No questions found
(a) ATP and coenzyme A both play important roles in respiration.
Fig. 1.1 represents the molecular structure of coenzyme A.
Fig. 1.1
(i) With reference to Fig. 1.1, state two structural similarities between coenzyme A and ATP.
1 .......................................................................................................................................
2 ....................................................................................................................................... [2]
(ii) Describe the role of coenzyme A in respiration.
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(b) Fig. 1.2 summarises the reactions that take place after glucose has entered a certain type of cell.
Fig. 1.2
(i) Suggest one type of cell in which the reactions shown in Fig. 1.2 could occur.
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(ii) State the mechanism by which glucose enters the cell.
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(iii) Name the type of reaction occurring at F and the type of reaction occurring at G.
F .........................................................................................................................................................
G ......................................................................................................................................................... [2]
(iv) With reference to Fig. 1.2, suggest one example of an ‘other metabolic pathway’ for phosphorylated glucose.
.......................................................................................................................................................... [1]
598
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(a) ATP and coenzyme A both play important roles in respiration.
Fig. 1.1 represents the molecular structure of coenzyme A.
Fig. 1.1
(i) With reference to Fig. 1.1, state two structural similarities between coenzyme A and ATP.
1 .......................................................................................................................................
2 ....................................................................................................................................... [2]
(ii) Describe the role of coenzyme A in respiration.
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(b) Fig. 1.2 summarises the reactions that take place after glucose has entered a certain type of cell.
Fig. 1.2
(i) Suggest one type of cell in which the reactions shown in Fig. 1.2 could occur.
.......................................................................................................................................................... [1]
(ii) State the mechanism by which glucose enters the cell.
.......................................................................................................................................................... [1]
(iii) Name the type of reaction occurring at F and the type of reaction occurring at G.
F .........................................................................................................................................................
G ......................................................................................................................................................... [2]
(iv) With reference to Fig. 1.2, suggest one example of an ‘other metabolic pathway’ for phosphorylated glucose.
.......................................................................................................................................................... [1]
503
590
576
(a) Fig. 2.1 shows the effect of temperature on the rate of photosynthesis of a plant at low light intensity and at high light intensity.
With reference to Fig. 2.1, describe and explain the effect of temperature on the rate of photosynthesis.
(b) Fig. 2.2 shows an absorption spectrum for chloroplast pigments and a photosynthetic action spectrum for the same plant.
(i) Distinguish between an absorption spectrum and an action spectrum.
absorption spectrum .............................................................................................................................. ..................................................................................................................................................
action spectrum ............................................................................................................................... .................................................................................................................................................. [2]
(ii) Explain why the two curves shown in Fig. 2.2 have similar shapes. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. [2]
(c) Describe the role in photosynthesis of an accessory pigment, such as carotene. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. [2]
570
558
501
(a) Fig. 2.1 shows the effect of temperature on the rate of photosynthesis of a plant at low light intensity and at high light intensity.
With reference to Fig. 2.1, describe and explain the effect of temperature on the rate of photosynthesis.
(b) Fig. 2.2 shows an absorption spectrum for chloroplast pigments and a photosynthetic action spectrum for the same plant.
(i) Distinguish between an absorption spectrum and an action spectrum.
absorption spectrum .............................................................................................................................. ..................................................................................................................................................
action spectrum ............................................................................................................................... .................................................................................................................................................. [2]
(ii) Explain why the two curves shown in Fig. 2.2 have similar shapes. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. [2]
(c) Describe the role in photosynthesis of an accessory pigment, such as carotene. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. ................................................................................................................................................................. [2]
531
559
580
(a) In order to produce the GM males, the researchers inserted the gene coding for a restriction endonuclease called I-PpoI. This restriction endonuclease was known to destroy the X chromosome of A. gambiae.
Explain the meaning of the term restriction endonuclease and suggest why I-PpoI destroys the X chromosome, but not the Y chromosome.
(b) The researchers introduced the gene for I-PpoI and also a gene for green fluorescent protein (GFP) into one of the autosomes (a chromosome other than X or Y) of male mosquitoes.
Explain why the researchers introduced the gene for GFP, as well as the gene for I-PpoI.
