Plus 1 Biology Question Paper (PDF) with Answers | 2024 March

Biology March 2024 Answer Key

FIRST YEAR HIGHER SECONDARY
EXAMINATION, MARCH 2024

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PART-A: BOTANY

I. Answer any 3 questions from 1 to 4. Each question carries 1 score. (3x1=3)

01. Fill in the blank:

The dark reaction of photosynthesis takes place at ________ of the chloroplast.

✅ Stroma.
02. Choose the correct answer: Monocot seed consists of one large and shield shaped cotyledon known as:

(a) Aleurone layer

(b) Scutellum

(c) Coleoptile

(d) Coleorhiza

✅ (b) Scutellum.
03. Which class of algae is commonly known as Brown algae?
✅ Phaeophyceae.
04. Which of these cell organelles is not covered by a membrane?

(a) Golgi bodies

(b) Endoplasmic reticulum

(c) Ribosomes

(d) Vacuoles

✅ (c) Ribosomes.

II. Answer any 9 questions from 5 to 15. Each question carries 2 score. (9x2=18)

05. (a) Write the name of the phase of Prophase-I of Meiosis in which crossing over takes place.

(b) What is the significance of crossing over?

Answer:

(a) Pachytene.

(b) Crossing over leads to the recombination of genetic material on the two chromosomes, which results in genetic variation among offspring.

06. Match the following:
Class of FungiExample
(a) Phycomycetes(i) Agaricus
(b) Ascomycetes(ii) Alternaria
(c) Basidiomycetes(iii) Rhizopus
(d) Deuteromycetes(iv) Penicillium
Answer:
Class of FungiExample
(a) Phycomycetes(iii) Rhizopus
(b) Ascomycetes(iv) Penicillium
(c) Basidiomycetes(i) Agaricus
(d) Deuteromycetes(ii) Alternaria
07. (a) What is Glycolysis?

(b) Where does it take place?

Answer:

(a) Glycolysis is the process of partial oxidation of glucose to form two molecules of pyruvic acid.

(b) It takes place in the cytoplasm of the cell.

08. (a) Write one function of Abscisic acid.

(b) Why Abscisic acid is known as 'Stress hormone'?

Answer:

(a) It stimulates the closure of stomata or induces seed dormancy.

(b) It is called a stress hormone because it increases the tolerance of plants to various kinds of stresses by closing stomata during water scarcity.

09. Write two differences between the anatomy of Stem and Root.
Answer:

Vascular Bundles: In stems, vascular bundles are usually conjoint (xylem and phloem on the same radius), whereas in roots, they are radial (xylem and phloem on different radii).

Xylem type: Stems exhibit endarch xylem (protoxylem towards center), while roots exhibit exarch xylem (protoxylem towards periphery).

10. Observe the pathway of Anaerobic respiration given below:

(a) Label the compounds marked as A & B.

(b) What happens to pyruvic acid in muscles if oxygen is inadequate?

Answer:

(a) A = Lactic acid, B = Ethanol

(b) In muscles, pyruvic acid is reduced to lactic acid by the enzyme lactate dehydrogenase.

11. (a) Write the function of stomata.

(b) What is the difference between the shape of Guard cells of Dicot plants and Monocot plants (Grasses)?

Answer:

(a) Stomata regulate the process of transpiration and gaseous exchange (O2 and CO2).

(b) In dicots, guard cells are bean-shaped/kidney-shaped, whereas in monocots (grasses), they are dumbbell-shaped.

12. Arrange the given functions of plant hormones in appropriate columns:

(a) Ripening of fruit

(b) Initiate rooting in stem cutting

(c) Induce parthenocarpy

(d) Breaks seed and bud dormancy.

AuxinsEthylene
 

Answer:
AuxinsEthylene
(b) Initiate rooting in stem cutting(a) Ripening of fruit
(c) Induce parthenocarpy(d) Breaks seed and bud dormancy
13. Write brief notes about:

(a) Thermoacidophiles

(b) Halophiles.

Answer:

(a) Thermoacidophiles: These are archaebacteria that live in extremely hot and acidic environments like hot springs.

(b) Halophiles: These are archaebacteria that live in extremely salty areas.

14. (a) Which plants are known as naked seeded plants?

(b) Why?

Answer:

(a) Gymnosperms.

(b) They are called naked seeded plants because their ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilization.

15. Cell cycle consists of four phases - G1, S, G2 and M. Write one important event takes place during each phase.
Answer:

G1 phase: Cell becomes metabolically active and grows continuously but does not replicate DNA.

S phase: DNA synthesis or replication takes place; the amount of DNA per cell doubles.

G2 phase: Proteins are synthesized in preparation for mitosis while cell growth continues.

M phase: The actual cell division or mitosis occurs (karyokinesis and cytokinesis).

III. Answer any 3 questions from 16 to 19. Each question carries 3 score. (3x3=9)

16. Leucoplasts are classified into three types based on the stored food.

(a) Which are they?

(b) Write the name of stored food present in them.

Answer:

(a) Amyloplasts, Elaioplasts, Aleuroplasts

(b) Amyloplasts: Store carbohydrates (starch).

Elaioplasts: Store oils and fats.

Aleuroplasts: Store proteins.

17. (a) What is aestivation?

(b) Write the name of aestivation marked as A, B, C and D in the given diagram.

Answer:

(a) Aestivation is the mode of arrangement of sepals or petals in a floral bud with respect to the other members of the same whorl.

(b) A = Valvate

B = Twisted

C = Imbricate

D = Vexillary.

18. (a) Which are the two types of cells that participate in C4 pathway?

(b) What is the name of the first C4 acid formed in this pathway?

(c) Write two examples of C4 plants.

Answer:

(a) Mesophyll cells and Bundle sheath cells.

