No questions found
(a) ATP and NAD both play important roles in respiration. Both compounds are nucleotides.
Fig. 1.1 represents the molecular structures of ATP and NAD.
Using Fig. 1.1, compare the structures of ATP and NAD.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [3]
(b) ATP provides an immediate energy source for metabolic processes such as anabolic reactions.
State two examples of anabolic reactions in a mammal that require ATP as an energy source.
1 ...............................................................................................................................................................
2 ............................................................................................................................................................... [2]
(c) Name the type of chemical reaction by which ATP is made during the Krebs cycle.
............................................................................................................................................................................... [1]
(d) Outline the roles of NAD in the cytoplasm of a cell.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [2]
(e) Carbohydrates and lipids are used as respiratory substrates.
Table 1.1 shows the energy values of carbohydrates and lipids.
[Table_1]
Explain why lipids have a higher energy value than carbohydrates.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [2]
546
509
502
(a) ATP and NAD both play important roles in respiration. Both compounds are nucleotides.
Fig. 1.1 represents the molecular structures of ATP and NAD.
Using Fig. 1.1, compare the structures of ATP and NAD.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [3]
(b) ATP provides an immediate energy source for metabolic processes such as anabolic reactions.
State two examples of anabolic reactions in a mammal that require ATP as an energy source.
1 ...............................................................................................................................................................
2 ............................................................................................................................................................... [2]
(c) Name the type of chemical reaction by which ATP is made during the Krebs cycle.
............................................................................................................................................................................... [1]
(d) Outline the roles of NAD in the cytoplasm of a cell.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [2]
(e) Carbohydrates and lipids are used as respiratory substrates.
Table 1.1 shows the energy values of carbohydrates and lipids.
[Table_1]
Explain why lipids have a higher energy value than carbohydrates.
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
...............................................................................................................................................................................
............................................................................................................................................................................... [2]
592
559
522
The concentration of carbon dioxide in the atmosphere and the light intensity often limit the rate of photosynthesis.
(a) Explain what is meant by a limiting factor in relation to photosynthesis.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
(b) Investigations were carried out in Florida, USA, into the effect of different concentrations of atmospheric carbon dioxide and of light intensity on the rate of photosynthesis of soybean plants.
Plants were grown from seed in outdoor, computer-controlled growth chambers at different concentrations of carbon dioxide. The upper parts of the chambers were transparent so that the plants received natural sunlight.
After the seedlings emerged, the air in the soil was separated from the air around the leaves by a gas-tight seal in each chamber.
Suggest why the air in the soil and the air around the leaves of the plants were separated.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
(c) In one investigation, two sets of plants, A and B, were grown from seed at different concentrations of carbon dioxide:
* A – normal atmospheric concentration of carbon dioxide (0.033%)
* B – normal atmospheric concentration of carbon dioxide x2 (0.066%).
Then, keeping each set of plants in its particular concentration of carbon dioxide, measurements were made of their rates of photosynthesis at different light intensities.
The results are shown in Fig. 2.1 on page 5.
With reference to Fig. 2.1:
(i) describe and explain, in terms of limiting factors, the results from the plants in set A
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
[3]
(ii) explain the difference between the results of set A and set B at high light intensities.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
[2]
(d) In a second investigation, two sets of plants, C and D, were grown from seed, as before, in different carbon dioxide concentrations:
* C – normal atmospheric concentration of carbon dioxide (0.033%)
* D – normal atmospheric concentration of carbon dioxide x2 (0.066%).
When the plants matured, conditions in the growth chambers were changed to investigate the rate of photosynthesis of each set of plants in different concentrations of carbon dioxide.
The results are shown in Fig. 2.2.
Suggest explanations for the higher rate of photosynthesis per unit area of leaf shown by the plants in set D compared with those in set C.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
597
579
584
The concentration of carbon dioxide in the atmosphere and the light intensity often limit the rate of photosynthesis.
