AS & A Level Biology - 9700 Paper 4 2016 Winter Zone 3

The Labrador retriever is a modern breed of dog that can have yellow, black or brown fur and pale, black or brown noses. The inheritance of fur and nose colour is the result of the interaction between genes at two different loci, the B locus and the E locus.

Fig. 1.1 shows a Labrador retriever.



Table 1.1 shows how gene interaction results in different phenotypes.

[Table_1]

A male Labrador retriever, heterozygous at the B locus and homozygous recessive at the E locus, was mated with a female Labrador retriever heterozygous at both loci.

(a) Explain the terms locus and homozygous.

locus ........................................................................................................................................................................
.......................................................................................................................................................................................

homozygous ...............................................................................................................................................................
............................................................................................................................................................................. [2]

(b) Use a genetic diagram to show the possible genotypes and phenotypes of the offspring from the mating between the two Labrador retrievers.

parental phenotypes

parental genotypes

gametes

offspring genotypes and phenotypes [6]

The Labrador retriever is a modern breed of dog that can have yellow, black or brown fur and pale, black or brown noses. The inheritance of fur and nose colour is the result of the interaction between genes at two different loci, the B locus and the E locus.

Fig. 1.1 shows a Labrador retriever.



Table 1.1 shows how gene interaction results in different phenotypes.

[Table_1]

A male Labrador retriever, heterozygous at the B locus and homozygous recessive at the E locus, was mated with a female Labrador retriever heterozygous at both loci.

(a) Explain the terms locus and homozygous.

locus ........................................................................................................................................................................
.......................................................................................................................................................................................

homozygous ...............................................................................................................................................................
............................................................................................................................................................................. [2]

(b) Use a genetic diagram to show the possible genotypes and phenotypes of the offspring from the mating between the two Labrador retrievers.

parental phenotypes

parental genotypes

gametes

offspring genotypes and phenotypes [6]

Most plants are C3 plants and are so-called because their first photosynthetic product is a three carbon compound. The enzyme ribulose bisphosphate carboxylase/oxygenase (rubisco) catalyses the fixation of carbon dioxide in the Calvin cycle and is used by both C3 and C4 plants.
Each molecule is made up of eight large polypeptides and eight small polypeptides. Fig. 2.1 shows a side view of the molecule.

(a)
(i) Outline how the biochemistry of C4 plants differs from that of C3 plants.
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.................................................................................................................................
.........................................................................................................................[2]

(ii) State why rubisco is said to have quaternary structure.
.................................................................................................................................
.........................................................................................................................[1]

(iii) Explain what makes a molecule such as rubisco soluble.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[2]

(b) The active sites of rubisco accept ribulose bisphosphate (RuBP) and either carbon dioxide or oxygen and can catalyse the two reactions shown below.
either

$ \text{RuBP} + \text{CO}_2 \rightarrow \text{unstable intermediate compound} \rightarrow 2 \text{GP (PGA)} $

or

$ \text{RuBP} + 2 \text{O}_2 \rightarrow \text{unstable intermediate compound} \rightarrow \text{GP (PGA)} + 2 \text{CO}_2 $

Explain the consequences to the plant of the reaction involving oxygen.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[2]

(c) In the absence of light, rubisco changes shape from an active form to an inactive form.
Explain why rubisco does not need to be in an active form in the absence of light.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[3]

Most plants are C3 plants and are so-called because their first photosynthetic product is a three carbon compound. The enzyme ribulose bisphosphate carboxylase/oxygenase (rubisco) catalyses the fixation of carbon dioxide in the Calvin cycle and is used by both C3 and C4 plants.
Each molecule is made up of eight large polypeptides and eight small polypeptides. Fig. 2.1 shows a side view of the molecule.

