Exam Review - Grade 8 - Booklet...

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ANSWER KEY

Science Exam Review Fluids Key Vocabulary: fluid Any substance that flows. Fluids can be a liquid or a gas. Examples of fluids… water, oil, oxygen, carbon dioxide gas. Non examples of fluids are things like sand and salt. They do appear to “flow” but each individual particle of sand or salt on their own is a solid substance. Viscosity A fluids resistance to flow. Viscous substances appear to have “thickness” and the internal friction (cohesion between particles is stronger). Temperature, size and density of particles, and the internal friction all affect viscosity. Flow Rate Flow rate is the volume of liquid that passes a point in a certain time. A substance with a high viscosity would have a slower flow rate. Density How tightly packed particles are in a given volume or space. Density can be measured using the formula D=M/V Buoyant force Buoyancy is the same as buoyant force. It is the force that is opposite to gravity in fluids. Ex. Force of the water pushing back up on an object… gravity pulling it down. Pressure The force acting per unit area. Pressure can increase if you compress a substance into a smaller space. Increase force can increase pressure. Compressibility Describes a substance that can be squeezed into a smaller space (area). Example: Gas is highly compressible. Hydraulic A hydraulic system is a system that uses liquid in a confined space to transfer force and do work. Pneumatic A pneumatic system is a system that uses gas in a confined space to transfer force and do work.


Draw diagrams for the three states of matter and describe the particles in each state.

How does matter change from one state to another? Ex. Discuss Density When you add heat to a solid the particles gain energy and move more quickly… the particles will spread out and be able to move past one another which would decrease the particles density. Most liquids are less dense than solids of the same substance. Water is weird. Water doesn’t follow the normal rules. Because water is a bent molecule and is a polar molecule (positive and negative charges) it is LESS DENSE as a solid. This is why ice floats. Give an example of a fluid that is very v iscous and one that

is not. Highly v iscous fluid = honey

Low v iscosity fluid = water

How can we compare or measure v iscosity? We can use the flow rate or how quickly the liquid will flow down an inclined surface (VISCOSITY RACE LAB)


Using particle theory, explain how temperature affects v iscosity. If you add heat (increase temperature) of a substance particles will move more quickly and spread out. This will reduce the viscosity allowing the substance to flow more quickly. What are the units used to measure volume? If the substance is a liquid we would need to use a measurement tool such as a beaker or measuring cups. We typically use ml (milliliters) For regular shaped solids (ex. Cube) we would need to use a formula (ex. Lxwxh) We would measure the side lengths with a ruler. The units for volume in this case is cm3

How do you find the volume of an irregularly shaped solid? Water displacement method. Ex. A jagged rock with no regular shape can’t be measured. No formula would work to find volume. If you drop it into water and observe the change in the water level. Ex. Water started at 50ml and went up to 55 ml we can say the change was 5 ml. Therefore the object must have a volume of 5 cm3 Use the density formula D=M/V for the following problems Find the density for a toy car that displaces 60 ml of water and has a mass of 82 g (show your work). D=M/V D= 82g/60ml D = 1.367 g/ml

• Knowing that the density of water is around 1g/ml we should assume any density higher (even 1.3) would sink in the water because it is more dense.


What is the density of a cube with a length of 8 cm and a mass of 25 g (show your work)? Volume = l x w x h D = M/V 8 x 8 x 8 25g/512cm3 V = 512 cm3 Density = 0.048 g/cm3

Mass = 25g

• Cube would float in water due to the very low density compared to water (1g/ml)

What happens when the buoyant force is greater than the force of grav ity? The object would sink. When an object sinks it is also called negative buoyancy. What makes up a hydraulic system? Liquids in a closed system that is pressurized. The liquids are then used to transfer force from one point to another to do “work” or have something happen. Give a body system example and a human-made example of a hydraulic system and a pneumatic system. Hydraulic body system: Circulatory System The heart acts as a pump and sends pressurized blood throughout body to circulate and deliver oxygen to cells. Hydraulic human-made: Water-pump or hydraulic lift

Pneumatic body system: Respiratory System The lungs control pressurized air (oxygen, carbon dioxide…etc.) and delivers those gases to the blood so it can be transported.


