Steps of Nutrition in Animals Explained with Examples (Amoeba and Paramecium)

ANAND CLASSES Study Material and Notes to learn a detailed, exam-oriented explanation of the topic “Different Steps in the Process of Nutrition in Animals” in Q&A format, suitable for CBSE Class 10 Biology as well as useful for NEET foundation and school-level competitive exams.

🔍 Different Steps in the Process of Nutrition in Animals – Exam Oriented Questions and Answers

❓Q1. What is nutrition? Why is it important for animals?

✅A.
Nutrition is the process by which living organisms obtain food and utilize it for growth, energy, repair, and maintenance.

• In animals, nutrition is essential because it provides the energy needed for bodily functions and helps in growth and repair.
• Animals are heterotrophs, so they depend on other organisms for their food.

❓Q2. What are the different steps involved in the process of nutrition in animals?

✅A.
The five steps involved in the process of nutrition in animals are:

1. Ingestion – Taking in food.
2. Digestion – Breaking down large molecules into smaller ones.
3. Absorption – Nutrients are absorbed into the bloodstream.
4. Assimilation – Nutrients are used by the body cells.
5. Egestion – Removal of undigested waste.

📌 Mnemonic to Remember: I D A A E (Ingestion, Digestion, Absorption, Assimilation, Egestion)

❓Q3. Explain the process of ingestion in animals.

✅A.

• Ingestion is the process of taking food into the body.
• In higher animals like humans, food is ingested through the mouth using hands or utensils.
• In simple organisms like Amoeba, ingestion occurs through pseudopodia which surround the food particle and engulf it.

❓Q4. What is digestion? Explain its types with examples.

✅A.
Our food contains very big molecules of carbohydrates (like starch), fats and proteins which cannot be absorbed in the body as such. They must be broken down into small, water soluble molecules which can be absorbed by the body. This happens in the process of digestion.

Digestion is the process by which large, complex, and insoluble food molecules are broken down into small, simple, and soluble molecules that can be absorbed by the body.

Types of digestion:

1. Physical digestion – Mechanical breakdown of food, e.g., chewing in the mouth.
2. Chemical digestion – Enzymatic breakdown using digestive juices, e.g., salivary amylase converting starch to sugar.

📌 Digestion starts in the mouth, continues in the stomach, and is completed in the small intestine.

❓Q5. Describe the process of absorption.

✅A.

• After digestion, the nutrients are small and soluble.
• These nutrients are absorbed through the walls of the small intestine into the bloodstream.
• The villi in the small intestine increase the surface area for absorption.

📌 The process in which the digested food passes through the intestinal wall into blood stream is called absorption.

❓Q6. What is assimilation? How is it useful?

✅A.
Assimilation is the process where the absorbed food is utilized by the body cells for:

• Producing energy through respiration.
• Growth and repair of tissues.

🧠 For example, glucose absorbed by blood is used in cells to produce ATP during respiration.

❓Q7. What is egestion? Why is it necessary?

✅A.

• Egestion is the removal of undigested and unabsorbed food from the body in the form of faeces.
• It is a necessary step to avoid the accumulation of waste which can be toxic.

🧻 In humans, egestion takes place through the anus.

📘 Nutrition in Simple Animals – Amoeba and Paramecium

❓Q8. How does Amoeba perform the five steps of nutrition?

✅A.
Amoeba eats tiny (microscopic) plants and animals as food which float in water in which it lives. The mode of nutrition in Amoeba is holozoic. The process of obtaining food by Amoeba is called phagocytosis (‘Phagocytosis’ means ‘cell feeding’).

Amoeba is a unicellular organism, and it performs all nutrition steps within a single cell:

1. Ingestion: Amoeba has no mouth or a fixed place for the ingestion of food (intake of food). Amoeba ingests food by using its pseudopodia. When a food particle comes near Amoeba, then Amoeba ingests this food particle by forming temporary finger-like projections called pseudopodia around it [see Figure]. The food is engulfed with a little surrounding water to form a food vacuole inside the Amoeba. This food vacuole can be considered to be a ‘temporary stomach’ of Amoeba.
2. Digestion: In Amoeba, food is digested in the food vacuole by digestive enzymes. The enzymes from surrounding cytoplasm enter into the food vacuole and break down the food into small and soluble molecules by chemical reactions [see Figure]. Thus, digestion in Amoeba takes place inside the food vacuole due to which the food dissolves (or food becomes soluble).
3. Absorption: The digested food present in the food vacuole of Amoeba is absorbed directly into the cytoplasm of Amoeba cell by diffusion [see Figure]. Since Amoeba consists of only one small cell, it does not require blood system to carry the digested food. The digested food just spreads out from the food vacuole into the whole of Amoeba cell. After absorption of food, the food vacuole disappears.
4. Assimilation: A part of the food absorbed in Amoeba cell is used to obtain energy through respiration. The remaining part of absorbed food is used to make the parts of Amoeba cell which lead to the growth of Amoeba. Thus, on assimilating food Amoeba grows in size [see Figure]. And then Amoeba can reproduce by dividing into two daughter cells.
5. Egestion: Amoeba has no fixed place (like anus) for removing the undigested part of food. When a considerable amount of undigested food collects inside Amoeba, then its cell membrane suddenly ruptures at any place and the undigested food is thrown out of the body of Amoeba [see Figure].

