CUET 2026 Biology May 25 Shift 2 Question Paper- Download Answer Key and Solution PDF

Concept:
Population growth under resource limitation follows the logistic growth model.
The logistic growth equation is:
\[ \frac{dN}{dt}=rN\left(\frac{K-N}{K}\right) \]
where: \[ N = Population density \] \[ r = Intrinsic rate of increase \] \[ K = Carrying capacity \]
Step 1: Understand unlimited resource growth.
When resources are unlimited, population increases exponentially and forms a: \[ J-shaped curve \]
Step 2: Understand limited resource growth.
When resources become limited:
Population growth slows down
Competition increases
Population stabilizes near carrying capacity
This produces an: \[ S-shaped (sigmoid) curve \]
Therefore, the correct answer is: \[ \boxed{S-shaped curve} \] Quick Tip: Remember: \[ Exponential growth \rightarrow J-shape \] \[ Logistic growth \rightarrow S-shape \] Carrying capacity (\(K\)) limits population growth.

Step 1: Check Assertion (A).
Viroids are:
Small infectious RNA molecules
Lack protein coat
Simpler than viruses
Hence Assertion (A) is true.
Step 2: Check Reason (R).
Viroids infect plants and can cause diseases such as: \[ Potato\ spindle\ tuber\ disease \]
Hence Reason (R) is also true.
Step 3: Check explanation relation.
Reason (R) gives an example of disease caused by viroids, but it does not explain why viroids lack protein coat.
Hence: \[ \boxed{Both\ A\ and\ R\ are\ true\ but\ R\ is\ not\ the\ correct\ explanation} \] Quick Tip: Remember: Virus = nucleic acid + protein coat Viroid = naked RNA only Prion = infectious protein particle

Step 1: Match Darwin.
Darwin proposed: \[ Theory\ of\ Natural\ Selection \]
Thus: \[ A \rightarrow I \]
Step 2: Match H.M.S. Beagle.
H.M.S. Beagle was the ship used during Darwin’s voyage.
Thus: \[ B \rightarrow II \]
Step 3: Match Mimicry and Pathogen.
Mimicry: \[ Protective\ resemblance \]
Pathogen: \[ Disease\ causing\ organism \]
Thus: \[ C \rightarrow III \] \[ D \rightarrow IV \]
Therefore: \[ \boxed{A-I,\ B-II,\ C-III,\ D-IV} \] Quick Tip: Remember: \[ Darwin \rightarrow Natural\ Selection \] \[ H.M.S.\ Beagle \rightarrow Darwin’s\ voyage \] \[ Pathogen \rightarrow Disease\ causing\ agent \]

Concept:
DNA ligase acts as a molecular glue in recombinant DNA technology.
Step 1: Understand function of DNA ligase.
DNA ligase:
Joins DNA fragments
Forms phosphodiester bonds
Helps produce recombinant DNA
Step 2: Eliminate incorrect options.
Restriction enzymes cut DNA
RNA polymerase synthesizes RNA
Helicase breaks hydrogen bonds
Therefore, the correct answer is: \[ \boxed{Joins\ DNA\ fragments\ together} \] Quick Tip: Remember: \[ Restriction\ enzyme \rightarrow Cuts\ DNA \] \[ DNA\ ligase \rightarrow Joins\ DNA \]

Concept:
Gel electrophoresis is a technique used to separate DNA fragments.
DNA molecules are negatively charged due to phosphate groups and move towards the positive electrode.
Step 1: Understand movement of DNA in gel.
When electric current is passed:
DNA fragments move through agarose gel
Smaller fragments move faster
Larger fragments move slower
Step 2: Identify basis of separation.
Since smaller fragments travel more distance in the same time: \[ DNA\ fragments\ are\ separated\ based\ on\ size \]
Therefore, the correct answer is: \[ \boxed{Size} \] Quick Tip: Remember: \[ Smaller\ DNA\ fragment \rightarrow Moves\ faster\ in\ gel \] \[ Larger\ DNA\ fragment \rightarrow Moves\ slower \]

Concept:
Oogenesis is the process of formation of female gametes.
Step 1: Understand primary oocyte formation.
During fetal life:
Oogonia divide mitotically
They form primary oocytes
Step 2: Identify arrest stage.
Primary oocytes begin meiosis-I but get arrested at: \[ Prophase-I \] specifically in diplotene stage.
Step 3: Understand completion.
The arrested oocyte resumes meiosis only after puberty during ovulation.
Therefore, the correct answer is: \[ \boxed{Prophase-I} \] Quick Tip: Remember: \[ Primary\ oocyte \rightarrow Prophase-I\ arrest \] \[ Secondary\ oocyte \rightarrow Metaphase-II\ arrest \]

Step 1: Identify menstrual phase.
During menstrual phase: \[ Endometrium\ breaks\ down \]
Thus: \[ A \rightarrow II \]
Step 2: Identify follicular phase.
During follicular phase: \[ Ovarian\ follicles\ grow \]
Thus: \[ B \rightarrow IV \]
Step 3: Identify ovulatory and luteal phases.
Ovulatory phase: \[ Ovulation\ occurs \]
Luteal phase: \[ Corpus\ luteum\ forms \]
Thus: \[ C \rightarrow I \] \[ D \rightarrow III \]
Therefore: \[ \boxed{A-II,\ B-IV,\ C-I,\ D-III} \] Quick Tip: Remember: Menstrual phase \(\rightarrow\) Endometrial shedding Follicular phase \(\rightarrow\) Follicle growth Ovulation \(\rightarrow\) Release of ovum Luteal phase \(\rightarrow\) Corpus luteum

Concept:
A flower contains male and female reproductive organs.
Step 1: Identify male reproductive parts.
Male reproductive organ: \[ Stamen \]
It consists of: \[ Anther + Filament \]
Step 2: Identify female reproductive part.
Female reproductive organ: \[ Pistil (Carpel) \]
It consists of:
Stigma
Style
Ovary
Therefore, the correct answer is: \[ \boxed{Pistil} \] Quick Tip: Remember: \[ Stamen \rightarrow Male\ part \] \[ Pistil/Carpel \rightarrow Female\ part \]

Step 1: Check Assertion (A).
RNA contains: \[ Adenine,\ Guanine,\ Cytosine\ and\ Uracil \]
Instead of thymine, RNA contains uracil.
Hence Assertion (A) is true.
Step 2: Check Reason (R).
Uracil pairs with adenine through hydrogen bonding.
Hence Reason (R) is also true.
Step 3: Check explanation relation.
The reason states the pairing property of uracil, but it does not explain why thymine is absent in RNA.
Thus: \[ \boxed{Both\ A\ and\ R\ are\ true\ but\ R\ is\ not\ the\ correct\ explanation} \] Quick Tip: Remember: \[ DNA \rightarrow Contains\ Thymine \] \[ RNA \rightarrow Contains\ Uracil \]

Concept:
Gene therapy is a modern biotechnological technique used to treat genetic disorders.
Step 1: Understand gene therapy.
Gene therapy aims to:
Replace defective genes
Correct abnormal genes
Introduce functional genes
Step 2: Eliminate incorrect options.
It is not limited to plants
It does not destroy all genes
It is unrelated to protein digestion
Therefore, the correct answer is: \[ \boxed{Replacement\ or\ correction\ of\ defective\ genes} \] Quick Tip: Remember: \[ Gene\ therapy \rightarrow Treats\ genetic\ disorders \] It works by introducing functional genes into cells.