(a) Explain what is meant by a limiting factor in relation to photosynthesis.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
(b) Investigations were carried out in Florida, USA, into the effect of different concentrations of atmospheric carbon dioxide and of light intensity on the rate of photosynthesis of soybean plants.
Plants were grown from seed in outdoor, computer-controlled growth chambers at different concentrations of carbon dioxide. The upper parts of the chambers were transparent so that the plants received natural sunlight.
After the seedlings emerged, the air in the soil was separated from the air around the leaves by a gas-tight seal in each chamber.
Suggest why the air in the soil and the air around the leaves of the plants were separated.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
(c) In one investigation, two sets of plants, A and B, were grown from seed at different concentrations of carbon dioxide:
* A – normal atmospheric concentration of carbon dioxide (0.033%)
* B – normal atmospheric concentration of carbon dioxide x2 (0.066%).
Then, keeping each set of plants in its particular concentration of carbon dioxide, measurements were made of their rates of photosynthesis at different light intensities.
The results are shown in Fig. 2.1 on page 5.
With reference to Fig. 2.1:
(i) describe and explain, in terms of limiting factors, the results from the plants in set A
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
[3]
(ii) explain the difference between the results of set A and set B at high light intensities.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
[2]
(d) In a second investigation, two sets of plants, C and D, were grown from seed, as before, in different carbon dioxide concentrations:
* C – normal atmospheric concentration of carbon dioxide (0.033%)
* D – normal atmospheric concentration of carbon dioxide x2 (0.066%).
When the plants matured, conditions in the growth chambers were changed to investigate the rate of photosynthesis of each set of plants in different concentrations of carbon dioxide.
The results are shown in Fig. 2.2.
Suggest explanations for the higher rate of photosynthesis per unit area of leaf shown by the plants in set D compared with those in set C.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
526
559
567
(a) (i) Define the term bioinformatics.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [2]
(ii) Outline how sequencing the genome of Plasmodium and the use of bioinformatics can
suggest new targets for anti-malarial drugs.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [3]
(b) In parts of the world where Plasmodium is resistant to chloroquine, one of the most effective
anti-malarial drugs currently in use is artemisinin. Artemisinin works by binding to an enzyme
in Plasmodium called PfATP6, acting as an inhibitor.
A substance called curcumin, which has long been used as a spice and yellow food colouring
in India and other countries, is also known to act against chloroquine-resistant Plasmodium.
A group of researchers predicted that curcumin acts by binding to the same enzyme as
artemisinin.
In order to test this hypothesis, and to try to find similar substances that might work even
better than curcumin, the researchers used theoretical modelling to:
• look at the chemical structures of various molecules with a similar structure to
curcumin (curcumin analogues)
• generate a three-dimensional model of the structure of the enzyme PfATP6
• investigate whether each curcumin analogue could bind to PfATP6.
The researchers predicted that several of the curcumin analogues would bind more strongly
than curcumin to PfATP6.
(i) Suggest advantages of using theoretical models in this research, rather than testing
possible drugs in the laboratory.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [3]
(ii) Suggest why theoretical modelling cannot completely replace laboratory trials in the
search for new drugs.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [2]
589
560
574
(a) (i) Define the term bioinformatics.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [2]
(ii) Outline how sequencing the genome of Plasmodium and the use of bioinformatics can
suggest new targets for anti-malarial drugs.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [3]
(b) In parts of the world where Plasmodium is resistant to chloroquine, one of the most effective
anti-malarial drugs currently in use is artemisinin. Artemisinin works by binding to an enzyme
in Plasmodium called PfATP6, acting as an inhibitor.
A substance called curcumin, which has long been used as a spice and yellow food colouring
in India and other countries, is also known to act against chloroquine-resistant Plasmodium.
A group of researchers predicted that curcumin acts by binding to the same enzyme as
artemisinin.
