CSIR Question Solution Hub

  Explanation: 1: Synchronous culture :  In this type of culture, all cells divide at approximately the same time, leading to a stepwise increase in the number of cells. 2: Continuous culture :  In a continuous culture ( chemostat ), the growth rate is maintained at a constant level by continuously adding fresh medium and removing old medium, resulting in a steady, exponential increase in cell numbers over time. 3: Asynchronous culture :  This is the typical bacterial growth curve in a batch culture, showing a lag phase , a log (exponential) phase , a stationary phase , and a death phase .  The cells divide at random times, leading to a smooth, S-shaped curve. 4: Diauxic growth :  This occurs when bacteria are grown in a medium containing two different carbon sources .  The bacteria first consume the preferred carbon source, leading to a period of exponential growth , followed by a lag phase while they switch to metabolizing the second, less preferred...

  Answer:   3. Leu will decrease and both Val and Ile will increase. Explanation: The problem states that IPMS activity is regulated exclusively by Leu, and the diagram shows that Leu is a product of the IPMS pathway.  The RNAi knockdown of IPMS would lead to a decrease in the production of Leu. The diagram also shows that both Leu and Val synergistically regulate the activity of AHAS .  With a decrease in Leu, the inhibitory effect on AHAS is reduced, leading to an increase in AHAS activity. An increase in AHAS activity leads to an increase in the production of 2-Oxoisovalerate , which is a precursor for both Val and the IPMS pathway. Therefore, the concentration of Val will increase. The problem states that Ile regulates TD activity , while Val can relax this feedback regulation.  With an increase in Val, the feedback regulation on TD by Ile is relaxed, leading to an increase in TD activity and consequently an increase in the production of Ile.   The...

  The correct answer is: Option 4: P = Optimum patch residence time ; Q = Time taken to travel between patches Explanation: The Marginal Value Theorem (MVT) is an important concept in behavioral ecology , especially used to describe foraging behavior — how animals decide when to leave a resource patch (like a flower, tree, or field) and move to a new one. Let’s go step by step 👇 🧠 Basic Idea When an animal forages, it gains food (energy) from a “patch.” At first, food is abundant — energy gain is high . As time goes on, food becomes harder to find — rate of gain decreases . So, the animal faces a decision: “Should I keep searching here or move to another patch?” ⚖️ The Principle (Charnov, 1976) The Marginal Value Theorem states: A forager should leave the current patch when the marginal rate of resource gain (the slope of the gain curve at that moment) drops to equal the average rate of gain from the environment (including travel time).   According...

  Explanation: 🔬 Experiment Summary Purpose: To test the helicase activity of E. coli DnaB under different conditions and substrates. 🧬 Substrates Used Substrate I: A partially unwound DNA (one strand radiolabeled). 5′–3′ direction on the radiolabeled strand (shown in figure). Substrate II: A forked DNA substrate (replication fork structure). 🧪 Experimental Conditions Condition DnaB ATP SSB Boiling Used to test helicase activity + + + or – + (control) Boiling → Denatures the DNA completely (gives fully single-stranded band = control for complete unwinding ). 📊 Gel Interpretation Top band → Duplex (unwound) DNA. Bottom band → Single-stranded (fully unwound) DNA. Boiled sample → Always gives bottom band . Migration direction → downward (so more unwound = faster migration). 🧠 Analysis Substrate I (partially unwound DNA): DnaB + ATP → no significant unwinding (band pattern same as duplex). Boiling → complete unwinding (lo...