3.1 Name the group of plant hormones that is responsible for the growth responses observed in the diagrams - NSC Life Sciences - Question 3 - 2018 - Paper 1
Question 3
3.1 Name the group of plant hormones that is responsible for the growth responses observed in the diagrams.
3.1.2 Name the external stimulus at:
(a) A
(b) D
3.1.... show full transcript
Worked Solution & Example Answer:3.1 Name the group of plant hormones that is responsible for the growth responses observed in the diagrams - NSC Life Sciences - Question 3 - 2018 - Paper 1
Step 1
Name the group of plant hormones that is responsible for the growth responses observed in the diagrams.
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Answer
The group of plant hormones responsible for the growth responses observed in the diagrams is called auxins.
Step 2
Name the external stimulus at:
(a) A
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Answer
The external stimulus at A is light.
Step 3
Name the external stimulus at:
(b) D
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Answer
The external stimulus at D is gravity.
Step 4
Give ONE observable reason why plant organ B is a stem.
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Answer
Plant structure B has been bent towards stimulus A, indicating it is likely a stem responding positively to light (phototropism).
Step 5
Explain the growth response observed in plant organ C.
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Answer
The growth response observed in plant organ C can be explained by the accumulation of auxins on the lower side of the root when it is exposed to gravity. This results in uneven growth, causing the root to bend downward, a phenomenon known as positive geotropism.
Step 6
Which pathway, A or B, represents a reflex arc?
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Answer
Pathway A represents a reflex arc.
Step 7
Give a visible reason in the diagram for your answer to QUESTION 3.2.1.
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Answer
The diagram shows that the nerve impulse does not travel to the brain; instead, it goes directly from the receptor to the effector via the spinal cord.
Step 8
Describe the importance of a reflex action in the human body.
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Answer
Reflex actions are important because they allow the body to respond rapidly to stimuli without needing to involve higher brain functions, thus providing immediate protection to the body.
Step 9
Identify the part of the nervous system represented by 1.
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The part of the nervous system represented by 1 is the spinal cord.
Step 10
Explain ONE way in which the myelin sheath is important in the functioning of neurons.
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Answer
The myelin sheath acts as an insulator for the nerve fibers and speeds up the transmission of nerve impulses, preventing short circuits.
Step 11
Describe how the person would be affected if the axon of neuron 2 was cut.
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Answer
If the axon of neuron 2 was cut, the person would be unable to feel the stimulus, as the impulse would not be transmitted to the effector.
Step 12
Describe pathway B.
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Pathway B describes the route an impulse would take from the sensory neuron to the central nervous system and then to the motor neuron, initiating a response.
Step 13
State what happens to the blood glucose concentration immediately after a meal is eaten.
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Answer
Immediately after a meal is eaten, the blood glucose concentration increases.
Step 14
Tabulate TWO ways in which eating fewer larger meals and eating many small meals affect the blood insulin levels differently.
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Answer
Fewer larger meals
Many smaller meals
Higher initial insulin concentration
Lower initial insulin concentration
Rises and falls three times a day
Rises and falls five times a day
Step 15
Explain why eating many small meals per day is better for a diabetic person than eating fewer large meals.
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Answer
Eating many small meals helps maintain a more stable blood glucose level because it reduces large spikes of glucose entering the bloodstream, which can help manage insulin production effectively.
Step 16
Which person, A or B, was exercising?
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Answer
Person B was the one who was exercising.
Step 17
Give TWO visible reasons for your answer to QUESTION 3.4.1.
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Answer
Person B's skin surface temperature is higher than that of Person A.
The visible sweating in Person B indicates an increase in body temperature due to exercise.
Step 18
Name ONE hormone that would have the same effect on the blood vessels that is observable in person A.
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One hormone that would have the same effect on the blood vessels observable in Person A is adrenaline.
Step 19
Explain why the skin temperature of person A was higher after 10 minutes.
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The skin temperature of person A was higher after 10 minutes because exercise increases blood flow to the skin, which helps in heat dissipation, whereas the sitting person (B) does not have this increased blood circulation.
