question_answer 73)

  Given below are a few statements related to external fertilization. I. The male and female gametes are formed and released, simultaneously. II. Only a few gametes are released into the medium. III. Water is the medium in a majority of organisms exhibiting external fertilization. IV. Offspring formed as a result, of external, fertilization have better chances of survival than those formed inside an organism. Choose the correct statements. (a) III and IV                                       (b) I and III                          (c) II and IV                         (d) I and IV

Answer:

                  (b) External fertilization occurs outside the body of the organism. It takes place inmost aquatic organisms, such as a majority of algae and fishes as well as amphibians .Organisms exhibiting external fertilization release a large number of gametes in the surrounding medium, (e.g., water) in order to enhance the chances of syngamy. A major disadvantage is that the offspring are extremely vulnerable to predators threatening their survival upto adulthood.