Maharashtra Board 12th Biology Exam 2025 : Most Important Question Answers for Last-Minute Revision

Maharashtra Class 12 Biology exam is approaching, and last-minute revision is crucial for scoring high. To help you prepare effectively, we have compiled the Most Important Multiple-Choice Questions (MCQs), Short Answer Questions, and Long Answer Questions from the syllabus, covering:

📌 Multiple Choice Question
📌 Match the Columns Questions 
📌 Short Answer Type Question
📌 Long Answer Type Question

MCQs play a vital role in your Biology exam. Apart from MCQs, the exam also includes short and long answer questions that require conceptual clarity and proper explanations. Practicing these questions will help you write precise and well-structured answers.

Prepare well with these essential questions and boost your confidence for the Maharashtra HSC Biology exam 2025.

Maharashtra Board Biology Most Important Question Answers

Multiple Choice Questions

1. Select the statement which explains best parasitism.

(a) One species is benefited.

(b) Both the species are benefited.

(c) One species is benefited, other is not affected.

(d) One species is benefited, other is harmed.

Ans. (d) One species is benefited, other is harmed.

2. What is celebrated on 5th June every year ?

(a) World ozone day

(b) Earth day

(c) World environment day

(d) Biodiversity day

Ans. (c) World environment day

3. Which is the most important service provided by environment ?

(a) Release of oxygen

(b) Formation of ozone layer

(c) Carbon assimilation in photosynthesis

(d) Agents of pollination

Ans. (c) Carbon assimilation in photosynthesis

4. Which is the most well-known pattern of biodiversity ?

(a) Species-Area relationship

(b) Latitudinal gradient

(c) Longitudinal gradient

(d) Altitudinal gradient

Ans. (b) Latitudinal gradient

👉 Maharashtra Board Class 12 Study Material

5. Name the scientist who studied ecosystem by using analogy of "The Rivet Poppet Hypothesis'.

(a) John Muir

(b) Alexander von Humboldt

(c) Robert May

(d) Paul Ehrlich

Ans. (d) Paul Ehrlich

6. Which of the following are new world monkeys ?

(a) Squirrel monkey, Spider monkey

(b) Orangutan, Baboons

(c) Squirrel monkey, Baboons

(d) Gibbons, Baboons

Ans. (a) Squirrel monkey, Spider monkey

7. Which of the following characteristic is not shown by the ape ?

(a) Prognathous face

(b) Tail is present

(c) Chin is absent

(d) Forelimbs are longer than hind limbs

Ans. (b) Tail is present

8. What is rhizosphere ?

(a) Root ball formed by growth of roots

(b) Covering of root tip

(c) Microenvironment around root

(d) Region of root hairs

Ans. (c) Microenvironment around root

9. Which hormone is known as stress hormone ?

(a) Auxin

(b) Gibberellin

(c) Ethylene

(d) Abscissic acid

Ans. (d) Abscissic acid

10. Pacemaker of heart is .............. .

(a) SA node

(b) AV node

(c) His bundle

(d) Purkinje fibres

Ans. (a) SA node

11. Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency ?

(a) Parathyroid hormone - Diabetes insipidus

(b) Luteinising hormone - Diabetes mellitus

(c) Insulin - Hyperglycaemia

(d) Thyroxine - Tetany

Ans. (c) Insulin - Hyperglycaemia

12. Which of the following diseases can be contracted by droplet infection ?

(a) Malaria

(b) Chicken pox

(c) Pneumonia

(d) Rabies

Ans. (c) Pneumonia

13. Where is antigen D present ?

(a) On Rhesus factor

(b) On the surface of RBCs

(c) On A antigen

(d) On AB antigen

Ans. (b) On the surface of RBCs

14. Which hormone is used in MOET method ?

(a) GH

(b) LH

(c) FSH

(d) ICSH

Ans. (c) FSH

15. First biopatent was procured for genetically engineered bacterium

(a) Pseudomonas

(b) Agrobacterium

(c) Azatobacter

(d) E-coli

Ans. (a) Pseudomonas

Match the Columns Questions 

1.

Ans.

(1) egg - (d) embryo

(2) nucellus - (c) perisperm

(3) outer integument - (a) testa

(4) inner integument - (b) tegmen

2.

