Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals

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Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals

Samacheer Kalvi 9th Science Organ Systems in Animals Textbook Exercises

I. Choose the correct answer:

Question 1.
Which of the following is not a salivary gland?
(a) Sublingual
(b) Lachrymal
(c) Submaxillary
(d) Parotid
Answer:
(b) Lachrymal

Question 2.
Stomach of human beings mainly digests
(a) Carbohydrates
(b) Proteins
(c) Fat
(d) Sucrose
Answer:
(b) Proteins

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Question 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
Answer:
(a) Epiglottis

Question 4.
Bile helps in the digestion of
(a) Proteins
(b) Sugar
(c) Fats
(d) Carbohydrates
Answer:
(c) Fats

Question 5.
The structural and functional unit of the kidney is
(a) Villi
(b) Liver
(c) Nephron
(d) Ureter

Question 6.
Which one of the following substances is not a constituent of sweat?
(a) Urea
(b) Protein
(c) Water
(d) Salt
Answer:
(b) Protein

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Question 7.
The common passage meant for transporting urine and sperms in male is
(a) Ureter
(b) Urethra
(c) Vas deferens
(d) Scrotum
Answer:
(b) Urethra

Question 8.
Which of the following is not a part of female reproductive system?
(a) Ovary
(b) Uterus
(c) Testes
(d) fallopian tube
Answer:
(c) testes

II. Fill in the blanks.

  1. The opening of the stomach into the intestine is called …………………
  2. The muscular and sensory organ which helps in mixing the food with saliva is ………………….
  3. Bile, secreted by liver is stored temporarily in ……………………
  4. The longest part of alimentary canal is ………………
  5. The human body functions normally at a temperature of about …………………..
  6. The largest cell in the human body of a female is ……………………

Answer:

  1. duodenum
  2. tongue
  3. the gall bladder
  4. small intestine
  5. 37°C
  6. an ovum

III. State whether the following statements are true or false. If false, correct the wrong statements:

  1. Nitric acid in the stomach kills microorganisms in the food – False
    Correct Statement: Hydrochloric acid kills the bacteria swallowed along with food.
  2. During digestion, proteins are broken down into amino acids – True
  3. Glomerular filtrate consists of many substances like amino acids, vitamins, hormones, salts, glucose, and other essential substances – True

IV. Match the following:

Organ Elimination
Skin a. Urine
Lungs b. Sweat
Intestine c. Carbon dioxide
Kidneys d. Undigested food

Answer:

  1. b. Sweat
  2. c. Carbon dioxide
  3. d. Undigested food
  4. a. Urine

V. Differentiate the following terms:

a. Excretion and Secretion
b. Absorption and Assimilation
c. Ingestion and Egestion
d. Diphyodont and Heterodont
e. Incisors and Canines
Answer:

a.

Excretion Secretion
The process of eliminating or expelling waste matter. a process by which substances are produced and discharged from a cell, gland, or organ for a particular function in the organism or for excretion.

b.

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

c.

Ingestion Egestion
The process of nutrition begins with intake of food, called ingestion. The undigested or unassimilated portion of the ingested food material is thrown out from the body through the anal aperture as faecal matter. This is known as egestion.

d.

Diphyodont Heterodont
In human beings two sets of teeth (Diphyodont) are developed in their life time. Permanent teeth are of four types (Heterodont).

e.

Incisors Canines
Type of teeth used for cutting and biting foods. Type of teeth used for tearing and piercing of food.

VI. Answer briefly:

Question 1.
How is the small intestine designed to absorb digested food?
Answer:
Small intestine comprises three parts- duodenum, jejunum and ileum. Ileum is the longest part of the small intestine. It contains minute finger like projections called villi where absorption of food takes place. They are approximately 4 million in number. Internally, each villus contains fine blood capillaries and lacteal tubes.

