Hormones and Their Actions Practice Questions
20 free Hormones and Their Actions practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following is a correct chemical classification for the hormones Pituitary and Hypothalamic?
- A Lipid-derived steroids
- B Iodinated thyroid derivatives
- C Peptides, polypeptides, and proteins
- D Modified amino-acid derivatives
Correct answer: Peptides, polypeptides, and proteins
Hormones like Insulin, Glucagon, and those from the Pituitary and Hypothalamus are chemically classified as peptides, polypeptides, or proteins. These are typically water-soluble and cannot cross the lipid bilayer of the cell membrane.
Which set of hormones belongs to the 'Steroids' category?
- A Epinephrine and Norepinephrine
- B Cortisol, Testosterone, and Progesterone
- C Thyroxine and Triiodothyronine
- D Insulin, Glucagon, and Somatostatin
Correct answer: Cortisol, Testosterone, and Progesterone
Steroid hormones are lipid-soluble and derived from cholesterol. This group includes hormones from the adrenal cortex (cortisol) and the gonads (testosterone and progesterone).
The hormone Epinephrine is chemically classified as a/an:
- A Proteinaceous peptide hormone
- B Lipid-derived steroid hormone
- C Amino-acid derivative
- D Iodothyronine compound
Correct answer: Amino-acid derivative
Epinephrine (adrenaline) is an amino-acid derivative, specifically derived from the amino acid tyrosine. It is secreted by the adrenal medulla during stress responses.
Hormones produce their effects on target tissues by binding to specific proteins called:
- A Hormone receptors
- B Secondary messengers
- C G-proteins
- D Effector proteins
Correct answer: Hormone receptors
Hormones act as intercellular messengers and only influence target tissues that possess specific hormone receptors. The binding of a hormone to its receptor leads to the formation of a hormone-receptor complex.
Where are the receptors for lipid-insoluble (water-soluble) hormones typically located?
- A Within the cytoplasm
- B On the nuclear membrane
- C On the plasma membrane
- D Inside the mitochondria
Correct answer: On the plasma membrane
Water-soluble hormones like peptides cannot pass through the cell membrane. Therefore, they bind to extracellular receptors located on the plasma membrane of the target cell.
Hormones which interact with membrane-bound receptors normally do not enter the target cell, but generate ________.
- A Primary messenger molecules
- B Secondary messengers
- C Specific DNA sequences
- D Ribosomal complexes
Correct answer: Secondary messengers
Since membrane-bound hormones cannot enter the cell, they trigger the production of secondary messengers like cyclic AMP, $IP_3$, or $Ca^{2+}$. These messengers then relay the signal to the cell's internal machinery.
Which of the following is NOT a common secondary messenger in hormone action?
- A Cyclic AMP
- B Inositol triphosphate (IP3)
- C Calcium ions
- D Sodium ions
Correct answer: Sodium ions
Common secondary messengers that mediate the action of water-soluble hormones include cyclic AMP ($cAMP$), $IP_3$ (Inositol triphosphate), and $Ca^{2+}$. Sodium ions are typically involved in nerve impulse conduction and osmotic balance rather than hormone signaling.
Receptors for steroid hormones and iodothyronines are mostly:
- A Extracellular in location
- B Membrane-bound on the surface
- C Intracellular and nuclear
- D On the Golgi apparatus
Correct answer: Intracellular and nuclear
Steroid hormones and thyroid hormones are lipid-soluble and can diffuse across the plasma membrane. They bind to intracellular receptors, which are often located in the nucleus.
The hormone-receptor complex in the case of steroid hormones primarily regulates:
- A Ion channel opening and flux
- B Gene expression and transcription
- C Cell membrane permeability changes
- D Cyclic AMP production via adenylate cyclase
Correct answer: Gene expression and transcription
Intracellular hormone-receptor complexes usually bind to specific DNA sequences in the nucleus. This interaction alters gene expression or chromosome function, leading to the synthesis of new proteins.
The physiological response to lipid-soluble hormones is generally ________ compared to water-soluble hormones.
- A Faster and more transient
- B Slower and more long-lasting
- C Identical in speed and duration
- D Immediate and short-lived
Correct answer: Slower and more long-lasting
Because lipid-soluble hormones act via gene expression and protein synthesis, their effects take longer to manifest. However, the changes they induce are usually more permanent or long-lasting than those triggered by secondary messengers.