Ans.

(1) Epididymis - (d) Maturation of sperms

(2) Sertoli cells - (c) Nourishment to developing sperms

(3) Vas deferens - (a) Transport of sperms

(4) Penis - (b) Copulatory organ

Short Answer Questions

(1) What is budding in plants ?

Ans. Budding in plants is an artificial method of propagation in which a single bud is joined or grafted on the stock plant.

(2) At which stage pollen grains are shed from anther in Angiosperms ?

Ans. In bicelled stage pollen grains are shed from anther in Angiosperms.

(3) Which glands contribute fluids to the semen ?

Ans. The glands which contribute fluids to the semen are seminal vesicles, prostate gland. Cowper's glands add mucus to semen.

(4) Where does fertilization and implantation occur ?

Ans. Fertilization of ovum takes place in the ampulla region of fallopian tube, whereas implantation occur in the endometrium of uterus.

(5) What are polygenes ?

Ans. When a character is controlled by two or more than two pairs of genes, the genes are called polygenes.

(6) State the major changes that took place in the evolution of man.

Ans. Major evolutionary changes seen in man :

1. Increase in size and complexity of brain and enhanced intelligence with increased cranial capacity.

2. Bipedal locomotion with erect posture.

3. Opposable thumb.

4. Shortening of forelimbs and lengthening of hind limbs.

5. Development of chin and orthognathous face.

6. Broadening of pelvic girdle, development of lumbar curvature.

7. Articulated speech, art, development of tools, social and cultural development.

(7) Explain the limitations of root pressure theory.

Ans. Limitation of root pressure theory :

1. Not applicable to tall plants above 20 metres.

2. Even in absence of root pressure ascent of sap is noticed.

3. In actively transpiring plants, root pressure is not developed.

4. In taller gymnosperms, root pressure is zero.

5. Xylem sap is under tension and shows negative hydrostatic pressure.

(8) Give any four physiological effects and application of ethylene.

Ans.

1. Ethylene is a gaseous growth inhibitor hormone.

2. It promotes ripening of fruits like bananas, apples and mangoes. The commercial application of ethephon is done.

3. It initiates growth of lateral roots.

4. Dormancy of buds and seeds is broken by its application.

5. It accelerates formation of abscission layer and thus abscission of leaves, flowers and fruits is observed.

6. Ethylene is responsible for checking growth of lateral buds thus causes apical dominance and retards flowering.

7. Process of senescence of plant organs is enhanced.

8. Epinasty, i.e. drooping of leaves and flowers results due to its application in some plants.

(9) A person met with a small accident and bleeds, but very soon stops bleeding. Explain the physiological process responsible for this.

Ans.

1. The bleeding stops due to blood clotting. It is extrinsic process as the tissue is damaged.

2. There are twelve clotting factors (I to XII). They interact in a cascade manner leading to formation of enzyme, Thromboplastin.

3. Thromboplastin helps in the formation of prothrombinase.

4. Prothrombinase inactivates heparin and converts prothrombin into thrombin.

5. Thrombin converts fibrinogen into fibrin. Fibrin is insoluble and forms mesh in which the blood cells are entangled forming a clot.

(10) Why is pancreas called a dual gland ?

Ans.

1. Pancreas is called a dual gland because it is exocrine as well as endocrine in nature.

2. The exocrine pancreas secretes digestive enzymes through acini.

3. The endocrine pancreas secretes hormones through its endocrine cells called Islets of Langerhans.

Long Answer Questions

1. (a) Give the term to describe the entry of pollen tube into the ovule through the following parts : (i) Micropyle, (ii) Chalaza, (iii) Integument

(b) State any five significances of double fertilization.

Ans.

(a) Terms to describe entry of pollen tube into the ovule :

(i) Through micropyle: Porogamy

(ii) Through chalaza : Chalazogamy

(iii) Through integument: Mesogamy

(b) Significance of double fertilization :

(i) Double fertilization is unique feature in Angiosperms in which seed with food store is produced.

(ii) Diploid zygote is produced through double fertilization which later forms new plant.

(iii) Triploid PEN forms nutritive endosperm tissue.

