Biology SL
Theme D: Continuity and change — Theme D
- 1.
Distinguish between the processes of mitosis and cytokinesis.
[3 marks] · no calculator - 2.
Marking analysis: A learner attempts the following task: “Distinguish between the processes of mitosis and cytokinesis.” Their response addresses only this point: “States that mitosis is the division of the nucleus, in which replicated chromosomes are separated into two genetically identical sets.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 3.
Outline the role of the cell cycle checkpoints in preventing uncontrolled cell division.
[3 marks] · no calculator - 4.
Marking analysis: A learner attempts the following task: “Outline the role of the cell cycle checkpoints in preventing uncontrolled cell division.” Their response addresses only this point: “States that checkpoints are points in the cell cycle at which the cell checks whether conditions (e.g. DNA integrity, cell size) are suitable to proceed.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 5.
Outline the semi-conservative model of DNA replication.
[3 marks] · no calculator - 6.
Marking analysis: A learner attempts the following task: “Outline the semi-conservative model of DNA replication.” Their response addresses only this point: “States that the two strands of the parent DNA molecule separate (helicase unwinds the double helix).” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 7.
Outline the roles of RNA polymerase and complementary base pairing during transcription.
[3 marks] · no calculator - 8.
Marking analysis: A learner attempts the following task: “Outline the roles of RNA polymerase and complementary base pairing during transcription.” Their response addresses only this point: “States that RNA polymerase binds to DNA and unwinds a section of the double helix at the gene to be transcribed.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 9.
Outline the process of translation at the ribosome, including the roles of mRNA, tRNA and codons.
[4 marks] · no calculator - 10.
Marking analysis: A learner attempts the following task: “Outline the process of translation at the ribosome, including the roles of mRNA, tRNA and codons.” Their response addresses only this point: “States that mRNA binds to a ribosome, and is read in sequential three-base codons.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 11.
In a monohybrid cross, two heterozygous parents Bb are crossed. State the expected genotype ratio and phenotype ratio when B is completely dominant over b.
[4 marks] · no calculator - 12.
Marking analysis: A learner attempts the following task: “In a monohybrid cross, two heterozygous parents Bb are crossed. State the expected genotype ratio and phenotype ratio when B is completely dominant over b.” Their response addresses only this point: “Identifies gametes B and b from each parent.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 13.
A DNA template strand has the sequence 3′–TAC GGA CTT–5′. Write the complementary mRNA sequence produced during transcription and state its direction.
[3 marks] · no calculator - 14.
Marking analysis: A learner attempts the following task: “A DNA template strand has the sequence 3′–TAC GGA CTT–5′. Write the complementary mRNA sequence produced during transcription and state its direction.” Their response addresses only this point: “Uses complementary base pairing with U opposite A in RNA.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 15.
Define the terms genotype and phenotype, and outline the relationship between them.
[3 marks] · no calculator - 16.
Marking analysis: A learner attempts the following task: “Define the terms genotype and phenotype, and outline the relationship between them.” Their response addresses only this point: “Defines genotype as the genetic make-up (alleles present) of an organism for a particular trait.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 17.
Explain, using an example, how the sex chromosomes determine biological sex in humans.
[3 marks] · no calculator - 18.
Marking analysis: A learner attempts the following task: “Explain, using an example, how the sex chromosomes determine biological sex in humans.” Their response addresses only this point: “States that humans have 23 pairs of chromosomes, one pair of which are the sex chromosomes (X and Y).” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 19.
A woman who is a carrier for a recessive X-linked condition (XᴬXᵃ) has children with a man who does not have the condition (XᴬY). Using a Punnett grid, determine the probability that a son will have the condition.
[4 marks] · no calculator - 20.
Marking analysis: A learner attempts the following task: “A woman who is a carrier for a recessive X-linked condition (XᴬXᵃ) has children with a man who does not have the condition (XᴬY). Using a Punnett grid, determine the probability that a son will have the condition.” Their response addresses only this point: “Identifies maternal gametes as Xᴬ and Xᵃ, and paternal gametes as Xᴬ and Y.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 21.
Outline what is meant by a gene mutation, and state one possible effect of a base substitution mutation on the protein produced.
[2 marks] · no calculator - 22.
Marking analysis: A learner attempts the following task: “Outline what is meant by a gene mutation, and state one possible effect of a base substitution mutation on the protein produced.” Their response addresses only this point: “States that a gene mutation is a permanent, random change in the nucleotide sequence of DNA.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator - 23.
