Micturition is the process by which the urine from the urinary bladder is excreted. As the urine accumulates, the muscular walls of the bladder expand. The walls stimulate the sensory nerves in the bladder, setting up a reflex action. This reflex stimulates the urge to pass out urine. To discharge urine, the urethral sphincter relaxes and the smooth muscles of the bladder contract. This forces the urine out from the bladder. An adult human excretes about 1 – 1.5 litres of urine per day.
Describe the role of liver, lungs and skin in excretion.
What is meant by the term osmoregulation?
Which of the following is not correct?
(a) Robert Brown discovered the cell.
(b) Schleiden and Schwann formulated the cell theory.
(c) Virchow explained that cells are formed from pre-existing cells.
(d) A unicellular organism carries out its life activities within a single cell.
Match the following (a) Cristae (i) Flat membranous sacs in stroma (b) Cisternae (ii) Infoldings in mitochondria (c) Thylakoids (iii) Disc-shaped sacs in Golgi apparatus
New cells generate from (a) bacterial fermentation (b) regeneration of old cells (c) pre-existing cells (d) abiotic materials
What are the steps involved in formation of a root nodule?
Describe the digestive role of chymotrypsin. What two other digestive enzymes of the same category are secreted by its source gland?
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