CBSE Class 12 Biology Important Questions 2025 with Answers

CBSE Class 12 Biology Important Questions: The CBSE Class 12 Board exams are one of the most crucial steps in a student’s academic journey. That is why practicing with CBSE Important Questions for Class 12 Biology is very useful for students. These questions are designed according to the cbse class 12 biology syllabus and are aligned with the latest exam pattern.

Many Class 12 students search for important questions for class 12 biology chapter wise pdf download so they can revise in a structured way. The important questions of biology class 12 are created by subject experts after analyzing previous year papers and important topics. With the help of class 12 biology important questions for cbse exam 2025, students can improve time management and accuracy.

Along with practicing important questions in biology for class 12 and important questions for class 12 biology cbse board, students should also use ncert solutions for class 12 biology to clarify concepts. These study resources provide a complete preparation strategy and help learners feel more confident before the exams.

CBSE Class 12 Biology Chapter-wise Important Questions

CBSE Class 12 Biology chapter-wise important questions and answers are very useful for students preparing for the CBSE Class 12 Board exams. These sets cover all the 13 chapters from the CBSE Class 12 Biology syllabus, so learners can practice each topic in detail. By solving these important questions of biology class 12, students can revise quickly and focus on the main points that usually come in exams. It also helps them in preparing for entrance exams like NEET.

10 Most Important Questions From Class 12 Biology – Simple Answers

1. Double fertilisation in flowering plants

Ans: It happens when two male gametes enter the ovule. One joins with the egg to form a zygote (baby plant), and the other joins with two polar nuclei to form endosperm (food for the seed). This helps the embryo and food supply develop together.

2. Hormonal control of menstrual cycle

Ans: FSH grows the egg in the ovary, LH causes ovulation, estrogen thickens the uterus wall, and progesterone keeps it ready for pregnancy. When hormone levels fall, menstruation starts.

3. Methods of birth control

Ans: Condoms (barrier), pills (hormonal), IUDs, and surgeries like vasectomy/tubectomy. They stop unwanted pregnancy, help control population, and reduce STIs.

4. Mendel’s law of segregation

Ans: Alleles (gene pairs) separate during gamete formation. In pea plant cross (tall × dwarf), F1 shows all tall, but F2 shows a 3:1 ratio (tall:dwarf).

5. DNA structure and role

Ans: DNA is a double helix with bases (A, T, G, C) and a sugar-phosphate backbone. It stores genetic code, makes mRNA, and guides protein formation in ribosomes.

6. Homologous vs. Analogous organs

Ans: Homologous: same origin, different function (human hand, bird wing).
Analogous: different origin, same function (bird wing, insect wing).

7. Barriers of immunity

Ans: Physical: skin, mucus.

Chemical: stomach acid, enzymes.

Biological: white blood cells. Together, they protect the body from infection.

8. Microbes in antibiotics

Ans: Some microbes make antibiotics that kill harmful bacteria. Example: Penicillium fungus makes penicillin.

9. Restriction enzymes in biotechnology

Ans: They cut DNA at special points, like scissors. This helps scientists remove and add genes for cloning and genetic engineering.

10. Effects of habitat loss

Ans: When habitats are destroyed, many species die or reduce in number. It causes loss of biodiversity, weakens ecosystems, and reduces genetic variety.

11. What is the role of placenta during pregnancy?

Ans: Placenta connects mother and baby. It supplies oxygen, food, and removes waste from the baby’s blood. It also makes hormones needed for pregnancy.

12. What is Hardy-Weinberg principle?

Ans: It says that in a large population, gene frequency stays constant if no evolution happens. Factors like mutation, migration, and natural selection can disturb it.

13. How does water move in plants?

Ans: Water moves from roots to leaves through xylem by transpiration pull, root pressure, and cohesion of water molecules.

14. What is apomixis in plants?

Ans: Apomixis is when seeds are formed without fertilisation. It helps produce plants with the same traits as the parent.

15. What are biogeochemical cycles?

Ans: They are natural cycles that recycle elements like carbon, nitrogen, and water between living things and the environment. Example: carbon cycle, nitrogen cycle.

How Do Class 12 Biology Important Questions Help in Exams?

The important questions of Biology Class 12 are a great study tool for students preparing for the CBSE Class 12 Board exams and entrance tests like NEET. These questions focus on the topics that are asked most often, so students can give extra attention to what really matters.

By solving these questions, students can:

• Understand concepts better – Repeated practice makes tough topics easier to remember and explain in exams.
• Get exam-style practice – The questions are framed like real exam questions (short, long, diagram-based), so students learn how to answer in the correct format.
• Improve time management – Regular practice helps students finish answers quickly and correctly during the exam.
• Reduce exam stress – When students are familiar with important and frequently asked questions, their anxiety decreases, and confidence grows.
• Revise smartly – These questions give a clear roadmap for revision. Instead of reading everything at once, students can focus chapter-wise.
• Prepare for competitive exams – Since these questions are based on NCERT Solutions for Class 12 Biology and the CBSE Class 12 Biology Syllabus, they also help in exams like NEET, AIIMS, and other medical entrances.
• Boost overall marks – Writing accurate and structured answers improves presentation skills and increases the chance of scoring higher.