Pneumatic human-made system: Pneumatic car jack…

nail/staple gun…

Explain the connection between force, area and pressure and prov ide examples. Increased force would increase pressure in a closed system and reduce the area the particles would have to move. Ex. Compressing air in an empty water bottle. Adding force (squeezing sides) would decrease the area inside the bottle… the gas particles would hit the sides of the bottle more frequently and the pressure would build up. If you increase area (ex. To float in water we spread our bodies out to increase surface area on the water)… this will decrease the force on the top of the water and decrease the pressure on the surface of water helping us float. Cells and Systems Key vocabulary: Levels of organization (liv ing things):

smallest - Organelle (part of a cell) à CELL à TISSUE à

ORGAN à ORGAN SYSTEM à ORGANISM - largest

• Not all liv ing things are multicellular • Not all liv ing things have this level of organization (ex. Body

systems) this is for complex multi-cellular liv ing tings • There are unicellular liv ing things that are only one cell in

size but still fit the characteristics of living things (require energy, reproduce, grow, move…etc)


Describe the function of the following parts of the cell:

a) nucleus Controls the cell (like the boss or the brain) and is responsible for directing all activities within the cell to ensure it is functioning properly

b) cell membrane The thin outer layer surrounding a cell (on a plant cell it is just inside the cell wall) The cell membrane is sometimes called semi-permeable or selectively permeable which means it only lets certain substances pass through into the cell. The cell requires nutrients and oxygen to survive. The cell membrane will only take in what the cell needs and let out what it doesn’t need.

c) cytoplasm The jelly-like substance (largely made up of water) inside cell that holds all cell organelles in place

d) vacuole Usually only found in plant cells. Very large in plant cells. If an animal cell has a vacuole it will be much smaller. Plants use the large vacuoles to store water and nutrients within each of their cells.

e) cell wall Only found in plant cells. A cell wall is a thick rigid (strong) outer layer that gives each plant cell a specific shape that is stronger and helps with plant stability as it grows. This is also semi-permeable like the membrane.

f) Mitochondria This is the “powerhouse” of the cell helping the cell by using the materials cells are delivered (oxygen and nutrients) and creating energy for the cell to function and work.


Define and give an example of the following:

a) selective (semi) permeability The cell membrane is sometimes called semi-permeable or selectively permeable which means it only lets certain substances pass through into the cell. The cell requires nutrients and oxygen to survive. The cell membrane will only take in what the cell needs and let out what it doesn’t need.

b) non-permeable Another word for this is IMPERMEABLE which just

means that it will not let any other substances pass through.


Structures of the heart (circulatory system):

septum The center “divide” that separates the right side from left side of the heart. The septum divides the oxygenated blood from the deoxygenated blood. aorta The aorta is the largest ARTERY in your body. It carries blood AWAY from the heart and sends blood to all other parts of your body. It is strong, muscular, and flexible enough to handle the pressure of blood being pumped from your heart. valves There are 4 valves in your heart. There are valves that open and close and prevent blood from flowing backwards in your heart. There is a valve between the atrium and ventricles separated blood from each chamber. There are also valves located in your pulmonary artery and your aorta. ventricles The ventricles are the name for the lower V-shaped chambers in the heart. atria (atrium) The atria are the upper smaller chambers in the heart. arteries Arteries carry blood AWAY from the heart. They are almost always oxygenated blood (except the pulmonary artery). Arteries are thicker and stronger due to the fact that they must be able to handle the pressure of blood pumping outward toward body.