(c) The researchers found that I-PpoI destroyed the X chromosome during meiosis in the GM male mosquitoes. This prevented these males from producing sperm containing an X chromosome.
However, I-PpoI was still active in zygotes produced by the fusion of female gametes with sperm containing a Y chromosome.
Explain why this meant that the GM males produced no offspring at all.
(d) The researchers modified the gene for I-PpoI, so that it produced a version of I-PpoI that was active only during meiosis in the males, and was not active in the zygote. They then tested the effect of introducing these GM males into a mosquito population.
- Several cages were set up. 50 adult male mosquitoes and 50 adult female mosquitoes without the I-PpoI gene were placed in each cage.
- 150 adult GM males were introduced into each cage. In half of the cages (A), these GM males had the normal gene for I-PpoI. In the rest of the cages (B), the GM males had the modified gene for I-PpoI.
- The mean number of adult female offspring per cage was determined over the next six generations.
Fig. 3.1 shows the results.
(i) Describe and suggest explanations for the differences between the mean numbers of adult females in the two sets of cages during the experiment.
(ii) Suggest possible difficulties that might arise if the technique of releasing GM male mosquitoes with the modified I-PpoI gene were used to try to control populations of A. gambiae that occur naturally in the wild.
513
522
548
(a) In order to produce the GM males, the researchers inserted the gene coding for a restriction endonuclease called I-PpoI. This restriction endonuclease was known to destroy the X chromosome of A. gambiae.
Explain the meaning of the term restriction endonuclease and suggest why I-PpoI destroys the X chromosome, but not the Y chromosome.
(b) The researchers introduced the gene for I-PpoI and also a gene for green fluorescent protein (GFP) into one of the autosomes (a chromosome other than X or Y) of male mosquitoes.
Explain why the researchers introduced the gene for GFP, as well as the gene for I-PpoI.
(c) The researchers found that I-PpoI destroyed the X chromosome during meiosis in the GM male mosquitoes. This prevented these males from producing sperm containing an X chromosome.
However, I-PpoI was still active in zygotes produced by the fusion of female gametes with sperm containing a Y chromosome.
Explain why this meant that the GM males produced no offspring at all.
(d) The researchers modified the gene for I-PpoI, so that it produced a version of I-PpoI that was active only during meiosis in the males, and was not active in the zygote. They then tested the effect of introducing these GM males into a mosquito population.
- Several cages were set up. 50 adult male mosquitoes and 50 adult female mosquitoes without the I-PpoI gene were placed in each cage.
- 150 adult GM males were introduced into each cage. In half of the cages (A), these GM males had the normal gene for I-PpoI. In the rest of the cages (B), the GM males had the modified gene for I-PpoI.
- The mean number of adult female offspring per cage was determined over the next six generations.
Fig. 3.1 shows the results.
(i) Describe and suggest explanations for the differences between the mean numbers of adult females in the two sets of cages during the experiment.
(ii) Suggest possible difficulties that might arise if the technique of releasing GM male mosquitoes with the modified I-PpoI gene were used to try to control populations of A. gambiae that occur naturally in the wild.
593
511
531
Food crops like wheat may be improved by selective breeding and genetic modification.
(a) Outline how wheat crops have been improved by selective breeding.
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(b) Variation in height of a strain of wheat plants in a field shows a continuous pattern of variation. Explain what is meant by continuous variation and explain why this type of variation occurs in a population.
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(c) Wheat and other crops have been genetically modified to be resistant to the herbicide glyphosate since 1996. Fig. 4.1 shows the area of glyphosate-resistant crops grown as a percentage of the total planted hectares (plotted points) and the number of weed species with resistance to glyphosate (bars).
Describe and explain the relationship between the area of glyphosate-resistant crops grown and the number of resistant weed species.
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(d) Suggest one social advantage and one environmental advantage of growing glyphosate-resistant wheat.
social advantage .................................................................................................................
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environmental advantage .................................................................................................................
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570
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Food crops like wheat may be improved by selective breeding and genetic modification.
(a) Outline how wheat crops have been improved by selective breeding.
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(b) Variation in height of a strain of wheat plants in a field shows a continuous pattern of variation. Explain what is meant by continuous variation and explain why this type of variation occurs in a population.
