Q35
5 marksLong AnswerSection D

(a) (i) Distinguish between hormonal co-ordination in plants and animals.

(ii) Which part of the brain is responsible for -

(1) intelligence

(2) riding a bicycle

(3) vomiting

(4) controlling hunger

(iii) How is brain and spinal-cord protected against mechanical injuries ?

OR

(b) (i) What are tropic movements ? Give an example of a plant hormone which (1) inhibits growth and (2) promotes cell division.

(ii) Explain directional movement of a tendril in pea plant in response to touch. Name the hormone responsible for this movement.

Control and Coordination
Nervous and Chemical Coordination
Official Answer

Part (a)


(i) Distinction between hormonal coordination in plants and animals:


FeatureHormonal Coordination in PlantsHormonal Coordination in Animals
Source of SecretionProduced by unspecialized cells (e.g., shoot tips, root tips) and diffuse to site of action.Secreted by highly specialized ductless glands called endocrine glands.
Transport MediumTransported via simple diffusion or through vascular tissues (xylem/phloem).Transported through the bloodstream (circulatory system) to target organs.
FunctionsMainly regulate growth, cell division, and directional (tropic) movements.Regulate a wide range of physiological processes, metabolism, homeostasis, and behavior.

(ii) Brain parts responsible for:

  1. Intelligence: Fore-brain (specifically the Cerebrum).
  2. Riding a bicycle: Cerebellum (part of the hind-brain).
  3. Vomiting: Medulla (part of the hind-brain).
  4. Controlling hunger: A separate centre associated with hunger in the Fore-brain.

(iii) Protection of Brain and Spinal Cord:

  • Brain: The brain is a delicate organ protected by sitting inside a bony box called the skull (cranium). Inside this bony box, the brain is further enclosed in a fluid-filled balloon (containing cerebrospinal fluid) which acts as a shock absorber to protect it from mechanical shocks and injuries.
  • Spinal Cord: The spinal cord is protected by a hard, bumpy, bony structure running down the middle of the back called the vertebral column or backbone.


OR


Part (b)


(i) Tropic Movements and Plant Hormones:

  • Tropic Movements: These are directional growth movements of plant parts in response to environmental stimuli (such as light, gravity, water, or chemicals). The movement can be either towards the stimulus (positive tropism) or away from it (negative tropism).
  • Plant Hormones:
  1. Inhibits growth: Abscisic acid.
  2. Promotes cell division: Cytokinin.

(ii) Directional Movement of a Tendril in response to touch:

  • Tendrils of climbing plants (like the pea plant) are highly sensitive to touch.
  • When a tendril comes in contact with a support, the plant hormone auxin synthesised at the shoot tip diffuses towards the side of the tendril that is away from the support (the shaded/outer side).
  • Since auxin stimulates cell elongation, the cells on the side away from the support grow and elongate much more rapidly than the cells in direct contact with the support.
  • This unequal growth on opposite sides causes the tendril to bend, circle around the support, and cling to it.
  • Hormone responsible: Auxin.
Fore-brainCerebellumMedullaCerebrospinal fluidVertebral columnAuxinAbscisic acidCytokininTropic movementsTendril

Marking Scheme

  • 1Part (a) (i): Any two correct differences between plant and animal hormonal coordination - 1.5 Marks
  • 2Part (a) (ii): Correctly identifying the brain parts for all four functions (0.5 marks each) - 2 Marks
  • 3Part (a) (iii): Explaining protection of brain (skull + fluid-filled balloon) and spinal cord (vertebral column) - 1.5 Marks
  • 4OR
  • 5Part (b) (i): Correct definition of tropic movements (1 mark), naming Abscisic acid (0.5 marks) and Cytokinin (0.5 marks) - 2 Marks
  • 6Part (b) (ii): Explaining the role of auxin in differential growth of tendrils away from support (2 marks) and naming Auxin (1 mark) - 3 Marks

Hint

For part (a), recall the functions of the fore-brain and hind-brain (cerebellum and medulla), and think about the fluid-filled balloon inside the skull. For part (b), remember that auxin promotes cell elongation on the side away from the stimulus, causing bending.

Quick Oral Answer

The cerebellum coordinates voluntary actions requiring precision, like riding a bicycle, while the medulla controls involuntary actions like vomiting. The brain is protected by the cranium and cerebrospinal fluid, and the spinal cord is protected by the vertebral column.

Analysis & Explanation

This question tests multiple core concepts from the 'Control and Coordination' chapter:

  1. Hormonal Coordination Comparison: Highlights the structural differences between plants (lacking specialized glands) and animals (possessing a complex endocrine system).
  2. Brain Anatomy and Functions: Tests the functional division of the brain. The fore-brain handles complex cognitive tasks (intelligence) and metabolic sensations (hunger), while the hind-brain manages involuntary reflexes (vomiting via medulla) and motor precision/balance (riding a bicycle via cerebellum).
  3. CNS Protection: Emphasizes the physical protection mechanisms (skull, cerebrospinal fluid, and vertebral column) evolved to safeguard delicate nervous tissues.
  4. Plant Tropisms and Hormones: Explains how plants use differential growth rates mediated by hormones like auxin to navigate their environment (thigmotropism in tendrils) in the absence of a nervous system.

Common Mistakes

  1. 1Confusing the roles of the cerebellum (voluntary precision/balance) and medulla (involuntary actions like vomiting).
  2. 2Forgetting to mention the fluid-filled balloon (cerebrospinal fluid) when explaining brain protection.
  3. 3Thinking that the side of the tendril in contact with the support grows faster, whereas it is actually the side away from the support that grows faster due to auxin accumulation.

Interesting Facts

The sensitive plant (Mimosa pudica) folds its leaves using turgor pressure changes (water movement) within seconds, which is independent of growth, whereas tendril bending is a growth-dependent movement that takes hours to days.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2024?

This question carries 5 marks in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Control and Coordination" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Nervous and Chemical Coordination" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2024 paper?

This is a Long Answer question from Section D in the CBSE Class 10 Science 2024 paper.