SACE Stage 2 Biology topics 1 to 4: exam-style practice quiz

AUG GCA UUU

ATG GCA TTT

UAC CGU AAA

TAC CGT AAA

half of the genes are copied and the other half are left out of each new molecule

each new DNA molecule contains one original strand and one newly made strand

the original molecule is kept whole and a completely new double helix is built

each new strand is made partly from old nucleotides and partly from new ones

the active site is rigid and exactly the same shape as the substrate before binding

the substrate changes the enzyme's amino acid sequence to create a new active site

the active site changes shape slightly as the substrate binds, fitting it more closely

any substrate can bind to any enzyme if the temperature is high enough

Deletion of a single nucleotide near the start of the gene

Substitution of a single nucleotide in the third base of a codon

Substitution of a single nucleotide in a non-coding intron

Deletion of three nucleotides that form one complete codon

So that the heat-resistant DNA polymerase can be denatured

So that the two DNA strands can separate from each other

So that the free nucleotides are broken down into bases

So that primers can bind to the separated single strands of DNA

Larger fragments move further through the gel towards the positive electrode

Smaller fragments move further through the gel towards the negative electrode

All fragments move the same distance, but they separate by their colour

Smaller fragments move further through the gel towards the positive electrode

3 : 1

2 : 1

1 : 2

6 : 1

Water leaves by osmosis because the distilled water has a higher solute concentration, so the cell shrinks

Solutes leave by active transport until both sides are equal, so the cell stays the same size

Water enters by osmosis because the cell's contents have a higher solute concentration, so it swells and may burst

Water enters by active transport using ATP, so the cell swells steadily until it divides

ethanol and carbon dioxide

carbon dioxide and water

glucose and oxygen

lactic acid (lactate)

negative feedback, which keeps thyroxine levels within a narrow range

positive feedback, which drives thyroxine levels higher and higher

a reflex arc, which produces a fast response through motor neurons

a nervous response, in which TSH acts as a neurotransmitter at a synapse

Mitochondria are found in every cell of every organism, including all bacteria

Mitochondria contain their own circular DNA and ribosomes similar to those of bacteria

Mitochondria produce ATP using glucose taken directly from the blood

Mitochondria have a single membrane that is identical to the cell membrane

behavioural isolation, a pre-zygotic isolating mechanism

temporal isolation, a pre-zygotic isolating mechanism

hybrid sterility, a post-zygotic isolating mechanism

hybrid inviability, a post-zygotic isolating mechanism