Life Processes - 1

The pulmonary vein is responsible for bringing oxygenated and pure blood into the heart.

When a pair of guard cells surrounding a stoma receives the signal to open the stomatal pore, it is filled with water, thus changing the cell's shape and opening the pore. When guard cells receive a signal to close the stoma. This initiates a loss of water and causes them to shrink and the pore closes. Thus, the correct answer is option C.

Peristalsis is the rhythmic contraction and relaxation of muscles of the alimentary canal that propels the food in downward direction.

Photosynthetic oxygen evolution occurs via the light-dependent oxidation of water. Green plants utilize the light energy to split the water molecule to protons and electrons for photosynthesis. Free oxygen is generated as a by-product of this reaction and is released into the atmosphere.

So, the correct answer is option A.

During heavy exercise, the demand for energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscles cells to fulfil the demand for energy. This anaerobic breakdown of glucose leads to the formation of lactic acid in muscles. The accumulation of lactic acid in muscles leads to muscle cramps. Hence, during heavy exercise, we get cramps in the legs due to the accumulation of Lactic acid.So, the correct answer is 'Lactic acid'.

Nephrons are the basic filtering units of a kidney each kidney poses a large number of nephron approximately 1-1.5 million the main components of a nephron are- glamorous ,women's capsule, a long renal tubule and collecting duct-
Functioning of a nephron - The blood enters the kidney through a long ranal tubal which branches into many capillaries associated with the glamorous.

The main functions of a nephron are:

1.Filtration
2.Ultrafiltration
3. Absorption
4. Reabsorption

• Aerobic respiration first occurs in cytoplasm and then in mitochondria.
• Anaerobic respiration occurs in cytoplasm itself.

The air we exhale contains CO₂. When carbon dioxide is passed through lime water or Ca(OH)₂ then it form calcium carbonate which is white in colour.

Salivary amylase, present in saliva, is the first digestive enzyme that gets mixed with food in the oral cavity during the process of mastication and bolus formation. The digestive enzyme salivary amylase hydrolyzes starch into maltose, malto-triose, dextrin and a small amount of glucose.

The small intestine is made up of duodenum, jejunum, and ileum. It receives the bile from the liver which helps in the breakdown of fats.