(a)
(i) Outline how the biochemistry of C4 plants differs from that of C3 plants.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[2]

(ii) State why rubisco is said to have quaternary structure.
.................................................................................................................................
.........................................................................................................................[1]

(iii) Explain what makes a molecule such as rubisco soluble.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[2]

(b) The active sites of rubisco accept ribulose bisphosphate (RuBP) and either carbon dioxide or oxygen and can catalyse the two reactions shown below.
either

$ \text{RuBP} + \text{CO}_2 \rightarrow \text{unstable intermediate compound} \rightarrow 2 \text{GP (PGA)} $

or

$ \text{RuBP} + 2 \text{O}_2 \rightarrow \text{unstable intermediate compound} \rightarrow \text{GP (PGA)} + 2 \text{CO}_2 $

Explain the consequences to the plant of the reaction involving oxygen.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[2]

(c) In the absence of light, rubisco changes shape from an active form to an inactive form.
Explain why rubisco does not need to be in an active form in the absence of light.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.........................................................................................................................[3]

(a) (i) Name the types of enzyme used in step 1 and step 2.
.......................................................................................................................[1]

(ii) Name the enzyme used in step 3.
.......................................................................................................................[1]

(iii) Explain why promoters were introduced along with the genes for \( \beta \)-carotene in step 3.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[2]

(iv) Describe the properties of plasmids that make them suitable for their roles in the production of Golden Rice.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[3]

(b) Rice is an important food crop in many different countries. Farmers in different parts of the world have developed rice varieties that grow well in the local climate and soil conditions.
Selective breeding programmes have been carried out in which Golden Rice was interbred with local rice varieties to produce varieties of Golden Rice that grow well in different localities.
Explain why the original Golden Rice had to be developed by genetic engineering, but locally-adapted varieties of Golden Rice could be developed by selective breeding.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[3]

(c) An investigation was carried out to check that \( \beta \)-carotene from Golden Rice can be converted to vitamin A in the body.
Golden Rice plants were grown using water whose molecules contained deuterium instead of ordinary hydrogen. Deuterium is an isotope of hydrogen that contains a neutron as well as a proton in its nucleus. The \( \beta \)-carotene synthesised in these rice plants contained deuterium.
Volunteers ate a measured dose of rice taken from these Golden Rice plants. The concentrations in the blood of vitamin A containing deuterium were measured on the day before they ate the rice, and then over the next 6 days.
Fig. 3.2 shows the results.

(i) Explain why the Golden Rice was grown using water containing deuterium.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[2]

(ii) Suggest why it took several hours after the Golden Rice had been eaten for the maximum concentration of vitamin A containing deuterium to be reached.
.......................................................................................................................
.......................................................................................................................[1]

(a) (i) Name the types of enzyme used in step 1 and step 2.
.......................................................................................................................[1]

(ii) Name the enzyme used in step 3.
.......................................................................................................................[1]

(iii) Explain why promoters were introduced along with the genes for \( \beta \)-carotene in step 3.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[2]

(iv) Describe the properties of plasmids that make them suitable for their roles in the production of Golden Rice.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[3]

(b) Rice is an important food crop in many different countries. Farmers in different parts of the world have developed rice varieties that grow well in the local climate and soil conditions.
Selective breeding programmes have been carried out in which Golden Rice was interbred with local rice varieties to produce varieties of Golden Rice that grow well in different localities.
Explain why the original Golden Rice had to be developed by genetic engineering, but locally-adapted varieties of Golden Rice could be developed by selective breeding.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[3]

(c) An investigation was carried out to check that \( \beta \)-carotene from Golden Rice can be converted to vitamin A in the body.
Golden Rice plants were grown using water whose molecules contained deuterium instead of ordinary hydrogen. Deuterium is an isotope of hydrogen that contains a neutron as well as a proton in its nucleus. The \( \beta \)-carotene synthesised in these rice plants contained deuterium.
Volunteers ate a measured dose of rice taken from these Golden Rice plants. The concentrations in the blood of vitamin A containing deuterium were measured on the day before they ate the rice, and then over the next 6 days.
Fig. 3.2 shows the results.

