Plus 1 Biology Question Paper (PDF) with Answers | 2025 March

Biology March 2025 Answer Key

FIRST YEAR HIGHER SECONDARY
EXAMINATION, MARCH 2025

๐Ÿ“ฅ Download PDF of this Question Paper

๐Ÿ’ก Click on the question to view the answer.

PART-A: BOTANY

I. Answer any 3 questions from 1 to 5. Each question carries 1 score. (3x1=3)

01. Diatoms belong to the following classifications:

(a) Chrysophytes

(b) Protozoans

(c) Dinoflagellates

(d) Euglenoids

✅ (a) Chrysophytes.
02. The stored food material present in Rhodophyceae is ________.
✅ Floridean starch.
03. Which type of venation do you observe in dicot leaf?
✅ Reticulate venation.
04. Name the stage of Meiosis during which Synaptonemal complex is formed.
✅ Zygotene.
05. In the following growth curve, what does the number '2' represent?
✅ Exponential (Log) phase.

II. Answer any 9 questions from 6 to 16. Each question carries 2 score. (9x2=18)

06. What do the terms Phycobiont and Mycobiont signify?
Answer:

In a lichen, the algal component is known as Phycobiont (autotrophic) and the fungal component is known as Mycobiont (heterotrophic).

07. Match the following:
III
(a) Chlamydomonas1. Moss
(b) Cycas2. Pteridophytes
(c) Selaginella3. Algae
(d) Sphagnum4. Gymnosperm
Answer:

III
(a) Chlamydomonas3. Algae
(b) Cycas4. Gymnosperm
(c) Selaginella2. Pteridophytes
(d) Sphagnum 1. Moss
08. Observe the figure and answer the following questions:

I. Name the parts (A) and (B).

II. Which parts of stomata constitute the stomatal apparatus?

Answer:

I. (A) Subsidiary cells, (B) Guard cells.

II. Stomatal aperture, guard cells, and surrounding subsidiary cells together constitute the stomatal apparatus.

09. Identify the types of vascular bundles given below and label the parts.
Answer:

(A) Conjoint closed. 1-Phloem, 2-Xylem

(B) Conjoint open. 3. Cambium

10. An accepted model of the structure of a cell membrane was proposed by Singer and Nicolson.

a. Name the model.

b. List the 2 major biomolecules which this membrane is composed of.

c. State one function of this membrane.

Answer:

(a) Fluid Mosaic Model.

(b) Lipids (phospholipids) and Proteins.

(c) Selective transport of molecules across it.

11. Find the odd one and justify your answer.

a. Stroma, Grana, Cristae, Stroma lamellae.

b. Chromatid, Fimbriae, Kinetochore, Centromere.

Answer:

(a) Cristae.

Justification: Cristae are found in Mitochondria, while the others are parts of Chloroplasts.

(b) Fimbriae.

Justification: Fimbriae are surface structures of bacteria, while the others are parts of a chromosome.

12. Expand the abbreviation RuBP. What is its role in Photosynthesis?
Answer:

Ribulose 1,5-bisphosphate.

Role: It acts as the primary CO₂ acceptor in the C₃ (Calvin) cycle.

13. In a C₃ plant a light dependent cyclic process is occurring that require oxygen.

(a) Name the process.

(b) In this process instead of producing, it consumes energy. Evaluate the statement.

Answer:

(a) Photorespiration.

(b) The statement is correct. In the photorespiratory pathway, there is no synthesis of ATP or NADPH. Instead, it results in the release of CO₂ with the utilization of ATP.

14. Pyruvate undergoes an oxidative decarboxylation by a complex set of reactions before entering the Krebs cycle.

a. Name the compound formed from this reaction which then enters Krebs cycle.

b. Name the enzyme that catalyses this reaction.

Answer:

(a) Acetyl CoA. (b) Pyruvate dehydrogenase.

15. (a) What is bolting?

(b) Which hormone is used for bolting?

Answer:

(a) Bolting is the internode elongation just prior to flowering in plants with rosette habit (e.g., cabbage).

(b) Gibberellins (GA).

16. Observe the figure given below:

a. Source of which plant hormone is indicated in the figure?

b. Write three roles of above identified hormone.

Answer:

(a) Auxin.

(b) 1. Helps to initiate rooting in stem cuttings.
2. Promotes flowering (e.g., in pineapples).
3. Prevents fruit and leaf drop at early stages.