SamacheerKalvi.Guru

Question 2.
Why do we sweat?
Answer:
Sweat palys an important role in maintaining body temperature. The human body functions normally at a temperature of about 37°C. When it gets hot sweat glands start secreting sweat, which contains water with small amounts of other chemicals like ammonia, urea, lactic acid and salts. This helps in cooling the body.

Question 3.
Mention any two vital functions of the human kidney.
Answer:
Two vital functions of the kidneys are;

  1. Maintain the fluid and electrolyte balance in our body.
  2. Maintain the osmotic pressure in blood and tissues.

Question 4.
What is micturition?
Answer:
When the urinary bladder is full the urine is expelled out through the urethra. This process is called micturition.

Question 5.
Name the types of teeth present in an adult human being. Mention the functions of each.
Answer:
Types of teeth and their functions

Types of teeth Functions
Incisors Cutting and biting
Canines Tearing and piercing
Premolars Crushing and grinding
Molars Crushing, grinding and mastication

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Question 6.
Explain the structure of nephron.
Answer:
Each kidney consists of more than one million nephrons. Nephrons or uriniferous tubules are structural and functional units of the kidneys. Each nephron consists of Renal corpuscle or Malphigian corpuscle and renal tubule. The renal corpuscle consists of a cup-shaped structure called Bowman’s capsule containing a bunch of capillaries called glomerulus.

Blood enters the glomerular capillaries through afferent arterioles and leaves out through efferent arterioles. The Bowman’s capsule continues as the renal tubule which consists of three regions proximal convoluted tubule, U-shaped hairpin loop, the loop of Henle and the distal convoluted tubule. The distal convoluted tubule which opens into the collecting tubule. The
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 1

VII. Answer in detail.

Question 1.
Describe the alimentary canal of man.
Answer:
Alimentary canal (digestive tract/gastro-intestinal tract):
The glands associated with the digestive system are the salivary glands, gastric glands, pancreas, liver and intestinal glands.

Structure of the Alimentary Canal:
Alimentary canal is a muscular coiled, tubular structure. It consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine (consisting of duodenum, jejunum and ileum), large intestine (consisting of caecum, colon and rectum) and anus.
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 2
Mouth: The mouth leads into the buccal cavity. It is bound by two soft, movable upper and lower lips. The buccal cavity is a large space-bound above by the palate (which separates the windpipe and food tube), below by the throat and on the sides by the jaws. The jaws bear teeth.

Teeth: Teeth are hard structures meant for holding, cutting, grinding and crushing the food. In human beings, two sets of teeth (Diphyodont) are developed in their lifetime. The first appearing set of 20 teeth called temporary or milk teeth are replaced by the second set of thirty-two permanent teeth, sixteen in each jaw. Each tooth has a root fitted in the gum (Theocodont). Permanent teeth are of four types (Heterodont), according to their structure and function namely incisors, canines, premolars, and molars.

Salivary glands: Three pairs of salivary glands are present in the mouth cavity. They are: parotid glands, sublingual glands and submaxillary or submandibular glands

  • Parotid glands are the largest salivary glands, which lie in the cheeks in front of the ears (in Greek Par – near; otid – ear).
  • Sublingual glands are the smallest glands and lie beneath the tongue.
  • Submaxillary or Submandibular glands lie at the angles of the lower jaw.
    The salivary glands secrete a viscous fluid called saliva, approximately 1.5 liters per day. It digests starch by the action of the enzyme ptyalin (amylase) in the saliva which converts starch (polysaccharide) into maltose (disaccharide). Saliva also contain an antibacterial enzyme called lysozyme.

Tongue: The tongue is a muscular, sensory organ which helps in mixing the food with the saliva. The taste buds on the tongue help to recognize the taste of food.

The masticated food in the buccal cavity becomes a bolus which is rolled by the tongue and passed through pharynx into the oesophagus by swallowing. During swallowing, the epiglottis (a muscular flap-like structure at the tip of the glottis, beginning of trachea) closes and prevents the food from entering into trachea (wind pipe).

