9th Std Science Solution in English | Lesson.20 Organ Systems in Animals

Lesson 20 Organ Systems in Animals

Organ Systems in Animals Book Back Answer

I. Choose the correct answer

1. Which of the following is not a salivary gland?

1. sublingual
2. lachrymal
3. submaxillary
4. parotid

Ans: lachrymal

2. Stomach of man mainly digests __________

1. carbohydrates
2. proteins
3. fat
4. sucrose

Ans: proteins

3. To prevent the entry of food into the trachea, the opening is guarded by ___________

1. epiglottis
2. glottis
3. hard palate
4. soft palate

Ans: epiglottis

4. Bile helps in the digestion of _________

1. proteins
2. sugar
3. fats
4. carbohydrates

Ans: fats

5. The structural and functional unit of the kidney is ________

1. villi
2. liver
3. nephron
4. ureter

Ans: nephron

6. Which one of the following substance is not a constituent of sweat?

1. urea
2. protein
3. water
4. salt

Ans: protein

7. The common passage meant for transporting urine and sperms in male is ______

1. ureter
2. urethra
3. vas deferens
4. scrotum

Ans: urethra

8. Which of the following is not a part of female reproductive system?

1. Ovary
2. uterus
3. testes
4. fallopian tube

Ans: testes

9. Excretion means _________

1. taking in oxygen from the air and giving out carbon dioxide
2. disposal of harmful germs and worms from our body
3. distribution of digested food to the body tissues through blood
4. removal of nitrogenous wastes generated in the body

Ans: removal of nitrogenous wastes generated in the body

II. Fill in the blanks

1. The opening of the stomach into the intestine is called _______

Ans: pyloric sphincter

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

Ans: tongue

3. Bile, secreted by liver is stored temporarily in _____

Ans: gall bladder

4. The longest part of alimentary canal is ________

Ans: small intestine

5. The human body functions normally at a temperature of about ________.

Ans: excretory system(urinary system)

6. The largest cell in the human body of a female is _________.

Ans: ovum (egg)

7. In the process of urine formation, maximum amount of water from the glomerular filtrate is reabsorbed in the ____

Ans: 37oC or 98.4oF

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.

Ans: False

Correct Ans: Hydrochloric acid in the stomach kills microorganisms in the food.

2. During digestion, proteins are broken down into amino acids.

Ans: True

3. Glomerular fltrate consists of many substances like amino acids, vitamins, hormones, salts, glucose and other essential substances.

Ans: True

4. Besides the normal constituents, the urine may pass out excess vitamins and not the antibiotics.

Ans: True

5. The process of release of ovum from ovary is called gestation.

Ans: False

Correct Ans:The process of release of ovum from ovary is called ovulation.

IV. Match the following.

V. Differentiate the following.

a. Excretion and secretion

Excretion : Removal of nitrogenous waste.

Secretion : Release the chemical substances like enzymes , hormones by the glands.

b. Absorption and assimilation

Absorption : Nutrients obtained after digestion by villi is called absorption.

Assimilalation : The incorporation of the absorbed food materials into tissue.

c. Ingestion and egestion

Ingestion : Intake of food by the organisms is called ingestion.

Egestion : The undigested food thrown out from the body through the anal aperture is called egestion.

d. Diphyodont and heterodont

Diphyodont : Two sets of teeth is called diphyodont.

Heterodont : If the teeth are different type than it is called heterodont.

e. Incisors and canines

Incisors : Teeth which are used to cut and bite the food.

Canines : Teeth which are used tear and pierce the food.

f. Sperm and ovum

Sperm : The male gamete is called sperm.

Ovum : The female gamete is called ovum.

V. Very short answer questions

1. How is the small intestine designed to absorb digested food?

Ileum part of the small intestine contains minute finger like projectors called villi absorbs digested food.

2. Why do we sweat?

To regulate our body temperature, so we sweat.

3. Mention any two vital functions of human kidney.

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

4. What is micturition?

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.

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

6. Explain the 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. 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.

7. How is it possible to control the urge to pass urine?

If the abdominal region muscle is stretched internally one can control urination.

8. Write the names of male and female sex hormone.

Male sex hormone : Testosterone
Female sex hormome : Oestrogen & progesterone

9. Arrange the following fve steps of nutrition in correct sequence: (digestion, assimilation, ingestion, egestion, absorption)

1. Ingestion
2. digestion
3. absorption
4. assimilation
5. egestion

10. The stomach secretes gastric juice, which contains hydrochloric acid. What is its function?

Hydrochloric acid kills the bacteria swallowed along with food.

VII. Answer in datail.

1. Describe the alimentary canal of man
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.

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 wind pipe 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 life time. 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.

Dental formula represents the number of different type of teeth present in each half of a jaw (upper and lower jaw). The types of teeth are denoted as incisors (i), canine (c), premolars (pm) and molars (m). The dental formula is presented as:

For Milk teeth in each half of upper and lower jaw:

2, 1, 2 / 2, 1, 2 = 10 x 2= 20

For Permanent teeth in each half of upper and lower jaw:

2, 1, 2, 3 / 2, 1, 2, 3 = 16 x 2= 32

Salivary glands:

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

a. Parotid glands

Parotid glands are the largest salivary glands, which lie in the cheeks in front of the ears (in Greek Par – near ; otid – ear).

b. Sublingual glands

Sublingual glands are the szallest glands and lie beneath the tongue.

c. Submaxillary or Submandibular glands

Submaxillary or Submandibular glands lie at the angles of the lower jaw.

