Grade 8 Integrated Science Journal
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Questions and Answers

What is the aim of the experiment described?

  • To analyze the nutritional content of foods
  • To determine the best cooking methods for different foods
  • To compare the amount of energy stored in different foods (correct)
  • To measure the color changes in burning food

The thermometer should touch the boiling tube to ensure accurate readings.

False (B)

What is the independent variable in the experiment?

The type of food

The dependent variable in the experiment is the amount of energy stored in the __________.

<p>food</p> Signup and view all the answers

Which of the following is NOT a controlled variable in the experiment?

<p>The type of food (C)</p> Signup and view all the answers

Name one safety precaution that must be observed during the experiment.

<p>Wear safety goggles</p> Signup and view all the answers

Match the apparatus with their purposes:

<p>Boiling tube = Contains water to measure temperature change Bunsen burner = Provides heat to burn the food Thermometer = Measures the temperature of the water Burning spoon = Holds food for burning</p> Signup and view all the answers

It is important to maintain the same __________ of foods being burnt in the experiment.

<p>mass</p> Signup and view all the answers

Which activity is NOT an observation in the laboratory?

<p>Tasting with tongue (D)</p> Signup and view all the answers

A glowing splint relights in the presence of carbon dioxide.

<p>False (B)</p> Signup and view all the answers

List three aspects considered unsafe in the laboratory as observed in the diagram.

<ol> <li>The test tube rack is too close to the edge of the bench. 2. The opening of the test tube is pointing to the girl. 3. The student’s long hair is not tied up.</li> </ol> Signup and view all the answers

The test for carbon dioxide involves passing it through limewater, which changes from ______ to milky.

<p>colourless</p> Signup and view all the answers

Match the gas with its corresponding test result:

<p>Oxygen = Splint relights Carbon dioxide = Solution changes to milky Water vapour = Cobalt chloride paper turns pink Noble gases = No simple tests</p> Signup and view all the answers

Which gases are present in the gas sample if the results showed dry cobalt chloride paper turning pink, hydrogencarbonate indicator turning yellow, and glowing splint goes out?

<p>Water vapour and carbon dioxide only (B)</p> Signup and view all the answers

The solution for hydrogencarbonate indicator turns red to yellow in the presence of carbon dioxide.

<p>False (B)</p> Signup and view all the answers

Anhydrous copper(II) sulphate turns from white to ______ when it comes into contact with water vapour.

<p>blue</p> Signup and view all the answers

Which process occurs when new substances such as glucose and oxygen are formed?

<p>Photosynthesis (B)</p> Signup and view all the answers

Boiling water is a chemical change.

<p>False (B)</p> Signup and view all the answers

What gas is produced during respiration?

<p>Carbon dioxide</p> Signup and view all the answers

Photosynthesis occurs in the presence of __________.

<p>light</p> Signup and view all the answers

Match the following tubes with the correct photosynthesis and respiration activity:

<p>Tube A = No photosynthesis, Yes respiration Tube B = Yes photosynthesis, Yes respiration Tube C = No photosynthesis, Yes respiration Tube D = No photosynthesis, Yes respiration</p> Signup and view all the answers

Which of the following processes is a physical change?

<p>Dissolving sugar in water (D)</p> Signup and view all the answers

What color does the hydrogencarbonate indicator turn in a tube with pond weed in bright light?

<p>Purple (B)</p> Signup and view all the answers

Magnesium oxide is formed as a product when magnesium burns in the presence of flame.

<p>True (A)</p> Signup and view all the answers

Fresh water shrimp can perform photosynthesis in the dark.

<p>False (B)</p> Signup and view all the answers

What is the observable change when water is added to a test tube initially containing a white substance?

<p>The color changes from white to blue.</p> Signup and view all the answers

What color will the hydrogencarbonate indicator turn in a tube containing fresh water shrimp in the dark?

<p>Yellow</p> Signup and view all the answers

When a glowing splint relights in oxygen gas, it signifies a __________ change.

<p>chemical</p> Signup and view all the answers

Which of the following is NOT considered a physical property of carbon?

<p>It can burn in the air (D)</p> Signup and view all the answers

A white solid is formed when magnesium ribbon burns, indicating a physical change.

