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7BC: Cells, Tissues and Organs 1
7BC: Cells, Tissues and Organs
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This unit will be about living things and what they are made up of. Before we begin studying that, we are going to spend some time looking at scientific experiments and fair tests.
Lesson 1: VariablesI am learning about different variables so I can understand the need for a fair test.
Recap questions:You want to find out whether more solute will dissolve in hot or cold water. Answer the questions below and then your teacher will demonstrate the experiment.1. What is a solute?2. Give an example of a solute3. What key word can be used for the water in this experiment?4. Once the water and solute have been mixed, what keyword can be used to describe the mixture?5. A student dissolves 10g of solute in 100g of water. What will the mass of the mixture be?6. A student uses a solute that is a solid. Draw a particle diagram of a solid. 7. What is solubility?8. Do you think more solute will dissolve in hot or cold water?9. Explain your answer.10. The student uses a solute that causes the water to change colour. By what process does the colour
spread out into the water?11. Does this happen quicker in liquids or gases? Explain your answer. During this experiment, there are a number of variables. The thing you are changing in this case is the temperature of the water. This is called the independent variable. The thing you are measuring is how many spatulas of solute can dissolve. This is called the dependent variable. Anything else that might affect the experiment must be controlled, for example the solute, water source, amount of stirring and volume of water. There are three types of variable:
Independent variable: the variable which the scientist changes Dependent variable: the variable the scientist observes, counts or measures Controlled variables: any variable which could affect the result and is therefore kept the same
Your teacher will now add weights to a spring. We are trying to find out how the mass on the spring affects how far it stretches.12. In this experiment, what is the dependent variable? 13. In this experiment, what is the independent variable?14. List as many variables that must be controlled as you can. 15. The spring is a solid. Explain why it does not flow.16. Give an example of a substance that does flow and explain why it
flows. 17. A student tries the experiment again with a warm spring. What
happens to the particles in the spring as they are warmed up?18. If it is heated enough, what will happen?19. The spring is made of steel. Steel melts at 1500°C and boils at
2750°C. What state will it be at 2000°C? Your teacher will now demonstrate to you what happens when calcium carbonate is added to acid. Your teacher wants to know how the size of the pieces added to the acid affects the volume of gas released. Answer the questions below:20. What did you observe when the calcium carbonate was added to the acid?21. In this experiment, what is the dependent variable?22. In this experiment, what is the independent variable?23. List as many variables that must be controlled as you can. 24. The gas can be collected in a syringe. Can the gas be compressed? Explain your answer. 25. The gas is warmed up. What happens to the particles?26. How does warming up the gas affect the pressure within the syringe?A student knows that when you heat a metal in the air, the mass of the metal increases. The student wishes to investigate this further so takes three different metals and prepares to heat them in the air.
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27. What is the student’s independent variable?28. What is the student’s dependent variable?29. What variables need to be controlled?A student knows that when pondweed is placed under water, it releases bubbles. The student wants to know how the temperature of the water affects the number of bubbles produced.30. What is the dependent variable?31. What is the independent variable?32. Which variables need to be controlled?A student knows that if you roll a ball down a hill and then on to a flat surface, it will eventually stop. The student wants to know how changing the height from which it is dropped affects the distance the ball travels. Below is a list of variables, for each one say if it is dependent, independent, or controlled.33. Mass of ball34. Size of ball35. Distance ball travels36. Angle of ramp37. Number of balls dropped at once38. Distance up the ramp the ball is dropped from39. Material ball is made of40. Smoothness of ramp surfaceThe fair test
A student has a golf ball and a tennis ball. They want to know which one bounces higher when it is dropped. The student drops the golf ball onto a wooden floor, and the tennis ball onto a piece of carpet. The golf ball bounces higher and the student says “I now know that golf balls are bouncier than tennis balls.”The student is wrong. They are wrong because they have not controlled all the variables. Instead of changing one thing (the ball), they have changed two things (the ball and the floor). This means they have more than one independent variable and the experiment is not a fair test.Another student wants to know the same thing: whether the golf ball or the tennis ball is bouncier. They stand on a table and drop the golf ball. They then stand on the floor and drop the tennis ball. The golf ball bounces higher and the student says “I now know that golf balls are bouncier than tennis balls.”41. The student is wrong. Use the first paragraph to write a refutation explaining why the student is
wrong. 42. Check your answer to question 41 by making sure you have written what the independent variables
being used are. 43. Write a short method explaining how a student could find out which ball is bouncier. Make sure to
include a list of all the variables that need to be controlled. A student makes parachutes out of plastic bags and toy soldiers. The student wants to know how the number of toy soldiers attached to each parachute affects the speed at which the parachute falls.44. What is the dependent variable?45. What is the independent variable?46. Which variables must be controlled?47. Why must these variables be controlled?48. Write a method that the student could follow to find out how the number of toy soldiers affects the
speed at which the parachute falls.