Tongue:

Muscular, sensory organ – Helps in mixing the food with the saliva.

Pharynx:

The 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:

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:

The 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.

Inactive pepsinogen is converted to active pepsin which acts on the proteins in the ingested food. Hydrochloric acid kills the bacteria swallowed along with food and makes the medium acidic while the mucus protects the wall of the stomach. The action of the gastric juice and churning of food in the stomach convert the bolus into a semidigested food called chyme. The chyme moves to the intestine slowly through the pylorus.

Small intestine:

The 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.

a. Duodenum

Duodenum is C-shaped and receives the bile duct (from liver) and pancreatic duct (from pancreas).

b. Jejunum

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 the enzymes like sucrase, maltase, lactase and lipase.

c. Ileum

Ileum forms the lower part of the small intestine and opens into the large intestine. Ileum is the longest part of the small

Liver:

Largest digestive gland of the body, reddish brown in colour. Bile salts help in the digestion of fats by emulsification (conversion of large fat droplets into small ones).

Pancreas:

Lobed, leaf shaped gland situated between the stomach and duodenum. Pancreas acts both as an exocrine gland and as an endocrine gland.

Large intestine:

The unabsorbed and undigested food is passed into the large intestine. It extends from the ileum to the anus. About 1.5 meters in length. Has 3 parts-caecum, colon and rectum.

Caecum:

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

Colon:

Much broader than ileum. 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).

Rectum:

Last part which opens into the anus muscles called anal sphincter which opens when passing stools.

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

Kidneys

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 through the Ureter.

Ureters:

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:

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 micturition (urination).

Functions of kidney

• Maintains the fluid and electrolytes balance in our body.
• Regulates acid-base balance of blood.
• Maintains the osmotic pressure in blood and tissues.
• Helps to retain the 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. 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 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
• 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. 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 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.

IX. Assertion and Reason

Direction: In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below. Of the four statements, given below, mark one as the correct answer.

1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion
2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
3. If Assertion is true but Reason is false
4. If both Assertion and Reason are false

1. Assertion: Urea is excreted out through the kidneys
   Reason: Urea is a toxic substance. Excess accumulation of urea in blood may lead to death

Ans: 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: both Assertion and Reason are true but Reason is not the correct explanation of Assertion

X. Thinking skills

1. If pepsin is lacking in gastric juice, then which event in the stomach will be affected?

1. digestion of starch into sugars
2. breaking of proteins into peptides
3. digestion of nucleic acids
4. breaking of fats into glycerol and fatty acids

Ans: breaking of proteins into peptides

2. Name the blood vessel that (a) enter malphigian capsule and (b) leaves malphigian capsule

1. Afferent arteriole
2. Efferent arteriole

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

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.

4. Why your doctor advises you to drink plenty of water?

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.

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

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

6. Rearrange the jumbled sequence of the different parts of alimentary canal in proper sequence.

(Oesophagus, Small intestine, Stomach, Large intestine, anus, mouth, rectum)

mouth,Oesophagus,Stomach, Small intestine, Large intestine, rectum,anus.

7. Select the substances given below that need to be excreted from the body.

(urea, amino acids, carbon dioxide, uric acid, glucose)

urea, uric acid, and carbon dioxide

9. Rearrange the jumbled words and fill in the blanks in the following passage to make it a meaningful description.

The human urinary system consists of a pair of kidney ( nyedik), which form the urine; a pair of ureter (ertreu), which conduct the urine (neuri) from kidneys to the urinary bladder (naryuri drebdal) for storage of urine and a urethera (reuhrat) through which the urine is voided by bladder contractions.

9. Label the parts of the alimentary canal of man and write any one function of each organ

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

IV. Identify the following parts:

1. It conducts food from pharynx to stomach by peristalsis

Oesophagus

2. Finger-like projections which enhances the absorbing capacity of small intestine

Villi

3. The bunch of capillaries inside the Bowman’s capsule

Glomerulus

4. Tin muscular tubes which carry urine from kidney to urinary bladder

Ureter

5. Small sac-like muscular structures that encloses testes

Scrotum

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

VI. Short answers questions

1. Define the following terms:

a) Digestion       b) Osmoregulation       c) Emulsification       d) Ovulation

a. Digestion

The breakdown of large complex insoluble food molecules into small, simpler soluble and diffusible particles by the action of digestive enzymes is called digestion.

b. Osmoregulation

The maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.

c. Emulsification

Conversion of large fat droplets into smaller ones in the digestive system is called Emulsification.

d. Ovulation

Release of ovum from an ovary is called ovulation

2. What are the end products of digestion of starch, proteins and fats respectively?

1. Starch – Glucose
2. Proteins – Amino acid
3. Fat – Fatty acid & Glycerol

3. What are the functions of ovaries and uterus in female reproductive system?

• Functions of ovary produce female gametes and secrete female sex hormones functions of uterus.
• supports the development of feetus.

4. Give reasons for the following:

a. Scrotum remains outside the body of human males.

To provide an optimum temperature for the formation of sperms. Scrotum remains outside the body

b. The wall of the stomach is not digested by its own enzyme.

Mucus protects the walls of stomach from digestion

5. Complete the following table:

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