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(c) Wheat and other crops have been genetically modified to be resistant to the herbicide glyphosate since 1996. Fig. 4.1 shows the area of glyphosate-resistant crops grown as a percentage of the total planted hectares (plotted points) and the number of weed species with resistance to glyphosate (bars).
Describe and explain the relationship between the area of glyphosate-resistant crops grown and the number of resistant weed species.
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(d) Suggest one social advantage and one environmental advantage of growing glyphosate-resistant wheat.
social advantage .................................................................................................................
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environmental advantage .................................................................................................................
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(a) Urban raccoons live in towns. Although they are nocturnal their large size means they may be noticed by humans. They may be found raiding bins containing food waste, or entering buildings.
Describe a method for estimating the size of a raccoon population in a town.
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[3]
(b) (i) Raccoons are classified in the phylum Chordata of the kingdom Animalia.
Name the domain to which raccoons belong.
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[1]
(ii) Outline three characteristic features of members of this domain.
1 ..................................................................................................................................................
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2 ..................................................................................................................................................
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3 ..................................................................................................................................................
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[3]
(c) It has been suggested that raccoons may threaten biodiversity and pose a risk to human health in Germany.
Explain how raccoons could cause problems for local biodiversity and for human health.
local biodiversity ..............................................................................................................................
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human health ...............................................................................................................................
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[3]
527
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(a) Urban raccoons live in towns. Although they are nocturnal their large size means they may be noticed by humans. They may be found raiding bins containing food waste, or entering buildings.
Describe a method for estimating the size of a raccoon population in a town.
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[3]
(b) (i) Raccoons are classified in the phylum Chordata of the kingdom Animalia.
Name the domain to which raccoons belong.
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[1]
(ii) Outline three characteristic features of members of this domain.
1 ..................................................................................................................................................
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2 ..................................................................................................................................................
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3 ..................................................................................................................................................
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[3]
(c) It has been suggested that raccoons may threaten biodiversity and pose a risk to human health in Germany.
Explain how raccoons could cause problems for local biodiversity and for human health.
local biodiversity ..............................................................................................................................
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human health ...............................................................................................................................
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[3]
525
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543
The sex chromosomes of domestic chickens are known as $W$ and $Z$.
\begin{itemize}
\item Male chickens have two $Z$ chromosomes.
\item Female chickens have one $W$ and one $Z$ chromosome.
\end{itemize}
A gene for feather colour in chickens is located on an autosome.
This gene $(C)$ has two alleles
\begin{itemize}
\item black $(C^B)$
\item splashed-white $(C^S)$.
\end{itemize}
When a chicken with black feathers is mated with a chicken with splashed-white feathers, all the offspring will have blue feathers.
A gene for feather pattern is located on the $Z$ chromosome but not on the $W$ chromosome. This gene has two alleles
\begin{itemize}
\item barred (striped) feathers $(A)$
\item non-barred feathers $(a)$.
\end{itemize}
(a) State the type of inheritance for feather colour and for feather pattern.
\textit{feather colour} .............................................................................................................................
\textit{feather pattern} ........................................................................................................................ [2]
(b) A male chicken with black, non-barred feathers was crossed with a female chicken with splashed-white, barred feathers.
All the offspring had blue feathers, but the males were barred and the females were non-barred.
Using the symbols given, draw a genetic diagram to show this cross.
\textit{parents} male, black, \quad \quad female, splashed-white,
\textit{phenotype} non-barred feathers \quad \quad barred feathers
\textit{parents}
\textit{genotype}
\textit{gametes}
\textit{offspring}
\textit{genotypes}
\textit{offspring}\textit{phenotypes} male, blue, barred feathers \quad \quad female, blue, non-barred feathers [5]
(c) Explain how the genotype of a male chicken with blue, barred feathers could be determined.
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532
The sex chromosomes of domestic chickens are known as $W$ and $Z$.
\begin{itemize}
\item Male chickens have two $Z$ chromosomes.
\item Female chickens have one $W$ and one $Z$ chromosome.
\end{itemize}
A gene for feather colour in chickens is located on an autosome.
This gene $(C)$ has two alleles
\begin{itemize}
\item black $(C^B)$
\item splashed-white $(C^S)$.
\end{itemize}
When a chicken with black feathers is mated with a chicken with splashed-white feathers, all the offspring will have blue feathers.