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Lesson 2: Animal and plant cellsI am learning about organelles to be able to identify plant and animal cells.
In biology, we call an entire living thing like a plant or an animal or a fish or a mushroom an organism. All organisms are comprised (made up of) cells. We will first look at two main categories of cells: animal and plant cells. Your teacher will draw diagrams of each type of cell, showing all the organelles and explaining what they do. You can use this table to help you when you start independent practice. What is the function of the nucleus? Controls the activities of the cell What is the function of the cell membrane? Controls what enters and leaves the cellWhat is the function of the cytoplasm? Where the chemical reactions take place.What is the function of the mitochondria? Where respiration takes place.What is respiration? How energy is released from glucoseWhat is the function of the ribosomes? Where protein synthesis takes place.What is the function of the cell wall? It strengthens the cell What is the function of the permanent vacuole? It keeps the cell rigid.What is the function of the chloroplasts? Where photosynthesis takes place.What is photosynthesis? How plants use light to make glucose
49. Complete the table below with one or two ticks for each row. The first one has been done for you.Organelle Found in Animal cells Found in plant cellsNucleus ✔ ✔
Cell membraneCell wallPermanent vacuole Ribosome ChloroplastMitochondriaCytoplasm
50. Answer the questions below in your exercise book.a) List the structures found in a human cell.b) What is the function of the nucleus and mitochondria?c) The Krebs cycle is an important part of respiration. Where does the Krebs cycle take place?d) What three cell structures are found only in plant cells and not in animal cells?e) What cell structure is responsible for making proteins?f) Salivary cells produce amylase, which is a type of protein. What type of cell structure will they
have a lot of?51. Use cover, write, check to start learning the names of the organelles and their functions
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Lesson 3: Microscopes and MagnificationI am learning about how microscopes can be used to magnify things too small to see
Cells are too small to be seen with the naked eye. Instead microscopes have to be used. Microscopes “magnify” things, this means they make them big enough to see. 52. Label the microscope below with the following words: (Objective lens, Eyepiece, Stage, Stage Clips,
Fine Focus, Course Focus, Light, Base, Arm)
Image size
The different lenses allow us to magnify more or less – to make something look bigger or smaller. We can measure how big something looks with a ruler. We call this the image size. Your teacher will show you how to use a ruler to measure the images below, and then you should do the rest.
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Unit conversions
Before we move on, we need to look at how we measure length and how we can use both cm and mm to do so. If you want to go from a cm to a mm measure, you need to multiply by 10, so 1cm is 10mm. If you want to go from mm to cm you need to divide by 10, so 1mm is 0.1cm.53. Convert the below into cm:
a. 10mmb. 1000mmc. 902mmd. 81.3mme. 0.2mm
54. Convert the below into mm:a. 5cmb. 28cmc. 1000cmd. 0.009cm
Magnification
In order to make the image size bigger, we have to use a different magnification. We do this by changing the lens on the microscope. Your teacher will show you how we can easily use the magnification and the actual size of an object to work out how large an image will look.
