Keywords to Remember
Keyword | Definition |
Nutrition | The process by which living organisms take in food and utilize it for energy, growth, and repair. |
Heterotrophs | Organisms that cannot prepare their own food and depend on other organisms for nutrition. |
Ingestion | The process of taking food into the body through the mouth. |
Digestion | The process of breaking down complex food into simpler substances that can be absorbed by the body. |
Absorption | The process of nutrients passing into the blood or body fluids from the digestive tract. |
Assimilation | The process by which absorbed food is utilized by the body cells for energy, growth, and repair. |
Egestion | The process of removing undigested food from the body in the form of faeces. |
Alimentary canal | The continuous tube in the human body from mouth to anus through which food passes and is digested. |
Salivary glands | Glands in the mouth that secrete saliva containing enzymes like salivary amylase to break down starch. |
Saliva | A digestive juice secreted in the mouth that starts the breakdown of starch. |
Oesophagus | Also known as the food pipe; a muscular tube that carries food from the mouth to the stomach. |
Stomach | A muscular organ where partial digestion of proteins takes place with the help of gastric juices. |
Liver | The largest gland in the body that secretes bile, which helps in the digestion of fats. |
Gallbladder | A small organ that stores bile produced by the liver. |
Bile juice | A digestive juice that helps break down fats into smaller droplets (emulsification). |
Pancreas | A gland that produces digestive enzymes and insulin. |
Small intestine | A long, coiled tube where complete digestion and absorption of nutrients take place. |
Villi | Tiny finger-like projections in the inner walls of the small intestine that increase surface area for absorption. |
Large intestine | The part of the digestive system where water is absorbed and undigested food is turned into faeces. |
Rectum | The last part of the large intestine where faeces are stored before being expelled. |
Anus | The opening through which faeces are egested from the body. |
Ruminants | Animals like cows and goats that chew cud and have a four-chambered stomach for digestion. |
Cud | Partly digested food returned from the stomach to the mouth for re-chewing in ruminants. |
Rumination | The process of chewing cud in ruminant animals. |
Enzymes | Biological substances that speed up the digestion of food. |
Something To Know
A. Fill in the blanks.
- The digestion of food in humans starts in the __________ and is completed
in the __________ .
Answer – mouth, small intestine
- __________ , present in the stomach, kills bacteria.
Answer – Hydrochloric
- The largest gland in the human body is the __________.
Answer – liver
- Partially digested food, that is chewed again by grass eating animals, is called the __________ .
Answer – cud
- Amoeba uses __________ its food. for locomotion and for capturing .
Answer – pseudopodia
B. Match the following:
- Gall bladder (a) Bile Juice
- Proteins (b) Cow
- Intestinal wall (c) Absorption
- Rumen (d) False feet
- Pseudopodia (e) Amino acids
Answer –
Column A | Column B | Answer |
1. Gall bladder | (a) Bile Juice | 1 → a |
2. Proteins | (e) Amino acids | 2 → e |
3. Intestinal wall | (c) Absorption | 3 → c |
4. Rumen | (b) Cow | 4 → b |
5. Pseudopodia | (d) False feet | 5 → d |
C. Tick (✓) the correct option.
- Organisms, that can synthesise their own food, are called—
heterotrophs
autotrophs
parasites
saprotropbs
Answer – autotrophs
- Cow is a/an—
saprotroph
autotroph
parasite
heterotroph
Answer – heterotroph
- Animals, that eat both plant materials and animals, are called—
herbivores
carnivores
omnivores
ruminants
Answer – omnivores
4.Which one of these is not a part of the alimentary canal?
stomach
liver
anus
large intestine
Answer – liver
- Bile juice is released by the—
salivary glands
liver
pancreas
large intestine
Answer – liver
D. Answer the following questions in brief.
- Define the following terms:
(a) Holozoic nutrition
Answer – It is a type of nutrition in which an organism takes in solid food and digests it inside the body.
(b) Alimentary canal
Answer – It is the passage in the human body through which food passes and gets digested and absorbed.
- Give the meaning of the terms:
(a) Assimilation
Answer – The process by which absorbed food is utilized by body cells for energy and growth.
(b) Rumination
Answer – The process in which partially digested food returns to the mouth in ruminants and is chewed again.
- Name the organs that make up the human alimentary canal.
Answer – Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus.
- State two differences between milk teeth and permanent teeth.
Answer – Milk teeth are temporary and start falling out around age 6; permanent teeth replace them.