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

Oesophagus or the food pipe is a muscular-membranous canal about 22 cm in length. It conducts food from pharynx to the stomach by peristalsis (wave-like movement) produced by the rhythmic contraction and relaxation of the muscular walls of alimentary canal.

Stomach is a wide J-shaped muscular organ located between oesophagus and the small intestine. The gastric glands present in the inner walls of the stomach secrete gastric juice. The gastric juice is colourless, highly acidic, containing mucus, hydrochloric acid and enzymes rennin (in infants) and pepsin.

Small intestine is the longest part of the alimentary canal, which is a long coiled tube measuring about 5 – 7 m. It comprises three parts- duodenum, jejunum and ileum.

  1. Duodenum is C-shaped and receives the bile duct (from liver) and pancreatic duct (from the pancreas).
  2. Jejunum is the middle part of the small intestine. It is a short region of the small intestine. The secretion of the small intestine is intestinal juice which contains enzymes like sucrase, maltase, lactase and lipase.
  3. Ileum forms the lower part of the small intestine and opens into the large intestine. Ileum is the longest part of the small intestine. It contains minute finger-like projections called villi (one millimeter in length) where absorption of food takes place. They are approximately 4 million in number. Internally, each villus contains fine blood capillaries and lacteal tubes.

The small intestine serves both for digestion and absorption. It receives

  • the bile from liver and
  • the pancreatic juice from pancreas in the duodenum. The intestinal glands secrete the intestinal juices.

Liver is the largest digestive gland of the body which is reddish brown in colour. It is divided into two main lobes, right and left lobes. The right lobe is larger than the left lobe. On the under surface of the liver, gall bladder is present. The liver cells secrete bile which is temporarily stored in the gall bladder.

Pancreas is a lobed, leaf shaped gland situated between the stomach and duodenum. Pancreas acts both as an exocrine gland and as an endocrine gland. The gland’s upper surface bears the islets of Langerhans which have endocrine cells and secrete hormones in which α (alpha) cells secrete glucagon and β (beta) cells secrete insulin.

The intestinal glands secrete intestinal juice called succusentericus which contains enzymes like maltase, lactase, sucrase and lipase which act in an alkaline medium. From the duodenum the food is slowly moved down to ileum, where the digested food gets absorbed

Large intestine
The unabsorbed and undigested food is passed into the large intestine. It extends from the ileum to the anus. It is about 1.5 meters in length. It has three parts- caecum, colon and rectum.

The caecum is a small blind pouch like structure situated at the junction of the small and large intestine. From its blind end a finger – like structure called vermiform appendix arises. It is a vestigeal (functionless) organ in human beings.

The colon is much broader than ileum. It passes up the abdomen on the right (ascending colon), crosses to the left just below the stomach (transverse colon) and down on the left side (descending colon).

The rectumis the last part which opens into the anus. It is kept closed by a ring of muscles called anal sphincter which opens when passing stools.

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Question 2.
Explain the structure of kidney and the steps involved in the formation of urine.
Answer:
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 3
Kidneys are bean-shaped organs reddish brown in colour. The kidneys lie on either side of the vertebral column in the abdominal cavity attached to the dorsal body wall. The right kidney is placed lower than the left kidney as the liver takes up much space on the right side. Each kidney is about 11 cm long, 5 cm wide and 3 cm thick. The kidney is covered by a layer of fibrous connective tissue, the renal capsules, adipose capsule and a fibrous membrane.

Internally the kidney consists of an outer dark region, the cortex and an inner lighter region, the medulla. Both of these regions contain uriniferous tubules or nephrons. The medulla consists of multitubular conical masses called the medullary pyramids or renal pyramids whose bases are adjacent to cortex. On the inner concave side of each kidney, a notch called hilum is present through which blood vessels and nerves enter in and the urine leaves out.

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

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

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 micturition (urination).

Functions of kidney:

  1. Maintain the fluid and electrolyte balance in our body.
  2. Regulate acid-base balance of blood.
  3. Maintain the osmotic pressure in blood and tissues.
  4. Help to retain important plasma constituents like glucose and amino acids.

