2.1 The diagram below shows part of a process involved in the production of a protein - English General - NSC Life Sciences - Question 2 - 2019 - Paper 2
Question 2
2.1 The diagram below shows part of a process involved in the production of a protein.
W
X
2 3
Y
... show full transcript
Worked Solution & Example Answer:2.1 The diagram below shows part of a process involved in the production of a protein - English General - NSC Life Sciences - Question 2 - 2019 - Paper 2
Step 1
Identify:
(a) Molecule Y
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Answer
Molecule Y is transfer RNA (tRNA).
Step 2
Identify:
(b) The group of nitrogen bases Z
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Answer
The group of nitrogen bases Z is the anticodon, which pairs with the corresponding codon on the mRNA.
Step 3
If X is the next amino acid required after W, then identify:
(a) Nitrogenous bases 1, 2 and 3
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The nitrogenous bases 1, 2, and 3 corresponding to the amino acid X are UGG.
Step 4
If X is the next amino acid required after W, then identify:
(b) The DNA base triplet that codes for X
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The DNA base triplet that codes for amino acid X is TGG.
Step 5
Name and describe the type of dominance shown by cross 4.
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The type of dominance shown by cross 4 is co-dominance. In this case, both parental traits (orange and yellow) are expressed equally in the offspring, resulting in the orange-yellow phenotype.
Step 6
Which shell colour is controlled by the recessive allele?
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The shell colour controlled by the recessive allele is black.
Step 7
Use information in the table to support your answer to QUESTION 2.3.2.
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Answer
In cross 1, both parents are yellow, and the offspring ratio is 27:9 for yellow to black. This indicates that black is the recessive phenotype as it only appears when both alleles are recessive.
Step 8
Which phenotype is dominant?
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The dominant phenotype is spotted.
Step 9
Explain your answer to QUESTION 2.4.1.
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Spotted frogs produced three times more offspring with spots than without spots, indicating that the spotted phenotype is dominant over the unspotted phenotype.
Step 10
A frog that is heterozygous for spotted back was crossed with a frog without spots.
Using the letters D and d, represent a genetic cross to show the expected genotypes and phenotypes of the F1 generation.
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Let D represent the dominant allele for spotted back and d represent the recessive allele for no spots.
P1:
Phenotype: Spotted x No spots
Genotype: Dd x dd
Gametes:
Dd: D, d
dd: d, d
F1 Generation Genotypes:
50% Dd (spotted)
50% dd (without spots)
Phenotypes:
50% spotted
50% without spots.
Step 11
Identify the independent variable in this investigation.
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The independent variable in this investigation is the type of antibiotic used.
Step 12
Identify TWO factors that should be kept constant during the investigation.
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Two factors that should be kept constant during the investigation are the age of the piglets and the amount of antibiotic administered.
Step 13
State TWO ways in which the scientists ensured the reliability of the investigation.
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The scientists ensured reliability by using a large sample size of 100 piglets and conducting the investigation over a six-month period to account for variability.
Step 14
Which antibiotic will you recommend for controlling E. coli in piglets?
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I would recommend using antibiotic B for controlling E. coli in piglets, as it showed a lower resistance compared to antibiotic A.
Step 15
Explain the results that are shown in the graph for antibiotic A in terms of natural resistance.
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The results indicate that the average percentage resistance of E. coli to antibiotic A increases over time. This suggests that more E. coli bacteria developed resistance to antibiotic A, potentially due to selective pressures in the environment.