55. A cell is 0.1mm and is magnified x10. What will its image size be?56. The same cell is magnified x100. What will its image size be?57. An object is 0.02cm and is magnified x40. What will its image size be?58. A student says that “microscopes make cells bigger.” Explain why the student is incorrect. The magnification equation
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We can combine everything we have learnt into an equation. This is like a recipe that scientists use to work things out quickly and easily. To calculate the size of a particular image in a microscope, we use the equation:
actual ¿×magnification=image¿¿
59. A cell has an actual size of 0.1mm. It is viewed with a microscope with a x40 magnification. What is the image size?
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60. A cell has an actual size of 0.2mm. It is viewed with a microscope with a x60 magnification. What is the image size?
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61. A cell has an actual size of 0.05mm. It is viewed under a microscope with magnification x100. What is the image size?
62. A microscope with magnification x50 is used to view a cell with an actual size of 0.01mm. What is the image size?
63. A cell has an actual size of 0.001mm. What is the image size if the magnification is x60?
64. A cell has an actual size of 0.01cm. It is viewed with a microscope with a x40 magnification. What is the image size?
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65. A cell has an actual size of 0.0005cm. It is viewed with a microscope with a x60 magnification. What is the image size?
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66. A cell has an actual size of 0.05cm. It is viewed under a microscope with magnification x100. What is the image size?
67. A microscope with magnification x75 is used to view a cell with an actual size of 0.02mm. What is the image size?
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68. A cell has an actual size of 0.0003cm. What is the image size if the magnification is x90?
69. A cell has an actual size of 1mm. Its image size when using a microscope is 10mm. What is the magnification?
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70. A cell has an actual size of 5mm. Its image size when using a microscope is 15mm. What is the magnification?
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71. A cell has an image size of 1mm. It is viewed with a microscope with a x50 magnification. What is the actual size?
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72. A cell has an image size of 0.1mm. It is viewed with a microscope with a x100 magnification. What is the actual size?
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73. A cell has an image size of 2mm. It is viewed with a microscope with a x80 magnification. What is the actual size?
74. A cell has an actual size of 0.03mm. It is viewed with a microscope with a x90 magnification. What is the image size?
75. A cell has an actual size of 0.03mm. Its image size when using a microscope is 15mm. What is the magnification?
76. A cell has an actual size of 0.005cm. Its image size when using a microscope is 10mm. What is the magnification?
77. When using a microscope, a cell has an image size of 0.15cm. Its actual size is 0.45mm. What is the magnification?
More on magnification
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Microscopes have two lenses, the eyepiece and the objective lens. We use both of these to calculate the total magnification of the microscope: The magnification of a light microscope can be calculated very easily. Total magnification = eyepiece lens magnification x objective lens magnification
Eyepiece Magnification
Objective Magnification
Overall Magnification
X10 X4 X10 X10 X10 X40 X10 X100
78. Complete the table79. Name 8 organelles80. Which organelles do plant cells have that animal cells do not?81. A student uses a microscope with an eyepiece magnification of x10 and an objective magnification
of x50. What is the overall magnification?82. A student uses a microscope with the same objective magnification but an eyepiece magnification
of x5. What is the overall magnification?83. A cell has an actual size of 0.001mm. Its image size when using a microscope is 3cm. What is the
total magnification?84. A cell has an actual size of 0.1mm. Its image size when using a microscope is 10cm. What is the
total magnification? (remember to convert cm to mm!)85. A cell has an actual size of 0.0015cm. It is viewed with a microscope with a x4.5 objective lens and
a x10 eyepiece lens magnification. What is the image size in mm?86. A cell has an image size of 0.6cm. It is viewed with a microscope with a x20 objective lens and a
x10 eyepiece lens. What is the actual size?87. A student has a cell with an actual size of 0.02mm. They have an eyepiece lens with x25
magnification. If they want the cell to have an image size of 5mm, what objective lens will they have to use?
