Life Processes Class 10 Notes: Nutrition, Respiration, Transport & Excretion

These life processes class 10 notes summarise the chapter on the basic functions that keep an organism alive: nutrition, respiration, transportation and excretion. Life processes are the maintenance activities that living things perform to stay alive, even when they are resting. Because the chapter is one of the most important in Biology, it regularly brings both short and long questions in the CBSE board exam. First, read the notes once for understanding. Then use the tables and the FAQ at the end for quick revision.

What Are Life Processes?

Living things need energy to repair worn-out parts, grow and move. They get that energy from food, so taking in food is the first step. After that, the body converts the food, moves it around and removes the waste. Together, these steps are called life processes. Molecular movements within the cell also continue constantly. Hence, maintenance never stops, and that idea runs through all the life processes class 10 notes below.

Four processes form the core of this chapter. Nutrition takes in food and breaks it down. Respiration releases energy from that food. Transportation carries materials to every part of the body, while excretion removes harmful waste.

Nutrition

Autotrophic Nutrition and Photosynthesis

Green plants prepare their own food by photosynthesis. The overall reaction is:

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O (in the presence of sunlight and chlorophyll)

Three events take place during photosynthesis. First, chlorophyll absorbs light energy. Next, light energy converts into chemical energy, and water splits into hydrogen and oxygen. Finally, carbon dioxide reduces to carbohydrates.

Plants take in carbon dioxide through stomata, which are tiny pores on the leaf surface. Because each pore has two guard cells, the plant can open and close it as needed. Stomata also release oxygen, but they lose water vapour as well. Therefore, plants close them when water is scarce.

Heterotrophic Nutrition

Animals and fungi cannot make food. Instead, they take it from other organisms. There are three common modes of nutrition:

• Holozoic: if food is ingested and digested inside the body, as in humans and Amoeba, the mode is holozoic.
• Saprophytic: when an organism absorbs food from dead and decaying matter, as bread mould does, it is saprophytic.
• Parasitic: because Cuscuta and tapeworm feed on a living host, they are parasites.

Amoeba surrounds food with pseudopodia and forms a food vacuole, where digestion happens. Paramecium, on the other hand, uses cilia to sweep food to a specific spot.

Nutrition in Human Beings

The alimentary canal starts at the mouth and ends at the anus. Digestion, therefore, follows this path.

From the Mouth to the Stomach

1. Mouth: first, teeth chew the food, and then the enzyme salivary amylase in saliva breaks starch into sugar.
2. Oesophagus: when rhythmic contractions called peristalsis begin, food moves down.
3. Stomach: since hydrochloric acid kills germs, pepsin can digest proteins while mucus protects the stomach lining.

From the Small Intestine to the Anus

1. Small intestine: bile from the liver makes the food alkaline and emulsifies fats, so that pancreatic enzymes can work. Trypsin digests proteins, and lipase digests fats. Finally, intestinal juice completes the digestion of carbohydrates, proteins and fats.
2. Absorption: because finger-like villi increase the surface area, they absorb digested food into the blood.
3. Large intestine: it absorbs water, and the remaining waste leaves through the anus.

Respiration

Respiration is the process of releasing energy from food. First, glucose breaks into pyruvate in the cytoplasm. After that, the pathway depends on whether oxygen is available. However, the energy goal is the same in every case.

Type	Where it occurs	Products	Energy
Aerobic	Mitochondria	Carbon dioxide, water	High
Anaerobic (yeast)	Cytoplasm	Ethanol, carbon dioxide	Low
Anaerobic (muscle)	Cytoplasm	Lactic acid	Low

The cell stores the released energy in ATP, its energy currency. When the cell needs energy, ATP breaks into ADP and inorganic phosphate, and that step releases a fixed amount of energy. Muscle cramps after heavy exercise happen because lactic acid builds up when the oxygen supply is short.

Respiration in Human Beings

Air passes through the nostrils, pharynx, larynx, trachea, bronchi and bronchioles before it reaches the alveoli. Rings of cartilage keep the trachea open. Since alveoli have very thin walls and a rich blood supply, gas exchange takes place there. Oxygen moves into the blood, while carbon dioxide moves out.

