Revision: Life Processes Science English Medium Class 10 CBSE

Biological substances that speed up the breakdown of complex food into simpler forms to aid in digestion are called enzymes.

The process by which organisms obtain energy and materials from external sources for growth, repair, and maintenance of life processes is called nutrition.

The mode of nutrition in which organisms prepare their own food from simple inorganic substances like carbon dioxide and water using sunlight in the presence of chlorophyll is called autotrophic nutrition.

The mode of nutrition in which organisms obtain their food from other organisms because they cannot synthesize it themselves is called heterotrophic nutrition.

An enzyme in saliva that breaks down starch (a complex carbohydrate) into simple sugars is called salivary amylase.

A digestive fluid secreted by salivary glands that moistens food and contains the enzyme salivary amylase to break down starch is called saliva.

It is a process of release of energy from food substances such as glucose and fats under the control of enzymes, to carry out life processes, by the living organisms.

The breakdown of glucose in the absence of oxygen to produce alcohol or lactic acid and a small amount of energy is called anaerobic respiration.

The breakdown of glucose in the presence of oxygen to produce carbon dioxide, water, and energy is called aerobic respiration.

Eupnea is the medical and physiological term for normal, unlabored, and quiet breathing in a healthy individual at rest. It represents an efficient respiratory state where the body maximizes oxygen intake while minimizing muscular effort.

Difficulty or labored breathing, often described as shortness of breath.

It is a type of reflex whose stimulus is in the nasal passage which causes spasmodic contraction of expiratory muscles that forcefully expel the air through the nasal passage.

It is a type of reflex whose stimulus is any foreign particle, resulting from deep inspiration followed by strong expiration, which forcefully expels the air through the mouth.

The trachea is commonly called a windpipe. It is a tube supported by cartilaginous rings that connect the pharynx and larynx to the lungs, allowing the passage of air. The trachea divides into right and left bronchi and enters the lungs.

The process of conversion of glucose molecules in food into energy-rich molecules, carbon dioxide and water with the help of oxygen is known as respiration.

Apnea is defined as the temporary cessation of breathing, marked by the absence of respiratory muscle movement and airflow.

The exchange of gases through moist skin and blood capillaries underneath is called cutaneous respiration.

Arteries are the blood vessels in which oxygenated blood is going away from the heart to all parts of the body.

Veins are the blood vessels that carry deoxygenated (impure) blood from the body cells to the heart.

The circulatory system is a transport system moving substances throughout our body with the help of blood.

The heart is a hollow muscular vertebrate organ that pumps blood through rhythmic contractions.

Diastolic pressure is the lower limit of blood pressure, recorded when the heart is at rest and the pressure in the arteries drops after the pulse wave has passed.

Blood pressure is the pressure that the blood flowing through the arteries exerts on their walls.

A sphygmomanometer is the instrument used to measure blood pressure in the arteries.

Hypertension is a condition in which the blood pressure consistently remains above 140/90 mm Hg.

A pulse is the rhythmic expansion and contraction of arteries (especially the radial artery at the wrist) due to the pumping action of the heart.

The sound or movement of the heart as it sends blood around the body is called heartbeat. Every heartbeat causes a pulse in the arteries.

The smallest or the final branch of an artery is called an arteriole.

An ARTERY is a vessel that carries blood away from the heart towards any organ.

A VEIN is a vessel that carries blood away from an organ towards the heart.

A venule is the smallest branch of a vein formed by the union of capillaries. It has a thin muscular coat and gradually joins with other venules to form larger veins.

Diapedesis is the movement of white blood cells from lymph capillary walls to neighbouring tissues, often for immunological defence.

The enzyme released by injured tissues and disintegrating platelets that initiates clotting is called thrombokinase (also known as Thromboplastin or Factor X or Stuart factor).

The solid mass left behind after clotting, formed by fibrin and trapped blood cells, is called clot or thrombus.

As the blood flows in the capillaries of the tissues, the plasma and the leukocytes "leak out" through their walls. This fluid bathes the cells and is called the tissue fluid or the intercellular or extracellular fluid.

Lymph is the fluid formed from tissue fluid that enters lymph vessels. It helps in returning excess fluid to the blood and plays a role in immunity.

The loss of water vapour from the aerial parts of a plant, mainly through stomata, is called transpiration.

The movement of soluble products of photosynthesis from the leaves to other parts of the plant through phloem is called translocation.

Micturition is the process of expelling urine out of the body through the urethra by opening the sphincter muscles and passing urine, involving the relaxation of the sphincter muscles between the urinary bladder and urethra. 

Excretion is the process that biological organisms use to expel or eliminate the waste products produced by their metabolism.

The kidney while removing wastes like urea from the blood also regulates its composition, i.e., the percentage of water and salts. This function is called osmoregulation.

The process of removal of chemical wastes (mainly nitrogenous wastes) from the body is known as 'excretion' (ex: out, crete: flow).

or

Excretion is the process of removal of harmful and unwanted nitrogenous waste products from the body.

Organs which are concerned with the formation, storage and elimination of urine constitute the 'excretory system'.

The apex of each pyramid in the medulla of the kidney that projects into the pelvis is called the papilla.

The kidney is composed of an enormous number of minute tubules called uriniferous tubules or nephrons or renal tubules or just kidney tubules. These are the structural and functional units of the kidney. 

Bowman's capsule is a thin-walled, cup-shaped structure in the nephron that surrounds the glomerulus and collects the filtrate from the blood.

The glomerulus is a knot-like network of blood capillaries located inside the Bowman's capsule, where blood filtration occurs.

The Malpighian capsule is the combined structure of the Bowman's capsule and glomerulus, forming the filtration unit of the nephron.

An artificial kidney is a dialysis machine that removes urea and excess salts from the blood when both kidneys fail, and returns the purified blood back into the body.