Lesson 4: Unicellular OrganismsI am learning about the features of unicellular organisms to be able to identify differences and similarities with multicellular organisms
A unicellular organism is a living thing that is just one cell. One type of unicellular organism that you may have heard of is bacteria. You may know bacteria as something that cause illness and infection, but bacteria can also have lots of useful functions too. For example, some bacteria live in your gut and can help you to absorb important nutrients from your food. There are many different types of unicellular organism, including: bacteria, protozoa, and unicellular fungi.You might be tempted to think that these organisms are very simple, but in fact they can be very complex. They have adaptations that make them very well suited for life in their environment.Bacteria (left picture) are very tiny, unicellular organisms. The structure of a bacterial cell is different to an animal or plant cell. For example, it does not have a nucleus. Yeast Cells (right picture) are a unicellular fungi organism. Yeast have a cell wall, like plants do but do not have chloroplasts.
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88. In biology, the word “function” is similar to the word “job.” What is the function of the
chromosome?89. A particular cell cannot move. What part would help it move?90. A particular cell has more ribosomes than the average cell. What do you think the function of that
cell is?91. A particular cell takes in glucose and excretes carbon dioxide. Which part of the cell controls this
process?92. A yeast cell is 0.004mm. If it is observed under a microscope with x400 magnification, how big will
the image of the yeast cell be?93. The cytoplasm is mostly liquid. Explain why it can flow. 94. When nutrients enter the cell, they diffuse through the cytoplasm. What is diffusion?95. Explain why diffusion through the cytoplasm is faster than diffusion through a solid. 96. Draw a particle diagram of a gas97. Explain why diffusion through a gas is fast
Reproduction of Unicellular Organisms:
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Like all living things, unicellular organisms must reproduce. This is done through simple binary fission where they just make copies of themselves and then divide into two.
98. Name one organelle that a bacteria cell does not have that a plant and animal cell do have. 99. What is the function of the flagellum? 100. Label the cell below diagram showing a yeast cell provided to you. 101. Name one organelle that is in both a yeast cell and a plant cell. 102. What is the function of a ribosome?103. State the three types of unicellular organisms. 104. State below whether each function of unicellular organisms is a use or a danger:
____Use__ Bacteria can be added to sewage to break down harmful chemicals__________ Bacteria live in the gut and help our digestive system __________ Bacteria and fungi digest dead organisms releasing useful nutrients __________ Bacteria can infect wounds on the skin after surgery causing infection __________ Fungi such as yeast are used in brewing and baking __________ Bacteria can reproduce in the body and release toxins causing disease __________ Fungi can infect parts of the body causing athletes foot and thrush __________ Fungi make antibiotics which can be used to treat bacterial infections
105. What happens at the start of binary fission?106. A cell undergoes (does) binary fission. How many cells are there at the end?107. If there are 100 cells and they each undergo binary fission, how many are there at the end?108. A cell undergoes binary fission once every hour. How many cells will there be in six hours time?109. The cell has an actual size of 0.01mm and is looked at under a microscope with x100
magnification. What is the size of the image?110. The microscope is changed for one that has a x10 eyepiece lens and x40 objective lens. What is
the size of the image?
Lesson 5: Diffusion
I am learning about how the rate of diffusion can be changed to explain why some cells have certain features
Recap questions:111. What is diffusion?112. In what state of matter does diffusion happen quickest?113. Explain why this is the case.114. Someone sprays deodorant in the front of a room. Is the front of the room an area of high or low
concentration? Explain your answer.115. Eventually, you can smell the deodorant from the back of the classroom. Explain why, using the
word particle in your answer.116. On a hot day, you can smell the deodorant at the back of the room much quicker than you can
when it is cold. Explain why.
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117. A student wants to know how the temperature of the room affects how quickly you can smell the deodorant at the back of the room. What is the independent variable?
