Life Processes – Class X Summary

 Living organisms are distinguished from non-living objects by the presence of certain vital processes called life processes. These processes ensure the survival, growth, and reproduction of organisms. The major life processes are nutrition, respiration, transportation, and excretion.

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1. Nutrition

Nutrition is the process by which organisms obtain food and energy for their activities.

(a) Modes of Nutrition

• Autotrophic nutrition: Organisms (like green plants) prepare their own food by photosynthesis using sunlight, water, and carbon dioxide.

• Heterotrophic nutrition: Organisms depend on other organisms for food. Types:

  • Saprotrophic (fungi) – feed on dead and decaying matter.

  • Parasitic (plasmodium, lice) – feed on hosts.

  • Holozoic (humans, animals) – ingest, digest, absorb, and assimilate food.

(b) Photosynthesis in Plants

$$6CO_2 + 6H_2O \xrightarrow{Sunlight, Chlorophyll} C_6H_{12}O_6 + 6O_2$$

• Raw materials: carbon dioxide, water.

• Site: chloroplasts.

• By-product: oxygen.

(c) Human Digestive System

• Mouth: Mechanical and chemical digestion (saliva contains amylase).

• Stomach: Gastric juices (HCl, pepsin) break proteins.

• Small intestine: Pancreatic enzymes and bile help digestion; absorption occurs through villi.

• Large intestine: Absorbs water and minerals; wastes are expelled.

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2. Respiration

Respiration is the process of releasing energy from food.

• Aerobic respiration: In the presence of oxygen.

  $$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + Energy$$

• Anaerobic respiration: In the absence of oxygen (yeast → alcohol; muscle cells → lactic acid).

• Human Respiratory System:

  • Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Lungs (alveoli).

  • Exchange of gases occurs at the alveoli by diffusion.

  • Respiratory pigment: Haemoglobin.

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3. Transportation

Transportation is the movement of essential substances such as food, gases, and wastes.

(a) In Human Beings

• Blood: A connective tissue (plasma, RBCs, WBCs, platelets).

• Heart: Pumps blood through arteries, veins, and capillaries.

  • Double circulation ensures oxygen-rich and oxygen-poor blood are separated.

• Lymph: Transports fats, plays a role in immunity.

(b) In Plants

• Xylem: Transports water and minerals (unidirectional).

• Phloem: Transports food (bidirectional).

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4. Excretion

Excretion is the removal of metabolic waste products.

(a) In Humans

• Excretory system: Kidneys, ureters, urinary bladder, urethra.

• Nephron: Structural and functional unit of the kidney.

• Kidneys filter urea, uric acid, and excess salts.

(b) In Plants

• Excrete oxygen during photosynthesis, carbon dioxide during respiration, resins, gums, latex.

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5. Summary Table

Life Process	In Humans	In Plants
Nutrition	Digestive system, holozoic mode	Photosynthesis, autotrophic mode
Respiration	Aerobic in mitochondria	Exchange via stomata, lenticels
Transportation	Blood (heart, arteries, veins, lymph)	Xylem and Phloem
Excretion	Kidneys (nephron units)	Stomata, resins, gums, gases

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6. Conclusion

Life processes are essential for maintaining the living state of organisms. Nutrition provides energy-rich molecules, respiration releases energy, transportation distributes materials, and excretion removes harmful wastes. Together, these processes ensure the proper functioning, growth, and survival of living beings.