NSC Life Sciences Human Evolution: Read the extract below.

Stem ce

Question

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 accident. He had no movement in any of his limbs because his nerve cells were damaged. Embryonic stem cells were used in an attempt to correct a defect in the spinal cord of the patient. He has now developed partial sensation throughout the body.

3.1.1 Explain why stem cells are suitable cells to use for the treatment of this patient.

3.1.2 Explain why some people prefer the use of umbilical cords as a source of stem cells rather than the use of human embryos.

A baby was kidnapped from a hospital immediately after she was born. Fifteen years later it was discovered that Mr and Mrs Thomas, who were raising her, were not her biological parents. Mr and Mrs George, whose baby was born around the same time, claimed that she was their child.

3.2 Name the individual whose blood group shows no contradiction.

3.2.2 Explain why Mr and Mrs George could possibly be the parents of this child.

In a study to establish the mode of locomotion of some species, scientists compared the pelvic structure of their fossils. They established that two of these species had the ability to walk upright permanently. The diagrams (A, B and C) below show the pelvic structure of three species, drawn to scale.

3.3.1 What term is used to describe organisms that are able to walk upright permanently?

3.3.2 Which TWO diagrams above represent the pelvis of the organisms in QUESTION 3.1?

3.3.3 Explain your answer to QUESTION 3.1.

3.3.4 State ONE feature of the spine of the organism represented by C.

Tabulate THREE differences between the skulls of humans and African apes.

3.4

3.5 Read the extract below.

Brine shrimp are small arthropods found in saltwater lakes. During favourable conditions female shrimps produce eggs that hatch into living young. However, when conditions are unfavorable, the shrimp produce cysts. Each cyst contains the embryo covered with a hard, protective covering. The embryo stops growing and is said to be dormant. The embryo can remain in this dormant state for many years and the cyst will only hatch at the optimum salt concentration.

Scientists wanted to investigate which salt concentration resulted in the highest percentage of hatched cysts.

They did the following:

- Prepared salt solutions of different concentrations: 0%, 0.5%, 1%, 1.5% and 2%.
- Placed 30 ml of each solution into five beakers
- Took samples from each beaker to ensure they contained the same number of cysts
- Decided on the different concentrations of solution to use
- Recorded this as the initial number of cysts
- Placed the samples into each of the five beakers
- Left the beakers at room temperature for 48 hours
- Recorded the number of cysts that hatched

The results are shown in the table below.

SALT CONCENTRATION (%)
NUMBER OF CYSTS USED AT THE START
NUMBER OF CYSTS THAT HATCHED
PERCENTAGE OF CYSTS THAT HATCHED
0
54
0
0
0.5
34
2
6
1
40
2
5
1.5
40
1
2.5
2
40
1
2.5

3.5.1 State TWO planning steps to consider before collecting the samples.

3.5.2 State the:
(a) Independent variable
(b) Dependent variable

3.5.3 Calculate the value of X in the table. SHOW ALL WORKING.

3.5.4 State THREE factors that were kept constant in order to ensure the validity of this investigation.

3.5.5 Which salt concentration resulted in the highest percentage of hatched cysts?

3.5.6 How did the theory of evolution through natural selection apply to the development of the brine shrimp.

Read the extract below - NSC Life Sciences - Question 3 - 2018 - Paper 2

Worked Solution & Example Answer:Read the extract below - NSC Life Sciences - Question 3 - 2018 - Paper 2