The interaction between two living organisms of different species which is beneficial to both but is not obligatory because they can live without each other is known as

Discuss the various types of positive interactions between species.

Which of the following is an example of a defense used by plants against herbivores?
$I.$ Production of caffeine,tannin,quinine
$II.$ More production of non-woody tissues
$III.$ Production of hairs,thorns,spines
$IV.$ Production of hormone-like chemicals that interfere with insect metamorphosis
Select the correct pair.

Barnacles growing on the back of a whale is an example of .........

Moderate grazing in grasslands by herbivores is a/an .....

Flamingos and fish compete in a lake for .......... .