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

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Biochemistry Exam 6- 2nd Year, 2nd Semester- PMU
hamza 123
Quiz by hamza 123, updated more than 1 year ago More Less
Med Student
Created by Med Student over 7 years ago
hamza 123
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Question 1

Question
Which of the following hormones derive from amino acids?
Answer
  • estradiol
  • epinephrine
  • thyroid hormones
  • calcitriol
  • dopamine

Question 2

Question
Which of the following statements about hyperthyroidism are TRUE?
Answer
  • the blood levels of TSH are higher
  • hypoglycemia
  • hyperglycemia
  • increased thermogenesis
  • decreased thermogenesis
  • the blood levels of TSH are lower

Question 3

Question
List at least three groups of plasma membrane receptors 1) [blank_start]Ion[blank_end] channels 2) [blank_start]G[blank_end]-[blank_start]Protein[blank_end] coupled receptor 3) [blank_start]Death[blank_end] receptors
Answer
  • Ion
  • G
  • Protein
  • Death

Question 4

Question
G protein-coupled receptors
Answer
  • 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

Question 5

Question
Which of the following statements are NOT TRUE?
Answer
  • 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

Question 6

Question
List at least 3 second messengers in the process of signal transduction 1) cyclic [blank_start]AMP[blank_end] 2) cyclic [blank_start]GMP[blank_end] 3) [blank_start]calcium[blank_end]
Answer
  • AMP
  • GMP
  • calcium

Question 7

Question
Which of the following statements about hypothyroidism are TRUE:
Answer
  • the blood levels of TSH are lower
  • the blood levels of TSH are higher
  • increased thermogenesis
  • decreased thermogenesis
  • unchanged metabolic rate

Question 8

Question
Which of the following statements are NOT TRUE?
Answer
  • 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

Question 9

Question
Which of the following statements are TRUE:
Answer
  • 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)

Question 10

Question
Based on their chemical composition hormones are:
Answer
  • peptide
  • autocrine
  • paracrine
  • steroid
  • derivatives of amino acids

Question 11

Question
Which of the following statements are TRUE:
Answer
  • 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)

Question 12

Question
Which of the following hormones are secreted by anterior pituitary gland:
Answer
  • ACTH
  • TSH
  • Angiotensin 2
  • Antidiuretic hormone (ADH)
  • Prolactin

Question 13

Question
Which of the following enzymes are involved in the biosynthesis of corticosteroids the adrenal cortex:
Answer
  • 21-hydroxylase
  • 1-α-hydroxylase
  • 3-hydroxysteroid dehydrogenase and Δ5,4-isomerase
  • cyt. P450 side chain cleavage enzyme (P450scc)
  • 5-α-reductase

Question 14

Question
Which of the following is NOT TRUE:
Answer
  • 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

Question 15

Question
Which of the following is NOT TRUE:
Answer
  • 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

Question 16

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

Question 17

Question
Which of the following is NOT TRUE:
Answer
  • 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

Question 18

Question
Which of the following about testosterone is NOT TRUE:
Answer
  • 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

Question 19

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

Question 20

Question
Which of the following is TRUE:
Answer
  • 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

Question 21

Question
Which of the following is TRUE:
Answer
  • 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

Question 22

Question
Which of the following hormones are secreted by the anterior lobe of the pituitary gland?
Answer
  • FSH
  • Prolactin
  • Renin
  • ADH
  • Oxytocin
  • TRH

Question 23

Question
Insulin:
Answer
  • can signal through MAPK pathway
  • triggers cAMP- dependent pathway
  • can signal through P13K-pathway
  • has dimeric receptors with intrinsic tyrosine kinase activity

Question 24

Question
Which are the mediators of the signal of lipophilic hormones?
Answer
  • Ca2+
  • Inositol-1,4,5-trisphospahte
  • hormone-receptor complex
  • DAG

Question 25

Question
Which of the following statements about thyroid hormones are TRUE?
Answer
  • 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

Question 26

Question
Which of the following statements about aldosterone are TRUE?
Answer
  • 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

Question 27

Question
Which of the following hormones are stored and released by the posterior lobe of the pituitary gland?
Answer
  • FSH
  • Prolactin
  • ACTH
  • ADH (vasopressin)
  • Oxytocin

Question 28

Question
Which of the following statements are TRUE:
Answer
  • 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

Question 29

Question
Which of the following hormones have cell-surface receptors?
Answer
  • epinerphrine
  • testosterone
  • calcitriol
  • insulin
  • dopamine
  • retinols

Question 30

Question
Based on their mechanism of action the hormones are:
Answer
  • Autocrine
  • Peptide
  • Steroid
  • Paracrine
  • Endocrine

Question 31

Question
Which of the following hormones bind to intracellular receptors:
Answer
  • Thyroid hormones
  • TSH
  • Glucagon
  • ACTH
  • Steroid hormones

Question 32

Question
Which of the following hormones have cell surface receptors:
Answer
  • Glucagon
  • Testosterone
  • Insulin
  • T4 and T3
  • Growth hormone

Question 33

Question
Which of the following statements about insulin receptor is TRUE
Answer
  • 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

Question 34

Question
Which of the following is TRUE:
Answer
  • 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

Question 35

Question
Which of the following is TRUE:
Answer
  • 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

Question 36

Question
Which of the following is NOT TRUE:
Answer
  • 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

Question 37

Question
Which of the following are second messengers:
Answer
  • C. AMP
  • Inositol- 1,4,5- triphosphate
  • Triacylglycerol
  • Diacylglycerol
  • Ca2+ and calmodulin

Question 38

Question
Which of the following hormones stimulate adenylyl cyclase:
Answer
  • Insulin
  • ACTH
  • Growth hormone
  • Testosterone
  • Glucagon

Question 39

Question
Which of the following hormones are cholesterol derivatives:
Answer
  • Calcitriol
  • Cortisol
  • T3 and T4
  • Estradiol
  • ACTH
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