Veins Carry blood back TOWARDS the heart. They are almost always deoxygenated blood (except the pulmonary vein). They are thinner and less muscular than arteries. capillaries Capillaries are the smallest (sometimes microscopic blood vessels). All cells in our body connect to capillaries (this is where oxygen and nutrients trade from blood to cells…etc) capillaries connect veins and arteries.


Major components of blood:

Red Blood Cell:_ Red Blood Cells make up 44% of blood. They are responsible for transporting or carrying oxygen to all cells in the body… they drop off the important oxygen and pick up carbon dioxide to return that to the lungs so we can exhale it. White Blood Cell: White blood cells make only 0.5% of blood. They are responsible for protecting the body against disease. They will attack and engulf germs and invading pathogens.

• White blood cells are a part of blood (circulatory system) but also play an important role in the IMMUNE SYSTEM so can be discussed as one of the connections between two different body systems

Platelets: Platelets help clot blood (when you have a cut they will stick together and block the cut… they will then dry and form a scab if the cut is exposed to the air outside of your body). They make up only 0.5% of your blood. Plasma: Plasma is the liquid component of your blood (largely made up of water) it is 55% of your blood. It carries dissolved nutrients and wastes as well as carries the other blood cells (allows them to flow) through the body vessels.


Describe 3 body systems and show the interactions they have between each other. How are they inter-related? 1 – Circulatory system sends blood around body to all cells. This works together with respiratory system because the blood needs to stop at lunds and “pick up oxygen” to feed cells oxygen so they can work. 2 – Circulatory system works with digestive system because blood needs to “pick up” nutrients after they are broken down and digested by the digestive system. Cells need nutrients to live and the blood needs to get the nutrients to all cells of body. 3 – Circulatory system works with immune system. White blood cells are part of blood but also part of immune response. WBC’s fight off invading pathogens, disease… etc. and your blood helps them get around throughout body. What do arteries do and how are they different from veins? And how are they both different from capillaries? Arteries carry blood away from the heart. Veins carry blood toward the heart. Capillaries are where exchange of nutrients, gases, and wastes happen with each and every one of our cells. Arteries are thicker, more muscular, strong, and flexible (need to handle pressure of blood pumping out of heart) Veins are thinner-walled and less flexible (they do not need to handle force or pressure as much as arteries) Arteries are almost always carrying oxygenated (red) blood and veins almost always carry deoxygenated. The pulmonary artery and vein are the only exception to this rule.


Explain the path of blood through the heart and lungs. If blood has just been pumped out of your heart and up toward your head to give your brain cells oxygen and nutrients where does the blood travel next? After providing oxygen to the brain, the blood cells will travel back to the heart through the largest vein called the Superior Vena Cava. Now in the right atrium (where blood collects from the body) the blood cell must pass through a valve to get to the right ventricle. To acquire oxygen, the blood cell will travel through the pulmonary artery to the LUNGS. The deoxygenated blood will receive oxygen through the alveoli (also known as air sacs) which are surrounded by capillaries which help this gas exchange happen. The blood cell will return to the heart’s left atrium by passing through the pulmonary vein. Another set of valves ensures the blood flows one way to the left ventricle. This ventricle is the thickest and most muscular. The heart muscle will contract and will need a great amount of pressure and force to get blood to the rest of the body. The blood will travel through the largest artery called the aorta before being distributed to the rest of the body. List the characteristics of liv ing things.

1) All liv ing things require energy (food and water) 2) All liv ings things must grow and reproduce 3) All liv ing things have some form of response to the

env ironment (response to stimulus) 4) All liv ing things produce waste 5) All liv ing things have a lifespan 6) All liv ing things can be unicellular (one cell) or

multicellular Describe Cell Theory.

1) All organisms (liv ing things) are made up one or more cells

2) Cells are the basic units of structure and function in all organisms.

3) All cells come from other cells (pre-existing cells) The cell theory is one of the major theories in science. It is the result of many discoveries from scientists over time.