(b) Oxaloacetic acid (OAA).

(c) Maize and Sorghum.

19. Observe the figure of Citric acid cycle.

(a) Where does it take place in a cell?

(b) Write the name of compounds marked as A, B, C and D in the figure.

Answer:

(a) Mitochondrial matrix.

(b) A = Citric acid

B = Succinic acid

C = Malic acid

D = Oxaloacetic acid (OAA).

PART-B: ZOOLOGY

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

01. The system of providing scientific name with two components is called ________.
✅ Binomial nomenclature.
02. Water vascular system is present in:

(a) Leech

(b) Neries

(c) Prawn

(d) Starfish

✅ (d) Starfish.
03. Name the nucleotide form of guanine.
✅ Guanylic acid.
04. The functional unit of a muscle contraction is called ________.
✅ Sarcomere.
05. Erythropoietin, a peptide hormone produced by ________.
✅ Juxtaglomerular (JG) cells of the kidney.

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

06. Classify the following into polypeptides and polysaccharides:

(Trypsin, Inulin, Insulin, Chitin)

Answer:

Polypeptides: Trypsin, Insulin.

Polysaccharides: Inulin, Chitin.

07. Observe the diagram of male reproductive system of Frog. Label a, b, c, d.
Answer:

a = Testis

b = Kidney

c = Urinogenital duct

d = Urinary bladder.

08. Give reason:

(a) AB blood group individuals are called universal recipients.

(b) SAN is called pacemaker of heart.

Answer:

(a) They can accept blood from persons with AB as well as the other groups (A, B, O) because their plasma lacks antibodies against both A and B antigens.

(b) The Sino-atrial node (SAN) can generate the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractile activity of the heart.

09. When substrate concentration increases, the velocity of enzymatic reaction rises at first. After attaining maximum velocity, it is not exceeded by any further rise in concentration of the substrate. Why?
Answer:

This is because the enzyme molecules are fewer than the substrate molecules and after saturation of these molecules, there are no free enzyme molecules to bind with the additional substrate molecules.

10. Distinguish between:

(a) Systole and Diastole

(b) Plasma and Serum

Answer:

(a) Systole is the contraction phase, while Diastole is the relaxation phase.

(b) Plasma is the fluid matrix of blood; Serum is plasma without the clotting factors.

11. Indicate whether the following statements are true or false:

(a) Reptiles are Ammonotelic animals.

(b) Lungs and liver also help in the elimination of excretory wastes.

(c) Inflammation of glomeruli of kidney is called renal calculi.

(d) Malpighian Tubules are the excretory structures of most of the insects including cockroaches.

Answer:

(a) False (They are uricotelic).

(b) True.

(c) False (It is called Glomerulonephritis).

(d) True.

12. Henle's loop plays an important role in concentrating the urine. How?
Answer:

Henle's loop helps maintain a high osmolarity of medullary interstitial fluid through a counter-current mechanism, which allows for the reabsorption of water from the collecting duct, thereby concentrating the urine.

13. Name the joint:

(a) The joint between adjacent vertebrae

(b) Joint between skull bones

(c) Joint between atlas and axis

(d) Joint between carpal and metacarpal of thumb

Answer:

(a) Cartilaginous joint.

(b) Fibrous joint (Sutures).

(c) Pivot joint.

(d) Saddle joint.

14. Which hormonal deficiency is responsible for the following?

(a) Diabetes insipidus

(b) Cretinism

(c) Diabetes mellitus

(d) Dwarfism

Answer:

(a) ADH (Vasopressin).

(b) Thyroid hormones (Hypothyroidism).

(c) Insulin.

(d) Growth Hormone (GH).

15. Give one word:

(a) Warm blooded animals

(b) The body surface is distinctly marked out into segments

(c) The property of a living organism to emit light

(d) Sexes are not separate

Answer:

(a) Homeothermic.

(b) Metamerism.

(c) Bioluminescence.

(d) Hermaphrodite (or Monoecious).

16. Match the following:
Feature/StructureOrganism
(a) Radula(i) Sycon
(b) Pinnae(ii) Hydra
(c) Osculum(iii) Equus
(d) Hypostome(iv) Loligo
Answer:
Feature/StructureOrganism
(a) Radula(iv) Loligo
(b) Pinnae(iii) Equus
(c) Osculum(i) Sycon
(d) Hypostome(ii) Hydra

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

17. Observe the diagram. Answer the following:

(a) Identify the symmetry.

(b) State any two phyla in which this condition can be seen.

Answer:

(a) Radial symmetry.

(b) Coelenterata (Cnidaria), Ctenophora, and Echinodermata (adults).

18. Explain the role of JGA in the regulation of kidney function.
Answer:

A fall in glomerular blood flow/pressure/GFR can activate the JG cells to release renin. Renin converts angiotensinogen in blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases glomerular blood pressure and GFR. It also stimulates the adrenal cortex to release aldosterone, which causes reabsorption of Na+ and water, leading to an increase in blood pressure.

19. Observe the diagram. Answer the question.

Label (a), (b), (c), (d).

(e) Name different types of synapses.

Answer:

(a) Synaptic vesicle

(b) Pre-synaptic membrane

(c) Synaptic cleft

(d) Post-synaptic membrane

(e) Electrical synapses and Chemical synapses.

20. Define:

(a) Tidal volume

(b) Residual volume

(c) Vital capacity

Answer:

(a) Tidal Volume (TV): Volume of air inspired or expired during a normal respiration (approx. 500 mL).

(b) Residual Volume (RV): Volume of air remaining in the lungs even after a forcible expiration.

(c) Vital Capacity (VC): The maximum volume of air a person can breathe in after a forced expiration; VC = ERV + TV + IRV.

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