Read the extract below - NSC Life Sciences - Question 3 - 2018 - Paper 2
Question 3
Read the extract below.
Stem cell surgery has been performed for the first time in South Africa at a Cape Town hospital. A patient became paralysed in a diving acci... show full transcript
Worked Solution & Example Answer:Read the extract below - NSC Life Sciences - Question 3 - 2018 - Paper 2
Step 1
Explain why stem cells are suitable cells to use for the treatment of this patient.
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Answer
Stem cells are suitable for the treatment of this patient because they are undifferentiated cells that have the potential to develop into any type of cell. This quality allows them to replace damaged nerve cells in the patient, thus offering a chance for restoring movement and sensation. Furthermore, embryonic stem cells, used in this case, can develop into a variety of specialized cells needed to repair the spinal cord.
Step 2
Explain why some people prefer the use of umbilical cords as a source of stem cells rather than the use of human embryos.
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Some people prefer umbilical cords as a source of stem cells because they are readily available at birth and their use does not involve the ethical concerns associated with harvesting stem cells from embryos. Umbilical cords are deemed as medical waste after birth and using them poses no moral issues, making them a more accepted option for stem cell therapy.
Step 3
How many ways can one individual control the inheritance of blood groups?
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One individual can control the inheritance of blood groups by having two alleles that determine the blood type. The alleles can be homozygous (both alleles the same) or heterozygous (two different alleles). The combination of these alleles from the parents influences the blood group inherited by the offspring.
Step 4
Name the individual whose blood group shows no codominance.
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The individual whose blood group shows no codominance is Mr Thomas, as he has blood group O, which is a recessive phenotype.
Step 5
Explain why Mr and Mrs George could possibly be the parents of this child.
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Mr and Mrs George could possibly be the biological parents of the child because they both have blood group A. The child, who has blood group O, can inherit this from the parents if both are heterozygous (Ao), allowing them to pass on a recessive allele for type O blood.
Step 6
What term is used to describe organisms that are able to walk upright permanently?
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The term used to describe organisms that can walk upright permanently is Bipedal.
Step 7
Which TWO diagrams above represent the pelvis of the organisms in QUESTION 3.1?
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Diagrams A and B are the two that represent the pelvis of organisms capable of walking upright permanently.
Step 8
Explain your answer to QUESTION 3.3.
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Answer
I identified diagrams A and B as representing bipedal organisms because their pelvic structures show adaptations for upright walking. In this case, they exhibit wider and shorter pelvises, which are features commonly associated with bipedal locomotion.
Step 9
State ONE feature of the spine of the organism represented by C.
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One feature of the spine of the organism represented by C is that it has a less curved C-shaped spine, which is more adapted for quadrupedal locomotion.
Step 10
Tabulate THREE differences between the skulls of humans and African apes.
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Answer
Feature
Humans
African Apes
Cranium Size
Larger cranium
Smaller cranium
Brow Ridges
Not well developed
Well developed
Jaw Structure
Smaller jaws
Larger jaws
Step 11
State TWO planning steps to consider before collecting the samples.
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Obtain permission from the relevant authority regarding the research.
Decide on the appropriate time and location to gather samples.
Step 12
State the: (a) Independent variable
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The independent variable is the salt concentration of the solutions used in the experiment.
Step 13
State the: (b) Dependent variable
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The dependent variable is the percentage of cysts that hatched.
Step 14
Calculate the value of X in the table. Show ALL working.
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The percentage of cysts that hatched when 0 cysts hatched from 54 is calculated by:
ext{Percentage} = rac{ ext{Number of Cysts Hatched}}{ ext{Total Number of Cysts}} imes 100 = rac{0}{54} imes 100 = 0\%
Step 15
State THREE factors that were kept constant in order to ensure the validity of this investigation.
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The volume of solution used in each beaker should remain the same.
The duration for which all samples are allowed to sit (48 hours).
The amount of shrimp (30 shrimp) used in each beaker should be constant.
Step 16
Which salt concentration resulted in the highest percentage of hatched cysts?
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The salt concentration of 0.5% resulted in the highest percentage of hatched cysts, with 6% of the cysts hatching.
Step 17
What is the theory of evolution through natural selection? Explain how this process could lead to the survival of the brine shrimp.
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The theory of evolution through natural selection states that individuals with traits better suited to their environment are more likely to survive and reproduce. In the case of brine shrimp, those that are resilient to changing salt concentrations have a higher chance of survival and passing on genes related to this trait. Over time, this can lead to a population that is better adapted to survive in varying salt conditions.
