CBSE 2025 · Region 5 · Set 1 · Q35 · 5 marks
(a)Analyse the given situations and interpret the possible reason for each :(i)Iodine deficiency in diet increases the possibility of a disease of swollen neck in a person.(ii)Some people in population may have very short heights (dwarfs).(iii)Thick facial hairs develop in boys at the age of $\displaystyle 10$-$\displaystyle 12$ years.(b)Explain two reasons which necessitate the need of chemical communication in multicellular organisms.(a)Differentiate between voluntary and involuntary action.(b)Define reflex action. With the help of a flow diagram, show the correct sequence of path of Nerve impulse from place of its ori in.
(a)
Analyse the given situations and interpret the possible reason for each :
(i)
Iodine deficiency in diet increases the possibility of a disease of swollen neck in a person.
(ii)
Some people in population may have very short heights (dwarfs).
(iii)
Thick facial hairs develop in boys at the age of $\displaystyle 10$-$\displaystyle 12$ years.
(b)
Explain two reasons which necessitate the need of chemical communication in multicellular organisms.
(a)
Differentiate between voluntary and involuntary action.
(b)
Define reflex action. With the help of a flow diagram, show the correct sequence of path of Nerve impulse from place of its ori in.
Marking-scheme solution
(A) (a)(i) Iodine is necessary for the thyroid gland to make thyroxin hormone, its deficiency causes goitre.
(ii) Deficiency of growth hormone in childhood causes dwarfism.
(iii) Secretion of testosterone during puberty in males.
(b) • Hormones or chemical compounds can potentially reach all cells of body steadily and persistently.
Hormones help to coordinate growth, development and responses to environment.
Control and CoordinationHormones in AnimalsAnalyselong_answermedium
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CBSE Class 10 Science past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.