Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 2.4 Major Organs of Human Body and Their Function offer valuable context and analysis.
WBBSE Class 9 Science Chapter 2.4 Question Answer – Major Organs of Human Body and Their Function
Very Short Questions and Answers : (1 mark for each question)
Which two layers constitute our skin?
Epidermis and hypodermis constitute our skin.
Which is the largest sense organ of our body?
Skin is the largest sense organ of our body.
Which organ of our body carries the sensory cells for perception of heat and pressure?
Skin of our body carries the sensory cells for perception of heat and pressure.
Which organ of our body can store the food for some time during digestion?
Stomach of our body can store the food for some time during digestion.
Which gland of human body is called a mixed gland?
Pancreas is called the mixed gland.
Which organ of the human digestive system acts as the killing field for most of the microbes, taken with food?
Stomach of human digestive system acts as the killing field for most of the microbes, which are taken with food.
Besides killing germs within the consumed food, what other function does HCl do inside stomach?
Besides killing germs within the consumed food, HCl activates pepsinogen into pepsin inside the stomach.
Name the paired organs which are protected by ribbones from all sides.
The lungs are the paired organs which are protected by ribbones from all sides.
Name the organ of human body which helps in neutralising the acidic food mass, coming into duodenum from the stomach.
Liver, of our body secretes bile, which neutralises the acidic food mass, coming into duodenum from the stomach.
Which organ is located just below the stomach at the left side of the abdomen?
The organ located just below the stomach at the left side of the abdomen is the spleen.
Name the largest gland of human body which is composed of densely packed tissues.
Liver is the largest gland of human body composed of densely packed tissues.
Name a highly extensible sac-like structure located at the left side of the upper abdomen.
Stomach is a highly extensible sac-like structure located at the left side of the upper abdomen.
Which organ removes dead RBCs from blood?
Spleen removes dead RBCs from the blood.
This elongated cord-like structure acts as the centre for reflex action of our body. What is it?
Spinal cord is the elongated cord-like structure, which acts as the centre for reflex action of our body.
The lumen of which organ always remains in acidic state?
The lumen of stomach always remains in acidic state.
Which two organs of our body contract and expand continuously throughout our lives?
Heart and lungs contract and expand continuously throughout our lives.
Which organ of our body remains protected in a roundish bony case known as cranium?
Brain remains protected in a roundish bony case known as the cranium.
Which paired structures keep our blood clean from metabolic wastes?
The kidneys keep our blood clean from metabolic wastes.
Name the organ of our body, through which blood passes along two different paths.
Heart is the organ of our body, through which blood passes along two different paths.
What is the position of heart in human body?
Hear is located in the chest cavity, in between the two lungs, slightly inclined towards the left.
Name the cells from which testosterone is secreted inside the testes of male.
Testosterone is secreted from the leydig cells of the testes in male.
Name two hormones secreted by the corpus luteum in female.
Two hormones secreted by the corpus luteum in female, are oestrogen and progesterone.
What is the process of production of ovum called?
The process of production of ovum is called oogenesis.
Short Questions and Answers : (2 marks for each question)
What is meant by organ?
An organised group of various specialised tissues which carry out a specific function of the body, is called an organ. Example-Heart, brain etc.
Mention the functions of skin of our body.
The functions of skin are as follows-
- Skin protects our body from mechanical injuries.
- Enzymes and salts, secreted through sweat, kill bacteria and other germs.
- Sensory cells in skin help us to feel heat, touch, pressure etc.
- Skin absorbs sun rays to synthesise vitamin D for the body.
What is a sebaceous gland?
The gland present in the dermis layer of the skin, that secretes an oily substance called sebum, which keeps the skin smooth, is called the sebaceous gland.
Mention the function of human heart.
The functions of human heart are as follows —
- Pumping of heart helps the blood to flow through blood vessels of the body.
- It drives oxygenated blood from left ventricle through systematic circulation to different organs and tissues of the body.
- Deoxygenated blood from right ventricle goes out to lungs through pulmonary circulation.
- Heart receives deoxygenated and oxygenated blood into its right auricle and left auricle respectively.
Name a hormone and the major enzyme secreted by the stomach.
Gastrin is a hormone secreted by the stomach and pepsin is the major enzyme secreted by the stomach.
Mention the location and function of human lungs.
Location: The two lungs are situated at the two sides of chest cavity within the rib cage.
- Lungs help in the intake of O2 rich air by inspiration and expulsion of CO2 rich air by expiration.
- Lungs also help in the excretion of few other toxic materials by expiration.
Name the two major blood vessels of the kidney and name the protective layer of kidney.
The two major blood vessels of the kidney are the renal vein and renal artery and the protective layer of kidney is called capsule.
Mention the functions of the human brain.
The functions of human brain are as follows —
- Brain processes all sensory informations like vision, smell, hearing, taste, touch etc. and generate responses accordingly.