In order to test this hypothesis, and to try to find similar substances that might work even
better than curcumin, the researchers used theoretical modelling to:
• look at the chemical structures of various molecules with a similar structure to
curcumin (curcumin analogues)
• generate a three-dimensional model of the structure of the enzyme PfATP6
• investigate whether each curcumin analogue could bind to PfATP6.
The researchers predicted that several of the curcumin analogues would bind more strongly
than curcumin to PfATP6.
(i) Suggest advantages of using theoretical models in this research, rather than testing
possible drugs in the laboratory.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [3]
(ii) Suggest why theoretical modelling cannot completely replace laboratory trials in the
search for new drugs.
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
......................................................................................................................... [2]
584
559
520
Maize is an important food crop that has been improved both by selective breeding and by genetic modification.
(a) Outline how selective breeding has been used to improve maize.
(b) Fig. 4.1 shows part of a maize cob. The cob is made up of many individual seeds called kernels. Each kernel results from a separate fertilisation of a male and a female gamete. Some kernels are yellow and some are purple.
Name the type of variation shown in Fig. 4.1. Suggest a genetic explanation for this pattern of variation in colour.
type of variation ...........................................................................................................................
explanation ................................................................................................................................
(c) Maize and other crops have been genetically modified since 1996 to produce the Bt toxin to kill insect pests.
Fig. 4.2 shows the area of Bt crops grown (plotted points) and the number of insect pest species in which resistance to Bt has been reported (bars).
[Image: Fig. 4.2]
(i) Describe and suggest an explanation for the relationship between the area of Bt crops grown and the number of resistant pest species.
......................................................................................................................................................
(ii) Suggest one social advantage and one environmental advantage of growing this Bt maize.
social advantage ..........................................................................................................................
environmental advantage ..............................................................................................................
507
592
598
Maize is an important food crop that has been improved both by selective breeding and by genetic modification.
(a) Outline how selective breeding has been used to improve maize.
(b) Fig. 4.1 shows part of a maize cob. The cob is made up of many individual seeds called kernels. Each kernel results from a separate fertilisation of a male and a female gamete. Some kernels are yellow and some are purple.
Name the type of variation shown in Fig. 4.1. Suggest a genetic explanation for this pattern of variation in colour.
type of variation ...........................................................................................................................
explanation ................................................................................................................................
(c) Maize and other crops have been genetically modified since 1996 to produce the Bt toxin to kill insect pests.
Fig. 4.2 shows the area of Bt crops grown (plotted points) and the number of insect pest species in which resistance to Bt has been reported (bars).
[Image: Fig. 4.2]
(i) Describe and suggest an explanation for the relationship between the area of Bt crops grown and the number of resistant pest species.
......................................................................................................................................................
(ii) Suggest one social advantage and one environmental advantage of growing this Bt maize.
social advantage ..........................................................................................................................
environmental advantage ..............................................................................................................
514
579
572
(a) Name and describe a method for estimating the abundance of water voles in a local area.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[4]
(b) Both water voles and mink are classified as class Mammalia, phylum Chordata, kingdom Animalia.
Outline two features of the cells of members of the kingdom Animalia that distinguish them from the cells of other multicellular eukaryotes.
1 ..................................................................................................................................................
......................................................................................................................................................
2 ..................................................................................................................................................
......................................................................................................................................................
[2]
(c) (i) Discuss the reasons why alien species should be controlled.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[3]
(ii) Suggest one way of controlling mink numbers in Great Britain.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[1]
558
516
530
(a) Name and describe a method for estimating the abundance of water voles in a local area.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[4]
(b) Both water voles and mink are classified as class Mammalia, phylum Chordata, kingdom Animalia.
Outline two features of the cells of members of the kingdom Animalia that distinguish them from the cells of other multicellular eukaryotes.
1 ..................................................................................................................................................
......................................................................................................................................................
2 ..................................................................................................................................................
......................................................................................................................................................