(i) Explain why the Golden Rice was grown using water containing deuterium.
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................
.......................................................................................................................[2]

(ii) Suggest why it took several hours after the Golden Rice had been eaten for the maximum concentration of vitamin A containing deuterium to be reached.
.......................................................................................................................
.......................................................................................................................[1]

(a) With reference to Table 4.1, describe the difference in effectiveness of the two drugs.


(b) Explain how the data in Table 4.1 show evidence that the use of chloroquine was discontinued after 1996.

(c) The researchers concluded that in both Kenya and Uganda the parasite had evolved resistance to sulfadoxine-pyrimethamine.
Explain how the parasites evolved resistance.

(d) The resistance of Plasmodium parasites to chloroquine was found to be due to a difference in the shape of one specific type of cell surface membrane protein.
Name the type of variation controlling chloroquine resistance in the Plasmodium population.

(e) The life cycle of Plasmodium is very complex, with a number of stages. The stages that infect human beings are haploid.
Suggest why the Hardy-Weinberg principle cannot be used to calculate the frequency of the allele for chloroquine resistance.

(a) With reference to Table 4.1, describe the difference in effectiveness of the two drugs.


(b) Explain how the data in Table 4.1 show evidence that the use of chloroquine was discontinued after 1996.

(c) The researchers concluded that in both Kenya and Uganda the parasite had evolved resistance to sulfadoxine-pyrimethamine.
Explain how the parasites evolved resistance.

(d) The resistance of Plasmodium parasites to chloroquine was found to be due to a difference in the shape of one specific type of cell surface membrane protein.
Name the type of variation controlling chloroquine resistance in the Plasmodium population.

(e) The life cycle of Plasmodium is very complex, with a number of stages. The stages that infect human beings are haploid.
Suggest why the Hardy-Weinberg principle cannot be used to calculate the frequency of the allele for chloroquine resistance.

Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method:
• insecticide was sprayed into each tree
• this killed the insects, which fell onto a sheet below the tree
• the dead insects were collected, identified and counted.

(a) The researchers considered each tree to be a small, distinct ecosystem.

Discuss whether or not an individual tree can be described as a small, distinct ecosystem.
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..............................................................................................................................................................[3]

(b) Table 5.1 shows summary statistics for some of the trees sampled in this study. The leaf canopy area is a measure of the size of the tree and the extent of its leaf cover.

Table 5.2 shows the diversity and abundance of some different taxonomic groups of insects in the study.

[Table 5.1]

Table 5.1
| tree species | number of trees | total leaf canopy area | number of insect species |
| | sampled | \(/m^2\) | on the single tree | on the single tree | mean for all trees |
| | | | with the smallest | with the largest | sampled |
| | | | diversity | diversity | |
| Acacia mellifera | 4 | 6.28 | 35 | 79 | 62 |
| Acacia nilotica | 12 | 23.72 | 65 | 188 | 98 |
| Acacia tortilis | 2 | 4.00 | 84 | 125 | ....... |

[Table 5.2]

Table 5.2
| taxon | number of species | total number of individuals |
|-----------------|------------------|---------------------------|
| Coleoptera (beetles) | 113 | 2 197 |
| Diptera (flies) | 58 | 1 029 |
| Formicidae (ants) | 14 | 7 467 |
| Hemiptera (bugs) | 121 | 11 875 |

(i) Complete Table 5.1 by calculating the mean number of insect species for Acacia tortilis. [1]

(ii) Select, from Tables 5.1 and 5.2, a name to fit the following taxonomic groups:
a genus .............................................................................................................................
a species ...........................................................................................................................[2]

(iii) Comment on the effects of sample size on the quality and accuracy of the data in Table 5.1.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................[2]

(c) This study was carried out in Mkomazi Game Reserve in Tanzania.

Suggest how research into insect diversity on Acacia trees is relevant to the conservation of bigger animals in the reserve, such as elephants.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................[3]

Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method:
• insecticide was sprayed into each tree
• this killed the insects, which fell onto a sheet below the tree
• the dead insects were collected, identified and counted.

(a) The researchers considered each tree to be a small, distinct ecosystem.