118. What is the dependent variable?119. Which variables need to be controlled?120. Explain why it is important to control these variables.Rate of Diffusion
The rate of diffusion is linked to how fast and easily the particles can move. This is very important in biology as particles need to move in and out of cells for organisms to be able to function. How quickly particles move depends on three factors outlined below: Concentration Gradient – The greater the difference in concentration, the quicker the rate of diffusion
121. In the diagrams above, explain why the rate of diffusion from A to B is higher than the rate from C to D.
122. Look at the diagrams below:
a. Will diffusion happen from A to B or from B to A?b. Once diffusion has finished, how many particles will be in A and B?c. Will diffusion happen from C to D or from D to C?d. Once diffusion has finished, how many particles will be in C and D?e. Will diffusion be quicker in A and B or in C and D? Explain your answer. f. Draw a concentration gradient diagram to show what A and B are like once diffusion has
completed.
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Surface area of the cell membrane- The greater the surface area, the faster the rate of diffusion
123. Explain why a cell which needs to take particles in from its surroundings would have a large surface area.
124. What is the relationship between surface area and rate of diffusion? 125. A cell has 10 particles in it, and 50 outside it. Overall, will diffusion take place into the cell or out of
the cell? 126. How many particles will be in the cell at the end of diffusion? 127. A student says there will be more particles in the cell at the end if it has a larger surface area.
Explain why this is incorrect. 128. Look at the diagram below:
a. Will diffusion be quicker in and out of cell A or cell B?b. Explain your answer.
Temperature – The higher the temperature, the more energy the particles will have, so they will move and mix more quickly 129. A student has two beakers, one at 50°C and the other at 75°C. They put a drop of ink in each
beaker. In which beaker will diffusion happen quicker?130. Explain your answer.
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131. Roots absorb water from the soil. Why are they more effective at this during the day than over night?
Pause and recap:
132. The photograph shows part of the surface of a plant root. This part of the root is covered with hundreds of structures like the one labelled X. Use the scale to measure the length Y–Z on the photograph.
133. The photograph shows the root magnified 100 times.
Calculate the actual length Y–Z in mm.134. Why do you think the root has that shape? 135. The cheek cell to the right is magnified 250 times. The
width of the cell is shown by the line D to E. Calculate the actual size of the cheek cell in mm.
136. A microscope has an eyepiece lens with a 10x magnification and an objective lens with a 4x magnification. A student looks at a cell using it and measures the image size to be 0.2cm. What is the actual size of the cell in mm?
Lesson 6: Specialised Cells I am learning about how the adaptations of certain cells can be used to predict their function
Humans and other animals are multicellular organisms meaning they are made up of multiple cells, in fact the average human is made of 37 TRILLION cells! The animal cell you have learnt about in the past is the general animal cell but animal cells have to be specialised for the body to function correctly. When a cell specialises it adapts to suit its function. Below are some examples of specialised animal cells.Type of specialised cell
Function Adaptations
Nerve cell Carry electrical impulses around the body
Very long to get around the body Lots of connections to send messages to other
cells Insulation around it to send messages quickly
Muscle cells Contract and relax to allow movement
Contain special fibres that can slide over one another
Contain lots of mitochondria to provide energy for contraction
Red blood cells Transport oxygen round the body
Contain haemoglobin to carry the oxygen No nucleus so they have more space for
haemoglobin Biconcave shape – large surface area so oxygen
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can diffuse in and out quicklyAnswer the questions below in your exercise book137. Why does the nerve cell have lots of connections138. What is a specialised cell?139. What is the function of the cell membrane?140. What is the function of the nucleus?141. Why don’t red blood cells have nucleuses? 142. What do ribosomes do?143. A nerve cell in the long section is 0.00007mm wide. How big will it look when viewed under x1000
magnification?144. What is the function of a nerve cell?145. Give two adaptations of a nerve cell?146. Why do nerve cells contain lots of mitochondria? 147. Complete the sentence stems:
a. Red blood cells have no nucleus because…Red blood cells have no nucleus but…Red blood cells have no nucleus therefore…
b. Muscle cells do lots of respiration because…Muscle cells do lots of respiration but…Muscle cells do lots of respiration therefore…
Specialised plant cells
Plants, like animals, are multicellular organism and as such contain many specialised cells. Just like animal specialised cells these plant cells contain certain features and adaptations that make them successful at their function. Specialised cell Function AdaptationsRoot hair cell Absorb water and minerals Large surface area available for water to
move into cell Lots of mitochondria to provide the energy
needed to move minerals No chloroplasts (no light underground)
Palisade cell Carry out photosynthesis Contain lots of chloroplasts Usually found in outer layers of leaf and
stem to absorb as much light as possible148. What is the function of a root hair cell?149. A palisade cell of a leaf is viewed under x400 magnification. The image is 1.2cm long. How big is
the cell in mm?150. What do plant cells have that stop them bursting?151. What is the function of mitochondria?152. Why do root hair cells have lots of mitochondria?153. Mitochondria can be seen by a light microscope but ribosomes cannot. Why not?154. What cell structure do palisade cells have lots of?155. Suggest why a cell within the trunk of a tree cannot carry out photosynthesis 156. Why don’t root hair cells contain chloroplasts?157. The image to the right 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.
