NAME ______________________ CLASS ________________B1 - Cell Biology

Animal and Plant Cells

Animal and plant cells have sub-cellular structures that are related to their functions.

1) The nucleus, cell membrane and mitochondria are organelles. Give 5 other organelles that I might find in a cell,

2) A Nerve cell is a specialised animal cella) What is its function?b) What are its key structures?

3) Give another example of a specialised animal cella) What is its function?b) What are its key structures?

4) A palisade cell is a specialised plant cell.a) What is its function?b) What are its key structures?

5) Give another example of a specialised plant cella) What is its function?b) What are its key structures?

Eukaryotes and Prokaryotes

The cell theory states that all living things are made of cells. A cell is the simplest unit of a living thing. We know of lots of different types of cell, including red blood cells, palisade cells, root hair cells etc. However all of these cells fall into two categories; Prokaryotic or Eukaryotic. Prokaryotes are smaller, simpler and archaic (came into being earlier). Differences can be seen in the table below.

6) What is the cell theory?7) What is a cell?8) Use the table above to state 3 differences between Prokaryotic and Eukaryotic cells 9) Use the table above to state 3 similarities between Prokaryotic and Eukaryotic cells 10) Which type of cell is the oldest and simplest?11) What is the function of the Nucleus?12) What is the function of the Mitochondria?13) What is the function of the Ribosomes?

Cell Components Prokaryotes Eukaryotes

Examples Bacteria Cells Animal and Plant cells DNA Y YThe DNA is enclosed in a nucleus (this helps to protect the DNA)

N Y

Cell membrane Y Y

Cell wall Y N (sometimes)

Ribosomes Y Y

Organelles are in a membrane (Membrane-bound)

N Y

NAME ______________________ CLASS ________________14) What is the function of the Cell Membrane?15) What is the function of the cell wall?16) What is the function of the cytoplasm?17) What is the function of the Vacuole?18) What is the function of the Chloroplast?19) Which type of cells do not have Chloroplasts?20) Which of the above organelles are not found in animal

cells?

This is a diagram of a Prokaryotic cell. The DNA is free and is not housed in a nucleus. This means it is not as well protected. The Flagellum is a tail like structure that enables the cell to move. This cell also has ribosomes and a cell wall.

21) What is one benefit of having DNA housed in a nucleus?22) What is a flagellum?23) Which is largest, a prokaryotic or eukaryotic cell?24) Eukaryotes have DNA enclosed in a membrane ….

a) Because ……b) But ………

25) Prokaryotes have a flagellum ….a) Because ……b) But ……

26) Some Eukaryotic cells have Chloroplasts…..a) Because ………b) But ……..c) Therefore ……….

Required Practical – Microscopes

Cells are very very small. If we want to study them we need to use a microscope. When we use a microscope we need to magnify (make it bigger) the image, but when we make the image bigger it also makes the image less crisp, like a blurry photo. Because of this we need to use the fine focus to improve the resolution (how clear the picture is).

NAME ______________________ CLASS ________________27) Label the microscope below using the words provided: (Objective lens, Eyepiece, Stage, Stage Clips,

Fine Focus, Course Focus, Light, Base, Arm)

28) Define the terms magnification and resolution.

Optical/light Microscope Electron microscopeUsed for hundreds of years Very recently inventedUses light rays Uses electron beams of high energySpecimen can be living Specimen is dead×1000 to 2000 magnification About ×2 000 000 magnificationNot possible to see internal structures inside the cytoplasm

Internal structures inside the cytoplasm are possible to see

Quite cheap Very expensiveAnyone can use this and observe images Highly trained scientists needed to operate and analyze

resultsNot much space needed Lots of space required2D image only 3D image can be producedNot possible to get better magnification with this technology

Technology can be improved over time

Below is a table that shows the differences between Light Microscopes (the ones we have in school) and electron microscopes.