📌 This type of feeding is called phagocytosis (cell-eating).

❓Q9. How does Paramecium obtain food?

✅A.
Paramecium is also a tiny unicellular animal which lives in water. Paramecium uses its hair like structures called cilia to sweep the food particles from water and put them into its mouth (see Figure).

The Paramecium has thin, hair-like cilia all over its body. The cilia move back and forth rapidly in water. When the cilia present around the mouth region of Paramecium move back and forth, they sweep the food particles present in water into the mouth of Paramecium (see Figure 30). This is the first step in the nutrition of Paramecium which is called ingestion. Ingestion is followed by other steps such as digestion, absorption, assimilation and egestion (as explained in the case of Amoeba).

Paramecium uses cilia (tiny hair-like structures) to:

• Sweep food particles into its mouth-like opening.
• Then digestion, absorption, assimilation, and egestion follow similarly as in Amoeba.

📌 Movement of cilia directs food particles from water into the body.

🧠 MCQs: Steps of Nutrition in Animals

1. Which of the following is the correct sequence of steps in nutrition in animals?

A) Digestion → Ingestion → Absorption → Assimilation → Egestion
B) Ingestion → Digestion → Absorption → Assimilation → Egestion
C) Egestion → Ingestion → Assimilation → Digestion → Absorption
D) Ingestion → Absorption → Digestion → Assimilation → Egestion
Answer: B
Explanation: The correct sequence is: Ingestion → Digestion → Absorption → Assimilation → Egestion.

2. The process of taking food into the body is called:

A) Digestion
B) Assimilation
C) Ingestion
D) Absorption
Answer: C
Explanation: Ingestion is the process of taking food into the body.

3. The breakdown of complex food substances into simpler forms is known as:

A) Assimilation
B) Digestion
C) Absorption
D) Egestion
Answer: B
Explanation: Digestion is the breakdown of complex food into simpler substances.

4. The process of passing digested food into the blood is called:

A) Ingestion
B) Absorption
C) Egestion
D) Assimilation
Answer: B
Explanation: Absorption is the process by which digested food passes into the blood or lymph.

5. The process in which absorbed food is utilized by body cells for energy, growth, and repair is called:

A) Egestion
B) Assimilation
C) Ingestion
D) Digestion
Answer: B
Explanation: Assimilation involves the use of absorbed nutrients by the body cells.

6. The removal of undigested food from the body is known as:

A) Digestion
B) Absorption
C) Egestion
D) Ingestion
Answer: C
Explanation: Egestion is the removal of undigested food from the body.

7. In which part of the digestive system does most digestion take place?

A) Mouth
B) Stomach
C) Small intestine
D) Large intestine
Answer: C
Explanation: Small intestine is the site where most digestion and absorption occur.

8. The finger-like projections in the small intestine that help in absorption are called:

A) Cilia
B) Villi
C) Alveoli
D) Nephrons
Answer: B
Explanation: Villi increase the surface area for absorption in the small intestine.

9. What is the function of the large intestine in the digestive system?

A) Digests proteins
B) Absorbs nutrients
C) Absorbs water and forms feces
D) Secretes digestive enzymes
Answer: C
Explanation: The large intestine absorbs water from the undigested food and forms feces.

10. Which organ stores bile and releases it when needed for digestion?

A) Liver
B) Stomach
C) Pancreas
D) Gallbladder
Answer: D
Explanation: The gallbladder stores bile produced by the liver and releases it into the small intestine.

🔍 Assertion-Reason Type MCQs: Steps of Nutrition in Animals

Q1.

Assertion (A): Digestion is necessary for breaking down complex food substances into simpler forms.
Reason (R): Only simpler food molecules can be absorbed into the blood.

Options:
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
Explanation: Digestion simplifies food, and only simpler substances like glucose and amino acids are absorbed.

Q2.

Assertion (A): The large intestine is the main site of nutrient absorption.
Reason (R): The large intestine has numerous villi for increasing surface area.

Options:
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 false, but R is true.
D) Both A and R are false.
Answer: D
Explanation: The small intestine is the main site of nutrient absorption, and it contains villi—not the large intestine.