Milk teeth are fewer in number (20), while permanent teeth are 32 in total.
- Name the four types of teeth in the human mouth.
Answer – Incisors, canines, premolars, molars.
- State the function of the (a) incisor teeth (b) premolar teeth.
Answer – (a) Incisor teeth: Used for cutting and biting food.
(b) Premolar teeth: Used for crushing and grinding food.
- State the role of acid in the human stomach.
Answer – Hydrochloric acid kills bacteria and provides an acidic medium for digestive enzymes to function.
- State the function of (a) bile juice and (b) pancreatic juice in the human digestive system.
Answer – (a) Bile juice helps in the emulsification of fats.
(b) Pancreatic juice contains enzymes that digest proteins, fats, and carbohydrates.
E. Answer the following questions
- Draw a neat, well labelled diagram of the human digestive system.
Answer – (You can draw or attach a labelled diagram showing: mouth, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, rectum, and anus.)
- Justify the following statements:
(a) Crow is an omnivore.
Answer – Crow eats both plant products (like grains) and animals (like insects).
(b) It is said that the mode of nutrition, in human beings and Amoeba, is quite similar.
Answer – Both use the holozoic mode of nutrition, involving ingestion, digestion, absorption, assimilation, and egestion.
- Give reasons for the following:
(a) Ingestion of food is difficult without teeth.
Answer – Teeth help in chewing and breaking down food into smaller pieces, aiding digestion.
(b) If we chew rice, or bread, for a few minutes, it starts tasting sweet.
Answer – Saliva converts starch into sugar, which tastes sweet.
(c) Bacteria are present in the caecum of ruminants.
Answer – They help in the digestion of cellulose, which ruminants cannot digest on their own.
- Explain how digested food gets absorbed into the blood.
Answer – The digested food in the small intestine is absorbed through the villi, tiny finger-like projections, into the blood capillaries.
- State, in one/two sentence/s each, the various processes involved in nutrition in ruminant animals.
Answer – Ingestion → Partial digestion in rumen → Regurgitation and rumination → Further digestion in intestine → Absorption.
- Explain ingestion of food, in amoeba, through a diagram.
Answer – (Include diagram showing pseudopodia surrounding food particle and forming a food vacuole.)
Value Based Question
The biology teacher, who was also the coach of the school cricket team, would often compare his team members with the different ‘organs’ of their digestive system. He would tell them to concentrate on their respective roles and to work as a team in a selfless and dedicated way. This, he would say, would enable them to succeed in wi lining matches in the same way as the ‘team’, of the organ s of the digestive system, ‘succeeds’ in digesting, and using, the ‘ingested food’.
- State two of the values that the teacher wanted his students to ‘have in them’.
Answer – Teamwork
Responsibility and dedication to individual roles
- Try to make a list of eleven names’ that are a part of the ‘team’ that makes up the human digestive system.
Answer – Mouth, teeth, tongue, salivary glands, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine.
- Have a group discussion on the. importance of ‘Team work’ in day- to-day life.
Answer – (Suggested answer for discussion: Teamwork helps accomplish tasks more efficiently, ensures collaboration and support, and leads to success in schools, families, workplaces, and sports.)
Something To Do
- Make a PowerPoint presentation on the various ways in which animals ingest their food. For example—
[Herbivores-Cow; Carnivores-Lion; Blood suckers-Leech; Fruit eating-birds; Fluid feeders-Butterflies, moth, earthworm; Insectivore-Frog]
Answer – Students will do this at their own.
- Collect data, from the parents of your five classmates, about their milk teeth. Tabulate your data as given below.
Answer –
S.No. | Name | Age at 1st tooth fell | Age at last tooth fell | Teeth lost | Teeth replaced |
1 | Aanya | 5 years | 11 years | 20 | 20 |
… | … | … | … | … | … |
Rest entries will be done by the students.
Use the collected data, to estimate the average age at which children lose their milk teeth.
- Make a model of the digestive system (using clay/plasticine to make the organs) and rubber pipes/ribbons to make the food pipe and small intestine.
Answer – Students will do this at their own.
- Activity—Assign a particular organ of the digestive system to each student and ask them to enact the role of it. The students need to follow the given guidelines. They should introduce themselves as a particular organ, explain its structure and function, its importance and significance in the human body and name some diseases, associated with the ‘organs’, represented by them.
The teacher can judge their role play by considering their presentation, content, visual aid used, clarity of the concepts, etc.
