प्रिय विद्यार्थियों,
आप सभी से अनुरोध है कि हमारे YouTube चैनल को ज़रूर सब्सक्राइब करें, ताकि आप हमसे हमेशा जुड़े रह सकें।

कभी–कभी कॉपीराइट या अन्य कारणों से ग्रुप डिलीट हो सकता है, ऐसे में दोबारा कनेक्ट होने का सबसे सुरक्षित माध्यम केवल YouTube ही रहेगा। वहाँ आपको नए ग्रुप की लिंक और सभी अपडेट्स सबसे पहले मिलेंगे।

👉 सब्सक्राइब करने में आपका कोई खर्च नहीं है, लेकिन यह आपके लिए बेहद उपयोगी रहेगा।
इसलिए अभी चैनल को सब्सक्राइब कर लें और नोटिफिकेशन बेल भी ऑन कर दें।

धन्यवाद! 🙏

https://youtube.com/shorts/eiuf25SuClI?si=nLKuBwZBq_I9EKt8

Q.321
During eukaryotic transcription initiation, the formation of the pre-initiation complex (PIC) requires sequential assembly of multiple transcription factors on the promoter DNA. Consider the following statements regarding the process:

1. TFIID, through its TBP (TATA-binding protein) subunit, first recognizes and binds to the TATA box.


2. TFIIA and TFIIB stabilize the TBP-DNA interaction and help in recruitment of RNA Polymerase II.


3. TFIIH possesses both helicase and kinase activity, which are essential for promoter melting and phosphorylation of the CTD tail of RNA Polymerase II.


4. The mediator complex directly interacts with enhancer-bound activators and facilitates communication with the PIC.


5. TFIIE binds after TFIIH and is responsible for releasing RNA Polymerase II from the promoter.



Which of the above statements are correct?

a) 1, 2, 3 and 4 only
b) 1, 3 and 5 only
c) 2, 4 and 5 only
d) All 1–5 are correct

Q.322
In eukaryotic DNA replication, the process of Okazaki fragment maturation on the lagging strand involves coordinated activities of multiple enzymes and proteins. Consider the following statements:

1. DNA polymerase α synthesizes a short RNA-DNA primer at the beginning of each Okazaki fragment.


2. DNA polymerase δ extends the Okazaki fragment but cannot remove the RNA primer.


3. RNase H removes all RNA nucleotides of the primer including the last ribonucleotide attached to DNA.


4. Flap endonuclease 1 (FEN1) removes RNA primers displaced as flaps by strand displacement synthesis.


5. DNA ligase I seals the nicks after primer removal to join Okazaki fragments into a continuous strand.



Which one of the following combinations of statements is correct?

a) 1, 2, 4 and 5 only
b) 1, 2, 3 and 5 only
c) 2, 3, 4 and 5 only
d) All 1–5 are correct

Q323. Which DNA replication model was proved correct by the Meselson–Stahl experiment?
a) Conservative
b) Dispersive
c) Semi-conservative
d) Rolling circle

Q324. Which of the following is NOT a second messenger in signal transduction?
a) cAMP
b) Ca²⁺ ions
c) Diacylglycerol (DAG)
d) ATP

Q325. In eukaryotic transcription, the TATA box is recognized by:
a) RNA polymerase I
b) TBP (TATA-binding protein)
c) Sigma factor
d) DNA helicase

Q326. Which protein is directly involved in vesicle fusion with target membranes?
a) SNARE proteins
b) Kinesin
c) Dynein
d) Actin

Q327. The adaptive immune system has the property of immunological memory because of:
a) Macrophages
b) Memory B and T cells
c) Natural killer cells
d) Complement proteins

Q328. Which type of microscopy allows visualization of live, unstained cells with contrast?
a) Bright-field microscopy
b) Phase-contrast microscopy
c) Electron microscopy
d) Fluorescence microscopy

Q329. In the lac operon, high glucose levels lead to:
a) Increased cAMP → increased transcription
b) Decreased cAMP → reduced transcription
c) Increased lactose uptake
d) Constitutive expression