Samacheer Kalvi 9th Science Solutions Chapter 20 Pdf

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Chapter 20
Organ systems in animals

Exercise

I. Choose the correct answer.

1) Which of the following is not a salivary gland?
a. Sublingual
b. Lachrymal
c. Submaxillary
d. Parotid
Ans: b. Lachrymal
Because, lachrymal glands are responsible for secretion of tears.

2) Stomach of human beings mainly digests __________
a. carbohydrates
b. proteins
c. fat
d. sucrose
Ans: b. proteins
Because, gastric glands are present in the inner walls of the stomach which secretes gastric juice. And gastric juice contains pepsin which plays an important role in digestion of proteins into peptides and amino acids.

3) To prevent the entry of food into the trachea, the opening is guarded by ____________
a. epiglottis
b. glottis
c. hard palate
d. soft palate
Ans: a. epiglottis
Because, during swallowing, the epiglottis which is a muscular flap like structure at the tip of glottis, beginning of trachea closes and prevents the food from entering into trachea i.e. wind pipe.

4) Bile helps in the digestion of _____________
a. proteins
b. sugar
c. fats
d. carbohydrates
Ans: c. fats
Because, bile salts helps in digestion of fats by bringing about their emulsification.

5) The structural and functional unit of the kidney is _____________
a. villi
b. liver
c. nephron
d. ureter
Ans: c. nephron
Because, nephrons or uriniferous tubules are the structural and functional units of kidney.

6) Which one of the following substance is not a constituent of sweat?
a. Urea
b. Protein
c. Water
d. Salt
Ans: b. Protein
Because, all other options are the constituents of sweat.

7) The common passage meant for transporting urine and sperms in male is ______
a. ureter
b. urethra
c. vas deferens
d. scrotum
Ans: b. urethra
Because, urethra is the only common passage meant for transporting urine and sperms in male.

8) Which of the following is not a part of female reproductive system?
a. Ovary
b. Uterus
c. Testes
d. Fallopian tube
Ans: c. Testes
Because, testes is the part of male reproductive system.

II. Fill in the blanks.

1) The opening of the stomach into the intestine is called ________
Ans: The opening of the stomach into the intestine is called duodenum.

2) The muscular and sensory organ which helps in mixing the food with saliva is ________.
Ans: The muscular and sensory organ which helps in mixing the food with saliva is tongue.

3) Bile, secreted by liver is stored temporarily in __________.
Ans:Bile, secreted by liver is stored temporarily in the gall bladder.

4) The longest part of alimentary canal is ____________
Ans:The longest part of alimentary canal issmall intestine.

5) The human body functions normally at a temperature of about ________.
Ans:The human body functions normally at a temperature of about 37oC.

6) The largest cell in the human body of a female is _________.
Ans:The largest cell in the human body of a female isan ovum.

III) State whether true or false. If false, correct the statement.

1) Nitric acid in the stomach kills microorganisms in the food.
Ans: False
Correct statement: hydrochloric acid in stomach kills the bacteria swallowed along with the food and makes the medium acidic.

2) During digestion, proteins are broken down into amino acids.
Ans: True
Because, gastric juice contains pepsin which plays an important role in digestion of proteins into peptides and amino acids.

3) Glomerular filtrate consists of many substances like amino acids, vitamins, hormones, salts, glucose and other essential substances.
Ans: True

IV. Match the following.
Ans:

Skin: Sweat

Lungs: Carbon dioxide

Intestine: Undigested food

Kidneys: Urine

V) Differentiate the following.

a) Excretion and Secretion
Ans:

Excretion is the process in which waste materials are removed from the body of living organisms.
And secretion is the only movement of some materials within the body and they are secreted from cells, organs or glands for specific functions inside the body.
Excretion involves the removal of wastes like urine, sweat, carbon dioxide while secretion involves the secretion and movement of harmonies and enzymes.

b) Absorption and Assimilation
Ans:

Absorption is the process by which nutrients are obtained after digestion are absorbed by villi and circulated throughout the body by blood and lymph and finally supplied to all body cells according to their requirements.
Assimilation means the incorporation of the absorbed food materials into tissue cells as their internal and homogeneous components.

C) Ingestion and Egestion
Ans:

The process of nutrition begins with intake of food called as ingestion.
The undigested and unassimilated part of the ingested food material is thrown out from the body through anal aperture as a faecal matter. This process is called as egestion or defaecation.

d) Diphyodont and Heterodont
Ans:

In human being two sets of teeth are developed in their lifetime, which are called as Diphyodont.
And permanent teeth are of four types, which are called as Heterodont.

e) Incisors and Can
Ans:

Incisors are the types of teeth which are 8 in number and their function is cutting and biting.
Canines are the types of teeth which are 4 in number and their function is tearing and piercing.

