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Biochemistry Exam 6- 2nd Year, 2nd Semester- PMU

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Biochemistry Exam 6- 2nd Year, 2nd Semester- PMU

Question 1 of 39

1

Which of the following hormones derive from amino acids?

Select one or more of the following:

  • estradiol

  • epinephrine

  • thyroid hormones

  • calcitriol

  • dopamine

Explanation

Question 2 of 39

1

Which of the following statements about hyperthyroidism are TRUE?

Select one or more of the following:

  • the blood levels of TSH are higher

  • hypoglycemia

  • hyperglycemia

  • increased thermogenesis

  • decreased thermogenesis

  • the blood levels of TSH are lower

Explanation

Question 3 of 39

1

Fill the blank spaces to complete the text.

List at least three groups of plasma membrane receptors
1) channels
2) - coupled receptor
3) receptors

Explanation

Question 4 of 39

1

G protein-coupled receptors

Select one or more of the following:

  • are associated with monomeric G-proteins

  • are receptors for lipophilic hormones

  • transmit the signal of epinephrine and glucagon

  • have an intracellular domain rich in tyrosine

Explanation

Question 5 of 39

1

Which of the following statements are NOT TRUE?

Select one or more of the following:

  • glucocorticoids are synthesized in zona glomerulosa of the adrenal gland

  • adrenal androgens are DHEA and 5-dihydrotestosterone

  • 5-dihydrotestosterone is more potent androgen than testosterone

  • renin stimulates the conversion of angiotensin 1 into angiotensin 2

  • 17-hydroxylase is the principle regulatory enzyme in streroidogenesis

Explanation

Question 6 of 39

1

Fill the blank spaces to complete the text.

List at least 3 second messengers in the process of signal transduction
1) cyclic
2) cyclic
3)

Explanation

Question 7 of 39

1

Which of the following statements about hypothyroidism are TRUE:

Select one or more of the following:

  • the blood levels of TSH are lower

  • the blood levels of TSH are higher

  • increased thermogenesis

  • decreased thermogenesis

  • unchanged metabolic rate

Explanation

Question 8 of 39

1

Which of the following statements are NOT TRUE?

Select one or more of the following:

  • CYP 450 side chain cleavage enzyme is the key regulatory enzyme in the synthesis of all the steroid hormones

  • 25-dehydrogenase is the main regulatory enzyme in the synthesis of calcitriol

  • calcitriol causes a decrease of blood Ca2+ levels

  • cortisol has a prominent hyperglycemic effect

Explanation

Question 9 of 39

1

Which of the following statements are TRUE:

Select one or more of the following:

  • testosterone is less potent androgen than 5-dihydrotestosterone

  • glucocorticoids are synthesized in zona fasciculata of the adrenal gland

  • angiotensin ll stimulates the production of aldosterone in zona glomerulosa of the adrenal gland

  • testosterone is converted into estradiol by 17-ketoreduetase (17β- dehydrogenase)

Explanation

Question 10 of 39

1

Based on their chemical composition hormones are:

Select one or more of the following:

  • peptide

  • autocrine

  • paracrine

  • steroid

  • derivatives of amino acids

Explanation

Question 11 of 39

1

Which of the following statements are TRUE:

Select one or more of the following:

  • phosphodiesterase is inhibited by insulin

  • epinerphrine and ACTH use cAMP as a second messenger

  • insulin uses PI3K signaling pathway

  • guanylyl cyclase activates protein kinase C (PKC)

Explanation

Question 12 of 39

1

Which of the following hormones are secreted by anterior pituitary gland:

Select one or more of the following:

  • ACTH

  • TSH

  • Angiotensin 2

  • Antidiuretic hormone (ADH)

  • Prolactin

Explanation

Question 13 of 39

1

Which of the following enzymes are involved in the biosynthesis of corticosteroids the adrenal cortex:

Select one or more of the following:

  • 21-hydroxylase

  • 1-α-hydroxylase

  • 3-hydroxysteroid dehydrogenase and Δ5,4-isomerase

  • cyt. P450 side chain cleavage enzyme (P450scc)

