Free Medical Doctor General Questions and Answers — Questions and Answers
Question 1: Which spinal canal segment will exhibit secondary curves with a concavity that is reversed?
- Thoracic
- Sacral
- Coccyx
- Cervical (Correct answer)
Correct answer: Cervical
The vertebral column has four natural curves: two primary (thoracic and sacral) and two secondary (cervical and lumbar). Primary curves are concave anteriorly (kyphotic), while secondary curves are concave posteriorly (lordotic). Therefore, the cervical segment, being a secondary curve, exhibits a lordotic curve, meaning its concavity is reversed compared to the primary curves, presenting anteriorly.
Question 2: Which of the following enables communication between the cytoskeleton and the extracellular matrix across the cell membrane?
- Intermediate filaments
- Proteoglycans
- Integrins (Correct answer)
- Cadherins
Correct answer: Integrins
Integrins are transmembrane receptor proteins that play a crucial role in cell adhesion and communication. They link the cell's cytoskeleton (specifically actin filaments) to components of the extracellular matrix (ECM), such as collagen, fibronectin, and laminin. This connection allows cells to sense and respond to their environment, influencing cell migration, differentiation, and survival.
Question 3: Which of the following describes how goblet cells and enteroendocrine cells are different?
- Their origin form a crypt stem cell
- The direction of release of secretion (Correct answer)
- Use of exocytosis for release of secretory products from the cell
- Their presence in small and large intestine
Correct answer: The direction of release of secretion
Both goblet cells and enteroendocrine cells originate from crypt stem cells and use exocytosis to release their secretory products. However, their direction of secretion differs significantly. Goblet cells secrete mucus onto the apical surface into the intestinal lumen, while enteroendocrine cells secrete hormones into the basolateral side, which then enter the bloodstream to act on distant targets.
Question 4: The Papez circuit's implicated nucleus is?
- Anterior nucleus of thalamus (Correct answer)
- VPL nucleus
- Pulvinar
- Infralaminar
Correct answer: Anterior nucleus of thalamus
The Papez circuit is a neural pathway involved in emotion and memory, particularly the formation of long-term memories. Key structures in this circuit include the hippocampus, fornix, mammillary bodies, mammillothalamic tract, anterior nucleus of the thalamus, cingulate gyrus, and entorhinal cortex. The anterior nucleus of the thalamus serves as a crucial relay station within this circuit.
Question 5: The synthesis of these substances occurs in the agranular endoplasmic reticulum:
- Lipid (Correct answer)
- Protein
- Vitamin D
- Carbohydrate
Correct answer: Lipid
The agranular (smooth) endoplasmic reticulum (SER) is primarily involved in the synthesis of lipids, including phospholipids, cholesterol, and steroid hormones. It also plays roles in detoxification of drugs and poisons, and storage of calcium ions. In contrast, the granular (rough) endoplasmic reticulum, with its ribosomes, is responsible for protein synthesis and modification.
Question 6: False regarding the expression of Eukaryotic genes in the cytosol is:
- EF2 shifts between GDP & GTP
- Capping helps in attachment of mRNA to 40 S Ribosome
- Releasing factor releases the polypeptide chain from the P site
- N formyl methionine tRNA will be the first t-RNA to come into action (Correct answer)
Correct answer: N formyl methionine tRNA will be the first t-RNA to come into action
This statement is false because N-formylmethionine tRNA (fMet-tRNA) is the initiator tRNA in *prokaryotic* protein synthesis. In *eukaryotic* gene expression, the first tRNA to come into action is methionine tRNA (Met-tRNA), which carries an unformylated methionine. The other options describe true aspects of eukaryotic translation.
Question 7: Concerned with by the C terminal end of the androgen receptor are:
- Increasing the affinity of receptor to DNA
- Increasing the level of transcription
- Ligand binding (Correct answer)
- Increasing biological half life
Correct answer: Ligand binding
The C-terminal end of steroid hormone receptors, including the androgen receptor, typically contains the ligand-binding domain (LBD). This domain is responsible for binding to the specific hormone (ligand), which then induces a conformational change in the receptor. This conformational change allows the receptor to translocate to the nucleus and bind to DNA to regulate gene transcription.
Free Medical Doctor General Questions and Answers
Which spinal canal segment will exhibit secondary curves with a concavity that is reversed?