2
mitosis exam questions with precise detailed answers || || || || || ||
Contrast the structures of ATP and a nucleotide found in DNA to give three differences. - ✔✔1.
|| || || || || || || || || || || || || || || || ||
ATP has ribose and DNA nucleotide has deoxyribose;
|| || || || || || ||
2. ATP has 3 phosphate groups and DNA nucleotide has 1 phosphate group
|| || || || || || || || || || || ||
3. ATP - base always adenine and in DNA nucleotide base can be different / varies;
|| || || || || || || || || || || || || || ||
Name two enzymes involved in the semi-conservative replication of DNA. - ✔✔1. (DNA)
|| || || || || || || || || || || || ||
helicase;
2. (DNA) polymerase;
|| ||
Sometimes, damage occurs during DNA replication. One enzyme involved in repairing damage to
|| || || || || || || || || || || ||
DNA is called ATR.
|| || || ||
ATR works as follows. || || ||
• ATR phosphorylates other enzymes involved in repairing DNA.
|| || || || || || || ||
• ATR also phosphorylates substrates required to repair DNA.
|| || || || || || || ||
When ATR phosphorylates other enzymes, these enzymes become able to bind to their substrates.
|| || || || || || || || || || || || ||
Use your knowledge of enzyme structure to suggest why. - ✔✔1. Changes tertiary structure of the
|| || || || || || || || || || || || || || ||
enzyme;
||
2. (Enzyme) active site formed / able to be formed / active site becomes complementary;
|| || || || || || || || || || || || || ||
The enzyme-catalysed reactions activated by ATR only occur if the substrates have been
|| || || || || || || || || || || || ||
phosphorylated.
Use your knowledge of energy changes in enzyme-catalysed reactions to suggest why. -
|| || || || || || || || || || || || ||
✔✔(Phosphorylation / phosphate) makes substrates more reactive / raises their energy level(s) / || || || || || || || || || || || || ||
lowers activation energy for the reaction;
|| || || || ||
, 2
Sometimes, a mutagenic agent causes DNA to break. A different enzyme called ATM binds to the || || || || || || || || || || || || || || || ||
broken DNA. This leads to the activation of a protein coded for by a tumour suppressor gene. The
|| || || || || || || || || || || || || || || || || ||
effect of ATM binding is to stop cell division until DNA is repaired.
|| || || || || || || || || || || ||
A mutation could result in a person having non-functional forms of the gene that produces ATM.
|| || || || || || || || || || || || || || ||
What can you predict about the possible effects of having a non-functional form of ATM? - ✔✔1.
|| || || || || || || || || || || || || || || || ||
ATM will not bind to (broken) DNA;
|| || || || || ||
2. DNA not repaired / cell still has broken DNA;
|| || || || || || || || ||
3. Cell division continues / tumour forms;
|| || || || || ||
4. Tumour suppressor (gene) not effective / not activated;
|| || || || || || || ||
5. May have no effect in diploid / heterozygous (organism);
|| || || || || || || || ||
6. (Which) still has a functional ATM / ATM gene;
|| || || || || || || || ||
Explain why the replication of DNA is described as semi-conservative. 2 marks - ✔✔each strand
|| || || || || || || || || || || || || || ||
copied / acts as a template; || || || || || ||
(daughter) DNA one new strand and one original || || || || || || ||
which has greater density n14 or n15? - ✔✔n15 has greater density
|| || || || || || || || || || ||
Which part of the DNA molecule contains nitrogen? - ✔✔base
|| || || || || || || || ||
Explain why the DNA from generation 1 is found in the position shown - ✔✔it has been
|| || || || || || || || || || || || || || || || ||
produced by semi-conservative replication / one old strand and one new.
|| || || || || || || || || || ||
one strand n14 and another n15.
|| || || || ||
The structure of virus DNA is different from the DNA of the other two organisms. Giving
|| || || || || || || || || || || || || || || ||
evidence from the table, suggest what this difference might be. - ✔✔viral DNA single-stranded /
|| || || || || || || || || || || || || || ||
not double-stranded;
|| ||
evidence from table e.g. not equal amount of A and T / C and G
|| || || || || || || || || || || || || ||
mitosis exam questions with precise detailed answers || || || || || ||
Contrast the structures of ATP and a nucleotide found in DNA to give three differences. - ✔✔1.
