Which of the following statements are incorrect ?
(i) Plant cells have centrioles which are absent in
almost all animal cells.
(ii) Ribosomes are the site of protein synthesis.
(iii) The middle lamella is a layer mainly of calcium
carbonate which holds the different neighbouring
cells together.
(iv) In animal cell, steroidal hormones are synthesized
by smooth endoplasmic reticulum.
Of the above statements
(a) (i) and (iii) (b) (iii) and (iv)
(c) (ii) and (iv) (d) (i) and (iv)
Answer:(a) The centrioles occur in nearly all animal cells, but absent in plant cells with few exceptions such as zoospores of algae, sperm cells of ferns, and motile algae. Middle lamella is a thin, amorphous and cementing layer between two adjacent cells. It is made up of pectates of calcium and magnesium.
