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15. Control and coordination
A section of Biology, 9700
Listing 10 of 130 questions
In mammals, the nervous system and the endocrine system coordinate responses to the changes in internal and external environments. Complete Table 8.1 to indicate the differences between the nervous system and the endocrine system. Table 8.1 feature nervous system endocrine system method of communication method of transmission transmission speed duration of effect shows the changes in the concentration of hormones in the blood during the menstrual cycle. days days A B C D concentration of ovarian hormones concentration of pituitary hormones With reference to , match hormones A, B, C or D to the correct statements 1 to 4. Each hormone may be used once, more than once or not at all. 1 made by the corpus luteum 2 stimulates the repair of the endometrium 3 maintains the endometrium 4 stimulates ovulation Outline the biological basis for contraceptive pills containing oestrogen and progesterone.
9700_s18_qp_41
THEORY
2018
Paper 4, Variant 1
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Thyrotoxic myopathy (TM) is a neuromuscular disorder caused by overproduction of the thyroid hormone thyroxine. One of the main symptoms of TM is muscle fatigue. outlines the effects of overproduction of thyroxine on striated muscle. increase in concentration of thyroxine in the blood increase in concentration of cyclic AMP in muscle fibres increase in release of Ca2+ in muscle fibres increase in muscle contractions muscle fatigue The concentration of thyroxine in the blood usually fluctuates around a set point. Name the mechanism that keeps the concentration of thyroxine in the blood close to its set point. Name the part of the striated muscle fibre that releases Ca2+. Describe the role of Ca2+, troponin and tropomyosin in the contraction of striated muscle. Cyclic AMP (cAMP) is also involved in the response of liver cells to glucagon. Describe the role of cAMP in the response of liver cells to glucagon. An increase in the concentration of thyroxine in the blood can lead to a condition called insulin resistance (IR). IR decreases the sensitivity to insulin of target cells, such as muscle and liver cells. Suggest how decreased sensitivity to insulin affects target cells.
9700_s20_qp_42
THEORY
2020
Paper 4, Variant 2
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Diabetes insipidus (Dis a condition in humans that causes a person to have an excessive thirst, which leads to increased drinking. One form of DI is caused by a tumour in the region of the hypothalamus concerned with osmoregulation. Explain how a tumour develops in the hypothalamus. Suggest how a tumour in the hypothalamus can lead to a person producing a large volume of dilute urine. The nervous and endocrine systems of a mammal co-ordinate responses to changes in the internal and external environment. Table 2.1 compares some features of the nervous and endocrine systems. Complete Table 2.1. Table 2.1 feature nervous system endocrine system signal impulse method of transmission of signal in blood type of communication chemical duration of effect
9700_s20_qp_43
THEORY
2020
Paper 4, Variant 3
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Questions Discovered
130