|| || || || || || || || || || || || || || || || ||
ATP has ribose and DNA nucleotide has deoxyribose;
|| || || || || || ||
2. ATP has 3 phosphate groups and DNA nucleotide has 1 phosphate group
|| || || || || || || || || || || ||
3. ATP - base always adenine and in DNA nucleotide base can be different / varies;
|| || || || || || || || || || || || || || ||
Name two enzymes involved in the semi-conservative replication of DNA. - ✔✔1. (DNA)
|| || || || || || || || || || || || ||
helicase;
2. (DNA) polymerase;
|| ||
Sometimes, damage occurs during DNA replication. One enzyme involved in repairing damage to
|| || || || || || || || || || || ||
DNA is called ATR.
|| || || ||
ATR works as follows. || || ||
• ATR phosphorylates other enzymes involved in repairing DNA.
|| || || || || || || ||
• ATR also phosphorylates substrates required to repair DNA.
|| || || || || || || ||
When ATR phosphorylates other enzymes, these enzymes become able to bind to their substrates.
|| || || || || || || || || || || || ||
Use your knowledge of enzyme structure to suggest why. - ✔✔1. Changes tertiary structure of the
|| || || || || || || || || || || || || || ||
enzyme;
||
2. (Enzyme) active site formed / able to be formed / active site becomes complementary;
|| || || || || || || || || || || || || ||
The enzyme-catalysed reactions activated by ATR only occur if the substrates have been
|| || || || || || || || || || || || ||
phosphorylated.
Use your knowledge of energy changes in enzyme-catalysed reactions to suggest why. -
|| || || || || || || || || || || || ||
✔✔(Phosphorylation / phosphate) makes substrates more reactive / raises their energy level(s) / || || || || || || || || || || || || ||
lowers activation energy for the reaction;
|| || || || ||
, 2
Sometimes, a mutagenic agent causes DNA to break. A different enzyme called ATM binds to the || || || || || || || || || || || || || || || ||
broken DNA. This leads to the activation of a protein coded for by a tumour suppressor gene. The
|| || || || || || || || || || || || || || || || || ||
effect of ATM binding is to stop cell division until DNA is repaired.
|| || || || || || || || || || || ||
A mutation could result in a person having non-functional forms of the gene that produces ATM.
|| || || || || || || || || || || || || || ||
What can you predict about the possible effects of having a non-functional form of ATM? - ✔✔1.
|| || || || || || || || || || || || || || || || ||
ATM will not bind to (broken) DNA;
|| || || || || ||
2. DNA not repaired / cell still has broken DNA;
|| || || || || || || || ||
3. Cell division continues / tumour forms;
|| || || || || ||
4. Tumour suppressor (gene) not effective / not activated;
|| || || || || || || ||
5. May have no effect in diploid / heterozygous (organism);
|| || || || || || || || ||
6. (Which) still has a functional ATM / ATM gene;
|| || || || || || || || ||
Explain why the replication of DNA is described as semi-conservative. 2 marks - ✔✔each strand
|| || || || || || || || || || || || || || ||
copied / acts as a template; || || || || || ||
(daughter) DNA one new strand and one original || || || || || || ||
which has greater density n14 or n15? - ✔✔n15 has greater density
|| || || || || || || || || || ||
Which part of the DNA molecule contains nitrogen? - ✔✔base
|| || || || || || || || ||
Explain why the DNA from generation 1 is found in the position shown - ✔✔it has been
|| || || || || || || || || || || || || || || || ||
produced by semi-conservative replication / one old strand and one new.
|| || || || || || || || || || ||
one strand n14 and another n15.
|| || || || ||
The structure of virus DNA is different from the DNA of the other two organisms. Giving
|| || || || || || || || || || || || || || || ||
evidence from the table, suggest what this difference might be. - ✔✔viral DNA single-stranded /
|| || || || || || || || || || || || || || ||
not double-stranded;
|| ||
evidence from table e.g. not equal amount of A and T / C and G
|| || || || || || || || || || || || || ||