<p>False (B)</p> Signup and view all the answers

What is the process called when you add more water to a test tube and stir until an observable change occurs?

<p>Dissolving</p> Signup and view all the answers

Match the following actions with the type of change they represent:

<p>Dissolving sugar in water = Physical Change Burning a piece of paper = Chemical Change Magnetizing a compass needle = Physical Change Rusting of iron = Chemical Change</p> Signup and view all the answers

Which structure is responsible for gas exchange in the lungs?

<p>Alveoli (D)</p> Signup and view all the answers

The ribcage provides mobility and flexibility during the process of gas exchange.

<p>False (B)</p> Signup and view all the answers

What is the primary role of goblet cells in the gas exchange system?

<p>To produce mucus.</p> Signup and view all the answers

The _____ allows air to pass into both lungs.

<p>trachea</p> Signup and view all the answers

Match the following structures with their functions:

<p>Larynx = Produces sound Diaphragm = Contracts to increase thoracic volume Rib = Protects the lungs Bronchus = Conducts air to one lung</p> Signup and view all the answers

During inhalation, which of the following muscles contracts to lower the ribcage?

<p>Internal intercostal muscle (B)</p> Signup and view all the answers

Describe how oxygen molecules move from the alveoli into the blood.

<p>Oxygen dissolves in the moist lining, then diffuses into the blood down the concentration gradient.</p> Signup and view all the answers

Ciliated cells help trap mucus and forward it toward the lungs.

<p>False (B)</p> Signup and view all the answers

What is the resistance of bulb X?

<p>10 Ω (C)</p> Signup and view all the answers

If two identical bulbs are connected in series, the current in the circuit increases.

<p>False (B)</p> Signup and view all the answers

What is the ammeter reading when the switch is closed with only bulb X connected?

<p>2.60 A</p> Signup and view all the answers

The voltmeter reading across bulb X with only one bulb connected is _____ V.

<p>26</p> Signup and view all the answers

How does adding an additional identical bulb in series affect the brightness of bulb X?

<p>Dimmer (D)</p> Signup and view all the answers

Match the voltage readings with their corresponding circuits:

<p>Circuit 1 = 26 V Circuit 2 = 13 V Circuit 1 with Y = 13 V Circuit 2 with Y = 6.5 V</p> Signup and view all the answers

The voltage across bulb X remains the same whether one bulb or two bulbs are connected in series.

<p>False (B)</p> Signup and view all the answers

Connecting one more bulb in _____ increases the total resistance in the circuit.

<p>series</p> Signup and view all the answers

Flashcards

What is NOT a lab observation?

Tasting with your tongue is not an accepted observation method in a laboratory setting. It is dangerous and can lead to harmful substances being ingested.

Unsafe lab practices

In a lab, safety is paramount. Three unsafe practices are: 1. A test tube rack too close to the edge of the bench, 2. A test tube pointing towards someone, and 3. Long, untied hair.

Oxygen Test

A glowing splint is used to test for oxygen. If the splint relights, the presence of oxygen is confirmed.

Carbon Dioxide Test

To test for carbon dioxide, pass the gas through limewater. If the limewater turns milky, carbon dioxide is present.

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Carbon Dioxide Test (Part 2)

An alternative test for carbon dioxide uses hydrogencarbonate indicator. When carbon dioxide is present, the indicator changes color from red to yellow.

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Water Vapor Test (Part 1)

Dry cobalt chloride paper is used to detect water vapor. In the presence of water, the paper turns from blue to pink.

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Water Vapor Test (Part 2)

Anhydrous copper(II) sulfate, which is white, turns blue when exposed to water vapor.

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Identifying Unknown Gas

By understanding the tests for different gases, you can identify an unknown gas based on the reactions it exhibits. For example, if a gas turns limewater milky and a glowing splint goes out, it is likely carbon dioxide.

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Energy Conversion in Burning Food

The process where energy stored in food is released as heat when the food is burnt.

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Independent Variable

The factor that is intentionally changed in an experiment (e.g., type of food).

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Dependent Variable

The factor that is measured and changes in response to the independent variable (e.g., amount of energy released).

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Controlled Variables

Factors that are kept constant to ensure a fair comparison between different trials (e.g., volume of water, mass of food).

