NSC Life Sciences Mitosis and Meiosis: 2.1 The diagram below represents

Question

2.1 The diagram below represents a phase of meiosis.

A

B

2.1.1 Identify the phase of meiosis in the diagram above.

2.1.2 Draw a diagram to show only the TWO gametes formed from cell A. (NO labels required.)

2.1.3 Tabulate TWO differences between prophase I and prophase II.

2.2 A clinostat is a device used to investigate plant growth responses. It has a disc that rotates very slowly when the clinostat is switched on.

During an investigation on plant responses to light, the procedure below was followed:
- Three pot plants of the same species were used.
- Each pot plant was placed on one of three identical clinostats.
- Each set of apparatus, A, B and C, was placed in a box with a single opening.
- Each clinostat was treated in a different way over a period of five weeks.

The results of the investigation are represented in the diagrams below.

2.2.1 Name the plant growth response to light.

2.2.2 State TWO factors that were kept constant during the investigation.

2.2.3 Give ONE reason why the results of this investigation may be considered to be unreliable.

2.2.4 In which apparatus (A, B or C) was the clinostat:
(a) Switched on and rotating slowly
(b) Switched off, but manually rotated through 180° once a week

2.2.5 Explain the effect of the unilateral light on the distribution of auxins in the plant in apparatus C.

2.3 The graph below shows the speed at which impulses are transmitted along sensory neurons, showing a suffering neuron with no myelin sheath present (covered with myelin sheath) and unmyelinated (no myelin sheath present).

2.3.1 Describe the direction of the impulse within a neuron.

2.3.2 Give the diameter range (in µm) when the speed of the impulse is fastest in unmyelinated axons than in myelinated axons.

2.3.3 Describe the relationship between axon diameter and the speed of impulses in myelinated axons.

2.3.4 Use evidence from the graph to explain the effect of multiple sclerosis on a sufferer whose motor neuron axons are greater than 1 µm in diameter.

2.4 TWO types of hearing loss occur in humans:
- Conductive hearing loss – occurs when sound vibrations cannot be conducted through the outer and middle ear
- Sensorineural hearing loss – occurs when sound waves in the inner ear do not correctly stimulate the nerve impulses that are transmitted to the brain.

The diagram below represents the human ear.

2.4.1 Give the LETTER and NAME of the part that:
(a) Transmits impulses to the brain
(b) Allows pressure to equalise between the outer ear and the middle ear

2.4.2 Give only the LETTER of TWO structures in the diagram of the ear that, when damaged, would result in the following:
- Conductive hearing loss
- Sensorineural hearing loss

2.4.3 Middle-ear infections are a common cause of hearing loss.

2.4.4 Name the part of the ear where ear wax is produced.

2.4.5 Explain how ear wax can be removed from the auditory canal.

2.1 The diagram below represents a phase of meiosis - NSC Life Sciences - Question 2 - 2019 - Paper 1

Worked Solution & Example Answer:2.1 The diagram below represents a phase of meiosis - NSC Life Sciences - Question 2 - 2019 - Paper 1

Identify the phase of meiosis in the diagram above.

Draw a diagram to show only the TWO gametes formed from cell A. (NO labels required.)

Tabulate TWO differences between prophase I and prophase II.

Name the plant growth response to light.

State TWO factors that were kept constant during the investigation.

Give ONE reason why the results of this investigation may be considered to be unreliable.

In which apparatus (A, B or C) was the clinostat: (a) Switched on and rotating slowly

(b) Switched off, but manually rotated through 180° once a week

Explain the effect of the unilateral light on the distribution of auxins in the plant in apparatus C.

Describe the direction of the impulse within a neuron.

Give the diameter range (in µm) when the speed of the impulse is fastest in unmyelinated axons than in myelinated axons.

Describe the relationship between axon diameter and the speed of impulses in myelinated axons.

Use evidence from the graph to explain the effect of multiple sclerosis on a sufferer whose motor neuron axons are greater than 1 µm in diameter.

Give the LETTER and NAME of the part that: (a) Transmits impulses to the brain

(b) Allows pressure to equalise between the outer ear and the middle ear.

Give only the LETTER of TWO structures in the diagram of the ear that, when damaged, would result in the following: - Conductive hearing loss

- Sensorineural hearing loss

Name the part of the ear where ear wax is produced.

Explain how ear wax can be removed from the auditory canal.

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