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MODEL PAPER 2025 BIOLOGY - MODEL PAPER 2025

Rajasthan Board (RBSE) - STD 12 Science - BIOLOGY (Rajasthan - English Medium). 40 questions in this chapter.

Question types

MODEL PAPER 2025 question types

40 questions across 6 question groups — pick any mix to generate a BIOLOGY paper with step-by-step answer keys.

40
Questions
6
Question groups
5
Question types
Sample Questions

MODEL PAPER 2025 questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (0.5 Marks)1 Mark
Eco R1 cuts the DNA between bases G and A only when the sequence of GAATTC is present. The number of nucleotides present in the resultant sticky ends that will be formed in each of the two strands of DNA after this enzyme cuts the DNA will be:
 Vector DNAForeign DNA
A1 & 55 &1
B2 & 44 &2
C2 & 55 & 2
D3 & 44 & 3
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Q 2M.C.Q (0.5 Marks)1 Mark
Suresh and Rajesh have defective haemoglobin due to genetic disorders. In Suresh, the problem is qualitative as he is having incorrectly functioning globin molecules while in Rajesh the problem is quantitative as he is having very few globin molecules. Identify the disorder they are suffering from.
SureshRajesh
AThalassemia - Autosomal Dominant blood disorderSickle Cell Anaemia - Autosomal linked Recessive trait
BSickle Cell Anaemia - Autosomal linked Dominant traitThalassemia - Autosomal Recessive blood disorder
CSickle Cell Anaemia – Autosomal linked Recessive traitThalassemia – Autosomal Recessive blood disorder
DThalassemia - Autosomal Dominant blood disorderSickle Cell Anaemia - Autosomal linkedDominant trait
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Q 4M.C.Q (0.5 Marks)1 Mark
Signals for parturition in human female originate from
  • A
    Fully developed foetus only
  • B
    Both placenta as well as fully developed foetus
  • C
    Placenta only
  • D
    Oxytocin released from maternal pituitary
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Q 5M.C.Q (0.5 Marks)1 Mark
During the secondary treatment of sewage, which of the following change in the effluent occur due to flocs?
  • ✓
    Reduction in BOD
  • B
    Increase in BOD
  • C
    Decrease in DO
  • D
    No change in DO or BOD

Answer: A.

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Q 61.5 Marks Questions2 Marks
Given below is the relationship between the HIV levels in the blood and helper T cell count in a person detected with AIDS. Study the relationship and answer the questions that follow.
Image
A. What kind of relationship is observed in the virus levels and the immune response after some days of the initial infection?
B. Does it completely clear the virus from the body permanently? Give reason for your answer.
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Q 71.5 Marks Questions2 Marks
The schematic representation given below shows a DNA strand and two types of mutations in the DNA strand.
Image
(i) Identify the type of mutation exhibited in I and II.
(ii) Which of the above mutation is more harmful? Give reason.
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Q 81.5 Marks Questions2 Marks
Given below is a schematic representation of a mRNA strandImage
(i) In the above sequence identify the translational unit in mRNA.
(ii) Where are UTRs found and what is their significance?
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Q 91.5 Marks Questions2 Marks
(i) It was estimated that if an evergreen forest has a GPP of 400 J/m2/day and 150 J/m2/day worth of carbon dioxide flows out of that forest, what is the NPP in that forest?
(ii) Explain why pyramids of energy must always be upright.
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Q 101.5 Marks Questions2 Marks
A culture plate of Lactobacillus shows blue-coloured colonies and colourless colonies. Explain the principle involved in the formation of such variance in the colour of colonies.
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Q 113 Marks Question3 Marks
A. Diagram given below depicts different species of Warbler birds feeding on different regions on a Spruce tree. Explain the mechanism which helps them to co-exist.
Image
B. What does Gause's exclusion principle state? Does it apply in the case shown above? Explain.
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Q 123 Marks Question3 Marks
The image below shows two germinated seeds X and Y which belong to the same species. Seed X is produced by apomixis whereas seed Y is a product of sexual reproduction.
Image
A. Write the number of embryo(s), embryo sac(s) and ovules in the ovary of seed X.
B. How multiples embryos are formed in citrus fruits?
C. What advantage will plants developed from seed Y have over seed X?
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Q 164 Marks Questions4 Marks
B.
(i) Name the two types of desirable approaches to conserve biodiversity? Explain with examples bringing out the difference between the two types.
(ii) State the features of a stable biological community?
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Q 174 Marks Questions4 Marks
B. In the future, genetic therapies may be used to prevent, treat, or cure certain inherited disorders in humans. Justify the statement with a suitable example.
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Q 184 Marks Questions4 Marks
(i) Explain the significance of each of the following features present in plants given below:, (a) In rose-bay plant the stamens ripen before the stigma., (b) In certain species of primrose, the flowers have short stamen and long style., (c) The bisexual flower of mustard exhibits rejection of self-pollen grain., (ii) Explain how autogamy is prevented in castor and papaya plant respectively.
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Q 194 Marks Questions4 Marks
A.
(i) Why is there a need to conserve biodiversity? (Any two reasons)
(ii) Name and explain any two causes that are responsible for the loss of biodiversity.
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Q 21Assertion (A) & Reason (B) MCQ1 Mark
Assertion (A): Cells of tapetum have more than one nucleus.
Reason (R): They undergo meiosis without cytokinesis.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true and R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is False but R is true.

Answer: C.

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Q 22Assertion (A) & Reason (B) MCQ1 Mark
Assertion (A): Deoxyribonucleoside triphosphates serve dual purposes.
Reason (R): They act as proof readers and provide energy.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true and R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is False but R is true.

Answer: C.

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Q 23Assertion (A) & Reason (B) MCQ1 Mark
Assertion (A): A floating cover placed over the slurry in a biogas plant keeps on rising.
Reason (R): This cover keeps on rising due to the gas produced in the tank by the microbial activity.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true and R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is False but R is true.
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Q 24Assertion (A) & Reason (B) MCQ1 Mark
Assertion (A): DNA fragments can be isolated by Gel electrophoresis on the basis of their size.
Reason (R): The larger the fragment size, the faster it moves.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true and R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is False but R is true.

Answer: C.

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Q 25Case study (4 Marks)4 Marks
Given below is the pattern of temperature in a person suffering from a non-viral disease transmitted by mosquitoes. Study the graph and answer the questions that follow:
Image
A. Explain the factor(s) responsible for this pattern of temperature.
B. How does this pathogen multiply in the human body?
C. How is this infection transmitted to humans?
OR
D. Which stages of the life cycle of this pathogen are completed in the mosquito's gut?
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Q 26Case study (4 Marks)4 Marks
Assuming that within a population of beetles where Hardy Weinberg conditions are met, the colour black (B) is dominant over the colour red (b). 40% of all beetles are red (bb).
Given this information, answer the questions below:
A. What is the frequency of red beetles?
B. Calculate is the percentage of beetles in the population that are heterozygous.
C. What is the frequency of homozygous dominant individuals?
OR
D. Assuming that Hardy Wienberg conditions are met in the beetle population consisting of 1500 beetles. How many beetles would you expect to be black and red in colour respectively?
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