growth and differentiation, transmission of information

and coordination (nerves and hormones), movement (muscles, organelles,

cells and organisms). (2 marks) [KA1]


QUESTION 11

Refer to the following diagram, which shows the structure of part of the cell membrane.

a. Name the molecules represented by W and X.

Molecule W: channel protein

Molecule X: phospholipid

(2 marks) [KA1]

b. Explain why the current model for the cell membrane is called the Fluid-Mosaic

Model.

The current model for the cell membrane is called the Fluid-Mosaic Model

because of its structure. “Fluid” refers to the membrane’s ability to allow the

phospholipids and proteins to move within the membrane structure (they are

not in a fixed position). “Mosaic” refers to the variety of proteins that are

embedded in or attached to the membrane.

(2 marks) [KA1]



c. Describe the characteristics of phospholipids that make them suitable to form

membranes.

Phospholipids are composed of a hydrophilic (water loving) head group and a

hydrophobic (water fearing) tail group, which causes them to form a bilayer.

The hydrophobic tails face toward the inside of the bilayer, away from the

aqueous external environment, and the hydrophilic heads face towards the

outside of the bilayer, towards the aqueous external environment. The

formation of this bilayer then creates a suitable barrier to protect the contents

of the cell.

(4 marks) [KA4]


QUESTION 12

Scientists studied a group of saltbush plants of the genus Atriplex. They measured the

amount of CO2 used by the saltbush leaves (UCO2) and compared this with the amount of

CO2 produced by the leaves (PCO2). A large range of different-aged plants were used for

the experiment. Twenty leaves of each plant age were tested in this experiment.

a. Write the chemical equation for the process that takes place in plants and uses CO2.

6CO2 + 6H20 → C6H12O6 + 6O2 (2 marks) [KA1]

b. State two factors that should be held constant in the experiment above.

Any two of the following: Temperature, time over which they test UCO2 and

PCO2, light intensity, size of the leaf, species of saltbush, plant living

conditions (eg amount of water, sunlight, soil conditions). (2 marks) [IAE1]

c. Explain why the scientists tested twenty leaves of each age.

Testing twenty leaves increases the sample size. This means that an average

can be taken, which minimizes the effect of random error on the data and

increases the precision of the data. (2 marks) [IAE4]

d. State where the PCO2 comes from.

Aerobic respiration (Citric acid cycle)

(2 marks) [KA2]




SECTION C – Extended Response Question

(16 marks)

Question 13 – 16 marks [KA1, KA4]

Some evolution theories suggest that prokaryotic cells were the first life on the planet.

However, most of the living things we see each day are multicellular organisms that are

made up of eukaryotic cells. The evolution theories suggest that over millions of years,

prokaryotic cells have slowly evolved to become more highly organised and specialized,

which has allowed the formation of large, multicellular organisms to occur. It is thought that

this evolutionary development of the eukaryotic cell has occurred through the process of

endosymbiosis.

Explain the process of endosymbiosis and describe one advantage of a symbiotic

relationship in bacteria.

Describe the evidence which suggests that eukaryotic cells evolved from

prokaryotic cells through an endosymbiotic event.

Clear, well expressed answer (2 marks)

Process: start with two independent bacteria, one engulfs the other, one lives and

the other one functions inside, both bacteria benefit from the arrangement, the

internal bacteria are then passed on from generation to generation. (2 marks)

One advantage of a symbiotic relationship: small cell could be able to break

down/remove the waste products of the larger cell; small cell could supply energy

for itself and the host cell; small cell is protected by the host cell. (2 marks)

Mitochondria and chloroplasts show evidence of an evolutionary pathway for the

development of eukaryotes (2marks)

Mitochondria and chloroplasts have their own DNA that is short and circular, DNA

does not match DNA sequences found in the nucleus (2 marks)

Mitochondria and chloroplasts reproduce by binary fission, not mitosis (2 marks)

Mitochondria and chloroplasts have a double membrane, suggesting an

endosymbiotic event has occurred (2 marks)

Molecules that make up the inner membrane of mitochondria and chloroplasts

resemble those in prokaryote membranes, and differ from those in eukaryote



membranes (2 marks).

END OF TEST

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STAGE 2 BIOLOGY | Topic 2: Cells as the Basis of Life · 2018. 8. 28. · In the Cells as the Basis...

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