[2]
(c) (i) Discuss the reasons why alien species should be controlled.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[3]
(ii) Suggest one way of controlling mink numbers in Great Britain.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
[1]
514
509
500
The fruit fly, Drosophila melanogaster, has eyes, a striped abdomen and wings longer than its abdomen. This is called a ‘wild-type’ fly.
Mutation has resulted in many variations of these features.
Table 6.1 shows diagrams of a wild-type fly and three other flies, each of which shows one recessive mutation.
[Table_6.1]
(a) Using appropriate symbols, complete the genetic diagram below.
symbols
......................................
......................................
......................................
......................................
\begin{align*} \text{parental phenotypes} & \quad \text{with eyes} \quad \text{X no eyes} \\ \text{} & \quad \text{black abdomen striped abdomen} \\ \text{parental genotypes} & \\ \text{gametes} & \\ \text{offspring genotypes} & \\ \text{offspring phenotypes} & \quad \text{with eyes} \quad \text{no eyes} \quad \text{with eyes} \quad \text{no eyes} \\ \text{} & \quad \text{black abdomen black abdomen striped abdomen striped abdomen} \end{align*}
(b) State how you would carry out a test cross.
................................................................................................................................
......................................................................................................................... [1]
(c) A cross was carried out between a fly heterozygous for striped abdomen and long wings and a fly with a black abdomen and short wings.
The results are shown below in Table 6.2.
[Table_6.2]
A chi-squared test (\( \chi^2 \)) was carried out on these data.
Complete Table 6.3 and calculate the value of \( \chi^2 \).
[Table_6.3]
\( \chi^2 = \sum \frac{(O-E)^2}{E} \)
(d) Table 6.4 shows \( \chi^2 \) values.
[Table_6.4]
Using Table 6.4, explain what conclusions can be made about the results of the \( \chi^2 \) test.
................................................................................................................................
............................................................................................................................
............................................................................................................................
............................................................................................................................
[2]
503
558
578
The fruit fly, Drosophila melanogaster, has eyes, a striped abdomen and wings longer than its abdomen. This is called a ‘wild-type’ fly.
Mutation has resulted in many variations of these features.
Table 6.1 shows diagrams of a wild-type fly and three other flies, each of which shows one recessive mutation.
[Table_6.1]
(a) Using appropriate symbols, complete the genetic diagram below.
symbols
......................................
......................................
......................................
......................................
\begin{align*} \text{parental phenotypes} & \quad \text{with eyes} \quad \text{X no eyes} \\ \text{} & \quad \text{black abdomen striped abdomen} \\ \text{parental genotypes} & \\ \text{gametes} & \\ \text{offspring genotypes} & \\ \text{offspring phenotypes} & \quad \text{with eyes} \quad \text{no eyes} \quad \text{with eyes} \quad \text{no eyes} \\ \text{} & \quad \text{black abdomen black abdomen striped abdomen striped abdomen} \end{align*}
(b) State how you would carry out a test cross.
................................................................................................................................
......................................................................................................................... [1]
(c) A cross was carried out between a fly heterozygous for striped abdomen and long wings and a fly with a black abdomen and short wings.
The results are shown below in Table 6.2.
[Table_6.2]
A chi-squared test (\( \chi^2 \)) was carried out on these data.
Complete Table 6.3 and calculate the value of \( \chi^2 \).
[Table_6.3]
\( \chi^2 = \sum \frac{(O-E)^2}{E} \)
(d) Table 6.4 shows \( \chi^2 \) values.
[Table_6.4]
Using Table 6.4, explain what conclusions can be made about the results of the \( \chi^2 \) test.
................................................................................................................................
............................................................................................................................
............................................................................................................................
............................................................................................................................
[2]
530
544
522
(a) An important function of control systems in mammals is homeostasis. Explain what is meant by the term homeostasis. ........................................................................................................................................................................................................................................................ [1]
(b) Insulin plays a part in homeostasis. It affects muscle and liver cells to bring about a decrease in blood glucose concentration, particularly after a meal.