Each receptor is specific to one hormone only and therefore receptors are:
- A Ubiquitous in all cells
- B Highly specific
- C Permissive in action
- D Synergistic by nature
Correct answer: Highly specific
Hormone receptors exhibit high specificity; each receptor is designed to recognize and bind with only one specific hormone. This ensures that hormones only affect their intended target cells.
Which of the following hormones would most likely require an intracellular receptor for its mechanism of action?
- A Insulin
- B Follicle Stimulating Hormone (FSH)
- C Thyroxine
- D Adrenaline
Correct answer: Thyroxine
Thyroxine ($T_4$) is an iodothyronine. Despite not being a steroid, thyroid hormones are lipid-soluble and utilize intracellular (specifically nuclear) receptors to regulate metabolism.
During the mechanism of action of FSH, what is the 'first messenger'?
- A Cyclic AMP
- B FSH itself
- C Ovarian cell membrane
- D Estrogen
Correct answer: FSH itself
In endocrine signaling, the hormone itself is considered the 'first messenger' as it carries the signal from the endocrine gland to the target cell's receptor.
Which process is triggered by the secondary messengers generated after the binding of a protein hormone to its receptor?
- A Direct gene activation
- B Biochemical responses
- C Mitochondrial fission
- D Receptor degradation
Correct answer: Biochemical responses
Secondary messengers initiate a cascade of biochemical responses within the cell. These biochemical changes eventually lead to the physiological responses characteristic of that hormone, such as ovarian growth in the case of FSH.
Steroid hormones are primarily derived from which precursor molecule?
- A Amino acids
- B Cholesterol
- C Nucleotides
- D Fatty acids
Correct answer: Cholesterol
Cholesterol is the parent compound from which all steroid hormones, including cortisol and sex steroids, are synthesized. This lipid nature allows them to pass easily through cellular membranes.
The binding of a hormone to its receptor leads to the formation of a:
- A Primary complex
- B Hormone-receptor complex
- C Secondary complex
- D Enzyme-substrate complex
Correct answer: Hormone-receptor complex
When a hormone molecule successfully fits into the binding site of its specific receptor, it forms a hormone-receptor (H-R) complex, which is the necessary step to initiate any cellular response.
Hormones like Cortisol act by interacting with:
- A Cell surface receptors
- B Intranuclear receptors
- C Ribosomal receptors
- D Lysosomal receptors
Correct answer: Intranuclear receptors
Cortisol is a glucocorticoid (steroid hormone). It crosses the plasma membrane and binds to receptors within the cell, which then move into the nucleus to act as transcription factors.
Which of the following describes 'synergistic effect' of hormones?
- A One hormone opposes the action of another
- B Two or more hormones act jointly for a greater combined effect
- C A hormone requires the presence of another to work at all
- D A hormone acts on the same gland that secreted it
Correct answer: Two or more hormones act jointly for a greater combined effect
Synergy occurs when multiple hormones work together to amplify a biological response. For example, several different hormones are required for the full development and function of mammary glands.
Which hormone's mechanism involves the activation of the enzyme Adenylate Cyclase?
- A Aldosterone
- B Adrenaline (Epinephrine)
- C Progesterone
- D Testosterone
Correct answer: Adrenaline (Epinephrine)
Protein and amino-acid derivative hormones like Adrenaline bind to membrane receptors that activate Adenylate Cyclase. This enzyme then converts ATP into $cAMP$, the secondary messenger.
A sudden increase in the concentration of $IP_3$ in the cytosol of a target cell is typically the result of:
- A Binding of a steroid hormone to cytoplasm
- B Activation of phospholipase C via a membrane receptor
- C Thyroid hormone binding to nuclear DNA directly
- D Passive diffusion of $IP_3$ from the bloodstream into the cell
Correct answer: Activation of phospholipase C via a membrane receptor
Inositol triphosphate ($IP_3$) is a secondary messenger generated when certain water-soluble hormones bind to membrane receptors. This binding activates the enzyme phospholipase C, which cleaves membrane lipids to produce $IP_3$ and $DAG$.