Haemoglobin in red blood cells carries oxygen. Carbon dioxide, however, dissolves more easily in water, so most of it travels in blood plasma. Plants, meanwhile, exchange gases through stomata in leaves and through lenticels in stems. Roots also take in oxygen from the air spaces in soil.

Transportation

Transport in Human Beings

The heart pumps blood through a closed network of blood vessels. It has four chambers: two atria on top and two ventricles below. Because oxygenated and deoxygenated blood do not mix, the body gets a steady, high energy supply. Birds and mammals show double circulation. As a result, blood passes through the heart twice in one complete cycle, once through the lungs and once through the body.

Arteries carry blood away from the heart, so they have thick, elastic walls. Veins bring blood back to the heart, and their valves stop backflow. Capillaries have walls that are one cell thick, which allows exchange with the tissues. Normal blood pressure is about 120 mm Hg during ventricular contraction (systolic) and 80 mm Hg during relaxation (diastolic). Meanwhile, platelets help blood clot at injuries, and lymph carries digested fat while it drains excess fluid from tissues.

Transport in Plants

Xylem and phloem form the transport system of a plant. Xylem tissue, which consists of vessels and tracheids, carries water and minerals from the roots to the leaves. At first, root pressure helps. In tall trees, however, the main force is transpiration pull, the suction created when water evaporates from leaves. Phloem, on the other hand, moves the sugar made in leaves to storage organs and growing parts. We call this movement translocation, and it uses energy from ATP.

Feature	Xylem	Phloem
Carries	Water and minerals	Food (sucrose)
Direction	Upward	Upward and downward
Energy needed	No	Yes

Excretion

Excretion is the removal of harmful metabolic wastes. In humans, the excretory system includes a pair of kidneys, two ureters, a urinary bladder and a urethra.

Each kidney has a large number of filtering units called nephrons. A nephron contains a cluster of capillaries called the glomerulus inside a cup-shaped Bowman’s capsule, followed by a long tubule. Urine forms in three steps:

1. Filtration: first, the glomerulus filters the blood.
2. Selective reabsorption: next, useful substances such as glucose and amino acids return to the blood.
3. Secretion and collection: finally, waste and extra water pass through the collecting duct to the ureter and the bladder.

When the kidneys fail, a patient may need dialysis. An artificial kidney removes nitrogenous waste from the blood by diffusion across a membrane. Because the dialysing fluid has the same osmotic pressure as blood but contains no nitrogenous waste, the waste moves out.

Plants, on the other hand, excrete differently. They release oxygen and carbon dioxide through stomata. They also store waste in old xylem, shed leaves and bark, and excrete resins and gums.

Common Mistakes in Life Processes Answers

• Students often write “respiration” when the question asks about “breathing”, but breathing is only the physical movement of air.
• Many forget the equation’s conditions, such as sunlight and chlorophyll.
• Some mix up pepsin and trypsin, although pepsin works in the stomach and trypsin works in the small intestine.
• If you call phloem dead tissue, you lose marks, because it is living tissue.
• While drawing the nephron, always label the glomerulus and Bowman’s capsule.

How to Revise Life Processes Class 10 Notes Quickly

A Three-Pass Method for Life Processes Class 10 Notes

Use a three-pass method. On the first day, read the notes and redraw the digestive system, the heart and the nephron. Next, test yourself with the tables on the second day. Finally, solve the NCERT intext and back exercise questions without looking at the notes. Furthermore, practise one long diagram-based answer from each section, because these carry the most marks. After this chapter, browse all Class 10 Science notes. For broader planning, see our Class 10 notes hub. If you struggle to begin, read how to stop procrastinating.

Conclusion: Make the Chapter Stick

These life processes class 10 notes show a clear pattern: every process in a plant has a matching process in an animal, and each one moves materials or energy where the body needs them. Similarly, learn the four processes as a connected story rather than four separate topics. Practise the diagrams, repeat the tables, and revisit the chapter a week later to lock it in. Then continue to the next chapter from the Class 10 Science notes or return to the The Note homepage.