29) Which microscope is more expensive?30) What is the magnification on an electron microscope?31) What is the magnification on a light microscope?32) What part of the microscope would you use to make an image bigger?33) What part of the microscope would you use to make an image clearer?34) Outline the method that a student would need to follow in order to prepare an onion slide. Include

the following terms: Iodine, Onion, Upper Layer, tweezers, Glass slide, Glass Square, Pipette35) A student says:

“In school we use electron microscopes because they are less expensive and smaller.” a) Is this student correct?b) Explain why electron microscopes are not commonly found in school labs but light microscopes

are (6 marks)36) A student wants to research how sperm cells move.

a) Which microscope should they use?b) Can they get a 3D image of the sperm cell during this experiment?c) Why not?d) After they have looked at how sperm cells move they want to understand how they move.

Which type of microscope should they use and why?

We also need to be able to work out the magnification that is being used. We can also use this equation to work out the actual size of a given structure. In order to do this you can use:

Magnification = Image size / Actual size

You can the rearrange this to work out actual size or image size. You will also need to be able to change the units accordingly.

NAME ______________________ CLASS ________________

37) Use the diagram to the right to help you complete the table below

38) Convert 0.4µm into nanometres (nm)39) Convert 3nm into micrometres (µm)40) Convert 19nm into millimetres (mm)41) Convert 0.00008mm into nanometres (nm)42) Convert 0.00065mm into micrometres (µm)43) Convert 3µm into nanometres (nm)

When we are working out magnification we use the equation:

Magnification = Image size / Actual size

44) A cell measures 112mm. The actual size is 0.28mm. Calculate the magnification.45) A cell measures 230mm. The actual size is 0.12mm. Calculate the magnification.46) A cell measures 345mm. The actual size is 0.65mm. Calculate the magnification.47) A cell measures 634mm. The actual size is 0.75mm. Calculate the magnification.48) A cell measures 122mm. The actual size is 130µm. Calculate the magnification. Don’t forget to

convert your units so that they are the same!49) The actual size is 134µm. A cell measures 875mm. Calculate the magnification.50) The actual size is 173µm. A cell measures 765mm. Calculate the magnification.51) A cell measures 888mm. The actual size is 18300nm. Calculate the magnification.52) The actual size is 123µm. A cell measures 285mm. Calculate the magnification.53) A student measures a cell. The cell measures 904mm. She knows that the actual size is 18500nm,

but needs to work out the magnification. Calculate the magnification.

Nanometre Micrometre Millimetre

5 0.005 0.000005

2

4

2

1

8

0.3

0.0004

0.2

5

0.000007

1.4

NAME ______________________ CLASS ________________When we are working out Image size we use the equation:

Image size = Magnification x Actual size

54) A cell has a magnification of 400x. The actual size is 1.85mm. Calculate the image size.55) A cell has a magnification of 200x. The actual size is 0.34mm. Calculate the image size.56) A cell has a magnification of 100x. The actual size is 0.24mm. Calculate the image size.57) A cell has a magnification of 500x. The actual size is 1.53mm. Calculate the image size.58) A cell has a magnification of 600x. The actual size is 1.26mm. Calculate the image size.59) A cell has a magnification of 300x. The actual size is 122µm. Calculate the image size. Don’t forget

to convert your units so that they are the same!60) The actual size is 164µm. A cell has a magnification of 400x. Calculate the image size.61) A cell has a magnification of 800x. The actual size is 21500nm. Calculate the image size.62) The actual size is 254µm. A cell has a magnification of 200x. Calculate the image size.63) A student uses a magnification of 100x to look at a root hair cell. The actual size of the root hair cell

is 16300nm. Calculate the size of the image that the student is looking at.