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How does burning food measure energy?

The heat released by burning food warms the water in a boiling tube. The greater the temperature change, the more energy the food released.

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Why are controlled variables important?

Controlled variables ensure that any differences observed in the experiment are due to the independent variable and not other factors.

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What's the aim of this experiment?

To compare the amount of energy stored in different foods by burning them and measuring the temperature change of water.

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Safety Precautions

Important rules to follow during the experiment to ensure safety, such as wearing safety goggles and handling materials carefully.

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Photosynthesis

The process where plants use sunlight, carbon dioxide and water to produce glucose (sugar) and oxygen.

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Respiration

The process where living organisms break down glucose to release energy, producing carbon dioxide and water as byproducts.

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Hydrogencarbonate indicator

A chemical solution that changes color depending on the pH (acidity or alkalinity) of its environment.

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Effect of light on photosynthesis

Photosynthesis requires light energy. In the presence of light, plants undergo photosynthesis, absorbing carbon dioxide and releasing oxygen.

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Effect of darkness on respiration

Respiration occurs in both light and dark conditions. In darkness, plants continue to respire, releasing carbon dioxide and absorbing oxygen.

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Hydrogencarbonate indicator color: Purple

Purple color indicates a basic (alkaline) environment, suggesting a higher concentration of oxygen and lower concentration of carbon dioxide.

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Hydrogencarbonate indicator color: Yellow

Yellow color indicates an acidic environment, suggesting a higher concentration of carbon dioxide and lower concentration of oxygen.

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Effect of respiration on hydrogencarbonate indicator

Respiration releases carbon dioxide, which makes the environment acidic, causing the hydrogencarbonate indicator to turn yellow.

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Dissolving sugar in water

A physical change where sugar molecules are dispersed in water but their chemical structure remains unchanged.

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Burning a piece of paper

A chemical change where paper reacts with oxygen, producing ash, carbon dioxide, and water.

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Rusting of iron

A chemical change involving iron reacting with oxygen and water to form iron oxide (rust).

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Physical property

A characteristic of a substance that can be observed or measured without changing its chemical composition.

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Chemical change

A process where new substances are formed with different chemical compositions and properties.

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Physical change

A change in the form or appearance of a substance, but not its chemical composition.

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Burning magnesium ribbon

A chemical change where magnesium reacts with oxygen, producing magnesium oxide, a white solid.

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What is the function of cartilage in the gas exchange system?

Cartilage helps keep the trachea, bronchi, and windpipe open, ensuring a clear passage for air.

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What structures line the bronchioles?

The bronchioles are lined by ciliated cells and goblet cells.

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What is the role of goblet cells in the bronchioles?

Goblet cells produce mucus, which traps dust, particles, and pathogens.

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How does oxygen move from the alveoli into the blood?

Oxygen dissolves in the moist lining of the alveoli and then diffuses across the membrane into the blood capillaries, moving from a high concentration to a low concentration.

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What is the mechanism of inhalation?

During inhalation, the diaphragm contracts and the external intercostal muscles also contract, expanding the volume of the thorax, lowering the air pressure inside the lungs, and drawing air in.

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What is the role of the larynx in the gas exchange system?

The larynx, or voice box, is a structure that makes sound.

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What is the role of the ribcage in the gas exchange system?

The ribcage is a bony structure that protects the lungs.

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What is the trachea?

The trachea, or windpipe, is the airway that allows passage of air into both lungs.

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Series Circuit

A circuit where components are connected in a single path, so the current flows through each component in turn.

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Parallel Circuit

A circuit where components are connected in separate branches, so current can flow through each component independently.

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Resistance in Series

Total resistance in a series circuit is the sum of individual resistances.

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Current in Series

The current is the same throughout a series circuit.

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Voltage in Series

The total voltage in a series circuit is divided among the components.

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Resistance in Parallel

The reciprocal of the total resistance in a parallel circuit is the sum of the reciprocals of individual resistances.

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Current in Parallel

The total current in a parallel circuit is the sum of the currents in each branch.

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Voltage in Parallel

The voltage across each component in a parallel circuit is the same.