158. 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
Recap Questions: 159. What are the common organelles in each specialised cell?
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160. Why is it important that red blood cells do not have a nucleus?161. Red blood cells are normally 0.006mm in size. How big would an image of a red blood cell in a
microscope with x20 magnification be?162. Which organelle is found in a large amount in a muscle cell? Why is this helpful?163. What is the purpose of nerve cells?164. Humans are multicellular, meaning they are made of more than one cell. List two types of
unicellular organisms. 165. What special name does a Red Blood Cell have for its structure?166. Where would cardiac muscle be found in the body?167. List two places that smooth muscle can be found in the body. 168. What is the purpose of having specialised cells?169. A student has a microscope with a magnification of x50. It has an image size of 1.5cm. What is its
actual size in mm?
Lesson 7: Principles of organisation and an example organ systemI am learning about how organ systems are dependent on the cells, tissues and organs that make them up
When you eat food, your body needs to break that food down into really small pieces which can easily diffuse around your body. It does this in the digestive system. We will learn about this system in more detail later, but it is a group of organs like the stomach and mouth that all work together to break down the food.The food is broken down in the stomach, mouth and small intestine. It is absorbed into the blood at the small intestine. These are all organs and are made of things called tissues. A tissue is a group of cells working together for a specific purpose. What is the Principles of Organisation of living things?
Cells < Tissues < Organs < Organ Systems
What is a ‘tissue’? A tissue is a group of cells with a similar structure and function.
What is an organ? Organs are groups of tissues performing specific functions
How do organs make up organisms? Organs are organised into organ systems, which work together to form organisms.
170. Your heart is an organ. What is an organ?171. Some of the cells in the heart are muscle cells. What is the function of these cells?172. How are they adapted to that function?173. When lots of muscle cells work together, they form a tissue. What is a tissue?174. There are also tissues in the heart made of nerve cells. What is the function of nerve cells and how
are they adapted to their function?175. How many types of tissue make up the heart?176. The heart and the blood vessels work together to pump blood around the body. What name is
given to a group of organs like this?
Revision Recap Questions: 177. What are the functions of the cell membrane?178. What is the role of the mitochondria?179. What is the function of ribosomes in a cell?180. _____________________: Controls the activities of the cell and stores genetic material.181. What do plant cells have that animal cells do not have?182. Groups of cells are known as ________________________.183. Tissues are organised into __________________________.184. What is the job of the digestive system?185. ____________________ are found in the nucleus and code for different characteristics.186. Which magnification should you start with on a microscope?187. What organelle do bacteria cells not have?
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188. A cell has an actual size of 0.01mm and is viewed under a microscope with an objective lens of x40 and an eyepiece lens of x10. What is its image size?
189. Where is chlorophyll found in a plant cell?190. Name two types of cells that have a cell wall.191. Name the process by which particles move into and out of cells.192. Name three specialised cells. 193. How is a red blood cell adapted to carry oxygen?194. List the adaptations of the root hair cell that help it to absorb water and nutrients.
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