VI. Answer briefly.

1) How is the small intestine designed to absorb digested food?
Ans:

The small intestine is the longest part of the alimentary canal which is a long coiled tube measuring about 5-7m.
It is made up of three parts that are duodenum, jejunum and ileum.
Duodenum is the C- shaped and it receives bile duct from liver and pancreatic duct from pancreas.
Jejunum is the middle part of small intestine and it is short region of small intestine.
The secretion of small intestine is intestinal juice which involves enzymes like sucrase, maltase, lactase and lipase.
Ileum is the lower part of small intestine which opens into the large intestine. Ileum is the longest part of the small intestine. It has minute finger like projections called as villi where the absorption of food takes place.
The small intestine serves for both digestion and absorption. It receives bile from liver and pancreatic juice from pancreas in the duodenum.

2) Why do we sweat?
Ans:

Skin is the outermost covering of the body. It stretches all over the body in the form of a layer. There are many structures and glands derived from the skin. It eliminates metabolic waste through perspiration.
The human body functions normally at a temperature of about 37°C. When the body becomes hotter sweat glands starts secreting sweat. Sweat is in the form of water with some chemicals like ammonia, urea, lactic acids and salts.
The sweat passes through the pores in the skin and get evaporated.
In this way, to maintain body temperature sweat glands secrete sweat.

3) Mention any two vital functions of human kidney.
Ans:

The kidneys are bean shaped organs reddish brown in colour. The kidneys are located on the either side of vertebral column in the abdominal cavity attached to the dorsal body wall.
The main vital functions of kidney are as follows:
It maintains fluid and electrolytes balance in the body.
Also it regulates acid base balance of the blood
It maintains osmotic pressure in the blood and tissues.
It helps to retain important plasma constituents like glucose and amino acids.

4) What is micturition?
Ans:

Each kidney consists of more than one million nephrons or uriniferous tubules which are the structural and functional units of the kidney. Each nephron consist of renal corpuscle or Malpighian corpuscle and renal tubule.
Substances such as K+ or H+ are secreted into the tubule. This tubular filtrate is finally known as urine, which is hypertonic in man. Finally the urine passes into collecting ducts to the pelvis and through the ureter into the urinary bladder.
When the urinary bladder is full urine is expelled out through the urethra. This process is called micturition.

5) Name the types of teeth present in an adult human being. Mention the functions of each.
Ans:

Teeth are hard structures meant for holding, cutting, grinding and crushing the food.
In human being two sets of teeth are developed in their lifetime called as Diphyodont.
Permanent teeth are of four types which are called as Heterodont.
According to their structures and functions they are named as incisors, canines, premolars and molars.
Incisors are the teeth 8 in number and their function is cutting and biting.
Canines are the type of teeth which are 4 in number and their function is tearing and piercing.
Premolars are the type of teeth which are 8 in number and their function is crushing and grinding.
Molars are the type of teeth which are 12 in number and their function is crushing, grinding and mastication.

6) Explain the structure of nephron.
Ans:

Each kidney consists of a millions of nephrons or uriniferous tubules which are the structural and functional units of the kidney.
Each nephron consist of renal corpuscle or Malpighian corpuscle and renal tubule.
The renal corpuscle consist of cup shaped structure called as Bowman’s capsule containing a bunch of capillaries called glomerulus.
Blood enters the glomerular capillaries through afferent arterioles and leaves out through the efferent arterioles.
The Bowman’s capsule continues as the renal tubule which consist of regions proximal convoluted tubule, U shaped hairpin loop, the loop of Henle and the distal convoluted tubule.
The nitrogenous wastes are drained into renal pelvis which leads to ureter and stores in the urinary bladder.
Urine is expelled out through the urethra.

Fig. Structure of Nephron

VII. Answer in detail.

1. Describe the alimentary canal of man
Ans:
Alimentary canal is the passage starting from mouth and ending with the anus. It is the muscular, coiled tubular structure consisting of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine and anus.

Fig. Human Digestive System showing alimentary canal

Mouth:

Mouth leads into the buccal cavity and it is bounded by two soft movable upper and lower lips. Buccal cavity is the large space bound above by the palate and below by the throat and on the sides by the jaws which bear teeth.
Teeth:

Teeth

are hard structures meant for holding, cutting, grinding and crushing the food.
In human being two sets of teeth are developed in their lifetime called as Diphyodont.
Permanent teeth are of four types which are called as Heterodont.
According to their structures and functions they are named as incisors, canines, premolars and molars.
Incisors are the teeth 8 in number and their function is cutting and biting.
Canines are the type of teeth which are 4 in number and their function is tearing and piercing
Premolars are the type of teeth which are 8 in number and their function is crushing and grinding.
Molars are the type of teeth which are 12 in number and their function is crushing, grinding and mastication.
Three types of salivary glands are present in the mouth cavity. This are parotid glands, sublingual glands and submaxillary glands.

