Life Science Chapter – 2D : Major organs of Human Body and their Functions Oriental Book Company solution for Madhyamik Students Class 9
| Material | : Madhyamik Life Science Solution |
| Subject | : Life Science |
| Class | : 9 (Madhyamik) |
| Publisher | : Oriental Book Company Private Limited |
| Chapter Name | : Major organs of Human Body and their Functions |
Multiple Choice Questions (MCQs)
(Each question carries 1 mark)
Question 1
The skin of man is containing of :
(a) Epidermis
(b) Stratum corneum
(c) Sweat and sebaceous gland
(d) All of them
Answer
(d) All of them
Explanation: Human skin has all these components — epidermis (outer layer), stratum corneum (outermost part of the epidermis), and sweat and sebaceous glands for secretion.
Question 2
Respiratory system is an :
(a) Enzyme producing system
(b) Excretory system
(c) Energy producing system
(d) All of them
Answer
(d) All of them
Explanation: The respiratory system helps in energy production (via oxygen supply), supports excretion (CO₂ removal), and also plays a role in enzyme action indirectly.
Question 3
Skeletal system form the body’s :
(a) Exoskeleton
(b) Endoskeleton
(c) Muscle arrangement
(d) Frame work
Answer
(d) Frame work
Explanation: The skeletal system provides a rigid structure or framework to support the body, protect internal organs, and enable movement by acting as attachment points for muscles. It’s like the foundation of a building.
Question 4
Excretory system is responsible :
(a) For elimination of water
(b) Maintain Osmoregulation
(c) Maintain fluid balance
(d) All of them
Answer
(d) All of them
Explanation: The excretory system (mainly kidneys, skin, lungs) removes waste materials from the body, especially excess water and nitrogenous wastes. It also helps in osmoregulation (maintaining water-salt balance) and in fluid balance which is critical for maintaining stable internal conditions (homeostasis).
Fill in the Blanks
(Each question carries 1 mark)
Question 1
___ is a largest digestive gland of our body.
Answer
Liver
Explanation: The liver is the largest digestive gland. It produces bile, which helps in the digestion of fats and also performs vital functions like detoxification, metabolism, and storage of nutrients.
Question 2
Lungs help in ___
Answer
Respiration
Explanation: Lungs are essential for respiration – they help in the exchange of gases, allowing oxygen to enter the blood and removing carbon dioxide from it.
Question 3
The stomach is a large ___ shaped sack.
Answer
J
Explanation: The stomach has a J-shaped curved structure, designed to store and churn food, and mix it with digestive juices for proper breakdown.
Question 4
Pancreas is ___ glands.
Answer
Both exocrine and endocrine
Explanation: The pancreas functions as both an exocrine gland (digestive enzymes) and an endocrine gland (insulin, glucagon).
Question 5
The ___ is main circulatory organ.
Answer
Heart
Explanation: The heart is the central organ of the circulatory system. It pumps blood throughout the body, supplying oxygen and nutrients and removing waste.
Question 6
Blood is filtered through ___
Answer
Kidneys
Explanation: The kidneys filter waste products like urea and excess salts from the blood, forming urine which is then excreted from the body.
Question 7
The brain lies within the cranium bounded by ____.
Answer
Meninges
Explanation: The meninges are three protective layers (dura mater, arachnoid mater, pia mater) that surround the brain inside the cranium and protect it from shocks and infections.
Question 8
Testis secretes ___ hormone.
Answer
Testosterone
Explanation: The testes in males produce testosterone, the main male sex hormone responsible for secondary sexual characteristics like deep voice, muscle growth, and facial hair.
State True or False
(Each question carries 1 mark)
Question 1
Skin involves in synthesis of vitamin D.
Answer
True
Explanation: When exposed to sunlight, the skin synthesizes vitamin D, which is important for calcium absorption and bone health.
Question 2
Kidney is a rod shaped structure.
Answer
False
Explanation: The kidney is bean-shaped, not rod-shaped. It has an outer cortex and an inner medulla, and plays a key role in filtering blood.
Question 3
Stomach is located in lower abdominal cavity.
Answer
False
Explanation: The stomach is located in the upper abdominal cavity, mainly on the left side under the rib cage, near the diaphragm.
Question 4
Each lung is covered by one membranous plura.