(i) Insulin is composed of two polypeptides which are made in β cells in the pancreas. State precisely where in β cells polypeptide molecules are synthesised. ............................................................................................................................................................ [1]
(ii) Name the process by which insulin is secreted from β cells. ............................................................................................................................................................ [1]
(iii) Describe the effects of insulin on muscle cells. ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................ [3]
(c) During periods of stress or extreme exercise more glucose needs to be released into the blood. The hormone adrenaline is released and binds to receptors on the cell surface membranes of liver cells. Describe how the effect of adrenaline on liver cells results in an increase in blood glucose concentration. ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ [5]
507
554
567
(a) An important function of control systems in mammals is homeostasis. Explain what is meant by the term homeostasis. ........................................................................................................................................................................................................................................................ [1]
(b) Insulin plays a part in homeostasis. It affects muscle and liver cells to bring about a decrease in blood glucose concentration, particularly after a meal.
(i) Insulin is composed of two polypeptides which are made in β cells in the pancreas. State precisely where in β cells polypeptide molecules are synthesised. ............................................................................................................................................................ [1]
(ii) Name the process by which insulin is secreted from β cells. ............................................................................................................................................................ [1]
(iii) Describe the effects of insulin on muscle cells. ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................ [3]
(c) During periods of stress or extreme exercise more glucose needs to be released into the blood. The hormone adrenaline is released and binds to receptors on the cell surface membranes of liver cells. Describe how the effect of adrenaline on liver cells results in an increase in blood glucose concentration. ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ ........................................................................................................................................................................................................................................................ [5]
523
581
508
(a) Fig. 8.1 is a diagram of a sensory neurone and some receptor cells.
Name the parts of the neurone labelled A, B, C and D.
A ....................................................
B ....................................................
C ....................................................
D .................................................... [4]
(b) Explain how the myelin sheath increases the speed of conduction of nerve impulses.
....................................................
....................................................
....................................................
....................................................
.................................................... [2]
(c) Fig. 8.2 shows the changes in the membrane potential of a sensory neurone when the receptor cells are stimulated.
Fig. 8.3 shows the strength of the stimuli applied to these receptor cells.
With reference to Fig. 8.2 and Fig. 8.3, describe the relationship between the strength of the stimulus and the resulting action potential.
....................................................
....................................................
....................................................
....................................................
.................................................... [2]
558
559
554
(a) Fig. 8.1 is a diagram of a sensory neurone and some receptor cells.
Name the parts of the neurone labelled A, B, C and D.
A ....................................................
B ....................................................
C ....................................................
D .................................................... [4]
(b) Explain how the myelin sheath increases the speed of conduction of nerve impulses.
....................................................
....................................................
....................................................
....................................................
.................................................... [2]
(c) Fig. 8.2 shows the changes in the membrane potential of a sensory neurone when the receptor cells are stimulated.
Fig. 8.3 shows the strength of the stimuli applied to these receptor cells.
With reference to Fig. 8.2 and Fig. 8.3, describe the relationship between the strength of the stimulus and the resulting action potential.
....................................................
....................................................
....................................................
....................................................
.................................................... [2]
585
590
553
(a) Outline how ATP is synthesised by oxidative phosphorylation. [8]
(b) Describe respiration in yeast cells in anaerobic conditions. [7]
556
501
501
(a) Outline how ATP is synthesised by oxidative phosphorylation. [8]
(b) Describe respiration in yeast cells in anaerobic conditions. [7]
521
549
594
(a) Describe the behaviour of chromosomes during meiosis. [9]
(b) Outline the differences between structural and regulatory genes. [6]
570
541
539
(a) Describe the behaviour of chromosomes during meiosis. [9]
(b) Outline the differences between structural and regulatory genes. [6]
556
561
579