Toungue:

The toungue is the muscular sensory organ which helps in mixing the food with saliva. The taste buds on the toungue helps in recognising the taste of the food.
During swallowing, the epiglottis closes and prevents the food entering into the trachea.

Pharynx:

It is a membrane lined cavity behind the nose and mouth, connecting them to oesophagus.
It serves as a pathway for the movement of the food from mouth to oesophagus.

Oesophagus:

It is the food pipe which muscular membranous canal about 22cm in length. It conducts food from pharynx to stomach by peristalsis.

Stomach:

It is a wide, muscular J shaped organ located between oesophagus and small intestine.
The gastric glands present in the inner walls of the stomach secrets gastric juice which is colourless, highly acidic and contains mucus, hydrochloric acid and enzymes renin and pepsin.

Small intestine:

The small intestine is the longest part of the alimentary canal which is a long coiled tube measuring about 5-7m. It is made up of three parts that are duodenum, jejunum and ileum.
Duodenum is the C- shaped and it receives bile duct from liver and pancreatic duct from pancreas.
Jejunum is the middle part of small intestine and it is short region of small intestine.
The secretion of small intestine is intestinal juice which involves enzymes like sucrase, maltase, lactase and lipase.
Ileum is the lower part of small intestine which opens into the large intestine. Ileum is the longest part of the small intestine. It has minute finger like projections called as villi where the absorption of food takes place.
The small intestine serves for both digestion and absorption. It receives bile from liver and pancreatic juice from pancreas in the duodenum.

Liver:

It is the largest digestive gland of the body which is reddish brown in colour. It is divided into two main lobes that are right and left lobes.
On the under surface of the liver gall bladder is present. The liver cells secrets bile which is temporarily stored in the gall bladder. Bile is reduced into the small intestine when food enters into it.
Bile salts helps in the digestion of fats.
The functions of liver are controls blood sugar and amino acid level, synthesize foetal red blood cells, and destroy red blood cells, stores iron, copper, vitamin A and D.
Also excretes toxic and metallic poisons.

Pancreas:

It is lobed, leaf shaped gland situated between stomach and duodenum.
Pancreas acts both as an exocrine gland and as an endocrine gland. The exocrine part of the pancreatic glands secretes pancreatic juice which contains three enzymes lipase, trypsin and amylase which acts on fats, proteins and starch respectively.
The excess sugars are converted into a complex polysaccharide and glycogen in the liver.

Large intestine:

The unabsorbed and undigested food is passed into the large intestine and it extends from ileum to anus.
It is about 1.5 m in length and has three parts caecum, colon and rectum.
The caecum is the small blind pouch like structure situated at the junction of the small and large intestine.
The colon is much broader than ileum and it passes up the abdomen on the right, crosses to the left just below the stomach and down on the left side.
The rectum is the last part which opens into the anus and which is kept closed by the ring of muscles called anal sphincter which opens when passing stools.
The undigested or unassimilated portion of the injested food material is thrown out from the body through the anal apereture as farcal matter. This process is called as egestion.

2. Explain the structure of kidney and the steps involved in the formation of urine
Ans:

Kidneys are bean shaped organs reddish brown in colour. Kidneys lie on the either side of vertebral column in the abdominal cavity attached to the dorsal body wall. The right kidney is placed lower than the left kidney as liver takes up much space on the right side.
Each kidney is about 11cm long, 5 cm wide and 3 cm thick.
The kidney is covered with a layer of fibrous connective tissue, the renal capsules, adipose capsule and a fibrous membrane.
Internally, kidney consists of an outer dark region called as cortex and inner lighter region called as medulla.
Both these region contains uriniferous tubules or nephrons.
On the inner concave side of each kidney, a notch called hilum is present through which blood vessels and nerves enter in and urine leaves out through ureter.

Fig. Longitudinal section of Human Kidney

Ureters:

Ureters are thin muscular tubes emerging out from hilum. Urine enters the ureter form the renal pelvis and is conducted along the ureter by peristaltic movements of its walls. Ureters carry urine from kidney to urinary bladder.

Urinary bladder:

Urinary bladder is a sac like structure, which lies in the pelvic cavity of the abdomen. It stores urine temporarily.

Urethra:

Urethra is a membranous tube which conducts urine to the exterior. The urethral sphincters keep the urethra closed and opens only at the time of urination.
There are many functions of kidney which are as follows:
Maintains fluid and electrolyte balance in our body.
Regulates acid base balance of blood.
Maintains osmotic pressure in blood and tissues.
It helps to retain plasma constituents like glucose and amino acid.