Discuss whether or not an individual tree can be described as a small, distinct ecosystem.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................[3]

(b) Table 5.1 shows summary statistics for some of the trees sampled in this study. The leaf canopy area is a measure of the size of the tree and the extent of its leaf cover.

Table 5.2 shows the diversity and abundance of some different taxonomic groups of insects in the study.

[Table 5.1]

Table 5.1
| tree species | number of trees | total leaf canopy area | number of insect species |
| | sampled | \(/m^2\) | on the single tree | on the single tree | mean for all trees |
| | | | with the smallest | with the largest | sampled |
| | | | diversity | diversity | |
| Acacia mellifera | 4 | 6.28 | 35 | 79 | 62 |
| Acacia nilotica | 12 | 23.72 | 65 | 188 | 98 |
| Acacia tortilis | 2 | 4.00 | 84 | 125 | ....... |

[Table 5.2]

Table 5.2
| taxon | number of species | total number of individuals |
|-----------------|------------------|---------------------------|
| Coleoptera (beetles) | 113 | 2 197 |
| Diptera (flies) | 58 | 1 029 |
| Formicidae (ants) | 14 | 7 467 |
| Hemiptera (bugs) | 121 | 11 875 |

(i) Complete Table 5.1 by calculating the mean number of insect species for Acacia tortilis. [1]

(ii) Select, from Tables 5.1 and 5.2, a name to fit the following taxonomic groups:
a genus .............................................................................................................................
a species ...........................................................................................................................[2]

(iii) Comment on the effects of sample size on the quality and accuracy of the data in Table 5.1.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................[2]

(c) This study was carried out in Mkomazi Game Reserve in Tanzania.

Suggest how research into insect diversity on Acacia trees is relevant to the conservation of bigger animals in the reserve, such as elephants.
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................[3]

(a) Fig. 6.1 shows the concentration of two hormones, oestrogen and progesterone, in a woman's blood during one menstrual cycle.
(i) With reference to Fig. 6.1, state the letter of the stage of the cycle during which ovulation occurs. [1]
(ii) State how Fig. 6.1 shows that the woman did not become pregnant during this cycle. [1]
(iii) Name the ovarian structure that secretes progesterone after ovulation. [1]
(iv) State the role of progesterone during stage D. [1]
(b) The combined contraceptive pill contains oestrogen and progesterone. Explain how this combined contraceptive pill works to prevent pregnancy. [4]

(a) Fig. 6.1 shows the concentration of two hormones, oestrogen and progesterone, in a woman's blood during one menstrual cycle.
(i) With reference to Fig. 6.1, state the letter of the stage of the cycle during which ovulation occurs. [1]
(ii) State how Fig. 6.1 shows that the woman did not become pregnant during this cycle. [1]
(iii) Name the ovarian structure that secretes progesterone after ovulation. [1]
(iv) State the role of progesterone during stage D. [1]
(b) The combined contraceptive pill contains oestrogen and progesterone. Explain how this combined contraceptive pill works to prevent pregnancy. [4]

(a) Fig. 7.1 is an electron micrograph of a section of striated muscle.

Fig. 7.1
Name structure P and the region represented by Q.
P .......................................................................................................
Q ....................................................................................................... [2]

(b) Describe the role of calcium ions (Ca²⁺ ions) in the shortening of a sarcomere.
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................................................................................................................... [5]

(c) A motor end plate of a neuromuscular junction is part of a modified cholinergic synapse.
Explain why mitochondria are present in the motor end plate of a neuromuscular junction.
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................................................................................................................... [3]

(a) Fig. 7.1 is an electron micrograph of a section of striated muscle.

Fig. 7.1
Name structure P and the region represented by Q.
P .......................................................................................................
Q ....................................................................................................... [2]

(b) Describe the role of calcium ions (Ca²⁺ ions) in the shortening of a sarcomere.
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
................................................................................................................... [5]

(c) A motor end plate of a neuromuscular junction is part of a modified cholinergic synapse.
Explain why mitochondria are present in the motor end plate of a neuromuscular junction.
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
................................................................................................................... [3]

(a) A respirometer can be used to measure the respiration rate of small invertebrates such as the common woodlouse, _Oniscus asellus_.

