3.1 In rice plants the allele for high yield (H) is dominant over the allele for low yield (h) - NSC Life Sciences - Question 3 - 2016 - Paper 2
Question 3
3.1 In rice plants the allele for high yield (H) is dominant over the allele for low yield (h). The allele for a tall stem (T) is dominant over the allele for a shor... show full transcript
Worked Solution & Example Answer:3.1 In rice plants the allele for high yield (H) is dominant over the allele for low yield (h) - NSC Life Sciences - Question 3 - 2016 - Paper 2
Step 1
3.1.1 Give the phenotype of variety A.
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Answer
The phenotype of variety A is high yield and short stem.
Step 2
3.1.2 Give ALL the possible genotypes of the gametes of variety B.
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Answer
The possible genotypes of the gametes of variety B are hT and ht.
Step 3
3.1.3 Give the genotype(s) of the variety the plant breeder wants to produce.
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Answer
The genotype of the variety the plant breeder wants to produce is HHtt.
Step 4
3.1.4 Explain why the plant breeder would want to produce a rice plant with a short stem.
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Answer
The plant breeder would want to produce a rice plant with a short stem because short-stemmed plants are less likely to break under windy conditions and are easier to harvest.
Step 5
3.1.5 Describe how the plant breeder would be able to produce rice plants with a high yield and short stems only.
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The plant breeder can produce rice plants with a high yield and short stems by crossing the HHtt variety (high yield, short stem) with another suitable variety, ensuring that the offspring exhibit the desired traits consistently.
Step 6
3.2 Tabulate THREE differences between Lamarckism and Darwinism.
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Lamarckism
Darwinism
Variation occurs when individuals in a population change due to environmental adaptation
Variation occurs through natural selection influenced by the environment
Change is passed on to offspring (inheritance of acquired characteristics)
Characteristics are inherited through genetic transmission
Emphasizes individual changes in populations
Focuses on population-level changes over generations
Step 7
3.3.1 Name FIVE characteristics that humans share with African apes.
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Olfactory brain centres reduced / reduced sense of smell
Eyes in front / Binocular vision
Eyes with cones / Colour vision
Elbow joints allowing for rotation of forearm
Sexual dimorphism / Distinct differences between males and females
Step 8
3.3.2 Describe how each of the following structures is different between humans and apes:
(a) Spine
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The human spine is more curved, resulting in an S-shape, whereas the ape spine is less curved and typically C-shaped.
Step 9
3.3.2 Describe how each of the following structures is different between humans and apes:
(b) Pelvic girdle
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The human pelvic girdle is short and wide, while the ape pelvic girdle is long and narrow.
Step 10
3.3.3 Explain the significance of the changes to the teeth of humans that show progression in evolution.
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The changes in human teeth, from larger canines to smaller teeth, reflect adaptation to a diet that has shifted from raw to cooked food, which signifies dietary evolution and the development of tool use for food preparation.
Step 11
3.4.1 How many grandsons do James and Tebogo have?
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James and Tebogo have 2 grandsons.
Step 12
3.4.2 What is:
(a) Grace's phenotype
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Grace's phenotype is normal (not albino).
Step 13
3.4.2 What is:
(b) John's genotype
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John's genotype is Aa.
Step 14
3.4.3 John and Joanna wish to have another child. What is the percentage chance that the child will:
(a) Be a girl
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The percentage chance that the child will be a girl is 50%.
Step 15
3.4.3 John and Joanna wish to have another child. What is the percentage chance that the child will:
(b) Have albinism
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The percentage chance that the child will have albinism is 25%.
Step 16
3.5 Describe how a gene mutation may result in the formation of a protein that is different from the one that is required.
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A gene mutation alters the sequence of nitrogen bases in DNA, leading to changes in the corresponding mRNA and codons. This results in a different amino acid sequence, which may code for a protein that has different properties or functionality compared to the required protein.