Optics Key vocabulary: spectrum

1) Electromagnetic spectrum describes the different forms of light (not all light is visible). Waves that are emitted from energy sources like the sun include: Radio waves, Microwaves, infrared, visible light, ultraviolet light, x-rays, and gamma rays.

2) Visible Light Spectrum includes the range of colours produced by white light. ROYGBIV are the colours humans can see when light is refracted and splits into the visible spectrum

frequency Frequency describes the number of waves (electromagnetic spectrum waves or light waves) that are able to pass by a certain distance in a given time. Ex – Gamma waves which are very small have a high frequency (many waves can pass a small distance in a short time) wavelength This is the length of a wave or distance from the top of one wave to the next. Radio waves have the largest wavelength. Gamma rays have the smallest wavelength. refraction Refraction refers to light bending or changing direction when it goes from one medium to a different medium (example air to water) rods Rods are one of the specialized cells (photoreceptors) in our eyes responsible for seeing in dim light conditions. cones Cones are the second specialized cell in our eyes (photoreceptors) that allow us to see colour. Cones are receptive to three different colours of light (RED, GREEN, BLUE)


concave and convex mirrors and lenses

Concave lenses are thinner at the middle. Rays of light that pass through the lens are spread out (they diverge). A concave lens is a diverging lens. When parallel rays of light pass through a concave lens the refracted rays diverge

CONVEX LENSES are thicker in the middle. Rays of light that pass through the lens and come together (they converge). When parallel rays of light pass through a convex lens the refracted rays come toward each other or converge.


A CONCAVE MIRROR is a mirror that is curved inward in the middle. It might help you to remember this if you think that when you look in a concave mirror, it looks like you are looking into a cave. INSIDE OF A SPOON is an example of a concave mirror. Image will appear upside down from farther away when looking into a concave mirror. Light rays bend inward and image appears flipped unless you are very close to the mirror and it will turn back right-side up. A CONVEX MIRROR, diverging mirror, or fish eye mirror is a curved mirror in which the reflective surface bulges toward the light source. Convex mirrors reflect light outwards, therefore they are not used to focus light. ... The image is smaller than the object, but gets larger as the object approaches the mirror.

terms related to types of light sources

Incandescent (Hot light) Luminescent (cool light)

4 types of luminescent light:

Fluorescent, Phosphorescent, chemiluminescent, bioluminescent

types of electromagnetic radiation

Radio waves, Microwaves, infrared, visible light, ultraviolet light, x-rays, and gamma rays.

the law of reflection


additive theory - subtractive theory

Give a real life example for each type of mirror:

a) plane: normal flat surfaced mirror (general bathroom mirror)

b) convex: security mirror in corner of stores

c) concave: makeup mirror

Mirror at a “funhouse” or in circus (flips you upside down)

Give a real life example for 4 different types of light sources:

Fluorescent – life examples include classroom tube lights and swirly bulb energy efficient light bults Phosphorescent – life examples include glow in the dark stickers and toys Chemiluminescent – life examples include glow sticks


Bioluminescent – life examples include anglerfish (finding nemo), fireflies, glowing jellyfish…etc. Incandescent – fire (flame of a match), traditional lightbulb that heats up with a metal filament What part of an incandescent bulb glows? filament

How do we know that light travels in straight lines?

Observations with light sources… properties of light (reflection) will show light bouncing at angles but maintaining a straight path unless refraction takes place and the path of light is bent Draw and label a diagram that shows light bouncing off a flat

(plane) mirror. *** SEE LAW OF REFLECTION ***

Sketch the following

lenses (show light refracting as it passes

through each):

a) Convex


b) Concave

What colour(s) are reflected when you look at the following

colour t-shirts:

a) Blue – BLUE light

b) White – All colours from spectrum of light

c) Red – Red light

d) Cyan – Both Green and Blue light

*** If the question is about reflection the main thing to discuss is the light (light is reflecting)…. The primary colours of light are Red, Green, Blue Explain why images are reflected in a mirror but not on a

white wall.

