Class XII Biology Sample Question Paper 2024-25

Questions and Answers

What is the maximum number of marks for the Biology exam?

70 (correct)

How many sections are included in the Biology question paper?

5 (correct)

What type of questions does Section-D include?

Fill in the blanks questions

Short answer questions

True or false questions

Case-based questions (correct)

What is the total number of questions in the Biology paper?

33 Signup and view all the answers

What is the marking scheme for the questions in Section-C?

3 marks each Signup and view all the answers

What must students draw whenever necessary?

Diagrams with correct labels Signup and view all the answers

How many options are provided for selection in questions with internal choices?

Two options only Signup and view all the answers

In which section does a question carry the highest mark value?

Section-E Signup and view all the answers

What is the correct mRNA sequence produced after transcribing the given DNA template strand?

5´ AUUGCC 3´ Signup and view all the answers

Which gas is primarily produced during the fermentation of idli-dosa dough?

CO2 Signup and view all the answers

What is the result of adaptive radiation typically characterized by?

Rapid divergence of traits among populations inhabiting a given geographical area Signup and view all the answers

What is the number of nucleotides present in the sticky ends formed after Eco R1 cuts DNA between G and A?

2 & 4 for Vector and Foreign DNA Signup and view all the answers

How does the secondary treatment of sewage alter the effluent due to the action of flocs?

Reduction in BOD Signup and view all the answers

In the context of cells of tapetum, what is the reason for their multiple nuclei?

They undergo meiosis without cytokinesis Signup and view all the answers

Which forest has the maximum energy loss by respiration?

Forest C Signup and view all the answers

What is a key function of deoxyribonucleoside triphosphates?

Proofreading during DNA synthesis Signup and view all the answers

How many embryos are produced in the ovary of seed X, which is produced by apomixis?

3 Embryos Signup and view all the answers

What is the main advantage of plants developed from seed Y over seed X?

Higher genetic variation Signup and view all the answers

What happens to the floating cover placed over the slurry in a biogas plant?

It keeps on rising due to gas production Signup and view all the answers

Where in the human ovary is the first meiotic division completed during oogenesis?

Mature Graafian follicle Signup and view all the answers

What is a key difference in the pairing of nitrogenous bases during DNA replication and transcription?

A pairs with T in replication, U in transcription Signup and view all the answers

In which process is the DNA segment copied into RNA?

Template transcription Signup and view all the answers

How are multiple embryos formed in citrus fruits?

Via polyembryony Signup and view all the answers

What is the chromosome number of the first polar body produced during oogenesis?

23 Signup and view all the answers

What does a negative hCG blood test imply?

Pregnancy is highly unlikely. Signup and view all the answers

Which hormone is primarily secreted by the tissue that produces hCG?

Progesterone Signup and view all the answers

In gel electrophoresis, how do DNA fragments behave based on their size?

Larger fragments move slower. Signup and view all the answers

What type of mutation is typically more harmful to DNA?

Nonsense mutation Signup and view all the answers

What is the significance of UTRs in mRNA?

They help stabilize mRNA. Signup and view all the answers

What phenomenon occurs when a sperm fertilizes an ovum?

The ovum creates a barrier to prevent additional sperm entry. Signup and view all the answers

What is the primary relationship observed between HIV levels and helper T cell counts shortly after infection?

Initial HIV levels peak while T cell counts drop. Signup and view all the answers

In a culture plate of Lactobacillus, what causes the variance in colony color?

pH changes in the medium. Signup and view all the answers

What is the primary reason only a segment of DNA is copied into RNA during transcription?

Specific genes are activated based on cell type. Signup and view all the answers

Which of the following correctly describes a step involved in Southern blot hybridization?

Blotted DNA is hybridized with a radiolabeled VNTR probe. Signup and view all the answers

How do bio-fertilizers primarily enrich soil nutrient quality?

By improving nitrogen fixation through microbial activity. Signup and view all the answers

In the context of PCR, what is the role of temperature cycling?

To allow for denaturation, annealing, and extension. Signup and view all the answers

What does Gause's exclusion principle state regarding species co-existing?

Two species competing for the same resources cannot coexist. Signup and view all the answers

What is one factor responsible for the temperature pattern observed in a person with a non-viral disease transmitted by mosquitoes?

Host immune responses triggering temperature variation. Signup and view all the answers

Study Notes

General Instructions

All questions are compulsory in the exam.
The question paper includes five sections with a total of 33 questions.
Section A: 16 questions worth 1 mark each (multiple choice).
Section B: 5 questions worth 2 marks each.
Section C: 7 questions worth 3 marks each.
Section D: 2 case-based questions worth 4 marks each.
Section E: 3 questions worth 5 marks each.
No overall choice; internal choices provided in some questions.
Diagrams must be neat and properly labeled where necessary.

Section A Highlights (1 Mark Questions)

Signals for parturition in humans originate from both the placenta and a fully developed fetus.
To produce 1600 seeds, 2000 meiotic divisions are required.
If a DNA sample has a thymine content of 27%, then the expected guanine content is 23%.
For transcription, the mRNA generated from a given DNA template strand is 5' AUUGCC 3'.
Idli-dosa dough rises due to CO2 production.
Adaptive radiation leads to rapid divergence of traits among populations in geographical areas.
Eco R1 restriction enzyme cuts DNA between bases G and A, forming sticky ends.
The secondary treatment of sewage reduces the BOD due to flocs.

Section B Highlights (2 Marks Questions)

Negative hCG levels imply no pregnancy; hCG is produced by the placenta.
The ovum blocks additional sperm entry by alterations in its membrane after the first sperm fertilization.
Not all copulations lead to fertilization due to various factors including timing and sperm viability.
Mutations can vary in type; specific examples are required for identification.
The Human Immunodeficiency Virus (HIV) can be tracked through T-cell counts and immune response dynamics.

Section C Highlights (3 Marks Questions)

Apomictic seeds can produce multiple embryos; sexual reproduction seeds have one embryo.
First meiotic division during oogenesis occurs in the ovarian follicle, resulting in a secondary oocyte and a polar body.
Central Dogma involves the processes of DNA replication, transcription into RNA, and translation into proteins.
Southern blotting utilizes radiolabeled probes to identify specific DNA sequences.

Section D Highlights (4 Marks Questions)

Hardy-Weinberg principle calculations include frequencies of alleles; example given with black and red beetles.
Patterns of temperature in diseases transmitted by mosquitoes can indicate the presence of specific pathogens, which multiply in the human body.
Transmission of diseases can occur through various forms, including vectors like mosquitoes.

Additional Information

Visual impairments adaptations provided, including simplified explanations without diagrams.
Critical understanding of ecological principles like Gause's exclusion principle noted for cooperative species.

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Description

Prepare for your Class XII Biology exam with this sample question paper designed for the 2024-25 session. This paper includes a variety of questions across multiple sections, testing your knowledge on key biological concepts. Ensure you cover all topics to achieve maximum marks in your upcoming assessment.