During the discussion in class, Rohan gives a statement that, "A tissue is a group of similar cells performing similar functions". But Rajiv counter argues that, "This is true in case of simple tissues but little different in case of complex tissues". Provide your explanation in view of the discussion in class.

Rohan's statement is correct for simple tissues, because simple tissues are made up of similar types of cells that perform similar functions. For example, parenchyma, collenchyma and sclerenchyma are simple tissues.

Rajiv's counter-argument is also correct because complex tissues are made up of different types of cells that work together to perform a common function. For example, xylem has tracheids, vessels, xylem parenchyma and xylem fibres, which together help in the transport of water and minerals. Similarly, phloem has sieve tubes, companion cells, phloem parenchyma and phloem fibres, which together help in the transport of food.

So, a better explanation is: A tissue is a group of cells that work together to perform a specific function; in simple tissues the cells are similar, while in complex tissues the cells are different but function together.