Questions answered are:
1. What is Nutrition? Why is it necessary for animals?
2. Explain the process of digestion in humans.
3. What are the different types of teeth in humans? What are their functions?
4. What is the role of saliva in digestion?
5. What is the function of bile, and where is it produced?
6. Explain the process of digestion in ruminants.
7. How does Amoeba capture and digest its food?
8. What causes diarrhoea, and how can it be treated?
9. Why do humans require a balanced diet?
Intext questions and answer
Book back questions and answer
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1. What is Nutrition? Why is it necessary for animals?
Nutrition is the process of obtaining food and utilizing it to provide energy for growth, repair, maintenance, and carrying out life processes.
- Necessity of Nutrition:
- Food provides the energy needed for performing daily activities such as walking, running, and thinking.
- It supplies essential nutrients like carbohydrates, proteins, fats, vitamins, and minerals, which are required for growth and development of the body.
- Nutrition ensures proper repair of damaged tissues and the functioning of various organs.
- It helps in maintaining immunity, keeping the body strong against infections.
2. Explain the process of digestion in humans.
Digestion in humans involves breaking down complex food into simpler substances that can be absorbed and utilized by the body. It occurs in the following steps:
- Ingestion:
- Food is taken into the body through the mouth.
- Buccal Cavity:
- The food is chewed by the teeth to break it into smaller pieces.
- Saliva, secreted by salivary glands, contains an enzyme called salivary amylase, which breaks down starch into simpler sugars.
- The tongue helps in mixing saliva with the food and in swallowing it.
- Oesophagus (Foodpipe):
- The food moves from the mouth to the stomach through the oesophagus by rhythmic contractions of its walls, called peristalsis.
- Stomach:
- The stomach is a J-shaped muscular bag that secretes three substances:
- Hydrochloric Acid: Kills harmful bacteria in the food and provides an acidic medium for enzyme action.
- Mucus: Protects the stomach lining from acid.
- Digestive Juices: Break down proteins into simpler substances.
- The stomach is a J-shaped muscular bag that secretes three substances:
- Small Intestine:
- It is the longest part of the alimentary canal, measuring about 7.5 meters.
- Digestive juices from the liver and pancreas act here:
- Bile juice from the liver breaks down fats into smaller droplets (emulsification).
- Pancreatic juice digests proteins, fats, and carbohydrates into simpler substances.
- The walls of the small intestine secrete additional digestive juices to complete digestion.
- The inner lining of the small intestine has finger-like projections called villi, which absorb the digested nutrients into the bloodstream.
- Large Intestine:
- Undigested food enters the large intestine, where water and some salts are absorbed.
- The remaining waste is stored in the rectum and expelled through the anus as faeces.
- Egestion:
- The process of removing undigested and unabsorbed food materials from the body is called egestion.
3. What are the different types of teeth in humans? What are their functions?
Humans have four types of teeth, each serving a specific function:
- Incisors:
- Located at the front of the mouth.
- These are flat and sharp, used for cutting and biting food.
- Canines:
- Pointed teeth located next to the incisors.
- They are used for tearing food, especially meat.
- Premolars:
- Located next to the canines.
- They have a flat surface and are used for chewing and grinding food.
- Molars:
- Located at the back of the mouth.
- They are larger and stronger, used for fine grinding of food.
Humans have two sets of teeth:
- Milk Teeth (Deciduous Teeth):
- These are the first set of teeth that appear during infancy and fall out between the ages of 6 and 8 years.
- Permanent Teeth:
- These replace milk teeth and usually last for a lifetime unless damaged due to disease or injury.
4. What is the role of saliva in digestion?
Saliva plays a crucial role in the process of digestion:
- Moistens Food:
- Saliva moistens and softens food, making it easier to chew and swallow.
- Breaks Down Starch:
- It contains an enzyme called salivary amylase (or ptyalin), which converts starch into simpler sugars.
- Lubricates Food:
- Saliva makes the passage of food through the oesophagus smooth.
- Protects the Mouth:
- It prevents dryness in the mouth and inhibits the growth of harmful bacteria.