III. Answer any 3 questions from 17 to 20. Each question carries 3 score. (3x3=9)

17. Observe the figures A and B.

a. Identify the type of inflorescence A & B.

b. Write any two differences between them.

Answer:

(a) A-Cymose, B-Racemose.

(b) In Racemose, the main axis continues to grow and flowers are in acropetal order.

In Cymose, the main axis terminates in a flower, limiting growth, and flowers are in basipetal order.

18. Given below is the diagrammatic representation of a particular stage of mitosis.

a. Identify the stage.

b. Write any two features of this stage.

c. Write any three significances of mitosis.

Answer:

(a) Anaphase.

(b) 1. Centromeres split and chromatids separate.

2. Chromatids move to opposite poles.

(c) 1. Growth of multicellular organisms.

2. Cell repair and replacement.

3. Maintenance of nucleocytoplasmic ratio.

19. Diagrammatic representation of Hatch and Slack pathway is shown below. Analyse the figure.

a. Identify the cells A and B.

b. Why this pathway is called C₄ pathway?

c. Write any 3 advantages of C₄ plants over C₃ plants.

Answer:

(a) A-Mesophyll cell, B-Bundle sheath cell.

(b) It is called the C₄ pathway because the first stable product of CO₂ fixation is a 4-carbon compound, Oxaloacetic acid (OAA).

(c) 1. They can tolerate higher temperatures.

2. They show a response to high light intensities.

3. They lack photorespiration, leading to higher productivity.

20. Observe the incomplete schematic representation given below and answer the questions.

a. Identify this pathway common for both aerobic and anaerobic respiration.

b. Complete the scheme by filling the boxes A, B, C and D.

c. Mention the three ways in which pyruvic acid is handled.

Answer:

(a) Glycolysis (EMP pathway).

(b) A-Glucose 6-phosphate

B-Glyceraldehyde 3-phosphate

C-2 Phosphoglyceric acid

D-Phosphoenolpyruvic acid.

(c) Lactic acid fermentation, Alcoholic fermentation, and Aerobic respiration (Krebs cycle).

PART-B: ZOOLOGY

I. Answer any 3 questions from 1 to 5. Each question carries 1 score. (3x1=3)

1. Expand: (a) ICBN (b) ICZN
Answer:

(a) International Code for Botanical Nomenclature.

(b) International Code of Zoological Nomenclature.

2. Give suitable terms for:

(a) Respiration through skin

(b) Respiration through lungs

Answer:

(a) Cutaneous respiration.

(b) Pulmonary respiration.

3. Inulin is a polymer of ________.
✅ Fructose.
4. Observe the given figures A and B. Identify and name them.
Answer:

(A) Actin (Thin) filament

(B) Myosin (Thick) filament/molecule.

5. Cerebral hemispheres are connected by a tract of nerve fibres called ________.
✅ Corpus callosum

II. Answer any 9 questions from 6 to 16. Each question carries 2 score. (9x2=18)

6. Write two external features that help to identify male and female frogs.
Answer:

Male frogs have sound producing vocal sacs and a copulatory pad on the first digit of the forelimbs. They are absent in female frogs.

7. (a) Write the correct path of cardiac impulse.

(b) Why SA Node is called 'Pacemaker'?

Answer:

(a) SA Node → AV Node → Bundle of His → Purkinje fibres.

(b) It is called the pacemaker because it initiates and maintains the rhythmic contractile activity (heartbeat) of the heart by generating action potentials.

8. Observe the given figure and answer the questions. Label A, B, C and D.
Answer:

A-Dorsal hollow nerve cord

B-Notochord

C-Pharyngeal gill slits

D-Post-anal tail.

9. Identify the phylum in which these organs/structures are present:

(a) Radula (b) Parapodia (c) Comb plates (d) Calcareous ossicles.

Answer:

(a) Mollusca

(b) Annelida

(c) Ctenophora

(d) Echinodermata

10. Differentiate Chondrichthyes and Osteichthyes.
Answer:

Chondrichthyes: Cartilaginous endoskeleton, mouth is ventral, gill slits without operculum.

Osteichthyes: Bony endoskeleton, mouth is terminal, gills covered by an operculum.