When we are working out Image size we use the equation:Actual size = Image size / Magnification

64) A cell is magnified x2000 and measures 6mm. Calculate the actual size in mm.65) A cell is magnified x1000 and measures 4mm. Calculate the actual size in mm66) A cell is magnified x6000 and measures 7mm. Calculate the actual size in mm.67) A cell is magnified x2000 and measures 2mm. Calculate the actual size in mm.68) A cell is magnified x5000 and measures 6mm. Calculate the actual size in mm. Don’t forget to

convert your units so that they are the same!69) A cell is measures 4mm and magnified x2000. Calculate the actual size in nm.70) A cell is measures 2mm and magnified x3000. Calculate the actual size in μm.71) A cell is magnified x1000 and measures 1mm. Calculate the actual size in nm.72) A cell is measures 8mm and magnified x3000. Calculate the actual size in μm.73) A student is looking at a diagram of a red blood cell. The diagram tells him that the cell has a

magnification of x5000. The student then measures the size of the image and finds that it is 7mm long. a) What equation would the student need to use in order to calculate actual size?b) Calculate actual size in nm

Use your answers to the questions above to answer the below questions: Don’t forget to convert your units so that they are the same!

74) A cell measures 635mm. The actual size is 0.21mm. Calculate the magnification.75) A cell is magnified x4300 and measures 9mm. Calculate the actual size in mm.76) A cell measures 623mm. The actual size is 0.12mm. Calculate the magnification.77) A cell has a magnification of 3000x. The actual size is 122µm. Calculate the image size 78) A cell measures 172mm. The actual size is 197µm. Calculate the magnification. 79) A cell is magnified x2000 and measures 11mm. Calculate the actual size in μm.80) Jenny is investigating palisade cells. She is using a light microscope to look at the structure of the

cell. She uses a magnification of 4000x. She then measures the size of the image she is looking at. It is 11mm. a) What is the main role of the palisade cell?b) What organelles would you expect to see?

NAME ______________________ CLASS ________________c) Will Jenny see the cell in 3D or 2D?d) What equation would she need to use in order to work out the actual size of the cell that she is

looking at?e) Calculate the actual size of the cell

Cell Specialisation

The structure of different types of cells relate to their function in tissues, an organ or organ system, or the whole organism. Cells may be specialised to carry out a particular function.

IMPORTANT WORDS THAT YOU WILL NEED TO KNOW!!!!

Specialised - Specialised cells are cells that have developed certain characteristics to perform a particular function.

Adapted – Become suitable for specific conditions

Structure – Physical features of the cell (e.g. a knife is sharp)

Function – The cells role, what is the cell meant to do (e.g. the function of a knife is to cut)

Support – To give assistance to (e.g. the knife being sharp supports its ability to cut)

Below is a table that summaries the three specialised plant cells that you need to know. You will need to explain the structure and function of each of these cells.

Model Answer – we will go through this together

Question: The Phloem is a specialised plant cell. How is the Phloem adapted to its function? (4 marks)

We answer this question by breaking it down into smaller parts:

a) What is the function of the Phloem cell?“To transport sugars around the plant”

b) How do sieve plates support the function of the Phloem cell?“They allow fluid containing sugar to pass though”

c) What do companion cells contain that help support its function?“That have lots of mitochondria”

SPECIALISED CELL: STRUCTURE: FUNCTION:

Root hair CELL Large surface area Thin cell wall Close to xylem

To absorb more water into cell To absorb water and minerals quickly and

easily So water and minerals can be quickly

transported

Xylem CELL Hollow shape No cell wall between cells Contain lignin

Allows water to flow through Allows them to form pipes To waterproof them and strengthen stems

Phloem CELL Sieve plates Companion cells contain

mitochondria

Allow fluid containing sugar to pass through To provide energy to the phloem cells.

NAME ______________________ CLASS ________________d) How does this support its function?

“This provides energy to the phloem cell.”

81) The Xylem is a specialised plant cell. How is the Xylem adapted to its function? (4 marks)a) What is the function of the Xylem?b) What are three structures of the xylem that help support its function?c) How do they support its function?

82) The Root Hair cell is a specialised plant cell. How is the Root hair cell adapted to its function? (4 marks)

Below is a table of all the specialised animal cells that you need to know. You will need to explain the structure and function of each cell.

