Body Systems
What is the difference between a unicellular and a multicellular organism?
A unicellular organism is made of one cell, while a multicellular organism is made of many cells.
What force opposes the movement of two surfaces rubbing against each other?
Friction.
What type of change occurs when ice melts into liquid water?
Physical change.
What is a mixture?
Two or more substances physically combined that are not chemically bonded together.
What is the purpose of an aim in a scientific investigation?
To state what the experiment is trying to find out.
What is the name of the process where one cell divides to produce two genetically identical daughter cells?
Mitosis.
What happens when two objects with the same electric charge are brought close together?
They repel each other.
What is the main difference between a physical change and a chemical change?
A physical change does not produce a new substance, while a chemical change produces one or more new substances.
What is the difference between a solute and a solvent?
A solute is the substance being dissolved, while a solvent is the substance that dissolves it.
What is the difference between an observation and an inference?
An observation is something noticed or measured, while an inference is a possible explanation based on observations.
What are the three main parts of a plant, and what is the function of each?
Roots: Absorb water and minerals.
Stem: Supports the plant and transports substances.
Leaves: Carry out photosynthesis.
Name the three types of field forces.
Gravitational, magnetic and electrostatic forces.
Name three signs that a chemical reaction may have occurred.
Colour change, gas production (bubbling) and temperature change.
What separation technique uses a magnet to remove magnetic materials from a mixture?
Magnetic separation.
What are the three types of variables in a scientific investigation, and what does each one mean?
Independent variable: The variable that is deliberately changed.
Dependent variable: The variable that is measured or observed.
Controlled variables: The variables that are kept the same to ensure a fair test.
What is the main function of the circulatory system, and which organ pumps blood around the body?
The circulatory system transports oxygen, nutrients and wastes around the body. The heart pumps the blood.
Explain one way to increase friction and one way to decrease friction between two surfaces.
Increase: Make the surfaces rougher.
Decrease: Apply a lubricant, such as oil, between the surfaces.
When vinegar and bicarbonate of soda are mixed, bubbles form. What does this tell us about the reaction?
A gas is being produced, providing evidence that a chemical reaction is occurring.
What separation technique is used to separate the different colours in ink?
Chromatography.
Why do scientists include headings and units in results tables?
To clearly identify what was measured and the units used, making results easier to interpret.
What is the word equation for cellular respiration, and why is this process important for cells?
Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP)
An object has a mass of 25 kg. Calculate its weight on Earth using a gravitational field strength of 9.8 N/kg.
Weight = mass × gravity = 25 × 9.8 = 245 N
When a piece of paper burns, is this a physical or chemical change? Explain your answer.
Chemical change, because new substances such as ash and gases are produced.
A student has a mixture of sand, salt and water. Describe two separation techniques they could use to obtain the sand and salt separately.
Filtration: Removes the sand from the saltwater. Evaporation: Removes the water, leaving the salt behind.
Why is it important to repeat an experiment multiple times and calculate an average of the results?
To improve the reliability of the results by reducing the impact of random errors and identifying any anomalies.
Explain how the digestive, respiratory and circulatory systems work together to provide cells with the materials needed for cellular respiration
The digestive system breaks down food and absorbs glucose, the respiratory system takes in oxygen, and the circulatory system transports glucose and oxygen to cells for cellular respiration.
Explain how an object can become positively or negatively charged through friction.
When electrons are transferred between objects, the object that loses electrons becomes positively charged, while the object that gains electrons becomes negatively charged.
Explain what happens to atoms during a chemical reaction.
Atoms are rearranged as chemical bonds break and new bonds form, producing new substances. The atoms themselves are not created or destroyed.
Explain how distillation can be used to obtain pure water from saltwater.
The saltwater is heated until the water evaporates. The water vapour is cooled and condenses back into liquid water, leaving the salt behind.
A student investigates the relationship between the length of a spring and the force applied to it. They collect numerical data for both variables. What type of graph should they draw to identify the relationship between the two variables?
A scatter plot with a line of best fit.
A patient has kidney failure and requires dialysis or a kidney transplant. Explain how these technologies help the patient and identify one challenge associated with each treatment.
Dialysis: Removes wastes and excess water from the blood, but requires regular treatment.
Kidney transplant: Can restore kidney function, but requires a suitable donor and ongoing medication to reduce the risk of rejection.
Explain how an electromagnet works and describe two ways to increase its strength.
An electromagnet produces a magnetic field when an electric current flows through a coil of wire. Its strength can be increased by adding more turns of wire to the coil or increasing the electric current.
Explain how chemical reactions are used to produce medicines and why scientists must test new medicines before they are used.
Chemical reactions are used to create the substances found in medicines. Scientists test new medicines to determine whether they are effective, safe and have any harmful side effects.
A hospital needs to separate blood into red blood cells, plasma and other components. Which separation technique is used, and explain how it works.
Centrifugation. Blood is spun rapidly in a centrifuge, separating its components into layers based on their different densities.
A student tests how water temperature affects the time sugar takes to dissolve. They use different amounts of sugar, different volumes of water and only conduct each test once. Identify two problems with the investigation and explain how to improve its validity and reliability.
Validity: Keep the amount of sugar and volume of water the same.
Reliability: Repeat each test several times and calculate an average.