5. What is the function of bile, and where is it produced?
Bile is a digestive juice that plays a vital role in the digestion of fats.
- Production: Bile is produced in the liver, the largest gland in the human body.
- Storage: It is stored in the gall bladder.
- Function:
- Emulsification of Fats: Bile breaks down large fat globules into smaller droplets, making it easier for enzymes to act on them.
- Neutralizes Acid: Bile neutralizes the acidic food coming from the stomach, providing an alkaline environment in the small intestine for enzyme action.
6. Explain the process of digestion in ruminants.
Ruminants like cows, buffaloes, and goats have a specialized digestive system to digest cellulose-rich food. The process is as follows:
- Ingestion and Storage in the Rumen:
- Ruminants swallow grass without chewing it properly.
- The grass is stored in a part of the stomach called the rumen, where it is partially digested by bacteria and forms cud.
- Chewing of Cud (Rumination):
- The cud is brought back to the mouth for thorough chewing. This process is called rumination.
- Chewing cud helps break down food further and mix it with saliva.
- Digestion of Cellulose:
- The bacteria in the rumen produce enzymes that digest cellulose, converting it into simpler compounds.
- Further Digestion:
- The partially digested food passes through the other compartments of the stomach for further digestion.
7. How does Amoeba capture and digest its food?
Amoeba, a single-celled organism, captures and digests food using its pseudopodia (false feet):
- Ingestion:
- When Amoeba senses food nearby, it extends its pseudopodia to surround and engulf the food particle, forming a food vacuole.
- Digestion:
- Digestive enzymes are released into the food vacuole. These enzymes break down complex food substances into simpler substances.
- Absorption:
- The digested nutrients are absorbed into the cytoplasm and used for growth, repair, and energy.
- Egestion:
- The undigested residue is expelled out of the body through the cell membrane.
8. What causes diarrhea, and how can it be treated?
Causes of Diarrhea:
- It is caused by infections, food poisoning, or indigestion.
- Harmful bacteria or viruses can irritate the intestine, leading to frequent watery stools.
Effects:
- Excessive loss of water and salts from the body leads to dehydration, which can be fatal if not treated promptly.
Treatment:
- Oral Rehydration Solution (ORS):
- A solution made of boiled water, sugar, and salt is given to the patient to replenish lost fluids and electrolytes.
- Plenty of Fluids:
- Drinking boiled and cooled water helps prevent further dehydration.
- Doctor’s Consultation:
- If diarrhea persists, medical advice is essential for proper treatment.
9. Why do humans require a balanced diet?
A balanced diet contains all the essential nutrients (carbohydrates, proteins, fats, vitamins, minerals, water, and fiber) in the right proportions.
- It is required for:
- Energy: Carbohydrates and fats provide energy for daily activities.
- Growth and Repair: Proteins are essential for the growth and repair of body tissues.
- Immunity: Vitamins and minerals strengthen the immune system.
- Body Functions: Water helps in transportation of nutrients and elimination of waste, while fiber aids digestion.
Intext Questions and Answers
- What is the role of saliva in the digestion of food?
Saliva, secreted by the salivary glands, contains an enzyme called salivary amylase, which breaks down starch into simpler sugars. Saliva also moistens the food, making it easier to chew and swallow.
2. What causes tooth decay, and how can it be prevented?
- Tooth decay is caused when bacteria in the mouth break down sugars to form acids. These acids damage the enamel, leading to cavities.
- Prevention:
- Brush teeth twice a day.
- Rinse the mouth after every meal.
- Avoid sugary foods and drinks.
3. Why does food sometimes enter the windpipe while swallowing?
The windpipe and foodpipe share a common passage in the throat. During swallowing, a flap-like valve called the epiglottis closes the windpipe. If it doesn’t close properly (e.g., when talking or laughing while eating), food may enter the windpipe, causing coughing or choking.
4. Why do ruminants chew cud?
Ruminants, like cows and buffaloes, chew cud to aid the digestion of cellulose. After swallowing, partially digested food (cud) is brought back to the mouth for further chewing, allowing bacteria in the rumen to break down cellulose effectively.