SPECIALISED CELL: STRUCTURE FUNCTION

MUSCLE CELL Special Proteins slide over each other

Lots of mitochondria Store glycogen

This helps to make it contract For energy required to contract Can be used for energy in respiration

NERVE CELL Lots of dendrites An axon Many mitochondria Insulated axon

To make connections to other cells Carries nerve impulses To allow chemical transmitters to be made Keeps signals travelling quickly

SPERM CELL Long tail Lots of mitochondria Large nucleus contains

genetic material (DNA)

To move around To produce energy for tail to work To pass on genetic material

83) The muscle cell is a specialised animal cell. How is the muscle cell adapted to its function? (4 marks – remember to use the framework that we used in the plant cell questions)

84) What are the three key structural features of a Nerve Cell which enable the cell to carry out its specialised function?

85) Explain why having lots of dendrites is really important for the function of the nerve cell86) Cells can be specialised for a particular job. The diagram shows the structure of a human sperm cell.

Describe how the long tail and the mitochondria support the function of the sperm cell.87) Nerve

cells are

NAME ______________________ CLASS ________________specialised for their function. The diagram shows the structure of a human nerve cell. Use the diagram and table above to explain how the nerve cell is adapted to its function (4 marks)

88) A Root Hair Cell has a large surface area……a) Because………..b) Therefore……….

89) A sperm cell has a tail…..a) Because………b) Therefore…….c) But…….

90) A student is asked how a muscle cell is adapted to its function. She writes:A muscle cell is a specialised animal cell. It has lots of mitochondria to help it move. It also stores glycogen for energy. This answer got her 2 marks out of a possible 4.Rewrite this sentence using key scientific terminology and adding more detail so that she can get 4 marks.

Mitosis

DNA molecules are large and complex. They carry the genetic code that determines the characteristics of a living organism. DNA is found in X shaped structures called chromosomes in the nucleus of each cell. There are 23 pairs of chromosomes (46 chromosomes altogether). Body cells divide in a series of stages known as the cell cycle. Cell division in the cell cycle involves a process called mitosis and it produces two identical cells. Mitosis is vital for growth, repair and replacement of worn out cells. Mitosis is a form of asexual (does not need a male and female) reproduction. Below is a diagram which shows the stages of Mitosis.

This normal body cell has four chromosomes in two pairs

Stage 1: Cell grows, increasing mass. Replicated DNA to form two copies of each chromosome.

Also increase numbers of organelles

This means when the cell splits the new cells will still have the correct number of organelles!!!

Stage 2: Mitosis – One set of chromosomes is pulled to the middle of the dividing cell and the nucleus divides

NAME ______________________ CLASS ________________

91) What is a chromosome?92) Are chromosomes normally in pairs or single?93) What is Mitosis?94) Why is Mitosis important?95) What does Asexual mean?96) How many chromosomes does a normal body cell have?97) What happens in the first stage of Mitosis?98) Why is this stage important?99) What happens in the second stage of Mitosis?100) What happens in the third stage of mitosis?101) What does identical mean?102) Why is it important that these cells are identical?103) Henry says:

“DNA is a large molecule that is large and simple. It carries the genetic code of an organism. This is what makes an animal look the way it does.”

a. Correct Henry’s statement so that it is correct and uses more scientific terminology.b. Henry also says that “DNA is found in X shaped structures called chromosomes in the nucleus

of each cell. There are 23 chromosomes in a cell.” He has made a mistake somewhere. Correct his statement.

104) Mitosis is important…….a) Because…………b) Therefore………….

105) This question is about the cell cycle. Figure 1 shows information about the cell cycle.

a) Which stage of the cell cycle in Figure 1 takes the most time?b) During mitosis cells need extra energy. Which cell structures provide most of this energy?

Culturing Microorganisms

Stage 3: Cytoplasm and cell membranes divide and form two identical (the same) daughter cells

NAME ______________________ CLASS ________________

Bacteria multiply by simple cell division (we call this binary fission) as often as once every 20 mins if they have enough nutrients and a suitable temperature. If we grow bacteria in a lab we can use agar gel to provide the nutrients needed. If this sample is uncontaminated we can use it to investigate the action of disinfectants and antibiotics.

Condition What is Required for bacteria growthTemperature 37°C – BUT in a school lab we never use this, as it may allow harmful pathogens to grow.

