3.1 Some horses have straight hair and others have curly hair - NSC Life Sciences - Question 3 - 2021 - Paper 2
Question 3
3.1 Some horses have straight hair and others have curly hair. A scientist wanted to clone a straight-haired male horse to meet the demand for horses with straight h... show full transcript
Worked Solution & Example Answer:3.1 Some horses have straight hair and others have curly hair - NSC Life Sciences - Question 3 - 2021 - Paper 2
Step 1
3.1.1 Explain why a somatic cell and NOT a sperm cell from horse S would provide the nucleus for the procedure.
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Answer
A somatic cell is diploid, which means it has a full set of chromosomes containing all the genetic material necessary for the development of a clone. In contrast, a sperm cell is haploid and contains only half the genetic material. Therefore, using a somatic cell ensures that the clone will have the complete genetic makeup required to develop properly.
Step 2
3.1.2 Before inserting the nucleus from the somatic cell of horse S, the nuclei from the ovum of horse T were removed. Explain the significance of this procedure.
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Removing the nuclei from the ovum of horse T is crucial as it allows the cloned organism to contain only the desired genetic material from horse S. This ensures that the characteristics of the straight-haired horse are fully expressed in the clone, free from any traits contributed by horse T.
Step 3
3.1.3 To which of the three horses (S, T or R) will the cloned offspring be genetically identical?
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The cloned offspring will be genetically identical to horse S because the nucleus from horse S contains all the genetic material necessary for the development of the clone.
Step 4
3.1.4 State TWO benefits of cloning.
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Cloning can produce organisms with desirable traits, such as specific health and productivity characteristics.
Cloning allows for the rapid multiplication of high-value livestock, thereby meeting market demand more efficiently.
Step 5
3.2.1 What type of evidence for evolution is represented here?
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The distribution of the coyote, jackal, and dingo provides biogeographical evidence for evolution, as it shows how closely related species occupy different geographical areas and adapt to their environments.
Step 6
3.2.2 What is a biological species?
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A biological species is defined as a group of organisms capable of interbreeding to produce fertile offspring and sharing common characteristics. They are reproductively isolated from other such groups.
Step 7
3.2.3 Describe how these three species could have evolved from a common ancestor.
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These three species likely evolved from a common ancestor that migrated to different regions and underwent adaptations to their specific environments. Over time, genetic divergence due to natural selection led to the development of distinct species, such as the coyote, jackal, and dingo.
Step 8
3.3.1 Use evidence from the graph to explain why higher doses of antibiotics will benefit the farmer economically.
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Higher doses of antibiotics significantly decrease the number of harmful bacteria, as shown in the graph. This reduction leads to healthier cattle, lowering veterinary costs and increasing productivity, thereby benefiting the farmer economically.
Step 9
3.3.2 Explain how the use of antibiotics in animal feed may result in the evolution of antibiotic-resistant bacteria.
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The widespread use of antibiotics creates an environment where only the bacteria that survive their effects can reproduce. This leads to genetic mutations that confer resistance, resulting in a population of antibiotic-resistant bacteria over time.
Step 10
3.4.1 State the:
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(a) Gall size (mm)
(b) Percentage of gallfly larvae killed by predatory birds (%)
Step 11
3.4.2 Write ONE advantage of the gall to the gallfly larvae.
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One advantage of the gall to the gallfly larvae is that it provides protection from predators, allowing the larvae to develop safely within the nutritious galls.
Step 12
3.4.3 Explain how the size of the galls produced is an example of continuous variation.
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The size of the galls represents continuous variation because it can take on a range of sizes, rather than being limited to discrete categories. This is influenced by genetic factors and environmental conditions affecting growth.
Step 13
3.4.4 State why the size of the galls is important to the survival of the larvae.
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The size of the galls is important to the survival of the larvae because larger galls may provide more food and space for developing larvae, while also minimizing their visibility to predators.
Step 14
3.4.5 Draw a line graph to represent the information in the table.
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To draw the line graph, label the x-axis as "Gall size (mm)" and the y-axis as "Percentage of gallfly larvae killed by predatory birds (%)." Plot the points corresponding to the data and connect them with lines to show the trend.
Step 15
3.5.1 Write down the LETTER(S) of the diagram(s) that represent:
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(a) X, Z (for bipedal organisms)
(b) C (for pelvic structure of a quadrupedal organism)
Step 16
3.5.2 Give a reason for your answer to QUESTION 3.5.1(b).
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The pelvic structure represented by C is long and narrow, which is characteristic of quadrupedal organisms that require stability and support for movement on four limbs.
Step 17
3.5.3 Describe ONE other structural difference between a bipedal and a quadrupedal organism.
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One structural difference is that bipedal organisms typically have a more upright spine adapted for vertical posture, while quadrupedal organisms have a horizontal spine that supports movement on four legs.