Dialysis is a medical process in which nitrogenous wastes and toxic substances are removed from the blood using an artificial machine when the kidneys fail to function properly.

1. Autotrophic organisms like green plants synthesize their own food through photosynthesis using carbon dioxide, water, sunlight, and chlorophyll.
2. The process of photosynthesis involves absorption of light by chlorophyll, splitting of water into hydrogen and oxygen, and conversion of carbon dioxide into carbohydrates.
3. The general equation of photosynthesis is: \[\ce{{6CO_2+12H_2O} ->[Chlorophyll][Sunlight] \underset{Glucose}{C6H12O6} + 6O2 +6H2O}\]
4. Carbon dioxide required for photosynthesis enters the plant through stomata, whose opening and closing is regulated by guard cells.
5. Along with water absorbed by roots, plants require minerals like nitrogen, phosphorus, iron, and magnesium from the soil for growth and synthesis of proteins and other compounds.

1. Glucose is first broken down in the cytoplasm into a 3-carbon molecule called pyruvate, releasing some energy.
2. In the absence of oxygen, pyruvate is converted into ethanol and carbon dioxide (in yeast) or lactic acid (in muscles), releasing less energy.
3. In the presence of oxygen, pyruvate is broken down in the mitochondria into carbon dioxide and water, releasing a large amount of energy.
4. The energy released during respiration is used to make ATP, which is the energy currency of the cell and used for all life processes.

1. In plants, exchange of gases (O₂ and CO₂) occurs through stomata by diffusion, depending on day or night.
2. Aquatic animals like fish breathe faster because water has less oxygen; they absorb oxygen through gills.
3. In terrestrial animals, oxygen is taken from the air using special respiratory organs like lungs.
4. In humans, air enters through nostrils, passes through the trachea and bronchi, and reaches the lungs, where gas exchange happens in tiny sacs called alveoli.
5. Oxygen is carried by haemoglobin in red blood cells, and carbon dioxide is mostly transported in dissolved form in blood.

• ATP (Adenosine Triphosphate) is the energy currency of the cell, storing energy in its phosphate bonds and releasing it when needed.
• ATP consists of adenine, ribose, and three phosphate groups, and is formed in cells to meet energy demands.
• When carbohydrates are lacking, the body uses lipids and proteins, which are converted into acetyl-CoA and oxidized via the Krebs cycle for energy.

1. The tricuspid valve (right atrio-ventricular valve) is located between the right atrium and right ventricle; it has three cusps held by chordae tendineae attached to papillary muscles.
2. The bicuspid or mitral valve (left atrio-ventricular valve) lies between the left atrium and left ventricle and has two cusps.
3. The pulmonary semilunar valve is located at the opening of the pulmonary artery from the right ventricle; it has three pocket-shaped cusps.
4. The aortic semilunar valve is found at the origin of the aorta from the left ventricle and also has three pocket-shaped cusps.

1. Platelets have a short lifespan of 3 to 5 days and are mainly destroyed in the spleen.
2. At the site of injury, platelets disintegrate and release thrombokinase (also called thromboplastin or Factor X), initiating clot formation.
3. Thrombokinase, in the presence of calcium ions, converts inactive prothrombin in the plasma into active thrombin.
4. Vitamin K is essential for the synthesis of prothrombin in the liver.
5. Thrombin converts soluble fibrinogen into insoluble fibrin, forming sticky threads at the wound.
6. The fibrin mesh traps blood cells, forming a clot that seals the wound and stops bleeding.
7. The clot contracts, squeezing out serum, and leaves behind a solid mass called a thrombus (clot).

1. Lymph is formed from tissue fluid and flows through lymph vessels due to the contraction of nearby muscles.
2. Lymph contains only WBCs (mainly lymphocytes) and is free from RBCs and platelets; it is made up of 94% water and 6% solids like proteins and fats.
3. It supplies nutrients and oxygen to areas where blood cannot reach, especially in deep tissues.
4. Lymph plays a role in draining excess tissue fluid and returning proteins and waste products to the bloodstream.
5. It helps in absorbing fats from the intestine and defending the body by removing bacteria and housing immune cells like lymphocytes.

1. Xylem vessels and tracheids form a continuous network that carries water and minerals from roots to all parts of the plant.
2. Water enters the roots due to active absorption of ions, creating a concentration difference that pulls water in from the soil.
3. Transpiration is the loss of water vapour from the aerial parts of the plant, mainly through stomata, and creates a suction pull that draws water upward.
4. Transpiration pull is the main force for upward water movement during the day, while root pressure plays a bigger role at night.

1. Humans have two bean-shaped kidneys, located on either side of the backbone and protected by the last two ribs.
2. The right kidney is slightly lower than the left due to the position of the liver.
3. Each kidney has a hilum where the ureter, renal artery, and renal vein are connected.
4. Internally, the kidney has an outer cortex and an inner medulla made up of conical structures called renal pyramids.
5. The kidney contains numerous nephrons (uriniferous tubules), which are the structural and functional units responsible for urine formation.

1. Each kidney contains about 2 million uriniferous tubules, each 4–5 cm long, with a total length of over 60 km aiding reabsorption.
2. The Malpighian capsule is formed by Bowman’s capsule and glomerulus, where filtration begins.
3. Proximal convoluted tubule (PCT) in the cortex is the first site of reabsorption; Loop of Henle extends into medulla and helps in water conservation.
4. Distal convoluted tubule (DCT) opens into the collecting duct, which transports urine to the pelvis.
5. Blood flows through the kidneys about 350 times a day, filtering approximately 160 litres of fluid daily, most of which is reabsorbed.
6. The kidneys produce around 1.2 litres of urine per day, and their blood supply involves afferent and efferent arterioles along with capillary networks.