Therefore, we use 25°C.Food Agar gel – a nutrient rich gel containing glucose for respiration and nitrogen so the

bacteria can make its own proteins and DNAOxygen Make sure oxygen is able to diffuse into the petri dish to allow the bacteria to aerobically

respire

106) What is binary fission?107) A student uses agar gel to investigate bacteria ……..

a) Because………..b) Therefore………..c) But…….

108) What type of respiration does the bacteria carry out?109) A student says

“Making sure oxygen is available is really important in bacteria growth” a) Is the student correct?b) Why?

Stem Cells

Stem cells are undifferentiated (not got a specific role) cells which are capable of differentiating into other cells with specialised roles.

Embryonic stem cells

Embryonic stem cells are stem cells that are taken from embryos. The advantages of using embryonic stem cells are:

Can create many embryos in a lab Painless technique Can treat many diseases Can become any type of cell (whereas bone marrow can treat a limited number).

However there are disadvantages to using embryonic stem cells:

Harm / death to embryo Embryo rights / embryo cannot consent Unreliable technique / may not work

NAME ______________________ CLASS ________________110) What is a stem cell?111) What are embryonic stem cells?112) A student argues that stem cells shouldn’t be used in scientific research.

“It is wrong to use embryonic stem cells because it harms the embryo and embryos can’t give consent! It’s not even a reliable technique to you might be causing the death of an embryo for no reason!”Another student wants to argue back that that using embryonic stem cells in research has lots of advantages. What could he say?

Adult stem cells

Adult stem cells are another way to treat disease. An example of these are bone marrow stem cells, these can also be used for treating diseases. The advantages of this method are:

No ethical issues / patient can give permission Can treat some diseases Procedure is (relatively) safe / doesn’t kill donor Tried and tested / reliable technique Patients recover quickly from procedure

However the disadvantages of this method are:

Risk of infection from procedure Can only treat a few diseases Procedure can be painful

113) What is an adult stem cells?114) State 3 advantages of using adult stem cells 115) Using adult stem cells a bad idea………..

a) Because……..b) Therefore……….c) But………….

Plant Stem cell

The stem cells from plant meristems can be used to make clones of the mature plant. This is important as it allows us to produce a large amount of plants quickly. This could help us save plants from extinction or produce large amounts of identical plants for scientific research. It can also be used in horticulture to create identical plants to sell.

116) Where can meristems be found in a plant?117) Why are meristems important?118) Explain the use of meristems in plants for human benefits (hint: agriculture).119) Meristem tissue is really important …….

a) Because……….b) Therefore……..

120) EXAM STYLE QUESTION:

Stem cells are used to treat some human diseases.

NAME ______________________ CLASS ________________

Stem cells can be collected from early embryos. These stem cells have not begun to differentiate, so they could be used to produce any kind of cell, tissue or organ. The use of embryonic stem cells to treat human diseases is new and, for some diseases, trials on patients are happening now.

Stem cells can also be collected from adult bone marrow. The operation is simple but may be painful. Stem cells in bone marrow mainly differentiate to form blood cells. These stem cells have been used successfully for many years to treat some kinds of blood disease. Recently there have been trials of other types of stem cell from bone marrow. These stem cells are used to treat diseases such as heart disease.

a) Evaluate the use of stem cells from embryos or from adult bone marrow for treating human diseases. You should give a conclusion to your evaluation.

Diffusion

Diffusion is the movement of particles from an area of high concentration to an area of low concentration. This goes down the concentration gradient. It is a passive process and therefore does not require energy:

This of when you spray perfume. At first you can’t smell it and then gradually the particles diffuse across the space until they are evenly spread out and you can smell it.

There are a few different conditions that will speed up the rate of diffusion. If the concentration gradient is very small (there is only a slight difference in the amount of particles) then the rate of diffusion is slower. If the temperature is higher, the rate of diffusion increases because the kinetic energy of the particle increases and the particles move faster.

121) Recall the definition of diffusion.122) Draw a diagram showing oxygen diffusing into a cell. Label the high and low concentrations.123) Describe how concentration gradient, temperature and surface area affect the rate of

diffusion.