Reflective surface causes light to bounce… nothing absorbs. Wall will also cause light to bounce, however, due to the opaque wall it is also absorbing light. You are buying a new light fixture. Explain the pros and cons

or differences of each.

a) incandescent light bulb Incandescent bulbs (hot light) will not be

energy efficient because so much of the energy is lost in the form of heat.


b) florescent light bulb Fluorescent light bulbs (cool light) will be more energy efficient because energy is NOT being lost to heat. They are, however, sometimes slower to turn on or they flicker beacause electricity is passing through a gas and can take time to emit light.

Water Systems Key vocabulary: heat capacity Describes the amount of heat needed to increase the temperature of a substance by 1 degree celcius. Water has a high heat capacity meaning it can take a lot of energy to heat up and a lot of time to cool. Runoff Water flowing along the surface of the ground (often due to gravity)

Basin A natural depression (indentation) in the ground where water can gather or collect. Basins can be large (like a lake) or small (like a puddle or pond) Water Table The upper boundary (layer) of the saturated zone. The water table is the level below which the ground is saturated with water. Saturated zone The area beneath the water table where water fills the spaces in the gravel, sand, silt, or rock. erosion Erosion is the gradual breaking down of materials caused by moving water. Erosion can dissolve rock, weakening it or turning it into tiny bits (fragments). These fragments can then be carried from one location to another. Deposition Deposition is the transporting and dropping off of sediments (rocks and soils…etc) carried by erosion. Percolation Filtration of water through soils and permeable rocks. Percolation describes the process of gravity pulling water down into the ground. The water will seep through porous materials and “filter” as it is pulled through layers of the earth.


Aquitard An impervious (water-proof) or impermeable layer of clay, silt, or rock that water can’t move through Aquifer An underground zone of rock or soil that contains and yields water (WATER POCKET) often located within the aquitard layer. Potable Safe drinking water Polar Molecule: Water is an example of a polar molecule. The molecule is bent and has positive and negative charges. The hydrogen both are positively charged and the oxygen is negatively charged making it adhesive (attracted) to many other types of molecules. Transpiration: Water evaporating from plants (plants releasing water in the form of vapor as a byproduct of photosynthesis) Describe the water cycle (why is it important… how does it work: The water cycle is a continuous pattern in nature in which water moves as it changes state above, on, and below the surface of Earth. The water cycle is self-renewing and constant. Water is needed to sustain all life on Earth.


ram What percentage of the Earth’s water is

a) fresh water 3%

b) salt water 97% Describe three methods humans can use to obtain water in places it is not readily found (or when supplies are limited)

1. Dig wells (try to make use of groundwater from saturated zone or auqifers)

2. Rainwater collection system (divert rainwater from rooftops into barrels)

3. Desalination (separating salt from saltwater)… distillation (uses evaporation and condensation to remove salt from water)


4. Filtration processes (trying to pass dirty water through filter system to clean it)…ex. Lifestraw technology

5. Melting water trapped in ice (glacial water) What do we know about ocean currents (explain minimum of 5 things). Ocean currents occur because of a combination of the following:

1. Salinity of water (amount of salt concentrated in water) 2. Heat capacity of water (amount of stored heat) 3. Rotation of the Earth on its axis in space 4. Wind and atmosphere affect oceans and surface water 5. Ocean currents develop a circular pattern (called GYRES) that create

rotation of water in large circles or cycles 6. Northern hemisphere currents flow clockwise…. Southern hemisphere

currents flow counterclockwise

What are and explain 3 methods used to control flooding.

1. Planting extra vegetation along riverbanks, floodways, and regions that may be at risk of flooding

2. Sandbagging (temporary to divert water away from structures, homes, and at risk areas)

3. Floodways – like large ditches around areas… ex. Winnipeg has a giant floodway around the whole city to divert excess water into

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