Life Processes: Nutrition and Photosynthesis

• Living organisms perform various life processes to sustain themselves.
• These processes include nutrition, respiration, circulation, excretion, control, coordination, reproduction, growth, and movement.

Nutrition

• Nutrition is the process of obtaining and utilizing food necessary for life.
• Organisms can be autotrophic, producing their own food, or heterotrophic, relying on others for food.
• Autotrophic nutrition is seen in plants via photosynthesis.
• Heterotrophic nutrition is found in animals, fungi, and some bacteria.

Photosynthesis

• Photosynthesis is how plants convert light energy into chemical energy in the form of glucose.
• Chlorophyll, present in chloroplasts, absorbs sunlight.
• Carbon dioxide from the air and water from the soil are the raw materials.
• The balanced chemical equation for photosynthesis is: 6CO2 + 6H2O + Light energy → C6H12O6 + 6O2.
• Plants also require nitrogen, phosphorus, and potassium for growth, which they absorb from the soil.

Heterotrophic Nutrition

• Heterotrophic nutrition involves consuming pre-made organic matter.
• It includes various methods such as holozoic, saprophytic, and parasitic nutrition.
• Holozoic nutrition involves ingestion, digestion, absorption, assimilation, and egestion; examples include humans and animals.
• Saprophytic nutrition involves feeding on dead and decaying organic matter; examples include fungi and some bacteria.
• Parasitic nutrition involves deriving nutrients from another living organism (the host); examples include parasites like tapeworms and leeches.

Respiration

• Respiration is the process of releasing energy from food.
• It involves breaking down glucose in cells to produce ATP (adenosine triphosphate), the energy currency of the cell.
• There are two main types: aerobic and anaerobic respiration.
• Aerobic respiration uses oxygen to completely break down glucose into carbon dioxide, water, and energy.
• Anaerobic respiration occurs without oxygen and results in less energy, producing lactic acid or ethanol as byproducts.

Aerobic Respiration

• Occurs in the presence of oxygen.
• Glucose is completely oxidized into carbon dioxide and water.
• This process yields a significant amount of ATP.
• The overall equation is: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP).

Anaerobic Respiration

• Occurs in the absence of oxygen.
• Glucose is incompletely broken down.
• Produces less ATP than aerobic respiration.
• In muscle cells, it leads to the formation of lactic acid, causing cramps.
• In yeast, it leads to the production of ethanol and carbon dioxide (fermentation).

Respiration in Plants

• Plants respire through stomata in leaves and lenticels in stems.
• Oxygen is used, and carbon dioxide is released, similar to animals.
• The rate of respiration in plants is generally lower compared to animals.

Circulation

• Circulation is the transport of essential substances like nutrients, oxygen, and hormones to cells and the removal of waste products.
• In animals, this is primarily done through the circulatory system, involving the heart, blood vessels, and blood.
• In plants, it occurs through the vascular tissues, xylem and phloem.

Circulation in Humans

• The human circulatory system consists of the heart, blood vessels (arteries, veins, capillaries), and blood.
• The heart is a muscular organ that pumps blood throughout the body.
• Arteries carry oxygenated blood away from the heart.
• Veins carry deoxygenated blood back to the heart.
• Capillaries are tiny vessels where exchange of materials occurs between blood and tissues.
• Blood consists of plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets.

Blood

• Plasma is the liquid component of blood, carrying nutrients, hormones, and waste products.
• Red blood cells (RBCs) contain hemoglobin, which binds to oxygen and transports it.
• White blood cells (WBCs) are part of the immune system, defending against infections.
• Platelets are involved in blood clotting.

Circulation in Plants

• Xylem transports water and minerals from the roots to the rest of the plant.
• Phloem transports sugars (produced during photosynthesis) from the leaves to other parts of the plant.
• Transpiration, the loss of water vapor from leaves, helps in the upward movement of water in xylem.
• Translocation is the movement of sugars in phloem, driven by differences in osmotic pressure.

Excretion

• Excretion is the process of removing metabolic waste products from the body.
• In animals, this is primarily done through organs like kidneys, skin, and lungs.
• In plants, waste products are stored in vacuoles or removed through leaves.

Excretion in Humans

• The human excretory system includes the kidneys, ureters, urinary bladder, and urethra.
• Kidneys filter blood and produce urine, which contains nitrogenous wastes like urea.
• Urine is transported through the ureters to the urinary bladder, where it is stored temporarily.
• It is then eliminated from the body through the urethra.
• Lungs excrete carbon dioxide, and skin excretes sweat containing salts and urea.

Excretion in Plants

• Plants excrete waste products such as resins, gums, and latex.
• These substances are stored in different parts of the plant.
• Some waste products are eliminated through shedding of leaves.
• Oxygen, produced during photosynthesis, is also a waste product.