- It acts as the centre for memory, intelligence, thinking and all other mental activities.
- Coordination among all organs of our body and their activities are maintained by the brain.
What is spinal cord? Mention the functions of spinal cord.
Spinal cord: The long, hollow, cylindrical structure extending from the posterior parts of medulla oblongata upto first lumber vertebra in the neural canal of vertebral column, is known as spinal cord.
- Spinal cord receives the nerve impulses from brain and conducts it to the muscles and visceral organs.
- Spinal cord controls different types of unconditioned reflexes.
Long Questions and Answers : (5 marks for each question)
Describe the location of human stomach. Mention its functions.
Location of human stomach
Stomach is situated on the left side of the upper abdomen, just below the muscular diaphragm.
Functions of human stomach
The functions of human stomach are as follows-
- Stomach is a large ‘J’ shaped sac-like structure that receives food from the oesophagus, stores it for some time and acts as a site of digestion of protein and fat.
- HCl, secreted from the oxyntic cells of stomach, helps in activating the gastric enzymes.
- Activated pepsin, present in gastric juice, acts upon proteins to break it into smaller derivatives, called peptones.
- Lipase, present in gastric juice, helps in the hydrolysis of fat.
- As the pH inside the stomach is acidic, microbes find it difficult to survive within it. Therefore, most microbes of the digestive flora remain within the gut and not in the stomach.
Mention the location of human liver. Mention its functions.
Location of human liver
Liver is present on the right ventral side of upper abdomen, just below the diaphragm.
Functions of human liver:
The functions of human liver are as follows-
- Liver secretes bile, which neutralises the acidic contents of the stomach.
- Bile salts emulsify fat and help in its digestion.
- Liver primarily absorbs nutrients from blood before supplying it to different parts of the body.
- It acts as the site of several metabolic activities.
- Urea is synthesised within the liver.
- Liver detoxifies various harmful components of the blood, like urea.
- It helps in the synthesis of blood-coagulating components like prothrombin, fibrinogen, etc.
Mention the location and functions of human kidney. Mention the location and functions of the pancreas in the human body.
Location of kidney
Kidneys are held at the back wall of abdominal cavity on either sides of the vertebral column. Right kidney is positioned slightly lower than the left one.
Functions of kidneys
The functions of kidneys are as follows-
- Formation of urine by filtration of blood.
- Maintains the water and electrolyte balance of our body.
- Regulates blood pressure by secretion of renin.
- Controls formation of RBC by secretion of erythropoietin.
Location of pancreas : Pancreas is located transversely on the posterior side of the abdomen, extending from the duodenum to the spleen.
Functions of pancreas
The functions of pancreas are as follows-
- It secretes different digestive enzymes for the digestion of proteins, carbohydrates and fats. The enzymes are trypsin, amylase and lipase.
- The pancreas produces essential hormones like insulin, glucagon and somatostatin in the body.
Mention the location of spleen in human body. Mention the functions of spleen.
Location of spleen : Spleen of human body is located on the upper far left side of the abdomen, below the left side of the stomach.
Functions of spleen
The functions of spleen are mentioned below.
- In embryonic state, spleen acts as the site of RBC formation.
- In adults, it produces lymphocytes (B-cells and T-cells) to help the proper functioning of immune system.
- Spleen separates out and removes damaged, inactive and aged RBC from the blood stream.
- It stores large quantity of RBC and leucocytes and releases it into the blood stream according to the need of the body.
What is ovary? Mention the position of human ovary and its functions.
Ovary: The primary sex organ or gonad of female body is called ovary.
Location of human ovary:
Human ovaries are located at the two sides of lower abdominal cavity in females. Each ovary is an almond shaped structure, which is held in the abdominal wall with a thin membranous structure, a fibrous cord, known as the ovarian ligament.
Functions of human ovary:
The functions of human ovary are mention below.
- Several primordial germ cells are present in the ovary, which ultimately mature as ovum or female reproductive cells.
- Ovary secretes hormones like oestrogen and progesterone. These two female hormones help to maintain the feminine features and reproductive cycle in female.
- Hormone relaxin, secreted from the ovary, facilitates labour during childbirth.
What is testis? Mention the location and functions of testis.
Testis : The primary sex organ or gonad of male body is called testis.
Location of testis
Human testis are paired structures, which are held in a sac-like structure, called scrotum, outside the lower abdomen in males. These are placed in between the penis and anus.
Functions of testis
The functions of testis are mentioned below.
- Male gametes (spermatozoa) are formed within the seminiferous tubules of testis.
- Spermatozoa are nourished and stored inside the testis.
- Testis secretes a hormone, named testosterone, which controls the development of masculine features like formation of beard, muscular body etc. in adult male. It also controls the maturity of spermatozoa.