Life Processes – Notes, MCQs, Quiz & Worksheet

Transpiration is the process where water vapor is released from aerial parts of the plant, primarily leaves. This creates a transpiration pull, which along with root pressure, helps in the upward movement of water and dissolved minerals through the xylem.

The green parts of the variegated leaf contain chlorophyll, which is essential for photosynthesis. Photosynthesis produces glucose, which is then stored as starch. Non-green parts lack chlorophyll and therefore cannot perform photosynthesis to produce starch.

The villi are finger-like projections that significantly increase the surface area of the small intestine. This large surface area is crucial for the efficient absorption of digested nutrients into the bloodstream and lymphatic system.

Double circulation in humans means blood passes through the heart twice per complete circuit of the body. One circuit (pulmonary) pumps deoxygenated blood to the lungs and back to the heart, while the other (systemic) pumps oxygenated blood to the rest of the body and back to the heart.

Platelets are crucial for blood clotting (coagulation). They initiate the clotting process by releasing factors that lead to the formation of a fibrin mesh, which traps blood cells and seals the wound.

When oxygen supply is insufficient during vigorous exercise, muscle cells switch to anaerobic respiration, producing lactic acid. The accumulation of lactic acid in muscle cells causes pain, cramps, and fatigue.

Bile, produced by the liver and stored in the gallbladder, does not contain enzymes. Its primary role is to emulsify fats in the small intestine, breaking down large fat globules into smaller ones, thereby increasing the surface area for lipase enzymes to act upon.

The primary driving force for water absorption and upward movement in plants is transpiration pull, which is created by the evaporation of water from leaves. Removing leaves (defoliation) eliminates this pull, significantly decreasing the rate of water absorption by the roots.

The C-shaped cartilaginous rings in the trachea provide structural support. They prevent the tracheal walls from collapsing inwards, ensuring that the airway remains open even when there is low air pressure during exhalation.

The proximal convoluted tubule (PCT) is the primary site for selective reabsorption of essential substances such as glucose, amino acids, salts, and a large amount of water from the filtrate back into the blood.

Heparin is a natural anticoagulant produced by the body, mainly in the liver and mast cells. It prevents blood from clotting inside blood vessels, ensuring free blood flow.

The lymphatic system is responsible for draining excess interstitial fluid (tissue fluid) back into the bloodstream and plays a crucial role in immunity. Impairment would lead to fluid accumulation (edema) and a compromised immune system.

The formation of water droplets inside the sealed container indicates the release of water vapor from the plant. This process is known as transpiration, where plants release excess water from their aerial parts.

The small intestine is characterized by its great length (allowing more time for digestion and absorption) and the presence of numerous villi and microvilli, which dramatically increase its internal surface area for efficient absorption of nutrients.

Anaerobic respiration produces significantly less energy (typically 2 ATP molecules) compared to aerobic respiration (around 38 ATP molecules) because glucose is only partially oxidized, meaning it is not completely broken down into carbon dioxide and water.

Stomata are tiny pores on the leaf surface crucial for the exchange of gases (taking in carbon dioxide for photosynthesis and releasing oxygen) and for regulating the rate of water loss through transpiration.

The epiglottis is a flap of cartilage that covers the opening of the trachea (windpipe) during swallowing. If it fails to function correctly, food or liquid can enter the trachea, leading to choking.

The main function of xylem tissue is the long-distance transport of water and dissolved minerals from the roots, where they are absorbed, up to the stems and leaves of the plant.

Wilting occurs when the rate of water loss from the plant, primarily through transpiration, exceeds the rate of water absorption by the roots. During the hottest part of the day, high temperatures and low humidity increase the transpiration rate.

The concentration of dissolved oxygen in water is significantly lower (around 1%) compared to oxygen in the air (around 21%). Therefore, aquatic organisms must breathe faster to obtain sufficient oxygen for their metabolic needs.

The human lungs achieve a large surface area for gas exchange primarily through the presence of millions of tiny air sacs called alveoli. These numerous, thin-walled structures, surrounded by a dense network of blood capillaries, collectively provide an enormous surface area (comparable to a tennis court) for efficient diffusion of oxygen into the blood and carbon dioxide out of it.

Excess amino acids cannot be stored in the body. They undergo deamination in the liver, where the amino group is removed and converted into urea, which is then transported to the kidneys for excretion in urine. The remaining carbon skeleton can be used for energy or converted to glucose or fat.

The left ventricle has thicker and more muscular walls because it is responsible for pumping oxygenated blood at high pressure to the systemic circulation, which supplies blood to all parts of the body, overcoming significant resistance.

Translocation of food (sugars) in phloem is an active process that requires energy (ATP). Sugars are actively loaded into the sieve tubes at the source and unloaded at the sink, creating a pressure gradient for bulk flow.

The symptoms described (jaundice, dark urine) are classic indicators of a problem with the liver. The liver is responsible for processing bilirubin, a yellow pigment formed from the breakdown of red blood cells. Malfunction leads to its accumulation in the body.

Gastric glands, located in the wall of the stomach, secrete gastric juice, which is a mixture of hydrochloric acid, pepsinogen (inactive form of pepsin), and mucus. The hydrochloric acid kills bacteria and provides an acidic medium for pepsin to act, while pepsin digests proteins. Mucus protects the stomach lining from the acidic environment.

Guard cells are specialized epidermal cells that surround each stoma. Their primary role is to regulate the opening and closing of stomata, thereby controlling gas exchange (CO2 intake, O2 release) and the rate of transpiration.

While some water is absorbed in the small intestine along with nutrients, the large intestine's primary function regarding digestive waste is to absorb most of the remaining water from the undigested food, compacting the waste into feces.

Veins carry blood back to the heart, often against gravity and at low pressure. The presence of valves prevents the backflow of blood, ensuring its unidirectional movement towards the heart. Arteries carry blood under high pressure, so valves are not needed.

Artificial kidney (dialysis) works on the principle of diffusion and ultrafiltration. The patient's blood is passed through a dialyzing unit containing a semi-permeable membrane. The unit has dialyzing fluid with the same solute concentration as normal blood, except for nitrogenous wastes. As blood flows, waste products like urea diffuse from the blood into the dialyzing fluid, while essential substances remain in the blood.