Answer – Students will perform this activity under the guidance of The teacher.
Additional Questions and Answer – 01
Fill in the Blanks (with Answers)
- The process of breaking down complex food into simpler forms is called __________.
Answer: digestion - The __________ stores bile produced by the liver.
Answer: gall bladder - The __________ intestine is the longest part of the digestive system.
Answer: small - __________ is the enzyme in saliva that breaks down starch into sugar.
Answer: Amylase - The finger-like projections in the small intestine are called __________.
Answer: villi - The mode of nutrition in Amoeba is __________.
Answer: holozoic - The __________ connects the mouth to the stomach.
Answer: esophagus - The process of taking food into the body is called __________.
Answer: ingestion - The undigested food is removed from the body through the process called __________.
Answer: egestion - In humans, __________ teeth are replaced by permanent teeth.
Answer: milk
Multiple Choice Questions (MCQs)
- The organ where most digestion and absorption occur is:
a) Large intestine
b) Stomach
c) Small intestine
d) Rectum
Answer: c) Small intestine - Which part of the digestive system absorbs water and forms feces?
a) Liver
b) Stomach
c) Small intestine
d) Large intestine
Answer: d) Large intestine - Which of the following animals shows rumination?
a) Dog
b) Tiger
c) Cow
d) Horse
Answer: c) Cow - What is the function of villi?
a) Chewing food
b) Producing bile
c) Absorbing nutrients
d) Digesting proteins
Answer: c) Absorbing nutrients - The enzyme that helps digest proteins in the stomach is—
a) Trypsin
b) Pepsin
c) Lipase
d) Amylase
Answer: b) Pepsin
True or False
- The liver produces bile which helps in digestion.
Answer: True - All animals have the same type of teeth.
Answer: False - Ingestion occurs in the large intestine.
Answer: False - Ruminants chew the cud to help in the digestion of cellulose.
Answer: True - Amoeba digests food inside food vacuoles.
Answer: True
Short Questions and Answers
- What is digestion?
Digestion is the process by which complex food is broken down into simpler soluble forms. - Name the main digestive glands in humans.
Salivary glands, liver, and pancreas. - What is the role of villi in the small intestine?
Villi increase the surface area for absorption of nutrients into the blood. - What is the function of bile?
Bile helps in the digestion and emulsification of fats. - Name any two organs of the digestive system in ruminants.
Rumen and omasum.
Competency-Based (Reasoning and Assertion) Questions
- Assertion (A): Ruminants can digest cellulose.
Reason (R): They have bacteria in their stomach that secrete enzymes to digest cellulose.
a) Both A and R are true, and R is the correct explanation.
b) Both A and R are true, but R is not the correct explanation.
c) A is true, R is false.
d) A is false, R is true.
Answer: a) Both A and R are true, and R is the correct explanation. - Assertion (A): Bile helps in protein digestion.
Reason (R): Bile contains bile salts that emulsify fats.
a) A is true, R is false.
b) Both A and R are true, but R is not the correct explanation.
c) A is false, R is true.
d) Both A and R are false.
Answer: c) A is false, R is true.
- Higher Order Thinking Skills (HOTS)
- Why do you think it is important for food to be broken down into simpler forms before absorption?
Answer: Food must be in simple soluble form so that it can pass through the walls of the intestine and be absorbed into the bloodstream for distribution to body cells. - How would digestion be affected if the liver stopped producing bile?
Answer: Fat digestion would be inefficient since bile emulsifies fats and prepares them for further breakdown by enzymes.
- Long Answer Questions (50–60 words each)
- Describe the process of digestion in the small intestine.
Answer: In the small intestine, food is mixed with digestive juices from the liver and pancreas. Bile emulsifies fats, and enzymes break down carbohydrates, proteins, and fats. The digested nutrients are then absorbed into the bloodstream through the villi, which are tiny projections that increase the surface area for absorption. - Explain the process of digestion in ruminants.
Answer: Ruminants first swallow food into the rumen, where it softens and partially digests. Later, they regurgitate it as cud and chew it again. The cud returns to other stomach chambers for further digestion. Microorganisms help break down cellulose. Finally, nutrients are absorbed and undigested parts are excreted.
Additional Questions And Answers – 02
Nutrition in Animals Questions and Answers
Fill in the Blanks
- Animals that cannot prepare their own food are called ________.
- Answer: Heterotrophs
- The process of taking in food by animals is called ________.