5. What is the function of bile juice, and where is it produced?
- Bile juice is produced in the liver and stored in the gall bladder.
- It helps in the digestion of fats by breaking them into smaller droplets, a process called emulsification.
6. Why does the small intestine have villi?
The small intestine has villi to increase the surface area for absorption. Each villus contains blood vessels that absorb nutrients like glucose, amino acids, and fatty acids into the bloodstream.
7. How does Amoeba capture and digest its food?
Amoeba uses pseudopodia (false feet) to surround and engulf its food. The food is enclosed in a food vacuole, where digestive enzymes break it down into simpler substances. The nutrients are absorbed into the cytoplasm, and the undigested residue is expelled.
8. What is diarrhea, and how can it be treated?
- Diarrhea is the condition of passing watery stools frequently.
- Treatment:
- Prevent dehydration by giving Oral Rehydration Solution (ORS) (water with salt and sugar).
- Consult a doctor if it persists.
Book-Back Questions and Answers
Fill in the Blanks
- The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation, and egestion.
- The largest gland in the human body is the liver.
- The stomach releases hydrochloric acid and digestive juices, which act on food.
- The inner wall of the small intestine has many finger-like outgrowths called villi.
- Amoeba digests its food in the food vacuole.
True or False
- Digestion of starch starts in the stomach. False
- The tongue helps in mixing food with saliva. True
- The gall bladder temporarily stores bile. True
- The ruminants bring back swallowed grass into their mouth and chew it for some time. True
Match the Following
| Column I | Column II |
| Carbohydrates | Sugar |
| Proteins | Amino acids |
| Fats | Fatty acids and glycerol |
Short Questions
- What are villi? What is their location and function?
- Villi are finger-like projections in the small intestine that increase the surface area for absorption.
- They absorb nutrients like glucose, amino acids, and fatty acids into the bloodstream.
- Where is bile produced, and which component of food does it help to digest?
- Bile is produced in the liver and stored in the gall bladder.
- It helps in the digestion of fats by breaking them into smaller droplets (emulsification).
- Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason.
- Cellulose can be digested by ruminants but not by humans.
- Ruminants have bacteria in their rumen that break down cellulose, while humans lack such bacteria.
- Why do we get instant energy from glucose?
- Glucose is a simple sugar that directly enters the bloodstream without requiring digestion.
- It is readily used by cells for energy production.
- Which part of the digestive canal is involved in:
(i) Absorption of food: Small intestine
(ii) Chewing of food: Buccal cavity
(iii) Killing of bacteria: Stomach
(iv) Complete digestion of food: Small intestine
(v) Formation of faeces: Large intestine
Long Questions
- Write one similarity and one difference between the nutrition in Amoeba and human beings.
Answer:- Similarity: Both involve ingestion, digestion, absorption, and egestion.
- Difference: Humans have a complex digestive system, while Amoeba uses pseudopodia and food vacuoles for digestion.
- Can we survive only on raw leafy vegetables/grass? Why or why not?
- No, humans cannot survive on raw leafy vegetables or grass because:
- Grass contains cellulose, which humans cannot digest due to the absence of cellulose-digesting bacteria.
- Humans require a balanced diet with carbohydrates, proteins, fats, vitamins, and minerals.
- No, humans cannot survive on raw leafy vegetables or grass because:
- Explain the process of digestion in ruminants.
- Ruminants quickly swallow grass, storing it in the rumen, where it is partially digested to form cud.
- Cud is regurgitated and chewed again for better digestion.
- Bacteria in the rumen help digest cellulose, which is a major component of grass.
- Match the items of Column I with suitable items in Column II:
| Column I | Column II |
| (a) Salivary gland | (iii) Saliva secretion |
| (b) Stomach | (iv) Acid release |
| (c) Liver | (i) Bile juice secretion |
| (d) Rectum | (ii) Storage of undigested food |
| (e) Small intestine | (v) Digestion is completed |
| (f) Large intestine | (vi) Absorption of water |
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