A gene for feather pattern is located on the $Z$ chromosome but not on the $W$ chromosome. This gene has two alleles
\begin{itemize}
\item barred (striped) feathers $(A)$
\item non-barred feathers $(a)$.
\end{itemize}
(a) State the type of inheritance for feather colour and for feather pattern.
\textit{feather colour} .............................................................................................................................
\textit{feather pattern} ........................................................................................................................ [2]
(b) A male chicken with black, non-barred feathers was crossed with a female chicken with splashed-white, barred feathers.
All the offspring had blue feathers, but the males were barred and the females were non-barred.
Using the symbols given, draw a genetic diagram to show this cross.
\textit{parents} male, black, \quad \quad female, splashed-white,
\textit{phenotype} non-barred feathers \quad \quad barred feathers
\textit{parents}
\textit{genotype}
\textit{gametes}
\textit{offspring}
\textit{genotypes}
\textit{offspring}\textit{phenotypes} male, blue, barred feathers \quad \quad female, blue, non-barred feathers [5]
(c) Explain how the genotype of a male chicken with blue, barred feathers could be determined.
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552
522
588
(a) In mammals, excess amino acids cannot be stored in the body. Outline the formation of urea from excess amino acids by liver cells.
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(b) The mammalian kidney is composed of many nephrons. Describe the process of ultrafiltration in the nephron.
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(c) Fig. 7.1 is a diagram of a nephron.
Complete Table 7.1 by naming a part of the nephron that corresponds to each of the statements.
[Table_1]
Table 7.1
statement | part of nephron
--|--
passes through the medulla | ...................................................
glucose is reabsorbed into the blood | ...................................................
ADH acts on its walls | ...................................................
most of the water is reabsorbed into the blood | ................................................... [4]
505
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538
(a) In mammals, excess amino acids cannot be stored in the body. Outline the formation of urea from excess amino acids by liver cells.
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(b) The mammalian kidney is composed of many nephrons. Describe the process of ultrafiltration in the nephron.
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(c) Fig. 7.1 is a diagram of a nephron.
Complete Table 7.1 by naming a part of the nephron that corresponds to each of the statements.
[Table_1]
Table 7.1
statement | part of nephron
--|--
passes through the medulla | ...................................................
glucose is reabsorbed into the blood | ...................................................
ADH acts on its walls | ...................................................
most of the water is reabsorbed into the blood | ................................................... [4]
543
542
595
(a) Fig. 8.1 is an electron micrograph of part of a cholinergic synapse.
On Fig. 8.1, use label lines and letters to label each of the following:
X – a structure that indicates that A is a pre-synaptic neurone
Y – an area that contains many voltage-gated Na+ channels
Z – an area that contains both acetylcholine and acetylcholinesterase. [3]
(b) Some insecticides have a similar structure to acetylcholine. Suggest how these insecticides may affect the functioning of acetylcholinesterase. [3]
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(c) Outline the roles of synapses in the nervous system. [2]
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523
534
553
(a) Fig. 8.1 is an electron micrograph of part of a cholinergic synapse.
On Fig. 8.1, use label lines and letters to label each of the following:
X – a structure that indicates that A is a pre-synaptic neurone
Y – an area that contains many voltage-gated Na+ channels
Z – an area that contains both acetylcholine and acetylcholinesterase. [3]
(b) Some insecticides have a similar structure to acetylcholine. Suggest how these insecticides may affect the functioning of acetylcholinesterase. [3]
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(c) Outline the roles of synapses in the nervous system. [2]
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509
568
590
(a) Outline the process of glycolysis. [6]
(b) Describe the series of reactions that make up the Krebs cycle. [9]
580
510
551
(a) Outline the process of glycolysis. [6]
(b) Describe the series of reactions that make up the Krebs cycle. [9]
580
513
556
(a) Explain how meiosis and fertilisation can result in genetic variation amongst offspring. [8]
(b) Describe the genetic control of protein production in a prokaryote using the \textit{lac} operon. [7]
[Total: 15]
558
589
561
(a) Explain how meiosis and fertilisation can result in genetic variation amongst offspring. [8]
(b) Describe the genetic control of protein production in a prokaryote using the \textit{lac} operon. [7]
[Total: 15]
559
561
515
