A person while climbing up a rocky hill comes into a panic state and fear. His body starts reacting in a "flight-or-flight" condition to adjust to the dangerous and stressful situation.
Based on the above facts, answer the questions that follow.
(a) (i) Name the hormone secreted in the blood of the person in this situation. [2]
OR
(a) (ii) Name the source gland of the hormone secreted in this condition. [2]
(b) State any two responses in the body of the person as a result of the secretion of this hormone. [1]
(c) How does the action of the chemical signal in terms of hormones differ from the electrical impulses via nerve cells ? [1]
A person while climbing up a rocky hill comes into a panic state and fear. His body starts reacting in a "flight-or-flight" condition to adjust to the dangerous and stressful situation.
Based on the above facts, answer the questions that follow.
(a) (i) Name the hormone secreted in the blood of the person in this situation. [2]
OR
(a) (ii) Name the source gland of the hormone secreted in this condition. [2]
(b) State any two responses in the body of the person as a result of the secretion of this hormone. [1]
(c) How does the action of the chemical signal in terms of hormones differ from the electrical impulses via nerve cells ? [1]
(a)(i) Adrenaline is the hormone secreted into the blood of the person in this fight-or-flight situation.
OR
(a)(ii) The adrenal glands are the source glands that secrete this hormone.
(b) Two bodily responses due to adrenaline secretion: (1) the heart beats faster, resulting in supply of more oxygen to the muscles; (2) the breathing rate increases because of contractions of the diaphragm and rib muscles. (Also acceptable: blood flow to the digestive system and skin is reduced, diverting blood to the skeletal muscles.)
(c) Hormonal (chemical) signals differ from nervous (electrical) signals in that a hormone is secreted directly into the blood and carried to different parts of the body, so it reaches all the cells of the body and produces wide-ranging, longer-lasting changes, but acts relatively slowly. Electrical nerve impulses, on the other hand, travel only along connected nervous tissue to specific target cells, act very fast, but a cell cannot generate and transmit impulses continuously — it needs time to reset before sending another impulse.
Marking Scheme
- 1Part (a): 1 mark for correctly naming adrenaline (i) OR 1 mark for correctly naming the adrenal gland (ii) — only one option to be attempted, worth 1 mark as indicated
- 2Part (b): 1 mark for stating any two correct bodily responses (faster heartbeat/more oxygen to muscles, increased breathing rate, reduced blood flow to digestive system and skin diverting blood to skeletal muscles)
- 3Part (c): 1 mark for correctly explaining the difference — hormonal signal is chemical, travels via blood, reaches all cells, acts slowly; nervous signal is electrical, travels via connected nerves only, acts fast but cannot be continuously generated
Hint
Recall the squirrel example in the chapter — what hormone and gland prepare the body for 'fight or flight', and how does a hormone reaching 'all cells of the body' differ from an electrical impulse confined to connected nerves?
Quick Oral Answer
In a fear/stress situation, the adrenal glands secrete adrenaline into the blood, which increases heart rate and breathing rate and diverts blood to skeletal muscles, preparing the body to fight or flee; unlike fast, nerve-restricted electrical impulses, this chemical signal is slower but reaches every cell in the body via the bloodstream.
Analysis & Explanation
This is a case-based question directly grounded in Section 6.3 'Hormones in Animals' of the chapter, which explains: "What do some animals, for instance squirrels, experience when they are in a scary situation? Their bodies have to prepare for either fighting or running away... if a chemical signal were to be sent as well, it would reach all cells of the body and provide the wide-ranging changes needed. This is done in many animals, including human beings, using a hormone called adrenaline that is secreted from the adrenal glands."
(a) The person climbing the rocky hill and panicking is in the same 'fight-or-flight' situation described for the squirrel in the text. The hormone is adrenaline (i), secreted from the adrenal glands (ii) — the chapter states adrenaline 'is secreted from the adrenal glands' and Fig. 6.7 locates these glands near the kidneys.
(b) The chapter explicitly lists the target-organ responses to adrenaline: "the heart beats faster, resulting in supply of more oxygen to our muscles. The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs. This diverts the blood to our skeletal muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles." Any two of these responses are valid, and together they prepare the body to fight or flee.
(c) The text contrasts the two modes of control and coordination: "If the body design in the squirrel relied only on electrical impulses via nerve cells, the range of tissues instructed to prepare for the coming activity would be limited. On the other hand, if a chemical signal were to be sent as well, it would reach all cells of the body." It also notes that electrical impulses 'will reach only those cells that are connected by nervous tissue' and that a nerve cell 'will take some time to reset its mechanisms before it can generate and transmit a new impulse,' whereas hormonal (chemical) signalling, though slower, 'can potentially reach all cells of the body, regardless of nervous connections, and it can be done steadily and persistently.' This is the key distinction expected in the answer.
Common Mistakes
- 1Naming the pituitary gland instead of the adrenal gland as the source of adrenaline.
- 2Giving only one response instead of two for part (b).
- 3In part (c), only stating that hormones are slow without explaining that they reach all cells of the body regardless of nervous connections, which is the key contrast made in the text.
- 4Confusing adrenaline's target organs — thinking it reduces heart rate instead of increasing it.
Interesting Facts
Adrenaline is also called epinephrine and is used medically as an emergency injection to counter severe allergic reactions (anaphylaxis) because it rapidly raises heart rate and blood pressure.
The adrenal glands sit atop each kidney, which is reflected in their name (ad- 'near' + renal 'kidney').
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2025?
This question carries 4 marks in the CBSE Class 10 Science 2025 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Control and Coordination" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Hormones in Animals - Adrenaline and the Endocrine System" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2025 paper?
This question appears in Section E in the CBSE Class 10 Science 2025 paper.