Distinguish between a gene and an allele.
[2 marks] · no calculator - 24.
Marking analysis: A learner attempts the following task: “Distinguish between a gene and an allele.” Their response addresses only this point: “States that a gene is a heritable factor (a section of DNA) that controls a specific characteristic, occupying a specific locus on a chromosome.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[2 marks] · no calculator - 25.
Explain why the number of possible genetically different gametes an organism can produce increases with the number of heterozygous gene pairs, using an organism heterozygous at two independently assorting loci as an example.
[3 marks] · no calculator - 26.
Marking analysis: A learner attempts the following task: “Explain why the number of possible genetically different gametes an organism can produce increases with the number of heterozygous gene pairs, using an organism heterozygous at two independently assorting loci as an example.” Their response addresses only this point: “States that during meiosis, independently assorting gene pairs on different chromosomes segregate independently of one another into gametes.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 27.
Cystic fibrosis is an autosomal recessive condition. Two unaffected parents, both carriers, have a child. Calculate the probability that the child is unaffected but a carrier.
[3 marks] · no calculator - 28.
Marking analysis: A learner attempts the following task: “Cystic fibrosis is an autosomal recessive condition. Two unaffected parents, both carriers, have a child. Calculate the probability that the child is unaffected but a carrier.” Their response addresses only this point: “Sets up the cross Ff × Ff, with F dominant (unaffected) and f recessive (affected).” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 29.
Outline the process of polymerase chain reaction (PCR) and state one application of this technique.
[3 marks] · no calculator - 30.
Marking analysis: A learner attempts the following task: “Outline the process of polymerase chain reaction (PCR) and state one application of this technique.” Their response addresses only this point: “States that the DNA sample is heated to separate (denature) the double strands, then cooled to allow short primers to bind to the target sequence.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 31.
Explain the mechanism by which increased atmospheric carbon dioxide concentration contributes to the enhanced greenhouse effect and global warming.
[4 marks] · no calculator - 32.
Marking analysis: A learner attempts the following task: “Explain the mechanism by which increased atmospheric carbon dioxide concentration contributes to the enhanced greenhouse effect and global warming.” Their response addresses only this point: “States that short-wavelength solar radiation passes through the atmosphere and is absorbed at the Earth's surface, which then re-emits energy as longer-wavelength infrared radiation.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 33.
Explain how repeated antibiotic use can increase the frequency of antibiotic resistance in a bacterial population by natural selection.
[5 marks] · no calculator - 34.
Marking analysis: A learner attempts the following task: “Explain how repeated antibiotic use can increase the frequency of antibiotic resistance in a bacterial population by natural selection.” Their response addresses only this point: “Random mutation produces variation in antibiotic resistance.” Evaluate the response against the complete 5-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[5 marks] · no calculator - 35.
Define natural selection and state the conditions necessary for it to occur.
[3 marks] · no calculator - 36.
Marking analysis: A learner attempts the following task: “Define natural selection and state the conditions necessary for it to occur.” Their response addresses only this point: “Defines natural selection as the differential survival and reproduction of individuals due to heritable variation in traits, resulting in a change in allele frequency in a population over generations.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 37.
Outline the roles of insulin and glucagon in regulating blood glucose concentration, including the gland that secretes each hormone and its target tissue.
[6 marks] · no calculator - 38.
Marking analysis: A learner attempts the following task: “Outline the roles of insulin and glucagon in regulating blood glucose concentration, including the gland that secretes each hormone and its target tissue.” Their response addresses only this point: “States that both hormones are secreted by the pancreas (islets of Langerhans).” Evaluate the response against the complete 6-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[6 marks] · no calculator - 39.
Distinguish between the roles of oestrogen and progesterone in regulating the menstrual cycle.
[4 marks] · no calculator - 40.
Marking analysis: A learner attempts the following task: “Distinguish between the roles of oestrogen and progesterone in regulating the menstrual cycle.” Their response addresses only this point: “States that rising oestrogen, secreted by the developing follicle, stimulates repair and thickening (proliferation) of the uterine lining (endometrium) after menstruation.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 41.
Explain how negative feedback maintains core body temperature when it rises above the normal set point.
[3 marks] · no calculator - 42.
Marking analysis: A learner attempts the following task: “Explain how negative feedback maintains core body temperature when it rises above the normal set point.” Their response addresses only this point: “States that thermoreceptors (e.g. in the hypothalamus and skin) detect that body temperature has risen above the set point.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator