BIO Biological tissues are typically made up of 98% water. Given that the density of water is 1.0 X 103 kg/m3, estimate the mass of (a) the heart of an adult human; (b) a cell with a diameter of 0.5 µm; (c) a honeybee.

Solution 60P Since, cells contain 98% of water, we can consider the cells are made of water and calculate the mass using the density of water. Step 1 a) The typical volume of human heart is V = 280 cm = 280 × 10 6m . The density of the water is = 1.0 × 10 kg/m 3 Hence the mass of a human heart is m = V = (280 × 10 6 m )(1.0 × 103kg/m ) = 0.280 kg Step 2 b) The volume of a sphere is given by d Where r is the radius of the sphere and is given by r = 2 where d is the diameter of the sphere. Now from the problem we know that d = 0.5 m 0.5 m Therefore the radius of the spherical cell is r == = 0.25 m = 0.25 × 10 6 m 2 2 So the volume of the cell is