Working Scientifically
In an investigation, the variable that the scientist deliberately changes is called the ______ variable
Independent Variable
Which type of energy resource can naturally be replaced over a relatively short period of time?
Renewable energy
What molecule contains the genetic instructions used by cells?
DNA
What is the formula for calculating speed?
Speed = distance ÷ time
What is the smallest unit of an element that still has the properties of that element?
An Atom
A student investigates whether different fertilisers affect plant growth. Name one variable that should be kept constant to make the investigation fair.
Name one human activity that can negatively affect Earth's ecosystems.
A gene is a section of what molecule?
DNA
What is the SI unit for speed?
metres per second (m/s)
What are the substances present before a chemical reaction called?
Reactants
A student measures the temperature of water three times and gets:
20.1°C, 20.2°C, 20.1°C
What does this tell you about the reliability of the measurements?
The measurements are highly reliable/consistent because repeated measurements are very similar.
What is the main reason increasing concentrations of greenhouse gases can cause Earth's average temperature to rise?
Greenhouse gases absorb and re-emit infrared radiation, trapping more heat in Earth's atmosphere.
Where are chromosomes found in a typical human cell?
Nucleus
A car travels 100 m in 5 seconds. What is its average speed?
20 m/s
What are the new substances formed during a chemical reaction called?
Products
Two groups investigate whether exercise increases heart rate.
Group A: Measures heart rate before and after exercise.
Group B: Measures heart rate before exercise but doesn't control how long each student exercises.
Which investigation is more valid, and why?
Group A, because it controls the conditions more effectively and allows a fair comparison of the effect of exercise on heart rate.
A town replaces a coal-fired power station with a solar farm.
Give TWO environmental benefits this could provide.
What is an Allele
A different version of a gene.
What does it mean if an object is accelerating?
Its velocity is changing. This could mean it is speeding up, slowing down or changing direction.
In a chemical reaction, the total mass of the reactants is 100 g.
What should the total mass of the products be?
100g
A student investigates whether fertiliser makes plants grow taller. They use fertiliser on Plant A and no fertiliser on Plant B. Plant A receives 500 mL of water each day, while Plant B receives 100 mL.
Can they confidently conclude that the fertiliser caused the difference in growth? Explain.
No. The amount of water is also different, so it is a confounding variable. The investigation is not a fair test because water could have caused the difference.
A coastal community is experiencing increased erosion. A proposal is made to remove vegetation along the coastline to create more space for housing.
Explain why this could make the erosion problem worse.
Vegetation helps stabilise soil and sand with its roots and reduces the movement of sediment. Removing it can leave the coastline more exposed to wind and wave erosion, increasing erosion.
What is the process of changing an organism's DNA to give it a desired characteristic called?
Genetic engineering
On a distance–time graph, what does a steeper line represent?
A greater speed.
What are the products of complete combustion?
Carbon Dioxide, Water + Energy