Reactions
Fill in the blanks:
The substances present at the start of a reaction are the __________.
The new substances formed are the __________.
Reactants; products
Fill in the blank:
A wave transfers __________ from one place to another.
Energy
Fill in the blank:
DNA has a __________ __________ shape.
Double helix
Fill in the blanks:
Evolution is a change in the inherited characteristics of a __________ over many __________.
Population; generations
Fill in the blanks:
The independent variable goes on the __________-axis. The dependent variable goes on the __________-axis.
x-axis; y-axis
Complete the general reaction:
metal + acid → salt + __________
Hydrogen gas
Which is not an electromagnetic wave:
radio waves, sound waves, ultraviolet or X-rays?
Sound waves
What does a shaded circle represent in a pedigree chart?
A female who has the characteristic being studied
In natural selection, which individuals are most likely to survive and reproduce?
Individuals that are best adapted to their environment because they have advantageous traits.
A student changes time and measures the volume of gas produced.
State one variable that should be controlled.
mass of solid, volume or concentration of acid, temperature, apparatus used
A solution has a pH of 2.
Is it acidic, neutral or basic? If it spills on skin, what should be done first?
Acidic; rinse the skin with plenty of water
A light ray strikes a mirror at an angle of incidence of 48°.
What is the angle of reflection?
48°
Arrange these from largest to smallest:
gene, chromosome, genome, DNA.
Genome → chromosome → DNA → gene
Four undisturbed rock layers are labelled A to D from top to bottom.
Which layer most likely contains the oldest fossil?
Layer D
Name three features required for a full-mark scientific graph.
Any three: appropriate title; correctly labelled axes and units; suitable even scale; uses most of the grid; accurate points; suitable line or curve
Zinc granules produce gas faster than the same mass of zinc strips.
Explain why.
Granules have a greater surface area exposed to the acid, causing more frequent successful collisions and a faster reaction.
A robot’s wheels push backwards against the floor, and the floor pushes the robot forwards.
Identify Newton’s law.
Newton’s Third Law
Green pods (G) are dominant over yellow pods (g).
State the phenotype of a plant with genotype Gg and identify whether it is homozygous or heterozygous.
Green pods; heterozygous
Put these stages in order:
reproduction, variation, population change, selection pressure, different survival.
Variation → selection pressure → different survival → reproduction → population change
A reaction produces 28 cm³ of gas in 40 seconds.
Calculate the average rate of gas production.
28 ÷ 40 = 0.7 cm³/s
Consider: Mg + 2HCl → MgCl₂ + H₂.
Identify the reactants and products, then state the number of hydrogen atoms on each side.
Reactants: Mg and HCl.
Products: MgClâ‚‚ and Hâ‚‚.
There are 2 hydrogen atoms on each side.
A robot is 12 m from its starting point at 5 seconds and 52 m away at 25 seconds.
Calculate its average speed.
Change in distance = 40 m.
Change in time = 20 s.
Average speed = 2 m/s.
Explain how a mutation in a DNA base could change the protein produced. Use the terms amino acid, shape and function.
The mutation may cause a different amino acid to be added. This could change the protein’s shape and affect its function.
A beetle population contains light and dark beetles. They live on dark bark and are hunted by birds.
Explain how dark beetles could become more common over generations.
Dark beetles are better camouflaged, so they are more likely to survive and reproduce. They pass the inherited dark-colour characteristic to their offspring, so it becomes more common over generations.
A student completes an investigation only once.
Explain how the reliability of the results could be improved.
Repeat the investigation several times, identify any anomalies and calculate a mean.