Tag: endocrine system in humans

Questions Related to endocrine system in humans

Steroid hormones 

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Work via second messenger

  2. Trigger rapid, short term response in cells

  3. Alter the activity of genes

  4. Initiate open channels in plasma membrane

Show answer
Correct Option: C
Explanation:
Steroid hormones are derived from cholesterol. They are in the form of lipids. Their receptors are intracellular i.e. located inside the cell. These hormones are lipid soluble and hence, cross the cell membrane easily to enter the cell. The hormone binds to receptor and a hormone-receptor complex is formed. The complex then binds to transcription factors which then bind to DNA and this causes activation and transcription of a particular gene. This leads to synthesis of specific proteins that affect the metabolism of cells.
Hence, steroid hormones alter the activity of genes.
So, the correct answer is 'Alter the activity of genes'.

Signalling between cells usually results in activation of protein by

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Kinases

  2. Proteases

  3. Lipases

  4. Nucleases

Show answer
Correct Option: A
Explanation:
Signalling is the communication between cells by means of signalling molecules. When a ligand binds to its receptor, ligand-receptor complex is formed which activate protein kinases. Kinases are the enzymes that transfer phosphate group to the target cells. Phosphorylation of target cells cause different changes in the cell.
So, the correct answer is 'Kinases'.

Which of these can pass easily through cell membrane of target cells and bind to internal receptors?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Thyroxine, insulin

  2. Somatostatin, Oxytocin

  3. Insulin, glucagon

  4. Cortisol, testosterone

Show answer
Correct Option: D
Explanation:

A. Thyroxine, insulin hormones are protein hormones. 

B. Somatostatin, oxytocin are protein hormones. 
C. Insulin, glucagon are protein hormones.
D. Cortisol, testosterone are steroid hormones. 
Steroid hormones are made up of fats and are not soluble in water, hence they can easily pass through the cell membrane.
So, the answer is Cortisol, testosterone. 

(A) Every receptor is unique for a hormone
(B) Every hormone is unique for a receptor.

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Both true

  2. Both false

  3. A true B false

  4. B true B false

Show answer
Correct Option: A
Explanation:

In the human body, every receptor is specific for a hormone and every hormone is specific for a receptor.

So, the correct option is ‘Both true’.

Which one of the following is proteinaceous in chemical nature?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Thyroxine

  2. Insulin

  3. Progesterone

  4. Oxytocin

Show answer
Correct Option: A
Explanation:

Thyroxine is a proteinaceous hormone, formed by the addition of iodine to amino acid tyrosine which is then combined with protein thyroglobulin

So, the correct answer is 'Thyroxine'

A dehydration synthesis reaction is also known as

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. A condensation reaction

  2. A hydrolysis reaction

  3. An isomeric reaction

  4. An energy-releasing reaction

Show answer
Correct Option: A
Explanation:

Dehydration means removal of water. It is a synthesis reaction where polymerization occurs in which the monomers are bound together which releases water as the end product or byproduct.

Hence, the correct answer is 'A condensation reaction'.

Choose the correct answer from the alternatives given.
Pick out the false statement pertaining to acromegaly:

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. oversecretion of somatotropin after adolescence causes this disease

  2. the person gets a giant stature

  3. long bones of the limbs elongate

  4. the person looks like a gorilla

Show answer
Correct Option: B
Explanation:

GH or STH (Growth or Somatotropin Hormone) stimulates body growth, protein, fat and carbohydrate metabolism. Hypersecretion of this hormone during the period of skeleteal growth causes gigantism characterized by excessive growth of bones, with the enlargement of internal organs as well. Hypersecretion in adulthood causes acromegaly. Here thr, bones become abnormally thick due to ossification of periosteum and thickening of soft tissues as well. 

So the correct answer is the person gets a giant structure. 

Which one of the following is not a second messenger in hormone action ?

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. cGMP

  2. Calcium

  3. Sodium

  4. cAMP

Show answer
Correct Option: C
Explanation:
Second messengers are the organic molecules and sometimes the metal ions, acting as intracellular signals, whose production or release usually amplifies a signal such as a hormone, received at the cell surface. Sodium (Na) is not a second messenger to be discovered. In addition to cyclic AMR Cyclic Guanosine Monophosphate (CGMP) functions as a second messenger in certain cases. Calcium ions (Ca++) also act as second messenger in phospholipase c - ca* second messenger system.

So, the correct answer is 'Sodium'.

Mark antagonistic hormones _______________.

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. Insulin and glucagon

  2. Adrenaline and nor adrenaline

  3. Calcitonin and parathormone

  4. Both A and C

Show answer
Correct Option: A

Choose the correct answer from the alternatives given.
A major difference in the mechanism of action between steroid and peptide hormones is that:

zoology endocrine system and chemical co-ordination mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

  1. steroid hormones affect the synthesis of proteins, whereas peptide hormones affect the activity of proteins already in the cell

  2. target cells react more rapidly to steroid hormones than they do to peptide hormones

  3. steroid hormones bind to a receptor protein, whereas peptide hormones bind to G protein

  4. steroid proteins affect metabolism, whereas peptide hormones affect membrane permeability

Show answer
Correct Option: A
Explanation:

Peptide hormones are hydrophilic due to which they are unable to cross the lipid plasma membrane. They bind to the receptors on the plasma membrane and affect the activity of proteins inside the cell called secondary messenger. These secondary messengers then perform the action required. The steroid hormones are hydrophobic, they can cross the plasma membrane directly and are able to affect the synthesis of proteins directly in the cells.

Hence, the correct answer is 'steroid hormones affect the synthesis of proteins, whereas peptide hormones affect the activity of proteins already in the cell'.