GRADE-8[UNIT-1] SOLVED EXERCISE

Unit – 1 Human Body                                                                                                                       Page No.19

Exercise

1. Multiple Choice Questions (Pages 19–20)

A. Essential components of a neuron:

Ans.→ b. Axon, dendrites, and nucleus                                                                       

B. Coordinates activities/processes data:

Ans.→a. Brain

C. Function of the cerebrum:

Ans.→c. Controlling thinking and decision-making

D. Extension of the CNS (brain to body):

Ans.→b. Spinal cord

E. Number of cranial nerve pairs:

Ans.→a. 12

F. Components of the autonomic nervous system:

Ans.→a. Sympathetic and parasympathetic systems

G. Function of the pituitary gland:

Ans.→d. Commanding and regulating other endocrine glands

H. Pineal gland location and function:

Ans.→d. In the brain, regulating the sleep-wake cycle

I. Function of the thyroid gland:

Ans.→ a. Regulating calcium in the blood (via the hormone calcitonin).

J. Hormones produced by gonads:

Ans.→b. Estrogen in females, testosterone in males (Note: the options are slightly simplified here).

K. Purpose of the reproductive system:

Ans.→b. To ensure the survival of the species

L. Barrier between uterus and vagina:

Ans.→d. Cervix

M. Where fertilization occurs:

Ans.→c. Fallopian tube

N. Role of the testes:

Ans.→a. Sperm production and testosterone secretion

O. Function of the epididymis:

Ans.→d. Maturing sperm

P. Role of the vas deferens:

Ans. → b. Transport sperm to the urethra for ejaculation

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2. Match the Organs with their Functions (Page 21)

Ans:

Column A	Column B
Cerebrum	Reasoning and cognitive functions
Fallopian tube	Provide a pathway for the ovum
Medulla	Oblongata reflex actions, such as heartbeat and breathing
Pancreas	Regulation of blood sugar levels through insulin production
Pineal gland	Production of melatonin to regulate the sleep-wake cycle
Testes	Production of sperm and contributing to male reproductive functions
Thyroid	Essential hormones (like thyroxine for metabolism)

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3. Briefly Answer the Following (Page 21)

• a. Central role of the nervous system: It acts as the body’s control center, coordinating all physical and mental activities by processing information.
• b. Function of the cerebellum: It manages balance, posture, and coordinates smooth muscle movements.
• c. Spinal cord damage: It can lead to paralysis or loss of sensation in the parts of the body below the site of the injury.
• d. Function of the seminal vesicle: It produces a fluid rich in sugar (fructose) that provides energy for sperm to swim.
• e. Why is the pancreas a “mix gland”? It is both an endocrine gland (releases insulin into the blood) and an exocrine gland (releases digestive enzymes through ducts).
• f. Organ beneath the bladder: The prostate gland.
• g. Testes hormone: Testosterone.
• h. Role of the male urethra: It serves as a dual-purpose exit for both urine and semen.
• i. Fertilization location: Typically in the Fallopian tube (also called the oviduct).
• j. Role of the testes: Producing sperm and the hormone testosterone.

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4. Descriptive Answers & Notes (Page 21)

• a. Three main parts of the nervous system: Central Nervous System (CNS), Peripheral Nervous System (PNS), and Autonomic Nervous System (ANS).
• b. Four major functions of the nervous system:
  1. Receiving sensory input.
  2. Processing and integrating information.
  3. Generating motor output (responses).
  4. Maintaining homeostasis.
• c. Exocrine vs. Endocrine: Exocrine glands (like sweat glands) use ducts to deliver secretions; endocrine glands are ductless and release hormones directly into the bloodstream.
• d. Purpose of reproduction: To ensure biological continuity so that a species does not go extinct.
• f. Four functions of the endocrine system:
  1. Regulating growth and development.
  2. Controlling metabolism.
  3. Managing reproduction.
  4. Balancing mood and sleep cycles.

Short Notes:

• i. Pineal Gland: A pea-sized gland in the brain that secretes melatonin to help you sleep.
• ii. Pituitary Gland: Known as the “Master Gland,” it controls many other glands and regulates growth.
• iii. Ovary: The female gonad that produces eggs (ova) and hormones like estrogen.
• iv. Pancreas: Found behind the stomach; it’s vital for controlling blood sugar levels.
• v. Testes: The male gonads responsible for creating sperm and testosterone.
• vi. Medulla Oblongata: The lowest part of the brainstem that controls involuntary life-support functions like breathing and heart rate.

SUMMARY OF THE UNIT[HUMAN BODY]

🧠 The Nervous System

• The Big Three:
  1. Cerebrum: The “thinker” (logic, memory, senses).
  2. Cerebellum: The “balancer” (movement and posture).
  3. Medulla: The “auto-pilot” (breathing and heartbeat).
• The Connector: The Spinal Cord links your brain to the rest of your body.
• The Messengers: Neurons use dendrites to receive signals and axons to send them.

🧪 The Endocrine System (Hormones)

• Master Gland: The Pituitary tells all the other glands what to do.
• Sleep: The Pineal gland makes melatonin to help you sleep.
• Sugar Control: The Pancreas uses insulin to keep your blood sugar steady.
• Metabolism: The Thyroid keeps your energy levels and calcium in check.

🧬 The Reproductive System

• Goal: Ensuring the survival of the species.
• Male Key Parts: Testes (sperm/testosterone) and Vas deferens (transport).
• Female Key Parts: Ovaries (eggs/estrogen) and Fallopian tubes (where fertilization happens).