Structure of Nephron
Each kidney consists of more than one million nephrons. Nephrons or uriniferous tubules are structural and functional units of the kidneys.
Each nephron consists of Renal corpuscle or Malphigian corpuscle and renal tubule. The renal corpuscle consists of a cup-shaped structure called Bowman’s capsule containing a bunch of capillaries called glomerulus. Blood enters the glomerular capillaries through afferent arterioles and leaves out through efferent arterioles.
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 4
The Bowman’s capsule continues as the renal tubule which consists of three regions proximal convoluted tubule, U-shaped hair pin loop, the loop of Henle and the distal convoluted tubule. The distal convoluted tubule which opens into the collecting tubule. The nitrogenous wastes are drained into renal pelvis which leads to ureters and stored in the urinary bladder. Urine is expelled out through the urethra.

Mechanism of Urine Formation
The process of urine formation includes the following three stages.

  • Glomerular filtration
  • Tubular reabsorption and
  • Tubular secretion

Glomerular filtration: Urine formation begins with the filtration of blood through epithelial walls of the glomerulus and Bowman’s capsule, The filtrate is called as the glomerular filtrate. Both essential and non-essential substances present in the blood are filtered.

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

Tubular secretion: Substances such as H+ or K+ ions are secreted into the tubule. Certain substances like potassium and a large number of drugs like penicillin and aspirin are passed into the filtrate in the distal convoluted 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 by urethral peristalsis (waves of constriction in the ureters.

The relaxation of sphincter muscles located at the opening of the urinary bladder into the urethra. When the urinary bladder is full the urine is expelled out through the urethra. This process is called micturition. A healthy person excretes one to two litres of urine per day.

VIII. Assertion and Reason.

Mark the correct answer.
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

Question 1.
Assertion: Urea is excreted out through the kidneys
Reason: Urea is a toxic substance.
Answer:
a. If both Assertion and Reason are true and Reason is the correct explanation of Assertion

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

XI. Match the parts of the given figure with the correct option.

Question 1.
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 5

1 2 3 4 5
a. Fallopian tube Oviduct Uterus Cervix Vagina
b. Oviduct Cervix Vagina Ovary Vas deferens
c. Ovary Oviduct Uterus Vagina Cervix
d. Fallopian tube Ovary Cervix Uterus Vagina

Answer:

  1. a. Fallopian tube,
  2. d. Ovary,
  3. d. Cervix,
  4. d. Uterus,
  5. a. Vagina

X. Higher Order Thinking Skills.

Question 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.
Answer:
kidney

Question 2.
Name the blood vessel that
a. enter Malpighian capsule and
b. leaves the Malpighian capsule.
Answer:
urinary bladder

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Question 3.
Why do you think that urine analysis is an important part of medical diagnosis?
Answer:
Urine is excreted from the human body which constitutes of mote than 95% water and other constituents like urea, chloride, sodium, potassium, creatinine and other dissolved ions, and inorganic and organic compounds. When there is an illness or disease, the constituents and its levels in urine also changes.

Therefore urinalysis is also an important diagnostic tool which may be used to screen for and/or help diagnose conditions such as a urinary tract infections, kidney disorders, liver problems, diabetes or other metabolic conditions.

Question 4.
Why your doctor advises you to drink plenty of water?
Answer:
The doctor advises to drink more water as;

  • Water helps to maximize physical performance.
  • Hydration has a major effect on energy levels and brain function.
  • Drinking water may help to prevent and treat headaches.
  • Drinking more water may help relieve constipation.

Question 5.
Can you guess why there are sweat glands on the palm of our hands and the soles of our feet?
Answer:
Sweating is important for thermal regulation. Sweat works as a defense against microbes to which our hands and feet are mostly exposed than the other parts of our body.

Activity

Question 1.
Look at the pictures given below and answer the questions that follow:
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 6

  1. Are the teeth of animals similar to ours?
  2. How is the shape of their teeth related to their food habit?

Answer:

  1. Not all the teeth are similar to ours.
  2. The lion is a carnivore and hence canine teeths are predominant.
    The buffalo is a herbivorous animal and incissors are predominant in them.