  • 5-α-reductase

Explanation

Question 14 of 39

1

Which of the following is NOT TRUE:

Select one or more of the following:

  • Cholesterol side chain cleavage by P450 scc results in production of pregnolone

  • Cortisol is produced in zone fasciculata

  • Aldosterone is produced in zona reticularis

  • Estrogens biosynthesis requires aromatase activity

Explanation

Question 15 of 39

1

Which of the following is NOT TRUE:

Select one or more of the following:

  • Thyroid hormones are made from tyrosine

  • The synthesis of thyroid hormones is stimulated by TSH

  • T4 is more active than T3

  • Iodine transport in the thyroid follicle is energy dependent

Explanation

Question 16 of 39

1

What happens to protein kinase A (PKA) following the binding of cAMP

Select one or more of the following:

  • the regulatory subunits of PKA dissociate, therby activating the catalytic subunits

  • PKA catalytic subunits bind to the regulatory subunits

  • the regulatory subunits dissociate from the catalytic subunits causing inactivation of the enzyme

Explanation

Question 17 of 39

1

Which of the following is NOT TRUE:

Select one or more of the following:

  • Thyroid hormones T3 and T4 derive from threonine

  • TSH and ACTH bind to cell surface G-proteins coupled receptors (GPCR)

  • Insulin is a polypeptide hormone that consists of A and B chain

  • ACTH and endorphins derive from a large precursor called POMC

Explanation

Question 18 of 39

1

Which of the following about testosterone is NOT TRUE:

Select one or more of the following:

  • Testosterone is a lipophilic hormone

  • Testosterone has cell surface receptors with tyrosine kinase activity

  • Testosterone is formed from dihydrotestosterone (DHT) in peripheral tissues

  • DHT is formed from testosterone in reaction catalyzed by 5-α-reductase

Explanation

Question 19 of 39

1

Ras protein is a key regulator in cell proliferation and its activity is enhanced by activated tyrosine kinase. Its action include:

Select one or more of the following:

  • Formation of c. AMP

  • Formation of c. GMP

  • Initiation of a cascade in which several kinases are activated sequentially by phosphorylation

  • Ras is a heterotrimeiric G-protein

Explanation

Question 20 of 39

1

Which of the following is TRUE:

Select one or more of the following:

  • Adrenaline and Glucagon inhibit glycogen phosphorylase

  • Cortisol stimulates gluconeogenesis and lipolysis

  • Aldosterone increases blood pressure

  • The major driving force for aldosterone biosynthesis is angiotensin II

Explanation

Question 21 of 39

1

Which of the following is TRUE:

Select one or more of the following:

  • The active form of vit. D3 is calcitriol

  • Vit. D3 is synthesized in the skin from 7- dehydrocholesterol under UV-light

  • Calcitriol inhibits the intestinal absorption of Ca2+ and phosphate

  • Calcitriol plays important role in bone mineralization

Explanation

Question 22 of 39

1

Which of the following hormones are secreted by the anterior lobe of the pituitary gland?

Select one or more of the following:

  • FSH

  • Prolactin

  • Renin

  • ADH

  • Oxytocin

  • TRH

Explanation

Question 23 of 39

1

Insulin:

Select one or more of the following:

  • can signal through MAPK pathway

  • triggers cAMP- dependent pathway

  • can signal through P13K-pathway

  • has dimeric receptors with intrinsic tyrosine kinase activity

Explanation

Question 24 of 39

1

Which are the mediators of the signal of lipophilic hormones?

Select one or more of the following:

  • Ca2+

  • Inositol-1,4,5-trisphospahte

  • hormone-receptor complex

  • DAG

Explanation

Question 25 of 39

1

Which of the following statements about thyroid hormones are TRUE?

Select one or more of the following:

  • T4 can be a product both of the thyroid and the peripheral tissues

  • T3 can be a product both of the thyroid and the peripheral tissues

  • T3 is more active than T4

  • Thyroid receptors are cytosolic intracellular

Explanation

Question 26 of 39

1

Which of the following statements about aldosterone are TRUE?