Imagine a ball on a slope. The ball will require you to add energy in order for it to

roll down the slope

Concentration gradient

High Concentration

Low Concentration

NAME ______________________ CLASS ________________124) Explain, in terms of surface area: volume, why single celled organisms have no need of a

transport system.125) Calculate the surface area and volume for a 1mm cube, 2mm cube and 4mm cube.126) Calculate the surface area to volume ratio for the 1mm, 2mm and 4mm cube.127) What is the exchange surface?128) How is the effectiveness of the exchange surface increased by having a large surface area?129) How is the effectiveness of the exchange surface increased by having a thin membrane?130) How is the effectiveness of the exchange surface increased by having efficient blood supply?131) How is the effectiveness of the exchange surface increased being ventilated 132) EXAM QUESTION: The image below shows part of a plant root.

The plant root is adapted for absorbing water from the soil.

Use information from the diagram to explain how this plant root is adapted for absorbing water.

133) The drawing shows part of a root hair cell.

(a) Use words from the list to label the parts of the root hair cell.

cell membrane cell wall cytoplasm nucleus vacuole

(b) The diagram shows four ways in which molecules may move into and out of a cell. The dots show the concentration of molecules.

NAME ______________________ CLASS ________________

The cell is respiring aerobically.Which arrow, A, B, C or D represents:

(i) movement of oxygen molecules; __________

(ii) movement of carbon dioxide molecules? __________

(c) Name the process by which these gases move into and out of the cell.

Osmosis

Osmosis only relates to water particles. It is the movement of water particles from a dilute solution to a concentrated solution, through a partially permeable membrane.

134) What moves in Osmosis?135) Define Osmosis136) A student wants to investigate osmosis. A carrot was placed in a dilute solution.

a) What will happen to its mass? Explain your answer.b) The carrot was placed in 0.4 mol/dm 3 solution. Its mass did not change. Explain why this

happened.c) What does this tell us about the concentration of the carrot?d) The carrot was placed in a concentrated solution. What will happen to its mass? Explain your

answer.137) What is the formula to calculate percentage change in mass?138) Why is percentage change used instead of change in mass?

Dilute solution- Higher concentration of water

Concentrated solution- Lower concentration of water

Water moves from Dilute Solution to Concentrated solution

NAME ______________________ CLASS ________________If the water concentration outside the cell is equal to the water concentration inside the cell the solution is termed isotonic.

A hypotonic solution has a higher water concentration that the cell this means water moves from the solution into the cell.

Finally, a hypertonic solution is one in which the water concentration in the solution is lower than the cell causing water to move from the cell into the solution.

139) What does Isotonic mean?140) If the solution is isotonic to the cell what is happening to the water?141) What does hypotonic mean?142) If the solution is hypotonic to the cell what is happening to the water?143) If this keeps happening what could happen to the cell?144) What does hypertonic mean?145) If the solution is hypertonic to the cell what is happening to the water? 146) If this keeps happening what could happen to the cell?147) Animals that live in fresh water have a constant problem with their water balance. The

single celled organism amoeba has a special vacuole that fills with water and then moves to the outside of a cell to burst. A new vacuole starts forming straight away. Explain in terms of osmosis why amoeba need vacuole (4)

Active Transport

Active transport is the movement of substances from a low concentration to a high concentration. This means moving against the concentration gradient and therefore requires energy.

Active transport has many important roles. Two examples are below:

Allow mineral ions to be absorbed into plant root hair cells from very dilute solutions in the soil. Plants require ions for healthy growth, so this movement is vital

Allow sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration, which is needed to produce energy.

Concentration gradient

High Concentration

Low Concentration

Imagine a ball on a slope. The ball will not roll up the

slope unless you give it energy.

NAME ______________________ CLASS ________________

148) What is active transport?149) Describe how root hair cells use active transport150) Why is this movement important in the plant?151) Explain why cells performing active transport require a lot of energy.152) Describe how the gut uses active transport.153) Why is this important?154) Compare active transport and diffusion (6)