Which of the following does not lose their nucleus at maturity?

State whether the following statement is true or false:
An individual nerve cell may be up to a metre long.

Differentiate between voluntary and involuntary muscles. Give one example of each type.

$(a)$ Voluntary muscles are also known as skeletal muscles. Justify.
$(b)$ Give two structural characteristics of these voluntary muscles.

Give reasons for the following:
$(i)$ Cells of sclerenchyma tissue have a narrow lumen.
$(ii)$ Branches of a tree move and bend freely in high wind velocity.
$(iii)$ It is difficult to pull out the husk of coconut.

What is the chemical substance that makes the cells of the sclerenchyma hard? Mention where this tissue is likely to be present.