(iv) Diploid condition of the plant is restored by fusion of haploid male and female gametes through syngamy.

(v) Double fertilization avoid polyembryony.

2. Describe outbreeding devices which encourage cross pollination.

Ans.

1. Unisexuality, dichogamy, prepotency, self sterility, heteromorphy and herkogamy are the outbreeding devices.

2. Unisexuality : The plants bear either male or female flowers. Due to unisexual nature, self-pollination is avoided. Plants are either dioecious, e.g. Papaya or monoecious, e.g. maize.

3. Heteromorphy : In same plants different types of flowers are produced. In these flowers, stigmas and anthers are situated at different levels. There is heterostyly and heteroanthy. This prevents self-pollination e.g. Primrose.

4. Herkogamy : In bisexual flowers we may come across mechanical device to prevent self-pollination. Natural physical barrier avoids contact of pollens with stigma. e.g. Calotropis where pollinia are situated below the stigma.

5. Prepotency : In prepotency pollens of other flower germinate rapidly rather than from the same flower. E.g. Apples.

6. Self sterility or Self incompatibility: It is a genetic mechanism in which pollen germination is inhibited on the stigma of the same flower. E.g. Tobacco, Thea.

3. (a) Which type of strains of bacteria were used by Griffith in his experiment ?

(b) Explain the four types of experiments performed by him.

(c) What conclusions were derived from these experiments ?

Ans. 

(a) 1. In 1928, Frederick Griffith, carried out experiments with bacterium Streptococcus pneumoniae (which causes pneumonia in humans and other mammals).

2. Griffith used two strains of Streptococcus pneumoniae :

(i) S-type (Virulent, smooth, pathogenic and encapsulated).

(ii) R-type (Non-virulent, rough, non-pathogenic and non-capsulated).

(b) Experiments carried out by F. Griffith :

(i) Mice were injected with R-strain bacteria and they survived (no pneumonia).

(ii) Mice injected with S-strain bacteria developed pneumonia and died.

(iii) When heat-killed S-strain bacteria were injected in mice, the mice survived.

(iv) On injecting a mixture of heat-killed S-bacteria and live R-bacteria, the mice died.

(c) Griffith concluded that the live R-strain bacteria must have picked up something (which he called transforming principle) from the heat killed S bacterium, and got changed into S-type. Transforming principle allowed R-type to synthesize capsule and it became virulent.

4. Describe the process of transcription in protein synthesis.

Ans. Transcription involves three stages, viz. Initiation, Elongation and Termination.

(1) Initiation :

(a) RNA polymerase binds to promoter site. 

(b) It then moves along the DNA and causes local unwinding of DNA duplex into two strands in the region of the gene.

(c) Only antisense strand functions as template.

(2) Elongation :

(a) The complementary ribonucleoside tri-phosphates get attached to exposed bases of DNA template chain.

(b) As transcription proceeds, the hybrid DNA-RNA molecule dissociates and makes m-RNA molecule free.

(c) As the m-RNA grows, the transcribed region of DNA molecule becomes spirally coiled and regains double helical form.

(3) Termination : When RNA polymerase reaches the terminator site on the DNA, both enzyme and newly formed m-RNA (primary transcript) gets released.

5. Describe Lac 'Operon'.

Ans. Lac operon consists of the following components:

1. Regulator gene :

(a) Regulator gene precedes the promoter gene.

(b) It may not be present immediately adjacent to operator gene.

(c) Regulator gene codes for a repressor protein which binds with operator gene and represses (stops) its action.

2. Promoter gene :

(a) It precedes the operator gene.

(b) It is present adjacent to operator gene.

(c) RNA Polymerase enzyme binds at promoter site. Promoter gene base sequence determines which strand of DNA acts a template.

3. Operator gene :

(a) It precedes the structural genes.

(b) When operator gene is turned on by an inducer, the structural genes get transcribed to form m-RNA.

4. Structural gene :

(a) There are 3 structural genes in the sequence lac-Z, lac-Y and lac-A.

(b) Enzymes produced are B-galactosidase, B-galactoside permease and transacetylase respectively.

(c) Inducer : Allolactose acts as an inducer. It inactivates the repressor by binding with it. 

Maharashtra Board Class 12 Study Material