Select one or more of the following:

  • its synthesis is stimulated by ACTH

  • its synthesis is stimulated by angiotensin ll

  • it decreases K+ and H+ excretion

  • it increases Na+ and water reabsotption

  • its receptors are cytosolic intracellular

  • it is synthesized in zona fasciculata of the adrenal cortex

Explanation

Question 27 of 39

1

Which of the following hormones are stored and released by the posterior lobe of the pituitary gland?

Select one or more of the following:

  • FSH

  • Prolactin

  • ACTH

  • ADH (vasopressin)

  • Oxytocin

Explanation

Question 28 of 39

1

Which of the following statements are TRUE:

Select one or more of the following:

  • divergention of the signal means that different signal pathways have the same common targets or intermediate components

  • crosstalk of the signals means that one signal molecule can transmit signals from different extracellular messengers (signal molecules)

  • acetylcholine transmit its signals through receptors associated with ion channels

  • acetylcholine transmit its signals through receptors associated with intrinsic serine-threonine kinase activity

Explanation

Question 29 of 39

1

Which of the following hormones have cell-surface receptors?

Select one or more of the following:

  • epinerphrine

  • testosterone

  • calcitriol

  • insulin

  • dopamine

  • retinols

Explanation

Question 30 of 39

1

Based on their mechanism of action the hormones are:

Select one or more of the following:

  • Autocrine

  • Peptide

  • Steroid

  • Paracrine

  • Endocrine

Explanation

Question 31 of 39

1

Which of the following hormones bind to intracellular receptors:

Select one or more of the following:

  • Thyroid hormones

  • TSH

  • Glucagon

  • ACTH

  • Steroid hormones

Explanation

Question 32 of 39

1

Which of the following hormones have cell surface receptors:

Select one or more of the following:

  • Glucagon

  • Testosterone

  • Insulin

  • T4 and T3

  • Growth hormone

Explanation

Question 33 of 39

1

Which of the following statements about insulin receptor is TRUE

Select one or more of the following:

  • it has intrinsic tyrosine kinase activity

  • it is located in the nucleus

  • it is a dimer composed of two α and two β subunits

  • it is coupled with G-protein

Explanation

Question 34 of 39

1

Which of the following is TRUE:

Select one or more of the following:

  • C.AMP is a key second messenger in the transduction of hormone signals

  • Adenylyl cyclase is activated by insulin

  • Adenylyl cyclase catalyzes the synthesis of AMP from ATP

  • Hormones like adrenaline, glucagon and ACTH use cGMP as second messenger

Explanation

Question 35 of 39

1

Which of the following is TRUE:

Select one or more of the following:

  • Insulin receptor has serine/threonine kinase activity

  • Binding of insulin to its membrane receptor stimulates the tyrosine kinase activity of the β-subunits

  • Insulin is a lipophilic hormone

  • Cortisol is a lipophilic hormone

Explanation

Question 36 of 39

1

Which of the following is NOT TRUE:

Select one or more of the following:

  • Cholesterol side chain cleavage by P450 scc results in production pregnenolone

  • Cortisol is produced in zona glomerulosa

  • Aldosterone is produced in zona reticularis

  • Testosterone biosynthesis requires aromatase activity

Explanation

Question 37 of 39

1

Which of the following are second messengers:

Select one or more of the following:

  • C. AMP

  • Inositol- 1,4,5- triphosphate

  • Triacylglycerol

  • Diacylglycerol

  • Ca2+ and calmodulin

Explanation

Question 38 of 39

1

Which of the following hormones stimulate adenylyl cyclase:

Select one or more of the following:

  • Insulin

  • ACTH

  • Growth hormone

  • Testosterone

  • Glucagon

Explanation

Question 39 of 39

1

Which of the following hormones are cholesterol derivatives:

Select one or more of the following:

  • Calcitriol

  • Cortisol

  • T3 and T4

  • Estradiol

  • ACTH

Explanation

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