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Study Notes

Grade 8 Integrated Science

  •  This is a science journal for Grade 8 students.
  •  The journal covers the academic year 2024-2025.
  •  The book is titled Book 2A.
  •  The school is the Hong Kong Baptist University Affiliated School, Wong Kam Fai Secondary and Primary School.

Goal Setting

  •  Students are encouraged to set SMART goals for their science studies.
  •  SMART goals stand for Specific, Measurable, Achievable, Relevant and Time-bound.
  •  Students should define their specific goals for improving their understanding of scientific knowledge and science process skills.
  •  Students should track their progress by selecting methods that help them understand and revise the topics including reviewing notes, completing assignments, making concept maps and actively participating in experiments.
  •  Students should complete their goals by the end of the first term.

Laboratory Safety

  •  Hazard warning labels are used to indicate the potential dangers of chemicals.
  •  Examples of labels include: Explosive, Oxidizing, Flammable, Toxic, Corrosive, Irritant, Harmful, Carcinogenic.
  •  Students should use the correct method for disposing chemical waste and putting extra solutions and solids into the correct waste containers.
  •  Experiments that produce dangerous substances require fume cupboards to prevent the release of harmful fumes
  •  Students should wear safety glasses when working with a Bunsen burner
  •  The Bunsen burner should be turned off when not in use.
  •  Materials should be returned to the correct containers when finished with.
  •  All accidents should be reported to the teacher immediately.

Summary of Tests of Gases

  •  This section provides the results of gas tests.
  •  Gases, such as oxygen and carbon dioxide, were tested.
  •  Specific tests and observations are included for each gas.

Test of Gases (Unknown Sample)

  •  Based on the results of the tests performed on an unknown gas sample, the presence of the following gases are identified: Oxygen and Carbon Dioxide. Water Vapor wasn't identified.

Photosynthesis and Respiration

  •  A diagram and table summarizing the relationship between photosynthesis and respiration.
  •  Photosynthesis takes place in plants only and converts light energy to chemical energy in food.
  •  Respiration takes place in both plants and animals, releasing chemical energy for other processes.

Starch Test

  •  Steps involved in a starch test and the purpose of each step.
  •  The purpose of soaking the leaves with ethanol is to dissolve chlorophyll.
  •  The use of iodine solution is mentioned, and the method of observing color change identifies if starch is present.
  •  The result of a starch test includes Iodine solution turning from brown to blue-black if starch is present.

Carbon Dioxide is needed for Photosynthesis

  •  Experiment designed to show that carbon dioxide is required for photosynthesis to produce starch.
  •  Independent variable is the presence or absence of carbon dioxide in two sets of identical plants.
  •  Plants were kept in sealed containers, one with potassium hydroxide (to remove carbon dioxide) and one with glass beads.
  •  A leaf from each plant was tested for starch.

Physical and Chemical Changes

  •  Changes to a piece of paper are categorized into physical and chemical.
  •  Cutting a piece of paper is a physical change.
  •  Burning a piece of paper is a chemical change.
  •  Examples of physical changes include changes in state and dissolving.
  •  Examples of chemical changes include burning of fuels, reactions between metals and acids and rusting of iron.

Usage of Ammeter and Voltmeter

  •  An ammeter measures current.
  •  A voltmeter measures voltage.
  •  Instructions show students how to use these devices correctly when measuring current in a circuit.

Series and Parallel Circuits

  •  Concepts related to Series and Parallel circuits are explained.
  •  How to determine the brightness of bulbs in series and parallel circuits.
  •  How the arrangement of bulbs affects the brightness and the amount of current.
  •  Students are guided to determine how the current and voltage changes if devices are connected in series and parallel.

Gas Exchange in Plants and Animals

  •  Describes how gas exchange surfaces are structured.
  •  Factors that enhance gas exchange: large surface area, thin surface, good blood supply, and good ventilation.
  •  Explains the function of structures such as: larynx, trachea, bronchi, bronchioles, alveoli, ribs, intercostal muscles and diaphragm.
  •  Describes how the air sacs are adapted for rapid diffusion of gases.

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This quiz covers essential topics from the Grade 8 Integrated Science journal for the academic year 2024-2025, focusing on goal setting and laboratory safety. Students will learn about setting SMART goals to enhance their understanding of science and the importance of safety in the lab. Engage in important science process skills while tracking your progress!

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