Answer
False
Explanation: Each lung is covered by two pleural membranes: the visceral pleura (touches the lung) and the parietal pleura (lines the chest wall), with pleural fluid in between.
Question 5
Human heart consists of two auricles and one ventricle.
Answer
False
Explanation: The human heart has four chambers: two auricles (atria) and two ventricles.
Question 6
The spinal chord is originating from medula oblongata.
Answer
True
Explanation: The spinal cord begins from the medulla oblongata, the lowest part of the brainstem, and extends down the vertebral column.
Columns Matching
(Each question carries 1 mark)
| Column I | Column II |
|---|---|
| (a) Skin | (f) Regulate body temperature |
| (b) Lungs | (e) Breathing organs |
| (c) Ovary | (d) Oestrogen |
| (d) Heart | (c) Blood circulation |
| (e) Islets of Langerhans | (b) Insulin |
| (f) Stomach | (a) Gastric gland |
Answer
| Column I | Column II |
|---|---|
| (a) Skin | (f)Regulate body temperature |
| (b) Lungs | (e) Breathing organs |
| (c) Ovary | (d) Oestrogen |
| (d) Heart | (c) Blood circulation |
| (e) Islets of Langerhans | (b) Insulin |
| (f) Stomach | (a) Gastric gland |
Choose the Odd One Out
(Each question carries 1 mark)
Question 1
Testosterone, Oestrogen, Progesterone, Pepsin
Answer
Pepsin
Explanation:
- Testosterone, Oestrogen, and Progesterone are hormones involved in reproduction.
- Pepsin is a digestive enzyme found in the stomach.
Question 2
Cardiac area, Fundus area, Pyloric area, Alveoli
Answer
Alveoli
Explanation:
- Cardiac area, Fundus area, and Pyloric area are parts of the stomach.
- Alveoli are air sacs in the lungs, involved in gas exchange.
Very Short Answer Type Questions
(Each question carries 1 mark)
Question 1
Which system is responsible for human breathing?
Answer
Respiratory system
Explanation: The respiratory system allows the intake of oxygen and the removal of carbon dioxide through breathing.
Question 2
What is the main function of skin?
Answer
Protection of the body
Explanation: The skin acts as a barrier protecting the body from germs, injury, and harmful UV rays, and also helps regulate temperature.
Question 3
Which system is responsible for digestion and assimilation of food?
Answer
Digestive system
Explanation: The digestive system breaks down food, absorbs nutrients, and removes waste.
Question 4
By whom food is absorbed from the intestine?
Answer
Villi
Explanation: Villi are finger-like projections in the small intestine that absorb nutrients from digested food.
Question 5
Through which system food and O₂ react, the body tissue?
Answer
Circulatory system
Explanation: The circulatory system transports food and oxygen to body tissues where they react to release energy.
Question 6
How many chambers are present in the heart of a man?
Answer
Four
Explanation: The human heart has 4 chambers – two atria (auricles) and two ventricles.
Question 7
What is the main function of reproduction?
Answer
To produce offspring
Explanation: Reproduction ensures the continuation of a species by producing new individuals.
Question 8
Which is the primary reproductive organ of a man and a woman?
Answer
Testis (in man) and Ovary (in woman)
Explanation: Testes produce sperm and testosterone; ovaries produce eggs and hormones like oestrogen and progesterone.
Question 9
Which system controls the function of all other organs and systems of the body?
Answer
Nervous system
Explanation: The nervous system controls and coordinates the activities of all other systems through the brain, spinal cord, and nerves.
Short Answer Type Questions (SA)
(Each question carries 2 marks)
Question 1
Name two glands situated in the skin. Mention its function.
Answer
The two glands situated in the skin are
- Sweat glands – Help in temperature regulation by releasing sweat.
- Sebaceous glands – Secrete sebum (oil) to keep the skin and hair moisturized and protected.
Question 2
Name the fibrils which are responsible for muscle movement.
Answer
Actin and Myosin
Explanation: These are protein filaments in muscle fibers that slide past each other to cause muscle contraction.
Question 3
Name two types of skeletons present in the body.
Answer
The two types of skeletons present in the body are
- Axial skeleton – Includes skull, vertebral column, and rib cage.