Samacheer Kalvi 9th Science Organ Systems in Animals Additional Questions

I. Short answers questions.

Question 1.
Write the function of the following organ systems: Muscular system, Endocrine system, Sensory system, Excretory system.
Answer:

  • Muscular system: Involved in the contraction and relaxation resulting movement.
  • Endocrine system: Co-ordinates the functions of all organ systems.
  • Sensory system: This helps in sight, smell, hearing, taste, and touch.
  • Excretory system: Elimination of nitrogenous waste products.

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Question 2.
What are the three stages of urine formation?
The process of urine formation includes the following three stages.

  1. Glomerular filtration
  2. Tubular reabsorption and
  3. Tubular secretion

Question 3.
What are the functions of liver?
Answer:
Functions of Liver

  • Controls blood sugar and amino acid levels
  • Synthesizes foetal red blood cells
  • Produces fibrinogen and prothrombin, used for clotting of blood
  • Destroys red blood cells
  • Stores iron, copper, vitamins A, and D.
  • Produces heparin (an anticoagulant)
  • Excretes toxic and metallic poisons
  • Detoxifies substances including drugs and alcohol

Question 4.
Draw the excretory system and label its parts.
Answer:
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 7

Question 5.
Draw a flow chart showing the route of urine flow.
Answer:
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 8

Question 6.
What is dialysis or artificial kidney?
Answer:
When kidneys lose their filtering efficiency, an excessive amounts of fluid and toxic waste accumulate in the body. This condition is known as kidney (renal) failure. For this, an artificial kidney is used to filter the blood of the patient. The patient is said to be put on dialysis and the process of purifying blood by an artificial kidney is called hemodialysis. When renal failure cannot be treated by drug or dialysis, the patients are advised for kidney transplantation.

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Question 7.
What is spermatogenesis?
Answer:
The process of formation of sperms is called spermatogenesis.

Question 8.
Describe the three parts of small intestine.
Answer:
The small intestine is the longest part of the alimentary canal. It comprises of 3 parts – duodenum, jejunum and ileum.

  • Duodenum is C-shaped and receives the bile duct (from liver) and pancreatic duct (from pancreas).
  • Jejunum is the middle part of the small intestine. It is a short region. It contains the enzymes like sucrase, maltase, lactase and lipase.
  • Ileum forms the lower part of the small intestine. It is the longest part of the small intestine. It contains minute finger like projections called villi. Absorption of food takes place here.

II. Long answers questions.

Question 1.
Tabulate the enzymes secreted by the digestive glands secrete in a human body.
Answer:

Digestive glands Enzymes
Salivary glands Ptyalin (Salivary amylase)
Gastric glands Pepsin
Rennin (in infants)
Pancreas Pancreatic amylase
Trypsin
Chymotrypsin
Pancreatic lipase
Intestinal glands Maltase
Lactase
Sucrase
Lipase

Question 2.
Describe the liver and list out its functions.
Answer:
Liver is the largest digestive gland of the body which is reddish brown in colour. It is divided into two main lobes, right and left lobes. On the undeside of the liver, the gall bladder is present. It stores the bile which is secreted by the liver. The bile is secreted into the smll intestine when food enters it. Bile helps in the digestion of fats.

Functions of Liver:

  • Controls blood sugar and amino acid levels
  • Synthesizes foetal red blood cells
  • Produces fibrinogen and prothrombin, used for clotting of blood
  • Destroys red blood cells
  • Stores iron, copper, vitamins A and D.
  • Produces heparin (an anticoagulant)
  • Excretes toxic and metallic poisons
  • Detoxifies substances including drugs and alcohol

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Question 3.
Draw a flowchart describing the process of digestion.
Answer:
Samacheer Kalvi 9th Science Solutions Chapter 20 Organ Systems in Animals 9

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