Fig. 8.1 shows a common woodlouse.



Fig. 8.2 shows a respirometer.



(i) Name solution X.
...........................................................[1]

(ii) The respirometer can be used to measure the effect of temperature on the rate of respiration of organisms.
Suggest _one_ factor that would need to be taken into account when using woodlice rather than germinating seeds.
...........................................................[1]

(iii) As respiration takes place, oxygen is used by the woodlice and the coloured liquid moves down the graduated tube.
Name the stage of aerobic respiration where oxygen is used.
...........................................................[1]

(b) A respirometer as shown in Fig. 8.2 was used to investigate the effect of temperature on the rate of respiration of woodlice.
• A student set up a respirometer containing 5 woodlice.
• The respirometer was placed in a water-bath maintained at 15 °C.
• The respirometer was left for 10 minutes to equilibrate.
• After a further 15 minutes the distance moved by the coloured liquid was measured.
• The volume of oxygen used by the woodlice was then calculated.
• The experiment was repeated, using the same woodlice and respirometer, at 25 °C.

(i) The results are shown in Table 8.1.

[Table_1]

Complete Table 8.1 by calculating the rates of oxygen uptake at 15 °C and 25 °C.
[2]

(ii) Explain the difference in the rates of oxygen uptake at 15 °C and 25 °C.
...........................................................[3]

(c) In anaerobic conditions, the pyruvate formed in glycolysis is converted to ethanol in yeast cells and to lactate in mammalian tissue.
Compare the pathways by which pyruvate is converted to ethanol or to lactate.
...........................................................[5]

(a) A respirometer can be used to measure the respiration rate of small invertebrates such as the common woodlouse, _Oniscus asellus_.

Fig. 8.1 shows a common woodlouse.



Fig. 8.2 shows a respirometer.



(i) Name solution X.
...........................................................[1]

(ii) The respirometer can be used to measure the effect of temperature on the rate of respiration of organisms.
Suggest _one_ factor that would need to be taken into account when using woodlice rather than germinating seeds.
...........................................................[1]

(iii) As respiration takes place, oxygen is used by the woodlice and the coloured liquid moves down the graduated tube.
Name the stage of aerobic respiration where oxygen is used.
...........................................................[1]

(b) A respirometer as shown in Fig. 8.2 was used to investigate the effect of temperature on the rate of respiration of woodlice.
• A student set up a respirometer containing 5 woodlice.
• The respirometer was placed in a water-bath maintained at 15 °C.
• The respirometer was left for 10 minutes to equilibrate.
• After a further 15 minutes the distance moved by the coloured liquid was measured.
• The volume of oxygen used by the woodlice was then calculated.
• The experiment was repeated, using the same woodlice and respirometer, at 25 °C.

(i) The results are shown in Table 8.1.

[Table_1]

Complete Table 8.1 by calculating the rates of oxygen uptake at 15 °C and 25 °C.
[2]

(ii) Explain the difference in the rates of oxygen uptake at 15 °C and 25 °C.
...........................................................[3]

(c) In anaerobic conditions, the pyruvate formed in glycolysis is converted to ethanol in yeast cells and to lactate in mammalian tissue.
Compare the pathways by which pyruvate is converted to ethanol or to lactate.
...........................................................[5]

(a) Explain how glucose is reabsorbed into the blood from a kidney nephron. [8]
(b) Describe the role of ADH when the water potential of blood decreases. [7]

(a) Explain how glucose is reabsorbed into the blood from a kidney nephron. [8]
(b) Describe the role of ADH when the water potential of blood decreases. [7]

(a) Describe the response of the Venus fly trap to touch. [8]
(b) Explain the control of gibberellin synthesis \textbf{and} outline how gibberellin stimulates stem elongation. [7]

(a) Describe the response of the Venus fly trap to touch. [8]
(b) Explain the control of gibberellin synthesis \textbf{and} outline how gibberellin stimulates stem elongation. [7]