- Answer: Ingestion
- The long muscular tube in the human body through which food passes is called the ________ canal.
- Answer: Alimentary
- The hardest substance in the human body that covers the teeth is called ________.
- Answer: Enamel
- The process of breaking down complex food into simple soluble forms is called ________.
- Answer: Digestion
- In ruminants, the largest chamber of the stomach where food is stored is called ________.
- Answer: Rumen
- The finger-like projections in the small intestine that help in absorption are called ________.
- Answer: Villi
- Amoeba captures its food using its false feet called ________.
- Answer: Pseudopodia
- The gland that secretes bile juice for fat digestion is the ________.
- Answer: Liver
- The elimination of undigested food from the body is called ________.
- Answer: Egestion
Multiple Choice Questions (MCQs)
- Which of the following animals is a herbivore?
- a) Lion
- b) Tiger
- c) Cow
- d) Bear
- Answer: c) Cow
- What type of nutrition do fungi like Rhizopus exhibit?
- a) Holozoic
- b) Parasitic
- c) Saprotrophic
- d) Autotrophic
- Answer: c) Saprotrophic
- Which part of the human digestive system absorbs the digested food?
- a) Stomach
- b) Small intestine
- c) Large intestine
- d) Oesophagus
- Answer: b) Small intestine
- What is the role of hydrochloric acid in the stomach?
- a) Breaks down carbohydrates
- b) Kills bacteria and provides an acidic medium
- c) Absorbs nutrients
- d) Stores bile juice
- Answer: b) Kills bacteria and provides an acidic medium
- Which teeth in humans are used for cutting food?
- a) Molars
- b) Canines
- c) Incisors
- d) Premolars
- Answer: c) Incisors
- In Amoeba, where does the digestion of food take place?
- a) Cell membrane
- b) Pseudopodia
- c) Food vacuole
- d) Cytoplasm
- Answer: c) Food vacuole
- What is the function of the epiglottis during swallowing?
- a) Digests food
- b) Prevents food from entering the windpipe
- c) Absorbs water
- d) Secretes bile
- Answer: b) Prevents food from entering the windpipe
- Which gland secretes pancreatic juice for digestion?
- a) Liver
- b) Salivary gland
- c) Pancreas
- d) Stomach
- Answer: c) Pancreas
- What is the role of villi in the small intestine?
- a) Secretes digestive juices
- b) Increases surface area for absorption
- c) Stores undigested food
- d) Breaks down proteins
- Answer: b) Increases surface area for absorption
- Which of the following is NOT a ruminant?
- a) Cow
- b) Deer
- c) Human
- d) Buffalo
- Answer: c) Human
True/False Questions
- All animals are autotrophs.
- Answer: False (Animals are heterotrophs)
- The process of digestion in humans begins in the stomach.
- Answer: False (Digestion begins in the buccal cavity)
- Ruminants have a four-chambered stomach.
- Answer: True
- Humans can digest cellulose due to bacteria in their stomach.
- Answer: False (Humans cannot digest cellulose; it acts as roughage)
- The liver secretes bile juice, which is stored in the gall bladder.
- Answer: True
- Parasitic nutrition benefits both the parasite and the host.
- Answer: False (The host is harmed in parasitic nutrition)
- The large intestine absorbs digested food.
- Answer: False (The large intestine absorbs water and minerals from undigested food)
- Amoeba uses pseudopodia to capture food.
- Answer: True
- Saliva in the buccal cavity helps break down proteins.
- Answer: False (Saliva breaks down starch into simpler sugars)
- The tongue helps in mixing saliva with food and swallowing.
- Answer: True
Short Questions and Answers
- What are heterotrophs?
- Answer: Heterotrophs are organisms, like animals, that cannot prepare their own food and depend on other sources for nutrition.
- Name the three types of heterotrophic nutrition.
- Answer: Saprotrophic, parasitic, and holozoic nutrition.
- What is the role of the tongue in digestion?
- Answer: The tongue mixes saliva with food, helps in swallowing, and detects tastes with its taste buds.
- What is the function of villi in the small intestine?
- Answer: Villi increase the surface area for absorption of digested food into the blood.
- What is rumination in ruminants?
- Answer: Rumination is the process where ruminants bring back cud from the rumen to the mouth and chew it thoroughly.
- Name one example of a parasitic organism.
- Answer: Tapeworm.
- What is the role of bile juice in digestion?
