Auxanometer is used to measure:

Example of positive geotropism is

Phytotron is

Growth is measured by a variety of parameters,some of which are an increase in:
$a.$ Dry weight
$b.$ Fresh weight
$c.$ Volume
$d.$ Cell number

Which one of the following has the least influence on cell elongation in a meristem?

Both animals and plants grow. Why do we say that growth and differentiation in plants is open and not so in animals? Does this statement hold true for sponges also?