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Biology 57-1-3 2025-2026 Science (English Medium) Class 12 Question Paper Solution

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Biology [57-1-3]
Marks: 70 CBSE
Science (English Medium)

Academic Year: 2025-2026
Date & Time: 27th March 2026, 10:30 am
Duration: 3h
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Note:

  1. Please check that this question paper contains 23 printed pages.
  2. Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.
  3. Please check that this question paper contains 33 questions.
  4. Please write down the serial number of the question in the answer-book at the given place before attempting it.
  5. 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the candidates will read the question paper only and will not write any answer on the answer-book during this period.

General Instructions:

Read the following instructions carefully and follow them:

  1. This question paper contains 33 questions. All questions are compulsory.
  2. Question paper is divided into FIVE sections - Section A, B, C, D and E.
  3. Section A - questions number 1 to 16 are multiple choice type questions. Each question carries 1 mark.
  4. Section B - questions number 17 to 21 are very short answer type questions. Each question carries 2 marks.
  5. Section C - questions number 22 to 28 are short answer type questions. Each question carries 3 marks.
  6. Section D - questions number 29 and 30 are case-based questions. Each question carries 4 marks. Each question has subparts with internal choice in one of the subparts.
  7. Section E - questions number 31 to 33 are long answer type questions. Each question carries 5 marks.
  8. There is no overall choice. However, internal choices have been provided in some questions. A candidate has to write answer for only one of the alternatives in such questions.
  9. Kindly note that there is a separate question paper for Visually Impaired candidates.
  10. Wherever necessary, neat and properly labelled diagrams should be drawn.

SECTION - A
Question Nos. 1 to 16 are Multiple Choice Type Questions, carrying 1 mark each. Choose the best option.
[1]1.

Perisperm present in seed of black pepper is remnant of ______.

Ovary

Nucellus

Anther

Megaspore

Concept: undefined - undefined
Chapter:
[1]2.

Interferons are most effective in making non-infected cells resistant against the spread of which of the following diseases?

Malaria

Ascariasis

Pneumonia

Cancer

Concept: undefined - undefined
Chapter:
[1]3.

Which of the following sacred groves is found in Meghalaya?

Jaintia hills

Bastar

Chanda

Sarguja

Concept: undefined - undefined
Chapter:
[1]4.

In an ecosystem, different species occupy different levels and vertical distribution of species is found. This is called ______.

Stratification

Layering

Fragmentation

Population

Concept: undefined - undefined
Chapter:
[1]5.

Which of the following statements about plasmids is incorrect?

Plasmids have the ability to replicate within the bacterial cell.

Their replication is controlled by chromosomal DNA.

They are autonomously replicating circular extra-chromosomal DNA.

They often carry antibiotic resistant genes.

Concept: undefined - undefined
Chapter:
[1]6.

Which connective tissue connects ovary to pelvic wall and uterus?

Tendons

Ligaments

Cartilage

Bone

Concept: undefined - undefined
Chapter:
[1]7.

Select the option that shows correct statements:

  1. Corpus luteum secretes progesterone.
  2. Only FSH attains a peak level in middle of cycle.
  3. LH surge induces rupture of graafian follicle.
  4. Luteal phase of menstrual cycle is also called proliferative phase.

Only (ii) is correct.

(i) and (iii) are correct.

Only (iv) is correct.

(ii) and (iv) are correct.

Concept: undefined - undefined
Chapter:
[1]8.

Which one of the following evidences does not support Darwin’s theory of natural selection?

Branching Descent

Small & directional variations

Appearance of new traits by mutations

Survival of the fittest

Concept: undefined - undefined
Chapter:
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[1]9.

Expression of a particular gene helps to identify transformants. What is this gene known as?

Plasmid

Structural gene

Selectable marker

Intron

Concept: undefined - undefined
Chapter:
[1]10.

A DNA molecule is 140 base pairs long. It has 20% thymine. How many guanine bases are present in the molecule?

64

84

32

56

Concept: undefined - undefined
Chapter:
[1]11.

Select the mismatched pair:

Mega diversity countries in the world - 12

Genetically different strains of rice in India - Less than 1000

Robert Mays estimation on global species diversity - 7 million species worldwide

Zoological parks - Ex-situ conservation

Concept: undefined - undefined
Chapter:
[1]12.

Pomato was produced by fusing protoplasts of ______.

Tomato and Potato

Pomegranate and Tomato

Pomegranate and Potato

Pomegranate, Potato and Tomato

Concept: undefined - undefined
Chapter:
For Questions number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) given below:
[1]13.

Assertion (A): Fossils provide direct evidence for evolution.

Reason (R): Fossils help to trace evolutionary relationships among organisms over time.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Concept: undefined - undefined
Chapter:
[1]14.

Assertion (A): In terrestrial ecosystem much larger fraction of energy flows through grazing food chain.

Reason (R): Grazing food chain may be connected to Detritus food chain at some levels.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Concept: undefined - undefined
Chapter:
[1]15.

Assertion (A): The milk produced by transgenic cow Rosie’ was nutritionally more balanced product for human babies than natural cow milk.

Reason (R): It was human protein enriched milk containing human alpha lactaglobulin.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Concept: undefined - undefined
Chapter:
[1]16.

Assertion (A): Flocs are masses of bacteria associated with fungal filaments in secondary treatment of sewage.

Reason (R): Flocs help in digestion of solid waste by anaerobic respiration.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Concept: undefined - undefined
Chapter:
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SECTION - B
[2]17.

A health officer visiting two different regions reported the following symptoms in patients:

Region A: Sustained high fever with-stomach pain, constipation and loss of appetite.

Region B: Inflammation in the lower limbs and genital organs.

Name the diseases likely affecting the patients in regions A and B. Write the scientific name of the causative organisms in both the cases.

Concept: undefined - undefined
Chapter:
[2]18. (a)
[1]18. (a) (i)

How does a farmer use dormancy of seed to his advantage?

Concept: undefined - undefined
Chapter:
[1]18. (a) (ii)

Differentiate between pea seed and castor seed.

Concept: undefined - undefined
Chapter:
OR
[2]18. (b)

Identify the stage of follicle where primary oocyte undergoes first meiotic division.

Also mention the products of this division.

Concept: undefined - undefined
Chapter:
[2]19.

What is the major advantage of producing plants by micropropagation?

Concept: undefined - undefined
Chapter:
[2]20. (a)

Mendel published his work on inheritance in 1865, but it remained unnoticed for over three decades.

State the reasons why his work was not recognised during his life time.

Concept: undefined - undefined
Chapter:
OR
[2]20. (b)

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