- Appendicular skeleton – Includes limbs and girdles (shoulder and pelvic girdles).
Question 4
What is hormone?
Answer
Hormones are chemical messengers secreted by endocrine glands that regulate various body functions like growth, metabolism, and reproduction.
Question 5
Name two types of skeletons present in the body.
Answer
The two types of skeletons present in the human body are:
- Axial Skeleton – It forms the central axis of the body and includes the skull, vertebral column, and rib cage.
- Appendicular Skeleton – It includes the limbs and girdles (shoulder girdle and pelvic girdle) that are attached to the axial skeleton.
Question 6
Name the artery which carries deoxygenated blood.
Answer
Pulmonary artery
Explanation: It is the only artery that carries deoxygenated blood from the heart to the lungs for oxygenation.
Question 7
Name the primary sex organs of a male. Where are they situated?
Answer
Testes is the primary sex organs of a male.
Situated in the scrotum, outside the abdominal cavity.
Question 8
Name two important digestive glands associated with digestive tract.
Answer
The two important digestive glands associated with digestive tract are
- Liver – Produces bile for fat digestion.
- Pancreas – Secretes digestive enzymes and hormones like insulin.
Question 8
What is diaphragm? Mention its function.
Answer
The diaphragm is a dome-shaped muscular structure that separates the chest cavity from the abdominal cavity.
Function: It plays a key role in breathing by contracting and relaxing to allow inhalation and exhalation.
Long Answer Type Questions
(Each question carries 5 marks)
Question 1
Name the process of digestion by pancreatic enzymes.
Answer
The process of digestion by pancreatic enzymes is known as chemical digestion. In this process, the pancreas plays a vital role by secreting digestive enzymes into the duodenum, the first part of the small intestine. These enzymes include amylase, which breaks down carbohydrates into simple sugars; trypsin, which breaks down proteins into smaller peptides; and lipase, which breaks down fats into fatty acids and glycerol. These enzymes act on the partially digested food received from the stomach and help in converting it into simpler forms that can be easily absorbed by the intestinal walls. This enzymatic activity ensures the complete and efficient digestion of food in the small intestine.
Question 2
Describe the structure of skin of man and its function.
Answer
The skin of man is the largest organ of the human body and has a layered structure. It consists of three main layers:
- Epidermis – This is the outermost layer made up of several sub-layers of cells. The topmost part, called the stratum corneum, contains dead cells that are constantly shed and replaced. The lower part of the epidermis contains living cells that divide and move upwards. It also includes melanin-producing cells, which give skin its color and protect against harmful UV rays.
- Dermis – Located beneath the epidermis, this thicker layer contains blood vessels, nerve endings, sweat glands, sebaceous (oil) glands, and hair follicles. It provides strength and elasticity to the skin due to the presence of collagen and elastin fibers.
- Hypodermis (Subcutaneous layer) – This innermost layer is made of fat and connective tissue, which helps in cushioning internal organs and insulating the body.
Functions of Skin:
- Skin protect us from mechanical injury, harmful microorganisms, and UV radiation.
- Skin regulates the body temperature through sweat and blood flow.
- Skin helps in excretion of waste products like urea and salts through sweat.
Question 3
Respiration can be divided into two processes, name them. Describe the mechanism of breathing in human beings.
Answer
Respiration can be divided into two main processes:
- External respiration – The exchange of gases between the lungs and the environment (atmosphere). Oxygen is taken in, and carbon dioxide is expelled.
- Internal respiration – The exchange of gases between the blood and the body’s cells. Oxygen is delivered to cells, and carbon dioxide is collected as a waste product.
Mechanism of Breathing in Human Beings:
The process of breathing includes two phases — inhalation and exhalation.
Inhalation (Inspiration):
- During inhalation, the diaphragm contracts and moves downward, while the intercostal muscles (between the ribs) contract to raise the rib cage. This increases the volume of the chest cavity, lowering the air pressure inside the lungs. As a result, air flows into the lungs from the outside (where the pressure is higher) to equalize the pressure.
Exhalation (Expiration):
- During exhalation, the diaphragm relaxes and moves upward, and the intercostal muscles relax, causing the rib cage to fall. This decreases the volume of the chest cavity and increases the pressure inside the lungs. As a result, air is pushed out of the lungs.