Q3.

Assertion (A): Egestion is the process of removing undigested food from the body.
Reason (R): The digested food is absorbed into the bloodstream through villi.

Options:
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: B
Explanation: Both statements are true, but they talk about different stages—egestion and absorption.

Q4.

Assertion (A): Assimilation occurs in the stomach.
Reason (R): The stomach produces digestive juices that break down food.

Options:
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 false, but R is true.
D) Both A and R are false.
Answer: C
Explanation: Assimilation occurs in body cells, not in the stomach. The stomach does produce digestive juices though.

Q5.

Assertion (A): Ingestion is the process of chewing food with teeth.
Reason (R): Teeth help in breaking down food into smaller pieces for easier swallowing.

Options:
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
Explanation: Ingestion includes the process of chewing, and teeth aid in mechanical digestion.

📘 Case-Based Questions: Steps of Nutrition in Animals

📍 Case Study 1: Digestion in Rohan’s Body

Rohan had a heavy lunch that included rice, dal, and vegetables. After eating, the food passed through various organs in his digestive system, starting from the mouth and ending at the anus. In the small intestine, nutrients were absorbed into the blood and transported to different body parts. His undigested food was later removed from his body as waste.

Read the case and answer the following questions:

Q1. What is the correct order of nutrition steps that occurred in Rohan’s body?
A) Digestion → Ingestion → Absorption → Egestion → Assimilation
B) Ingestion → Digestion → Absorption → Assimilation → Egestion
C) Ingestion → Digestion → Assimilation → Absorption → Egestion
D) Egestion → Assimilation → Absorption → Digestion → Ingestion
Answer: B

Q2. Which part of Rohan’s digestive system is responsible for maximum nutrient absorption?
A) Stomach
B) Small intestine
C) Large intestine
D) Mouth
Answer: B

Q3. What is the function of villi present in the small intestine?
A) Secretion of bile
B) Absorption of water
C) Increase surface area for absorption of nutrients
D) Digestion of carbohydrates
Answer: C

Q4. Which process involves the removal of undigested food from Rohan’s body?
A) Ingestion
B) Digestion
C) Assimilation
D) Egestion
Answer: D

📍 Case Study 2: Swati’s Biology Experiment

Swati conducted an experiment in school to trace the journey of food in the digestive system. She labeled a chart with various stages such as mouth, esophagus, stomach, small intestine, and large intestine. She observed that bile is secreted by the liver and stored in the gallbladder, and helps in digestion of fats.

Read the case and answer the following questions:

Q1. What role does bile play in digestion?
A) Digests carbohydrates
B) Digests proteins
C) Emulsifies fats
D) Absorbs vitamins
Answer: C

Q2. Which organ secretes bile in Swati’s chart?
A) Gallbladder
B) Liver
C) Pancreas
D) Stomach
Answer: B

Q3. Which of the following is not a step in nutrition?
A) Assimilation
B) Respiration
C) Ingestion
D) Egestion
Answer: B

Q4. What is the main function of the large intestine in the digestive system?
A) Absorb nutrients
B) Store bile
C) Absorb water and form feces
D) Digest proteins
Answer: C

📋 Important Exam-Based Points

✨ Do You Know?

• Cilia in Paramecium help in locomotion and feeding.
• Amoeba grows by assimilating food and can reproduce by dividing into two cells.
• In humans, most digestion and absorption occurs in the small intestine.
• Food vacuole in Amoeba acts like a temporary stomach.

🧠 Quick Revision Table

📝 Practice Question for Exam

Q. Write short notes on the following:
(a) Digestion in Amoeba
(b) Ingestion in Paramecium
(c) Five steps of animal nutrition

🧪 Worksheet & Test Paper (Short Format)

Section A: MCQs (1 mark each)

1. The process of taking food into the body is called:
   a) Digestion
   b) Absorption
   c) Ingestion ✅
   d) Assimilation
2. In Amoeba, food is digested in:
   a) Cytoplasm
   b) Mitochondria
   c) Food vacuole ✅
   d) Nucleus

Section B: Short Answer (2–3 marks each)

1. What is egestion?
2. Describe how nutrients are absorbed in humans.

Section C: Long Answer (5 marks)

1. Describe in detail the five steps of nutrition in animals with examples from Amoeba and Paramecium.

🎯 Final Revision Points

✅ Nutrition includes ingestion, digestion, absorption, assimilation, and egestion.
✅ Amoeba uses pseudopodia; Paramecium uses cilia for ingestion.
✅ Food vacuole in Amoeba performs digestion and temporary storage.
✅ Villi in the small intestine increase absorption efficiency.
✅ Egestion removes waste to maintain health.

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