Which of the following structures helps in the respiration of lichens?

It is responsible for potato spindle tuber disease.

$D$.$J$. Ivanowsky is famous for the discovery of which of the following?

Lichen is usually cited as an example of 'symbiosis' in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
$A$. Both will survive and grow normally and independent from each other.
$B$. Both will die.
$C$. Algal component will survive while the fungal component will die.
$D$. Fungal component will survive while algal partner will die.
Based on your answer,how do you justify this association as symbiosis?

What is the part labeled '$A$' in the given cross-section of a foliose lichen?

$DNA$ is absent in: