CBSE Class 12 Biology Important 5 Mark Questions with Answers

Author at PW

January 20, 2026

Cbse class 12 biology questions for the 5-mark section are designed to test a student's comprehensive understanding of complex biological processes and their ability to illustrate them with diagrams. These high-weightage questions typically cover major units like Reproduction, Genetics, and Biotechnology, requiring detailed, step-by-step explanations that align with the specific marking schemes provided by the board.

Check out: CBSE Class 12th Books

How the 5-Mark Questions Work in Exams

In the cbse class 12 biology question pattern, Section E is where you'll find the 5-mark questions. These are often called "long-answer" questions. To get full marks here, you don't just need to write a lot; you need to be very organized. A good answer usually has a clear heading, a simple definition, and a neat diagram.

When you look at a cbse class 12 biology question bank, you'll see that certain topics appear almost every year. For example, the way DNA replicates or how a human embryo grows are very common. By practicing these specific topics, you can walk into the exam room feeling much more confident.

Common 5-Mark Questions and Simple Answers

Here are some of the most important cbse class 12 biology questions and answers simplified for quick learning.

1. Structure of the DNA Double Helix

One of the most famous cbse class 12 biology questions asks you to describe the DNA model proposed by Watson and Crick.

The Basics: DNA is made of two long chains that twist around each other like a twisted ladder or a spiral staircase.
The Parts: Each step of the ladder is made of base pairs (A always pairs with T, and C always pairs with G). The sides are made of sugar and phosphate.
Important Fact: The two strands run in opposite directions, which scientists call "anti-parallel."

2. The Process of Fertilization in Plants

This question asks how a seed starts to grow inside a flower after a pollen grain arrives.

Pollination: The pollen grain lands on the stigma and grows a long tube down to the ovary.
Double Fertilization: This is a special process in plants where two separate fusions happen. One makes the embryo (the baby plant), and the other makes the food for the embryo (called endosperm).
Final Result: After this, the ovule turns into a seed, and the ovary becomes the fruit we eat.

3. Recombinant DNA Technology Steps

This is a high-priority topic in the cbse class 12 biology question bank. It explains how scientists change the genes of a living thing to make something useful, like insulin.

Cutting: Scientists use "molecular scissors" called restriction enzymes to cut DNA at specific spots.
Copying: They use a process called PCR (Polymerase Chain Reaction) to make millions of copies of that specific gene.
Joining: The new gene is "pasted" into a carrier called a vector (like a plasmid) using an enzyme called ligase.
Growing: This new DNA is put into a host cell (like bacteria) to grow the product on a large scale.

Check out: Class 12th Sample Papers

Tips for Writing Better Long Answers

To make sure the examiner gives you full marks, follow these simple steps -

Use a Pencil for Diagrams: Don't ever use a pen for your drawings. Use a sharp pencil and label everything clearly on the right side of the drawing.
Write in Points: Try not to write big blocks of text. Use bullet points so the teacher can see your main ideas at a glance.
Highlight Key Words: If you mention an important word like "Transcription" or "Plasmid," underline it so it stands out.
Watch the Clock: Try to spend about 10 to 12 minutes on each 5-mark question. This gives you enough time to think and draw.

Check out: Class 12th Question Banks

Why Use PW CBSE Class 12 Biology Study Material?

Preparing for your board exams is much easier when you have resources built specifically for school students. The PW Store offers a cbse class 12 biology PYQ, Question Bank & Revision Notes that simplifies your school syllabus and focuses on scoring high in your final assessments.

Easy to Understand: We explain everything in plain English so you don't get confused by hard words in your school textbooks.
Based on NCERT: Every answer we provide follows the NCERT syllabus strictly, which is what the CBSE wants to see.
Targeted School Prep: Our notes focus on school-level clarity and board exam presentation styles.
Good Practice Questions: We give you plenty of questions to practice so you're ready for any school unit test or final exam.

CBSE Class 12 Biology Important 5 Mark Questions FAQs

Q1: Do I need to draw a diagram for every 5-mark question?

In almost every case, yes! Even if the question doesn't specifically ask for one, a diagram helps the examiner understand your answer better and shows you know the topic. PW's cbse class 12 biology questions and answers always include diagrams to show you exactly what to draw.

Q2: Which chapters are the most important for 5-mark questions?

The chapters on "Genetics," "Reproduction," and "Biotechnology" are usually the most important ones for these long-answer questions. They carry the most weight in the exam.

Q3: Can I write my answers in my own words?

Yes, you can! Just make sure you use the correct scientific terms where they are needed. Our cbse class 12 biology question bank helps you learn these terms in a very simple way.

Q4: What if I run out of time during the exam?

If you're short on time, draw the diagram first and label it. In the cbse class 12 biology question pattern, a good diagram can still get you a lot of marks even if you don't have time to write a long explanation.