Life Processes Class 10 Notes | Nutrition & Photosynthesis Explained (Part 2)

Introduction

In continuation of Life Processes, this part focuses on heterotrophic nutrition and digestion, which are essential for understanding how organisms obtain and process food. While plants prepare their own food, animals and humans depend on other sources for nutrition.

In this blog, we provide clear and structured notes on heterotrophic nutrition, digestion in microorganisms, and the human digestive system. These notes are designed to help Class 10 students understand concepts easily and prepare effectively for exams.

 In this part, you will learn:

• Types of heterotrophic nutrition

• Nutrition in Amoeba and Paramecium

• Human digestive system (mouth to intestine)

• Important enzymes and their functions

📺 Watch the video explanation below for better understanding.

🎥 VIDEO SECTION

https://www.youtube.com/watch?v=mQChpXBYdEs

Heterotrophic Nutrition

Heterotrophic nutrition is a mode of nutrition in which organisms depend on other organisms for their food. These organisms cannot prepare their own food and rely on plants or other animals for energy.

Types of Heterotrophic Nutrition

Heterotrophic nutrition can be classified into three types:

1. Saprotrophic Nutrition

Organisms obtain food from dead and decaying matter.

• They secrete digestive enzymes outside the body

• Convert complex substances into simpler forms

👉 Example:

• Mushroom

2. Parasitic Nutrition

Organisms derive food from a living host.

• The host is harmed in this process

• Parasites depend completely on the host

👉 Example:

• Leech

3. Holozoic Nutrition

This is the most common mode of nutrition in animals.

• Organisms consume solid food

• Food is digested into simpler substances

👉 Example:

• Humans

Nutrition in Unicellular Organisms

Amoeba

Amoeba takes in food through a special process:

• Uses temporary finger-like projections called pseudopodia

• Surrounds and engulfs food

• Forms a food vacuole

Inside the vacuole:

• Food is digested

• Nutrients are absorbed into cytoplasm

• Undigested food is expelled

Paramecium

• Food enters through a specific region called oral groove

• Hair-like structures called cilia help move food

Nutrition in Human Beings

Human digestion occurs in the alimentary canal, a long tube extending from mouth to anus.

1. Mouth

Digestion begins in the mouth.

• Food is chewed by teeth

• Mixed with saliva

• Tongue helps in mixing

Important Points:

• Saliva contains salivary amylase

• Breaks down starch into simple sugars

• Food moves to oesophagus through muscular movements

2. Oesophagus

• Food pipe connecting mouth and stomach

• Moves food using peristalsis (muscular movement)

  
  

3. Stomach

The stomach is a muscular organ where digestion continues.

Gastric glands release:

• Hydrochloric acid (HCl) → Creates acidic medium

• Pepsin → Digests proteins

• Mucus → Protects stomach lining

👉 Food is released slowly into the small intestine.

4. Small Intestine

This is the most important part of digestion.

• Long and coiled structure: This is the longest part of the alimentary canal and is extensively coiled

• Site of complete digestion :The length of the small intestine differs in various animal

• Herbivores eating grass need a longer small intestine to allow the cellulose to be digested

• Meet is easier to digest and carnivorous like tigers have a shortest small intestine

• It is the site of the complete digestion of carbohydrate proteins and fats

• It received the secretion of the liver and pancreas for this purpose

• The food coming from the stomach is acidic and has to be made Alkaline

• Pancreatic enzymes to act by juice from the liver accomplishes this

• Fats are present in the intestine in the form of large globules which makes it difficult for enzymes to act on them

• Bile salts break them down into smaller globules  increasing deficiency of enzyme action

• The pancreas secrete pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for Breaking Down emulsified fats

Key Functions:

• Receives bile from liver

• Receives pancreatic juice

Digestion Process:

• Proteins → Amino acids

• Carbohydrates → Glucose

• Fats → Fatty acids + Glycerol

Role of Bile and Enzymes

• Bile salts break large fat globules into smaller ones

• Pancreas releases enzymes:

  • Trypsin → Digests proteins

  • Lipase → Breaks fats

Villi (Very Important)

The inner lining of small intestine has finger-like projections called villi.

Functions:

• Increase surface area

• Help in absorption of nutrients

• Rich in blood vessels

5. Large Intestine

• Absorbs water from undigested food

• Remaining waste is removed through anus

IMPORTANT QUESTIONS

1. What is enzyme?

👉 Biological catalyst that breaks complex substances into simpler ones

2. Sequence of alimentary canal:

👉 Mouth → Oesophagus → Stomach → Small intestine → Large intestine

3. Which part receives bile?

👉 Small intestine

4. First enzyme in digestion?

👉 Salivary amylase

5. Function of villi:

• Increase absorption

• Transport nutrients to body

6. Why small intestine is longer in herbivores?

👉 To digest cellulose in plants

7. Functions of digestive components:

• Hydrochloric acid → acidic medium

• Pepsin → protein digestion

• Bile salts → fat breakdown

• Trypsin → protein digestion

• Lipase → fat digestion

8. What will happen if mucus is not secreted  by the gastric gland

👉Fails to protect the inner lining of the stomach from the action of the acid under normal condition

9. How small intestine design to absorb digested food

👉 The inner lining of the small intestine has numerous finger like projection called villi.These villi absorb the digested food

10. Small intestine in herbivorous longer than in carnivores give reason

👉 Herbivores eating grass need a longer small intestine to allow the cellulose to be digested

11. An enzyme secreted  from gastric glands in stomach that acts on protein  is

👉 Pepsin

12. Identify the labelled parts P,Q and R in the given diagram below explain how the digestion takes place in the part Q and R

👉 P= Oesophagus

Q = Stomach

R = Small intestine

In stomach it releases hydrochloric acid, pepsin and  mucus. Acid helps to maintain the acidic medium, mucus helps to protect the inner lining of stomach, pepsin helps to digest the protein

Small intestine : Complete digestion will takes place in small intestine it converts protein into amino acid,carbohydrate into glucose and fats into fatty acid and glycerol.