Thyroxin is a hormone produced in the thyroid gland. State one function of thyroxin.

The action of thyroxin is similar to steroid hormones. Describe the action of steroid hormones.

The World Health Organization recommends that the iodine intake should be supplemented in pregnant women due to their increased requirements. Outline the need for iodine supplementation.

a. regulates the «basal» metabolic rate/BMR

b. controls body temperature

[Max 1 Mark]

a. steroid hormone passes through cell/plasma membrane

b. binds to receptor «proteins» in cytoplasm

c. receptor–hormone complex travels to nucleus

d. binds to DNA/chromatin

e. promotes/inhibits the transcription of specific genes

f. codes for/produces specific proteins

[Max 3 Marks]

a. iodine is an essential nutrient/cannot be synthesized by the body

b. iodine is required for thyroid hormones/thyroxin production

c. some areas in the world have iodine deficient soil/low iodine in their diet

d. supplementation will reduce stunted growth and mental development/cretinism in babies born to mothers associated with thyroid deficiency

e. thyroid deficiency will lead to health problems

[Max 2 Marks]