- Answer: Bile juice, secreted by the liver, helps in the digestion of fats.
- How does Amoeba digest its food?
- Answer: Amoeba digests its food in a food vacuole using digestive juices, after capturing it with pseudopodia.
- What is the hardest substance in the human body?
- Answer: Enamel, which covers the teeth.
- What happens to undigested food in the large intestine?
- Answer: The large intestine absorbs water and minerals from undigested food, and the remaining waste is stored as faecal matter.
Competency-Based Questions (Reasoning and Assertion)
- Assertion (A): Digestion in humans begins in the buccal cavity.
Reason (R): Saliva in the buccal cavity contains enzymes that break down starch into simpler sugars.- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
- Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): Ruminants can digest cellulose.
Reason (R): Ruminants have bacteria in their rumen that help break down cellulose.- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
- Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): Parasitic nutrition benefits the host organism.
Reason (R): Parasites obtain food from the host while causing harm to it.- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
- Answer: d) A is false, but R is true.
- Assertion (A): The small intestine is the main site of absorption in humans.
Reason (R): The small intestine has villi that increase the surface area for absorption.- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
- Answer: a) Both A and R are true, and R is the correct explanation of A.
- Assertion (A): Amoeba exhibits holozoic nutrition.
Reason (R): Amoeba ingests food using pseudopodia and digests it in a food vacuole.- a) Both A and R are true, and R is the correct explanation of A.
- b) Both A and R are true, but R is not the correct explanation of A.
- c) A is true, but R is false.
- d) A is false, but R is true.
- Answer: a) Both A and R are true, and R is the correct explanation of A.
High Order Thinking Skill (HOTS) Questions and Answers
- Why can’t humans digest cellulose, but ruminants can?
- Answer: Humans lack the bacteria needed to digest cellulose, so it acts as roughage. Ruminants have bacteria in their rumen and caecum that break down cellulose, allowing them to digest it.
- How does the structure of the small intestine support its function in digestion?
- Answer: The small intestine has villi, which are finger-like projections that increase the surface area for absorption. This allows efficient absorption of digested nutrients into the blood for assimilation.
- Why does the taste of bread change when chewed for a few minutes?
- Answer: Saliva contains enzymes that break down starch in bread into simpler sugars, which taste sweet. This chemical change during chewing causes the taste to change from starchy to sweet.
- How does the epiglottis contribute to safe swallowing in humans?
- Answer: The epiglottis is a flap that closes the windpipe during swallowing, preventing food from entering the lungs and ensuring it passes safely into the oesophagus, avoiding choking.
- Why is the liver considered a vital organ in digestion?
- Answer: The liver secretes bile juice, stored in the gall bladder, which is essential for digesting fats in the small intestine. Without bile, fat digestion would be inefficient, affecting nutrient absorption.
Long Questions and Answers (50-60 words)
- Explain the process of digestion in the human stomach.
- Answer: In the stomach, food is mixed with gastric juices containing mucus, hydrochloric acid, and enzymes. Mucus protects the stomach lining, hydrochloric acid kills bacteria and provides an acidic medium, and enzymes break down proteins into simpler substances like amino acids, preparing the food for further digestion in the small intestine.
- Describe how ruminants digest cellulose in their food.
- Answer: Ruminants, like cows, store food in the rumen, where bacteria partially digest cellulose into cud. They regurgitate and chew the cud during rumination, breaking it down further. Bacteria in the caecum complete the digestion of cellulose, allowing ruminants to extract energy from plant materials that humans cannot digest.
- What are the roles of the liver and pancreas in human digestion?
- Answer: The liver secretes bile juice, stored in the gall bladder, which digests fats in the small intestine. The pancreas secretes pancreatic juice, which breaks down carbohydrates, proteins, and fats into simpler forms like glucose, amino acids, and fatty acids, aiding complete digestion in the small intestine.
- How does Amoeba obtain and digest its food?
- Answer: Amoeba captures food like bacteria using pseudopodia, forming a food vacuole around it. Digestive juices are secreted into the vacuole to break down the food. The digested nutrients are absorbed for energy and growth, while undigested waste is expelled from the cell through egestion, completing the holozoic nutrition process.
- Explain the role of the large intestine in the human digestive system.
- Answer: The large intestine absorbs water and minerals from undigested food received from the small intestine. The remaining waste is compacted into faecal matter and stored in the rectum. This waste is then eliminated through the anus via egestion, ensuring the body retains necessary water and removes waste efficiently.