Science : Chapter 20 : Organ Systems in Animals
I. Choose the correct answer
1. Which of the following is not a salivary gland?
- sublingual
- lachrymal
- submaxillary
- parotid
Ans : lachrymal
2. Stomach of man mainly digests __________
- carbohydrates
- proteins
- fat
- sucrose
Ans : proteins
3. To prevent the entry of food into the trachea, the opening is guarded by ___________
- epiglottis
- glottis
- hard palate
- soft palate
Ans : epiglottis
4. Bile helps in the digestion of _____________
- proteins
- sugar
- fats
- carbohydrates
Ans : fats
5. Excretion means ____________
- taking in oxygen from the air and giving out carbon dioxide
- disposal of harmful germs and worms from our body
- distribution of digested food to the body tissues through blood
- removal of nitrogenous wastes generated in the body
Ans : removal of nitrogenous wastes generated in the body
6. The structural and functional unit of the kidney is _____________
- villi
- liver
- nephron
- ureter
Ans : nephron
7. Which one of the following substance is not a constituent of sweat?
- urea
- protein
- water
- salt
Ans : protein
8. The common passage meant for transporting urine and sperms in male is ______
- ureter
- urethra
- vas deferens
- scrotum
Ans : urethra
9. Which of the following is not a part of female reproductive system?
- Ovary
- uterus
- testes
- fallopian tube
Ans : testes
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. Organs which are concerned with the formation, storage and elimination of urine constitute the _________.
Ans :
6. The human body functions normally at a temperature of about ________.
Ans : excretory system(urinary system)
7. In the process of urine formation, maximum amount of water from the glomerular filtrate is reabsorbed in the ____.
Ans : 37oC or 98.4oF
8. The largest cell in the human body of a female is _________.
Ans : ovum (egg)
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 )
Ans : Hydrochloric acid in the stomach kills microorganisms in the food.
2. During digestion, proteins are broken down into amino acids. ( True )
3. Glomerular fltrate consists of many substances like amino acids, vitamins, hormones, salts, glucose and other essential substances. ( True )
4. Besides the normal constituents, the urine may pass out excess vitamins and not the antibiotics. ( True )
5. Te process of release of ovum from ovary is called gestation. ( False )
Ans : The process of release of ovum from ovary is called ovulation.
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. Te 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
V. Very short answer questions
1. Arrange the following fve steps of nutrition in correct sequence: (digestion, assimilation, ingestion, egestion, absorption)
- Ingestion
- digestion
- absorption
- assimilation
- egestion
2. Te stomach secretes gastric juice, which contains hydrochloric acid. What is its function?
Hydrochloric acid kills the bacteria swallowed along with food.
3. 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.
4. Why do we sweat?
To regulate our body temperature, so we sweat.
5. State any two vital functions of human kidney.
- Maintain the fluid and electrolytes balance in our body.
- Regulate acid-base balance of blood.
- Maintain the osmotic pressure in blood and tissues.
6. How is it possible to control the urge to pass urine?
If the abdominal region muscle is stretched internally one can control urination.
7. Write the names of male and female sex hormone.
Male sex hormone : Testosterone
Female sex hormome : Oestrogen & progesterone
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. Name the types of teeth present in an adult human being. Mention the functions of each.
| Types of teeth | Number of teeth | Functions |
| Incisors | 8 | Cutting and biting |
| Canines | 4 | Tearing and piercing |
| Premolars | 8 | Crushing and grinding |
| Molars | 12 | Crushing, grinding and mastication |
3. What are the end products of digestion of starch, proteins and fats respectively?
- Starch – Glucose
- Proteins – Amino acid
- Fat – Fatty acid & Glycerol
4. 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.
5. Differentiate the following terms:
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. Sperm and ovum
Sperm : The male gamete is called sperm.
Ovum : The female gamete is called ovum.
d.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.
e. Diphyodont and heterodont
Diphyodont : Two sets of teeth is called diphyodont.
Heterodont : If the teeth are different type than it is called heterodont.
f. Incisors and canines
Incisors : Teeth which are used to cut and bite the food.
Canines : Teeth which are used tear and pierce the food.
6. 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.
7. Match the following:
| Organ | Elimination |
| Skin | Urine |
| Lungs | Sweat |
| Intestine | Carbon dioxide |
| Kidneys | undigested food |
Ans : 1 – B, 2 – C, 3 – D, 4 – A
8. 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
9. Complete the following table:
| Enzymes | Nutrient (Substrate) | End products of digestion |
| Erepsin (peptidase) | proteins and peptides | Amino acid |
| Maltase | Maltose | glucose |
| Sucrase | sucrose | Glucose and Fructose |
| Lactase | Lactose | glucose and galactose |
| Lipase | fats | fatty acids and glycerol |
VII. Match the parts of the given figure with the correct option.
| 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 |
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.
- If both Assertion and Reason are true and Reason is the correct explanation of Assertion
- If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- If Assertion is true but Reason is false
- 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?
- digestion of starch into sugars
- breaking of proteins into peptides
- digestion of nucleic acids
- breaking of fats into glycerol and fatty acids
Ans : breaking of proteins into peptides
2. 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.
3. 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
4. Name the blood vessel that (a) enter malphigian capsule and (b) leaves malphigian capsule
- Afferent arteriole
- Efferent arteriole
5. 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.
6. Label the parts of the alimentary canal of man and write any one function of each organ