Structure of Nephron:

Each kidney consists of a millions of nephrons or uriniferous tubules which are the structural and functional units of the kidney.
Each nephron consist of renal corpuscle or Malpighian corpuscle and renal tubule.
The renal corpuscle consist of cup shaped structure called as Bowman’s capsule containing a bunch of capillaries called glomerulus.
Blood enters the glomerular capillaries through afferent arterioles and leaves out through the efferent arterioles.
The Bowman’s capsule continues as the renal tubule which consist of regions proximal convoluted tubule, U shaped hairpin loop, the loop of Henle and the distal convoluted tubule.
The nitrogenous wastes are drained into renal pelvis which leads to ureter and stores in the urinary bladder.

3) Urine is expelled out through the urethra.

Fig. Structure of Nephron

The process of urine formation involves three steps that are namely glomerular filtration, tubular reabsorption and tubular secretion.

Glomerular filtration:

Urine formation begins with the filtration of blood through epithelial walls of glomerulus and Bowman’s capsule. And the filtrate formed is called glomerular filtrate.

Tubular reabsorption:

The filtrate in the proximal tubule consist of essential substances such as glucose, amino acids, vitamins, sodium, potassium, bicarbonates and water which are reabsorbed into the blood by the process of selective reabsorption.

Tubular secretion:

Substances such H+ or K+ ions are secreted into the tubule and this tubular filtrate is finally called as urine which is hypertonic in man.
Finally the urine is passes into collecting ducts to the pelvis and through the ureter into the urinary bladder. When the urinary bladder is full, the urine is expelled out through the urethra. This process is called as micturition.

VIII. Assertion and reason type questions. Mark the correct answer as:

a. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
b. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
c. If Assertion is true but Reason is false.
d. If both Assertion and Reason are false.
1) Assertion: Urea is excreted out through the kidneys.
Reason: Urea is a toxic substance.
Ans: a. if both Assertion and Reason are true and Reason is the correct explanation of Assertion.

2) Assertion In both the sexes gonads perform dual function.
Reason: Gonads are also called primary sex organs.
Ans:a. if both Assertion and Reason are true and Reason is the correct explanation of Assertion.

IX) Higher Order Thinking Skills

1) If pepsin is lacking in gastric juice, then which event in the stomach will be affected?
a. digestion of starch into sugars.
b. breaking of proteins into peptides.
c. digestion of nucleic acids.
d. breaking of fats into glycerol and fatty acids.
Ans: b. breaking of proteins into peptides.
Because, pepsin play an important role in digestion of protein into peptides and amino acids, and this is absorable form which is absorbed by small intestine. So due to lack of pepsin the event breaking of proteins into peptides in the stomach will be affected.

2) Name the blood vessel that
(a) Enter malphigian capsule and
(b) Leaves malphigian capsule.
Ans:
Urinary bladder is the only one vessel which enters Malpighian capsule and leaves Malpighian capsule.

3) Why do you think that urine analysis is an important part of medical diagnosis?
Ans:

Urine analysis is the important part of medical diagnosis because it is the excreted part from the body and contains most of the water and urea, sodium, potassium, chloride, dissolved ions and other constituents also.
When we have any problem related to health, then the percentage or level of this constituents in the urine also changes. So it makes easy to diagnose the issue.
The problems like urinary tract infections, kidney problems, and sugar problems are diagnosed or detected by urine analysis.

4) Why your doctor advises you to drink plenty of water?
Ans:

Doctor advices us to drink plenty of water, because of it kidney functions becomes normal and urine formation increases which flush out the toxins from body through urine.
More intake of water increases energy level of our body and also brains functions.
Due to more water drinking, the body works properly and which prevents from all diseases.
Also the problems related to head like headache will be diagnosed.
Due to the more water drinking the diseases like kidney stones also cured easily.
In short, in our body immunity and physical activity water plays most important role.
So we have to drink plenty of water daily.

5) Can you guess why there are sweat glands on the palm of our hands and the soles of our feet?
Ans:

Skin is the outermost covering of the body. It stretches all over the body in the form of a layer. There are many structures and glands derived from the skin. It eliminates metabolic waste through perspiration.
The human body functions normally at a temperature of about 37°C. When the body becomes hotter sweat glands starts secreting sweat. Sweat is in the form of water with some chemicals like ammonia, urea, lactic acids and salts.
The sweat passes through the pores in the skin and get evaporated.
In this way, to maintain body temperature sweat glands secrete sweat.
Thus, body temperature is regulated through sweating.
But, mostly palm of our hands and soles of our feet be in contact with or exposed to microbes and to avoid their infection to any organ of our body sweat glands are present on them.
Because palm of our hands and soles of our feet are mostly in contact with other objects than other body parts.

X. Match the parts of the given figure with the correct option.
Ans:

Here is your Solution of Samacheer Kalvi 9th Science Chapter 20 ORGAN SYSTEMS IN ANIMALS

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Samacheer Kalvi 9th Science Solutions Chapter 20 Pdf