11. Complete the Table (Hints are given).
PICTURE
Hints
  • Monocytes
  • Eosinophil
  • 20–25%
  • Phagocytic
  • Inflammatory response
  • 0.5–1%
Answer:

(A) Eosinophil

(B) 0.5-1%

(C) Phagocytic

(D) Inflammatory response.

12. (a) In human some ribs are bicephalic. Why?

(b) Write the different components of Rib cage.

Answer:

(a) They are called bicephalic because each rib has two articulation surfaces on its dorsal end for attachment with the vertebrae.

(b) Thoracic vertebrae, ribs, and sternum together form the rib cage.

13. Observe the given figure and answer the questions.

(a) Label A and B.

(b) Differentiate cortical and juxtamedullary nephrons.

Answer:

(a) A-Afferent arteriole, B-Bowman's capsule.

(b) In Cortical nephrons, the loop of Henle is very short and extends only very little into the medulla. In Juxtamedullary nephrons, the loop of Henle is very long and runs deep into the medulla.

14. Name the following:

(a) hypoglycaemic hormone

(b) hypercalcaemic hormone

(c) emergency hormone

(d) antidiuretic hormone.

Answer:

(a) Insulin

(b) Parathyroid hormone (PTH)

(c) Adrenaline (Epinephrine)

(d) Vasopressin (ADH).

15. (a) Draw the structure of

    (i) Glycerol

    (ii) Serine.

(b) Name the given:

    (iii) Most abundant protein in animal world.

   (iv) Two aromatic amino acids.

Answer:
PICTURE

(b) (iii) Collagen

      (iv) Tyrosine, Phenylalanine (or Tryptophan).

16. (a) Write any two classes of enzymes.

(b) What are cofactors? What happens if it is removed?

Answer:

(a) Dehydrogenases and Hydrolases.

(b) Cofactors are non-protein constituents bound to the enzyme to make it catalytically active. If the cofactor is removed, the catalytic activity is lost.

III. Answer any 3 questions from 17 to 20. Each question carries 3 score. (3x3=9)

17. Observe the figures A and B and answer the questions.

(a) Identify body forms A and B.

(b) How will you differentiate them?

(c) What is metagenesis?

Answer:

(a) A-Polyp, B-Medusa.

(b) Polyp is sessile and cylindrical (e.g., Hydra); Medusa is umbrella-shaped and free-swimming (e.g., Jellyfish).

(c) Metagenesis is the alternation of generation seen in cnidarians (e.g., Obelia) where polyps produce medusae asexually and medusae form polyps sexually.

18. (a) Write the functions of (i) Renin (ii) ANF.

(b) Explain the role of lungs and liver in elimination of excretory wastes.

Answer:

(a) Renin regulates blood pressure and blood volume. It converts angiotensinogen into angiotensin I, which leads to the formation of angiotensin II.

When Blood pressure is increased, ANF causes vasodilation to decrease blood pressure.

(b) Lungs remove large amounts of CO₂ and water.

Liver secretes bile containing bilirubin, biliverdin, cholesterol, etc., which are excreted with digestive wastes.

19. Observe the figure and answer the questions.

(a) Label A, B, C and D.

(b) Write location of

    (i) Unipolar neuron

    (ii) Bipolar neuron

Answer:

(a) A-Nucleus

    B-Myelin sheath

    C-Node of Ranvier

    D-Axon terminal.

(b) (i) Unipolar: Embryonic stage.

    (ii) Bipolar: Retina of eye.

20. Differentiate:

(a) Inspiratory reserve volume and expiratory reserve volume.

(b) Residual volume and functional residual capacity.

(c) Expiratory capacity and inspiratory capacity.

Answer:

(a) Inspiratory reserve volume (IRV): Additional volume of air that can inspire by a forcible inspiration. It is 2500-3000 ml.

Expiratory reserve volume (ERV): Additional volume of air that can expire by a forcible expiration. It is 1000-1100 ml.

(b) Residual volume (RV): Volume of air remaining in lungs after a forcible expiration. It is 1100-1200 ml.

Functional residual capacity (FRC): Volume of air remaining in the lungs after a normal expiration (ERV + RV). It is 2100-2300 ml.

(c) Inspiratory capacity (IC): Total volume of air inspired after a normal expiration (TV + IRV). It is 3000-3500 ml.

Expiratory capacity (EC): Total volume of air expired after a normal inspiration (TV + ERV). It is 1500-1600 ml.

Post a Comment (0)